2.Frequency, time and phase measurement

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中英对照频谱效率

中英对照频谱效率频谱效率（Spectral efficiency、Spectrum efficiency）是指在数位通信系统中的带宽限制下，能够传送的资料总量。

在有限的波频谱下，物理层通信协议能够达到的使用效率有一定的限度。

➢链路频谱效率数字通信系统的链路频谱效率（Link spectral efficiency）的单位是bit/s/Hz，或(bit/s)/Hz（较少用，但更准确）。

其定义为净比特率（有用信息速率，不包括纠错码）或最大吞吐量除以通信信道或数据链路的带宽（单位：赫兹）。

调制效率定义为净比特率（包括纠错码）除以带宽。

频谱效率通常被用于分析数字调制方式的效率，有时也考虑前向纠错码（forward error correction, FEC）和其他物理层开销。

在后一种情形下，1个“比特”特指一个用户比特，FEC的开销总是不包括在内的。

例1：1kHz带宽中能够传送毎秒1000bit的技术，其频谱效率或调制效率均为1 bit/s/Hz。

例2：网的V.92调制解调器在模拟网上以56,000 bit/s的下行速率和48,000 bit/s的上行速率传输。

经由交换机的滤波，频率限制在300Hz到3,400Hz之间，带宽相应为 3400 − 300 = 3100 Hz 。

频谱效率或调制效率为56,000/3,100 = 18.1 bit/s/Hz（下行）、48,000/3,100 = 15.5 bit/s/Hz（上行）。

使用FEC 的架空调变方式可达到最大的频谱效率能够利用标本化定理来求得，信号的字母表(运算机科学)利用符号数量M来组合、各符号使用 N = log2 M bit来表示。

此情形下频谱效率若不使用编码间干涉的话，无法超过2N bit/s/Hz 的效率。

举例来说，符号种类有8种、每个各有3bit 的话，频谱效率最高不超过6 bit/s/Hz。

在使用前向错误更正编码的情形时频谱效率会降低。

比如说使用1/2编码率的FEC时，编码长度会变为1.5倍，频谱效率会降低50%。

rigiscan检查报告分析

rigiscan检查报告分析RigiScan is a device used to measure nocturnal penile tumescence (NPT) and erectile function in men. It measures and records changes in penile rigidity and circumference throughout the night while a person is asleep. The data collected during a RigiScan examination can provide insights into the quality of nocturnal erections and overall erectile function.A RigiScan report typically includes several parameters that are analyzed to assess erectile function. These parameters may include:1. Nocturnal penile tumescence (NPT) data: This refers to the frequency and duration of spontaneous erections that occur during the night. Normal NPT data would typically show multiple erection episodes throughout the night.2. Rigidity measures: RigiScan measures the rigidity of the penis during erections using the Rigidity Unit (RU). The report may provide information about the average rigidity, maximum rigidity, and the time taken to achieve maximum rigidity. Higher rigidity values generally indicate better erectile function.3. Erectile dysfunction assessment: The RigiScan report may include an assessment of erectile dysfunction (ED) based on the erectile response during the night. The report may classify ED as mild, moderate, or severe based on the severity and duration of NPT-related erectile responses.4. Other parameters: The report may also include information on other parameters such as the number of spontaneous erections, duration of erections, and the time taken to achieve an erection.It's important to note that the interpretation of a RigiScan report should be done by a qualified healthcare professional, typically a urologist or sexual medicine specialist, as they have the expertise to assess the results and provide appropriate recommendations or treatment options based on the findings.。

QuestionnaireandAnswerSheetMECHANICALGENERAL1

Questionnaire and Answer Sheet:MECHANICAL GENERAL 1机械综合11. QuestionWhat is the purpose of a penetrameter or IQI?使用透度计或者IQI （像质计）的目的是什么？AnswerIndicates radiographic sensitivity and quality of the techniques.显示出射线照相术的灵敏度和该技术的质量。

2. QuestionWhat is meant by the term sensitivity with regard to radiography?关于射线照相术的灵敏度的意思是什么？AnswerThe ability of a radiographic technique to reveal defects of a specific size.是指射线照相术技术显示规定尺寸缺陷的能力。

3. QuestionWhat are the limitations of magnetic particle inspection and liquid penetrant inspection?磁粉检验和液体渗透检验的局限性是什么？AnswerM.P. can be used only on ferromagnetic materials to detect surface subsurface discontinuities.L.P. can be used to detect defects open to the surface.Both M.P. and L.P. require surface preparations before testing.磁粉检验仅使用在铁磁性材料上，从而发现表面、近表面的不连续性。

液体渗透能使用在发现表面开口的缺陷上。

毕业设计说明书外文翻译---时间和频率的基本原理

毕业设计说明书英文文献及中文翻译学院：信息与通信工程专业：电子信息科学与技术2011年 6月外文文献原文Fundamentals of Time and Frequency IntroductionTime and frequency standards supply three basic types of information：time-of-day，time interval，and frequency. Time-of-day information is provided in hours，minutes，and seconds，but often also includes the date (month，day，and year). A device that displays or records time-of-day information is called a clock. If a clock is used to label when an event happened，this label is sometimes called a time tag or time stamp. Date and time-of-day can also be used to ensure that events are synchronized，or happen at the same time.Time interval is the duration or elapsed time between two events. The standard unit of time interval is the second(s). However，many engineering applications require the measurement of shorter time intervals，such as milliseconds (1 ms = 10 -3 s) ，microseconds (1 μs = 10 -6 s) ，nanoseconds (1 ns = 10 -9 s) ，and picoseconds (1 ps = 10 -12 s). Time is one of the seven base physical quantities，and the second is one of seven base units defined in the International System of Units (SI). The definitions of many other physical quantities rely upon the definition of the second. The second was once defined based on the earth‟s rotational rate or as a fraction of the tropical year. That changed in 1967 when the era of atomic time keeping formally began. The current definition of the SI second is the duration of 9，192，631，770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom.Frequency is the rate of a repetitive event. If T is the period of a repetitive event，then the frequency f is its reciprocal，1/T. Conversely，the period is the reciprocal of the frequency，T = 1/f. Since the period is a time interval expressed in seconds (s) ，it is easy to see the close relationship between time interval and frequency. Thestandard unit for frequency is the hertz (Hz) ，defined as events or cycles per second. The frequency of electrical signals is often measured in multiples of hertz，including kilohertz (kHz)，megahertz (MHz)，or gigahertz (GHz)，where 1 kHz equals one thousand (103) events per second，1 MHz equals one million (106) events per second，and 1 GHz equals one billion (109) events per second. A device that produces frequency is called an oscillator. The process of setting multiple oscillators to the same frequency is called synchronization.Of course，the three types of time and frequency information are closely related. As mentioned，the standard unit of time interval is the second. By counting seconds，we can determine the date and the time-of-day. And by counting events or cycles per second，we can measure frequency.Time interval and frequency can now be measured with less uncertainty and more resolution than any other physical quantity. Today，the best time and frequency standards can realize the SI second with uncertainties of ≈1×10-15.Physical realizations of the other base SI units have much larger uncertainties.Coordinated Universal Time (UTC)The world‟s major metrology laboratories routinely measure their time and frequency standards and send the measurement data to the Bureau International des Poids et Measures (BIPM) in Sevres，France. The BIPM averages data collected from more than 200 atomic time and frequency standards located at more than 40 laboratories，including the National Institute of Standards and Technology (NIST). As a result of this averaging，the BIPM generates two time scales，International Atomic Time (TAI)，and Coordinated Universal Time (UTC). These time scales realize the SI second as closely as possible.UTC runs at the same frequency as TAI. However，it differs from TAI by an integral number of seconds. This difference increases when leap seconds occur. Whennecessary，leap seconds are added to UTC on either June 30 or December 31. The purpose of adding leap seconds is to keep atomic time (UTC) within ±0.9 s of an older time scale called UT1，which is based on the rotational rate of the earth. Leap seconds have been added to UTC at a rate of slightly less than once per year，beginning in 1972.Keep in mind that the BIPM maintains TAI and UTC as ……paper‟‟ time scales. The major metrology laboratories use the published data from the BIPM to steer their clocks and oscillators and generate real-time versions of UTC. Many of these laboratories distribute their versions of UTC via radio signals which section 17.4 are discussed in.You can think of UTC as the ultimate standard for time-of-day，time interval，and frequency. Clocks synchronized to UTC display the same hour minute，and second all over the world (and remain within one second of UT1). Oscillators simonized to UTC generate signals that serve as reference standards for time interval and frequency.Time and Frequency MeasurementTime and frequency measurements follow the conventions used in other areas of metrology. The frequency standard or clock being measured is called the device under test (DUT). A measurement compares the DUT to a standard or reference. The standard should outperform the DUT by a specified ratio，called the test uncertainty ratio (TUR). Ideally，the TUR should be 10：1 or higher. The higher the ratio，the less averaging is required to get valid measurement results.The test signal for time measurements is usually a pulse that occurs once per second (1 ps). The pulse width and polarity varies from device to device，but TTL levels are commonly used. The test signal for frequency measurements is usually at a frequency of 1 MHz or higher，with 5 or 10 MHz being common. Frequency signalsare usually sine waves，but can also be pulses or square waves if the frequency signal is an oscillating sine wave. This signal produces one cycle (360∞or 2πradians of phase) in one period. The signal amplitude is expressed in volts，and must be compatible with the measuring instrument. If the amplitude is too small，it might not be able to drive the measuring instrument. If the amplitude is too large，the signal must be attenuated to prevent overdriving the measuring instrument.This section examines the two main specifications of time and frequency measurements—accuracy and stability. It also discusses some instruments used to measure time and frequency.AccuracyAccuracy is the degree of conformity of a measured or calculated value to its definition. Accuracy is related to the offset from an ideal value. For example，time offset is the difference between a measured on-time pulse and an ideal on-time pulse that coincides exactly with UTC. Frequency offset is the difference between a measured frequency and an ideal frequency with zero uncertainty. This ideal frequency is called the nominal frequency.Time offset is usually measured with a time interval counter (TIC). A TIC has inputs for two signals. One signal starts the counter and the other signal stops it. The time interval between the start and stop signals is measured by counting cycles from the time base oscillator. The resolution of a low cost TIC is limited to the period of its time base. For example，a TIC with a 10-MHz time base oscillator would have a resolution of 100 ns. More elaborate Tics use interpolation schemes to detect parts of a time base cycle and have much higher resolution—1 ns resolution is commonplace，and 20 ps resolution is available.Frequency offset can be measured in either the frequency domain or time domain.A simple frequency domain measurement involves directly counting and displaying thefrequency output of the DUT with a frequency counter. The reference for this measuremen t is either the counter‟s internal time base oscillator ， or an external time base. The counter‟s resolution ， or the number of digits it can display ， limits its ability to measure frequency offset. For example ， a 9-digit frequency counter can detect a frequency offset no smaller than 0.1 Hz at 10 MHz (1×10-8). The frequency offset is determined asmeasure nominal nominal(f -f )f= f Where f measur is the reading from the frequency counter ， and f nominal is the frequency labeled on the oscillator‟s nameplate ， or specified output frequency.Frequency offset measurements in the time domain involve a phase comparison between the DUT and the reference. A simple phase comparison can be made with an oscilloscope. The oscilloscope will display two sine waves. The top sine wave represents a signal from the DUT ， and the bottom sine wave represents a signal from the reference. If the two frequencies were exactly the same ， their phase relationship would not change and both would appear to be stationary on the oscilloscope display. Since the two frequencies are not exactly the same ， the reference appears to be stationary and the DUT signal moves. By measuring the rate of motion of the DUT signal we can determine its frequency offset. Vertical lines have been drawn through the points where each sine wave passes through zero. The bottom of the figure shows bars whose width represents the phase difference between the signals. In this case the phase difference is increasing ， indicating that the DUT is lower in frequency than the reference.Measuring high accuracy signals with an oscilloscope is impractical ， since the phase relationship between signals changes very slowly and the resolution of the oscilloscope display is limited. More precise phase comparisons can be made with a TIC. If the two input signals have the same frequency ， the time interval will notchange. If the two signals have different frequencies ， the time interval wills change ， and the rate of change is the frequency offset. The resolution of a TIC determines the smallest frequency change that it can detect without averaging. For example ， a low cost TIC with a single-shot resolution of 100 ns can detect frequency changes of 1 × 10 -7 in 1 s. The current limit for TIC resolution is about 20 ps ， which means that a frequency change of 2 ×10 -11 can be detected in 1 s. Averaging over longer intervals can improve the resolution to <1 ps in some units [6].Since standard frequencies like 5 or 10 MHz are not practical to measure with a TIC ， frequency dividers or frequency mixers are used to convert the test frequency to a lower frequency. Divider systems are simpler and more versatile ， since they can be easily built or programmed to accommodate different frequencies. Mixer systems are more expensive ， require more hardware including an additional reference oscillator ， and can often measure only one input frequency (e.g.， 10 MHz) ， but they have a higher signal-to-noise ratio than divider systems.If dividers are used ， measurements are made from the TIC ， but instead of using these measurements directly ， we determine the rate of change from reading to reading. This rate of change is called the phase deviation. We can estimate frequency offset as follows ：tf=T ∆Where △t is the amount of phase deviation ， and T is the measurement period. To illustrate ， consider a measurement of +1 μs of phase deviation over a measurement period of 24 h. The unit used for measurement period (h) must be converted to the unit used for phase deviation (μs). The equation becomes11t 1us f offset ===1.1610T 86400000000us -∆⨯（），，，As shown，a device that accumulates 1 μs of phase deviation/day has a frequency offset of 1.16 × 10 -11 with respect to the reference. This simple example requires only two time interval readings to be made，and △t is simply the difference between the two readings. Often，multiple readings are taken and the frequency offset is estimated by using least squares linear regression on the data set，and obtaining △t from the slope of the least squares line. This information is usually presented as a phase plot，as shown in Fig. 17.6. The device under test is high in frequency by exactly 1×10 -9，as indicated by a phase deviation of 1 ns/s.Dimensionless frequency offset values can be converted to units of frequency (Hz) if the nominal frequency is known. To illustrate this，consider an oscillator with a nominal frequency of 5 MHz and a frequency offset of +1.16 ′10 -11. To find the frequency offset in hertz，multiply the nominal frequency by the offset：(5 ×106) (+1.16×10 -11) = 5.80×10 -5 =+0.0000580 Hz Then，add the offset to the nominal frequency to get the actual frequency：5，000，000 Hz + 0.0000580 Hz = 5，000，000.0000580 HzStabilityStability indicates how well an oscillator can produce the same time or frequency offset over a given time interval. It doesn‟t indicate whether the time or frequency is “right” or “wrong，” but only whether it stays the same. In contrast，accuracy indicates how well an oscillator has been set on time or on frequency. To understand this difference，consider that a stable oscillator that needs adjustment might produce a frequency with a large offset. Or，an unstable oscillator that was just adjusted might temporarily produce a frequency near its nominal value. Figure 17.7 shows the relationship between accuracy and stability.Stability is defined as the statistical estimate of the frequency or time fluctuations of a signal over a given time interval. These fluctuations are measured with respect to a mean frequency or time offset.Short-term stability usually refers to fluctuations over intervals less than 100 s. Long-term stability can refer to measurement intervals greater than 100 s ， but usually refers to periods longer than 1 day.Stability estimates can be made in either the frequency domain or time domain ， and can be calculated from a set of either frequency offset or time interval measurements. In some fields of measurement ， stability is estimated by taking the standard deviation of the data set. However ， standard deviation only works with stationary data ， where the results are time independent ， and the noise is white ， meaning that it is evenly distributed across the frequency band of the measurement. Oscillator data is usually no stationary ， since it contains time dependent noise contributed by the frequency offset. With stationary data ， the mean and standard deviation will converge to particular values as more measurements are made. With no stationary data ， the mean and standard deviation never converge to any particular values. Instead ， there is a moving mean that changes each time we add a measurement. For these reasons ， a non-classical statistic is often used to estimate stability in the time domain. This statistic is sometimes called the Allan variance ， but since it is the square root of the variance ， its proper name is the Allan deviation. The equation for the Allan deviation (σy (τ)) is2y i+i y -y στ1（（） where y i is a set of frequency offset measurements containing y 1， y 2， y 3， and so on ， M is the number of values in the y i series ， and the data are equally spaced in segments τ seconds long. Or2x i+1i -2x +x στi+2（（x ） Where x i is a set of phase measurements in time units containing x 1， x 2， x 3，and so on，N is the number of values in the xi series，and the data are equally spaced in segments τ seconds long. Note that while standard deviation subtracts the mean from each measurement before squaring their summation，the Allan deviation subtracts the previous data point. This differencing of successive data points removes the time dependent noise contributed by the frequency offset. An Allan deviation graph is shown in Fig. 17.8. It shows the stability of the device improving as the averaging period (τ) gets longer，since some noise types can be removed by averaging. At some point，however，more averaging no longer improves the results. This point is called the noise floor，or the point where the remaining noise consists of no stationary processes such as flicker noise or random walk. The device measured in Fig. 17.8 has a noise floor of ~5 × 10 -11at τ = 100 s.Practically speaking，a frequency stability graph also tells us how long we need to average to get rid of the noise contributed by the reference and the measurement system. The noise floor provides some indication of the amount of averaging required to obtain a TUR high enough to show us the true frequency where xi is a set of phase measurements in time units containing x1，x2，x3，and so on is the number of values in the xi series，and the data are equally s paced in segments τ seconds long. Note that while standard deviation subtracts the mean from each measurement before squaring their summation，the Allan deviation subtracts the previous data point. This differencing of successive data points removes the time dependent noise contributed by the frequency offset. An Allan deviation graph is shown in Fig. 17.8. It shows the stability of the device improving as the averaging period (τ) gets longer，since some noise types can be removed by averaging. At some point，however，more averaging no longer improves the results. This point is called the noise floor or the point where the remaining noise consists of no stationary processes such as flicker noise or random walk. The device measured in Fig. 17.8 has a noise floor of ~5 × 10 -11at τ = 100 s.Practically speaking，a frequency stability graph also tells us how long we needto average to get rid of the noise contributed by the reference and the measurement system. The noise floor provides some indication of the amount of averaging required to obtain a TUR high enough to show us the true frequency offset of the DUT. If the DUT is an atomic oscillator (section 17.4) and the reference is a radio controlled transfer standard (section 17.5) we might have to average for 24 h or longer to have confidence in the measurement result. Five noise types are commonly discussed in the time and frequency literature：white phase，flicker phase，white frequency，flicker frequency，and random walk frequency. The slope of the Allan deviation line can help identify the amount of averaging needed to remove these noise types (Fig. 17.9). The first type of noise to be removed by averaging is phase noise，or the rapid，random fluctuations in the phase of the signal. Ideally，only the device under test would contribute phase noise to the measurement，but in practice，some phase noise from the measurement system and reference needs to be removed through averaging. Note that the Allan deviation does not distinguish between white phase noise and flicker phase noise. Table 17.2 shows several other statistics used to estimate stability and identify noise types for various applications.Identifying and eliminating sources of oscillator noise can be a complex subject，but plotting the first order differences of a set of time domain measurements can provide a basic understanding of how noise is removed by averaging. Figure 17.10 was made using a segment of the data from the stability graph in Fig. 17.8. It shows phase plots dominated by white phase noise (1 s averaging) ，white frequency noise (64 s averages) ，flicker frequency noise (256 s averages)，and random walk frequency (1024 s averages). Note that the white phase noise plot has a 2 ns scale，and the other plots use a 100 ps scale.外文文献中文翻译时间和频率的基本原理介绍时间和频率标准应用于三种基本信息类型：时间，时间间隔和频率.时间信息有小时，分，秒.通常还包括日期(年，月，日).用来显示和记录时间的器件叫做钟表，如果钟表标记了一件事的发生，那么这个标记叫做时间标签或时间印记.日期和时间能确保事情的同步或同时发生.时间间隔是两个事件持续或断续的时间，时间间隔的标准单位是秒，然而许多工程上应用要求更短的时间间隔，像毫秒，微秒，纳秒，和皮秒，时间是七个基本物理量之一，并且秒是国际单位体制制定七个基本单位之一.许多区其他物理量的定义是依靠秒而定义的.秒曾经定义根据地球回转率.原子时代正式开始在1967年目前SI定义秒为：秒是铯133原子(Cs133)基态的两个超精细能级之间跃迁所对应的辐射的9，192，631，770个周期所持续的时间。

ABCofTime and Frequency Analysis

®Application NoteABC of Time &Frequency AnalysisPM6681 Timer/Counter/Analyzerwith TimeView ™softwareOscilloscopes areused to analyze changes in amplitude, but not changes in frequency. The traditionalmeasurement tool for analyzing the frequency content of a signal is the Spectrum Analyzer. This can find static (fixed) frequencies or give a statistical (averaged) picture of dynamic (changing)frequencies. To view frequencies which are changing, a third type of tool is needed: the Time &Frequency Analyzer (TFA),sometimes also called Modulation Domain Analyzer.The three basic signal analysis tools.To analyze all the dynamic characteristics of a signal, threeBackgroundWhy are oscilloscopes such popular instruments? They do not measure voltages very accurately. Even the cheapest DVM can produce more accurate results whenmeasuring static voltages. Y es,that's it: oscilloscopes let you view dynamic voltages,voltages that vary over time.This ability makesoscilloscopes ideally suited for viewing and analyzing most types of dynamic signals. And the absence of this dynamic signal view limits theapplications of voltmeters to the checking and calibration of static signals.Dynamic signal analysis of amplitude and frequencyAmplitude and frequency content are the two most important characteristics of any signal.basic tools are needed:•Oscilloscope•Spectrum or FFT Analyzer •Time & Frequency Analyzer An oscilloscope lets you view voltage variations over time, a Spectrum or FFT Analyzer lets you view voltage distribution over frequency, and a TFA lets youview frequency variation over time (see Fig. 1).All three tools are needed for a complete signal analysis that covers all three axes: Voltage,Frequency and TimeFig. 1 A sinusodial signal withsquarewave frequency modulation as shown on an oscilloscope (V vs. t),a spectrum analyzer (V vs. f) and a TFA (f vs. t).All these instruments are needed for a complete picture of the signal.The TimeView Time &Frequency Analyzer from Fluke consists of three parts:•Fast sampling front-end (PM 6681)•Standard PC with GPIB interface•TimeView control and analysis SWThe signal to be characterized is connected to the front-end input (PM 6681 timer/counter/-analyzer). All setting controlsare made from the PC. Graphscan be printed on the PCprinter, and settings and results are stored as ASCII files, thatcan easily be imported intovarious programs for detailedanalysis (e.g. EXCELspreadsheet).Capturing single-shot events (free-run capture)Single-shot events occur justonce. Or the repetition rate may be so low that you only want to measure on one cycle (e.g.temperature cycling ofoscillators). To characterizethe PM 6681 front-end makes repeated frequencymeasurements that are stored in its internal memory.Sample rateThere is a "dead-time" between measurements of 120µs (see Fig.2). With a Measuring Time MT,the sample rate for eachfrequency measurement is:Sample rate = 1/(MT+120 µs)An MT of 100 µs (TimeView default value) means that TimeView will take frequency samples (0 ... 4.5 GHz), with 6-7digits resolution, every 220 µsor approx. 4500 times/s.Time-stamping PM 6681 will "time-stamp"each measurement in a block.,by means of a separate time-stamp clock (125ns resolution).The time given by this clock is read and stored together with the start of all subsequent measurements.When data capture is finished,the values and the corresponding time-stamps are transferred to the PC as a two-dimensional array, andTimeView handles the display and analysis. In this way TimeView knows both theactual measurement values and the time at which the measurement was made.The time-stamping feature is especially important for non-continuous signals such as when measuring frequency in bursts, or the pulsewidth of random pulses.Capturing repetitive events (repetitive sampling)Even though free-running capture has a sample rate of well over 8000 values/s, this is not enough in someapplications. Consider for example the measurement of the output settling time of a VCO or a synthesizer. Here you could expect settling times of a few microseconds. To measure this,you need to improve the time scale, so it corresponds toFig. 3 Free-running frequency samplesfrom a stable signal source. The diagram shows frequency vs. time.Fig. 4Using repetitive sampling,many measurements are made at fairly long intervalsand put together to show a fast frequency transition. Each measurement can be delayed down to 100 ns with respect to the previous measurement.Fig. 5Repetitive sampling of a fast-changing frequency output from a UHF VCO.millions of measurements/s. TimeView does this on periodic repetitive events, in a way called repetitive sampling.With this capture method, TimeView measures not once but several times in subsequent cycles. Each measurement is somewhat delayed in the cycle, with respect to the previous measurement. When enough samples are taken, these are put together to show a picture of the fast frequency transient (see Fig. 4).The delay between subsequent measurements can be set in steps down to 100ns. This corresponds to a virtual sampling rate of 10 MS/s. As with repetitive sampling in a DSO, there must be either an external synchronization signal or a unique trigger pointsomewhere in the signal.An example is given in Fig. 5, which shows the frequency response of a VCO. The VCO is controlled via a repetitive pulse with a fast risetime. The input voltage toggles between two levels (high/low), and consequently the output frequency should switch between two frequency values (high/low frequency). The actual frequency response (f vs.t) is recorded by TimeView's repetitive sampling. In the graph, cursor measurements show that the frequency swing is approx. 29 MHz (from 433 to 462 MHz) and the "risetime" between cursor positions is 10.7µs.Viewing frequencies that vary with timeThere is a great variety of frequency sources. In some, the frequency is rock-stable, while in others the output frequency varies strongly. Examples of varying frequencies are found in frequency hopping communication. Fig. 6 shows a military frequency agile communication carrier, with pseudorandom frequencychanges every 7ms. Thepurpose of this rapid change ofcarrier frequency is of course toprevent "the enemy" fromlistening.Another example is thefrequency hopping in spread-spectrum communication, foundfor example in noisy industrialenvironments or in wirelessLANs. Here, the purpose is toprovide better-qualitycommunication with lessinterruptions.Yet other examples of varyingfrequency are various frequencysweep signals. These are foundin LF audio testing of consumerelectronics equipment, as wellas in very high-frequency radar"chirps".Fig. 7 shows an example of afrequency sweep from 100 to200kHz, made by a modernfunction generator. This generatoruses digital technology tosynthesize the output frequency.This is why the frequency ischanging in 20 discrete stepsduring the sweep period. An old-fashioned analog sweepgenerator would give a straightline instead, as shown in Fig. 8.Needless to say, thevisualization of frequencies thatchange over time can only bemade by a TFA, and not by anoscilloscope or a spectrumanalyzer.Measuring jitter andfrequency noiseIn today’s computer and digitaltelecommunications systems, itis more essential than everbefore to keep system jitterunder control. But what is jitter?Jitter is the cycle-to-cyclevariations of a periodic event;be it period, pulsewidth or timeinterval variations. Examples areperiod variations of a computerclock oscillator or clock-to-datajitter in a communicationssystem. A large amount of jittercan sometimes be detected onanalog scopes, and is seen forexample as a fuzzy edge of apulse (see Fig. 9).To measure the jitter, you needto do a lot of single pulsewidthmeasurements, and statisticallyprocess the samples to get themax., min. and standarddeviation values from thesamples. The ∆(max.-min.) iscalled the peak-to-peak jitter,but normally the most importantmeasure is the RMS jitter(standard deviation).Fig. 6An example of the use offrequency hopping is in militaryfrequency agile communication.Fig. 8 A frequency sweep made by ananalog generator.Fig. 7 A frequency sweep made by adigital synthesized generator.Fig. 9Jitter can sometimes bedetected,but not measured,using an oscilloscope.An oscilloscope can indicate peak-to-peak jitter but never RMS jitter, whereas TimeView can accurately calculate both types of jitter, and can also display the distribution of the actual measurements in a distribution histogram. Such a histogram may help to reveal the "nature of jitter". A random jitter gives a Gaussian distribution, like the example shown in Fig. 10.Jitter caused by a sine modulation gives a histogram that looks like a bathtub, as in Fig. 11.Jitter caused by a squarewave modulation, on the other hand, gives a histogram with two distinct bars at the maximum or minimum values (see Fig. 12). Measuring frequency modulationA frequency modulated (FM) signal is difficult to characterize with a normal oscilloscope. The frequency varies, and therefore the period is also changing. You cannot get stable triggering, and figuring out the nature of the signal turns into guesswork. TimeView and other TFAs can characterize FM easily. Simplybecause a TFA displaysfrequency that varies over time,and that is exactly what FM isall about.A representation of a frequencymodulated carrier in a frequencyvs. time graph is shown in Fig.13.From Fig. 13, you can quicklyconclude that the carrier isapprox. 10MHz, with afrequency deviation of approx.2% (0.2MHz). By looking at thetime axis, you can see that themodulation is periodic andsinusoidal, with a frequency ofapprox. 50kHz µ20 (smodulation cycle). So, at onequick glance, we have anindication of all three importantfrequencies in an FM signal:•Carrier frequency f c•Frequency deviation f dev•Modulation frequency f modFFT analysisTo analyze the modulation inmore detail, you can use thebuilt-in FFT function. Whenapplied to the “frequency vs.time” signal shown in Fig.13,the result will be a “frequencyvs. frequency” graph as shownin Fig. 14.Just as a "normal" FFT operationon a voltage vs. time graph willshow the spectral content of theoriginal signal, the FFT graphshows the spectral content ofthe frequency vs. time graph.Fig. 14 shows the revealedmodulation frequencies alongthe X axis, just as in a "normal"FFT on voltage vs. time. Alongthe Y axis we find the carrierand the frequency deviationsfrom the carrier caused bymodulation.In Fig. 14 you find two cursors,shaped as an "X". The leftcursor tells us that the carrier is10MHz. The right cursor showsthat the modulation frequency is50kHz, causing a deviation ofthe carrier of 250kHz.The statistical distributionhistogram can also give valuableinformation about themodulation (see Fig. 15). Fromthe shape of the distributionhistogram, we can conclude thatthe modulation is sinusodial(bathtub shape). We can alsoread the maximum frequencydeviations, as well as the carrierfrequency (average frequencyover an integral number ofmodulation cycles).Finding very small unwantedFig. 10Random jitter gives a Gaussian distribution.Fig. 11Jitter caused by sinusodialfrequency modulation gives adistribution like a "bathtub".Fig. 12Jitter caused by a squarewavefrequency modulation gives a"2-bar" distribution.Fig. 13FM as shown in a frequency vs.time graph:the "Frequencyscope".Fig. 14The FFT function reveals carrier,modulation frequency anddeviation.Fig. 15The histogram of frequency vs.time data shows that themodulating signal is sinusodial.modulation sourcesTimeView is an excellent tool for frequency stability analysis,and an ideal complement to a spectrum analyzer, whose strength is amplitude stability analysis.Furthermore TimeView can be used for troubleshooting designs in order to track down thecauses of noise or interference.Look at Fig. 16, which shows the output frequency from a pulse generator, with a certain amount of jitter. The jitter appears to be of a random nature (see the distribution histogram in Fig. 17).Fig. 18 shows that there is a dominant 100Hz modulation source, i.e. the power supply is causing FM on the output signal.Fig. 16Frequency vs. time from apulse generator.Fig. 17The histogram of frequencyvs. time data indicates random noise.Fig. 18The FFT of frequency vs. timedata shows that a 100 Hz modulation source is causingthe noise.®Fluke CorporationP.O. Box 9090, Everett, WA 98206 Fluke Europe B.V.P.O. Box 1186,5602 BD Eindhoven,The NetherlandsFor more information call:In the U.S.A.: (800) 443-5853or Fax: (425) 356-5116In Europe/M-East:+31 (0)40 2 678 200or Fax: +31 (0)40 2 678 222In Canada: (905) 890-7600or Fax: (905) 890-6866From other countries:+1(425) 356-5500or Fax: +1 (425) 356-5116Web access: ©Copyright 1998 Fluke Corporation.All rights reserved.。

2.Phase and frequency error Test SOP

Frequency error and phase error Test1.Test Purpose:The frequency error is the difference in frequency, after adjustment for the effect of the modulation and phase error, between the RF transmission from the MS and either the RF transmission from the BS; or the nominal frequency for the ARFCN used.The phase error is the difference in phase, after adjustment for the effect of the frequency error, between the RF transmission from the MS and the theoretical transmission according to the intended modulation.To verify that the frequency error and phase error of the MS under test conditions are within conformance test specification.2.Instrument for Test:1.Universal Radio Communication Tester CMU 200 or Agilent8960.2.DC Power supply Agilent E3631A or E3642A.3.Test Condition:Temperature Supple V oltageNTC 25℃ 3.8 V oltETC (L) -20℃ 3.4 V oltETC (H) +60℃ 4.2 V olt4. Test Structure:5. Test Method:I. Manual Settings:(1) Turn on the power of Agilent 8960 and power supply, wait for at least 15 minutes.(2) Finish the connection of test structure.(3) Set the power supply voltage to test condition. (4)Press(5) Set the compensation loss values:(6) Set BCH parameters:(7)Set TCH Parameters:RF IN/OUT AmptedOffset Setup BCH Parameter Cell PowerCell BandBroadcast ChanSet BCH Cell PowerSet BCH Cell BandSet BCH Broadcast ChannelTCH Parameter Traffic Band Traffic Chan Set TCH Cell BandSet TCH Cell Channel(8) Set IMEI number: The number is ¡001011234567890¡ or ¡001010123456789¡.(9) Establish a call connection:SeePressPick up See (10) M easure TX Power of DUT:OriginatePhase & Frequency Error Active Cell Idle Active Cell Alerting Active CellConnectPhase & Freq.SetupSet some detailsChange. ViewChoose number or graphII. Software Settings:(1) Power sweep method_TX : You can set the PCL(power control level)which you want to test and can select ¡all power level sweep¡ or ¡user defined¡. If you select ¡user defined¡, you should set the number of PCL you want to test and it¡s corresponding PCL values in four supported bands.(2) Channel sweep method_TX : You can set the TCH(Traffic channel)which you want to test and can select ¡all traffic channel sweep¡ or ¡user defined¡. If you select ¡user defined¡, you should set the number of TCH you want to test and it¡s corresponding TCH values in four supported bands.6. Test Specification:(1) For all measured bursts, the frequency error shall be less than 0.1 ppm.(2) For all measured bursts, the RMS phase error shall not exceed 5 degrees.(3) For all measured bursts, each individual phase error shall not exceed 20 degrees.7.Notice:You must check the following items before test:(1)Compensation loss value of each path at each tested frequency iscorrect.(2)It is recommended that using a 3dB attenuator between the instrumentand the DUT to eliminate the mismatch effect.(3)If you use auto test program to process this test, you must ensure thatthe GPIB address settings of the instrument and the test program are the same.。

EM266(DT266) SERIES DIGITAL CLAMP METER 说明书

OWNERS MANUALRead this owners manual thoroughly before useEM266(DT266) SERIES DIGITAL CLAMP METERWARRANTYThis instrument is warranted to be free from defects in material and workmanship for a period of one year. Any instrument found defective within one year from the delivery date and returned to the factory with transportation charges prepaid, will be repaired, adjusted, or replaced at no charge to the original purchaser. This warranty does not cover expandable items such as battery.If the defect has been caused by a misuse or abnormal operating conditions, the repair will be billed at a nominal cost.SAFETY INFORMATIONThe digital multimeter has been designed according to IEC-61010 concerning electronic measuring instruments with a measurement category (CAT II ) and pollution degree 2.ELECTRICAL SYMBOLSAlternating CurrentDirect CurrentCaution, risk of danger, refer to the operating manualbefore use.Caution, risk of electric shock.Earth (ground) TerminalFuseConforms to European Union directivesThe equipment is protected throughout by doubleinsulation or reinforced insulation.A WARNINGTo avoid possible electric shock or personal injury, follow these guidelines:• Do not use the meter if it is damaged. Before you use the meter, inspect the case. Pay particular attention to the insulationsurrounding the connectors.• Inspect the test leads for damaged insulation or exposed metal.Check the test leads for continuity. Replace damaged test leads before you use the meter.• Do not use the meter if it operates abnormally. Protection may be impaired. When in doubt, have the meter serviced.• Do not operate the meter around explosive gas, vapor, or dust. • To avoid damages to the instrument, do not exceed the maximum limits of the input values shown on the meter.• Before use, verify the meter's operation by measuring a known voltage.• When servicing the meter, use only specified replacement parts. • Use with caution when working above 30V AC RMS, 42V peak, or 60V DC. Such voltages pose a shock hazard.• When using the probes, keep your fingers behind the finger guards on the probes.• Connect the common test lead before you connect the live test lead. When you disconnect test leads, disconnect the live test lead first.• Remove the test leads from the meter before you open the battery door.• Do not operate the meter with the battery door or portions of thecover removed or loosened.•To avoid false readings, which could lead to possible electric shock or personal injury, replace the batteries as soon as the low battery indicator (" ") appears.•When an input terminal is connected to dangerous live potential it is to be noted that this potential at all other terminals can occur! •After you press the Data Hold button to enter Data Hold mode, caution must be used because hazardous voltage may be present. •CATII-Measurement Category II is for measurements performed on circuits directly connected to low voltage installation.(Examples are measurements on household appliances, portable tools and similar equipments.) Do not use the meter formeasurements within Measurement Categories III and IV.CAUTIONTo avoid possible damage to the meter or to the equipment under test, follow these guidelines:•Disconnect circuit power and discharge all capacitors beforetesting resistance, insulation resistance, continuity or diode. •Use the proper terminals, function, and range for your easurements. •Never measure current while the test leads are inserted into the input jacks.•Before rotating the range switch to change functions, disconnect test leads from the circuit under test.•Remove test leads from the meter before opening the meter case.FRONT PANEL DESCRIPTION1. Transformer JawsPick up the AC current flowing through the conductor.2. "DATA HOLD" ButtonPress this button to hold the present reading on the display, press again to release the display.For model 260D, this button is used for holding peak.3. Functio n / Range Switc hFunction / Range switch for selecting measuremen t functio n and range.4. Displa y3 1/2 digits LCD, Max. reading 1999.5. Drop－proof Wrist Strap:Prevent the instrumen t from slipping off the hand while in use.6. "EXT" Jac kPlug-in connecto r for the banana plug "EXT" from the extensional insulation resistance tester unit.7. "COM" Jac kPlug－in connecto r for the black test lead while measuring voltage, resistanc e and continuity; and for connectin g the banana plug "COM" from the insulation tester unit while measuring insulation resistance.8. V/ΩInput Jac kPlug－i n connecto r for the red test lead while measuring voltage, resistanc e and continuity; and for connectin g the banana plug "V/Ω" from the insulation tester unit while measuring insulation resistance.9. Trigge rPress the level to open the transforme r jaws; when the finger pressing on the level is released, the jaws will close again.MODEL S AND FUNCTIONSACV ACA DCV ΩInsulationTEM PF200mV200V750V20A200A1000A200mV2V20V200V1000V200Ω2kΩ20kΩ200kΩ2MΩ20MΩ－2000MΩ°C, °F2kHz1mA, 2.8V<50Ω266********266C***************266C+****************260D*****************266F*****************266F T***************INTRODUCTIONThe meter is a portable, 3-1/2 digits LCD clamp meter with insulation test function (with optional 500V insulation tester unit), designed for being used by electricians, technicians, serviceman and hobbyists who need an instrument that is accurate, reliable, and always ready for use. It is powered by a standard 9V battery, and can provide150-200 operating hours, which depends on the type of battery and using conditions. It has rugged structure design, good feeling held in operator's hand and convenient use.TECHNICAL SPECIFICATIONSThe following specifications assume a l-year calibration cycle and operating conditions of temperature scale of 18°C to 28°C (64°F to 82°F) with relative humidity up to 80% unless otherwise noted. Accuracy specifications take the form of:± [(% of Reading)+(Number of Least Significant Digits)]Range 20A 200A1000A Resolution10mA100mA1AAccuracy(50Hz - 60Hz)+ (2.5% + 8)+ (2.5% + 5)+ (2.5% + 5) for 800A and belowIf >800A, the reading is only for reference.AC CurrentFrequency response: 50~60HzIndication: Average (rms of sine wave) Overload protection: 1200A within 60seconds, Jaw opening: 2"(5cm)Frequency range: 45 - 400Hz I nput impedance: 9MΩ Indication: Average (rms of sine wave) Overload protection: 200mV range: 250V AC;the other ranges: 750V rms ACOverload protection: 200mV range: 250V AC;the other ranges: 1000V DC/AC peak. Input impedance: 9MΩInsulation Test (with optional 500V insulation tester unit)AC VoltageDC VoltageRange 20MΩ 2000MΩResolution 10kΩ 1MΩAccuracy +(2% + 2 )500MΩ: +(4% + 2) >500MΩ: +(5%+ 2)Range 200mV 200V 750VResolution 0.1mV 100mV 1VAccuracy +(1.2% + 5) +(2.0% + 5)Range 200mV 2V 20V 200V 1000V| Resolution0.1mV 1mV 10mV 100mV1VAccuracy+(0.8% + 3) +(1.2%+ 5)ResistanceUse K type thermocoupleNote:1. Accuracy does not include error of the thermocouple probe.2. Accuracy specification assumes ambient temperature is stableto ±1°C. For ambient temperature changes of ±5ic, ratedaccuracy applies after 1 hour.Range 2 kHz Resolution1HzAccuracy+(1.5%+ 5)Range 200Ω 2kΩ 20 kΩ 200 kΩ 2MΩ Resolution0.1Ω1Ω10Ω100Ω1kΩAccuracy+(1.2% + 5)+(1.0% +3)+(1.5%+ 5)Range 0°C - 750°C 32°F~1382°F Resolution1°C1°FAccuracy0^-400^: ±(1%+5)400r~750lC: ±(2%+5)32T-752T: ±(1%+9)752T-1382T: ±(2%+9)TemperatureOverload protection: 250V rms ACDiode and Continuity TestGENERAL SPECIFICATIONSDisplay: 3 1/2-digit LCD, with a max. reading of 1999Overrange Indication: only figure" 1 " displayed on the LCD Negative Polarity Indication: " - " displayed automatically Sampling Rate: about 2-3 times/secOperating Temperature: 0°C~40°C, <75%RHStorage Temperature: -10°C~50°C, <85%RHBattery: 9V, 6F22 or equivalentLow Battery Indication: " " shown on the displayDimensions: 240 X 102 X 47mmWeight: about 300g (including battery) 10Range DescriptionThe approx. forward voltage drop of the diode wil Ibe displayed on the LCD.When the resistance is less than about 50Ω, the built-inbuzzerwill sound.OPERATING INSTRUCTIO NAC Curren t Measuremen t1. Make sure the "Data Hold" switch is not pressed.2. Set the Function/Rang e switch to the desired ACA range.3. Press the trigge r to open the transforme r jaws and clamp oneconducto r only. It is impossible to make measurement s when two or three conductor s are clamped at the same time.4. The value displayed on the LCD is the AC current flowing throug hthe conductor.Insulatio n Resistanc e Test1. Set the rotary switch of the clamp meter to the 2000MΩrange.In this condition, it is normal that the reading is unstable.2. Insert the three banana plugs V/Q, COM, EX T of the insulationtester unit to the correspondin g V/Q, COM, EX T input jacks on the clamp meter.3. Set the range switch of the insulation tester unit to the 2000MΩposition.4. Connect the test leads from the insulation tester unit to theapplianc e to be tested.5. Set the insulation tester Power switch to the "ON" position.6. Push the " 500V" button, the red LE D "500V" will light. Thereading on the LCD of the clamp meter is the insulation resistance value; if the reading is below 19MΩ, set the rotary switch of the the clamp meter and the range switch of the insulation tester unit to 20MΩ range position to increase the measuremen t accuracy.117. If the insulation tester unit is not used, the power switch mustset to OFF position. And the test leads must be removed from the input jacks; this can extend the battery life and prevent electrical shock hazard.DC Voltage Measurement1. Connect the red test lead to the "V/Ω" jack and the black testlead to the "COM" jack.2. Set the rotary switch to the desired DCV range. If the voltage tobe measured is not known beforehand, set the range switch to the highest range and then turn down range by range untilsatisfactory resolution is obtained.3. Connect the test leads to the source or load to be measured.4. Read the voltage value displayed on the LCD along with thepolarity of the red test lead.AC Voltage Measurement1. Connect the red test lead to the "V/Ω" jack and the black testlead to the "COM" jack.2. Set the rotary switch to the desired ACV range. If the voltage tobe measured is not known beforehand, set the range switch to the highest range and then turn down range by range untilsatisfactory resolution is obtained.3. Connect the test leads to the source or load to be measured.4. Read the voltage value displayed on the LCD.12Resistanc e Measuremen t1. Connect the red test lead to the "V/Ω" jack and the black testlead to the "COM" jack.2. Set the rotary switch to the desired Ω. range.3.Connect the test leads to the resisto r to be measured andread the value displayed on the LCD.Note:For resistance about 1 Mfi and above, the meter may take a few second s to stabilize. This is normal for high resistance readings.Diode Test1. Connect the red test lead to the "V/Ω" jack and the black testlead to the "COM" jack. (The polarity of the red test lead ispositive"+".)2. Set the rotary switch to range.3. Connect the red test lead to the anode of the diode to be testedand the black test lead to the cathode of the diode. The approximat e forwar d voltage drop of the diode will be displayed on the LCD.If the connectio n is reversed, only figure "1" will be shown.13Audible Continuity Test1. Connect the red test lead to the "V/Ω" jack and the black testlead to the "COM" jack.2. Set the rotary switch to range.3. Connect the test leads to the two terminals of the circuit to betested. If the resistance Is less than about 50Ω, the built-in buzzer will sound.Temperature MeasurementNoteTo avoid possible damage to the meter or otherequipment, remember that while the meter is ratedfor 0°C to +750°C and 32°F to 1382°F, the K TypeThermocouple provided with the meter is rated to250°C. For temperatures out of that range, use ahigher rated thermocouple.The K Type Thermocouple provided with the meteris a present, it is not professional and can only beused for non-critical reference measurements.For accurate measurements, use a professionalthermocouple.1. Connect the K type thermocouple to the correspondingmeasurement socket.2. Set the rotary switch to the desired temperature range.3. Touch the K type thermocouple to the object to be measured.4. Wait a while, read the temperature value displayed on the LCD.14Frequenc y Measuremen t1. Connect the red test lead to the "V/Ω" jack and the black testlead to the "COM" jack.2. Set the rotary switch to the frequenc y (2kHz) range.Connect the test leads to the source or load to be measured. 3. Read the frequenc y value displayed on the LCD.MAINTENANC E•Before opening the case, always disconnec t the test leads from all live circuits.•Periodically wipe the case with a damp cloth and mild detergent.Do not use abrasives or solvents.BATTERY REPLACEMEN TWhen the symbol" " appears on the display, it shows that the batter y should be replaced. To replace the battery, open the batter y door, replace the exhausted battery with a new one of the same type, reinstall the battery door. Some models of this series use screws for fastening the door, please install the screws.15ACCESSORIESInstruction manual: 1 copyTest leads: 1 pairNote:In normal condition, the insulation tester is not provided. If needed, you can buy from our company.PRESENTK Type Thermocouple: 1 piece (only 266C, 266C+, 266FT) NOTE1. This manual is subject to change without notice.2. Our company will not take the other responsibilities for any loss.3. The content of this manual can not be used as the reason to use the meter for any special applications.DISPOSAL OF THIS ARTICLEDear Customer, If you at some point intend to dispose of this article, then please keep in mind that many of its components consist of valuable materials, which can be recycled. Please do not discharge it in the garbage bin, but check with your local council for recycling facilities in your area.16 。

气科院大气物理面试英语专业词汇[1]

大气科学系微机应用基础Primer of microcomputer applicationFORTRAN77程序设计FORTRAN77 Program Design大气科学概论An Introduction to Atmospheric Science大气探测学基础Atmospheric Sounding流体力学Fluid Dynamics天气学Synoptic Meteorology天气分析预报实验Forecast and Synoptic analysis生产实习Daily weather forecasting现代气候学基础An introduction to modern climatology卫星气象学Satellite meteorologyC语言程序设计 C Programming大气探测实验Experiment on Atmospheric Detective Technique云雾物理学Physics of Clouds and fogs动力气象学Dynamic Meteorology计算方法Calculation Method诊断分析Diagnostic Analysis中尺度气象学Meso-Microscale Synoptic Meteorology边界层气象学Boundary Layer Meteorology雷达气象学Radar Meteorology数值天气预报Numerical Weather Prediction气象统计预报Meteorological Statical Prediction大气科学中的数学方法Mathematical Methods in Atmospheric Sciences专题讲座Seminar专业英语English for Meteorological Field of Study计算机图形基础Basic of computer graphics气象业务自动化Automatic Weather Service空气污染预测与防治Prediction and Control for Air Pollution现代大气探测Advanced Atmospheric Sounding数字电子技术基础Basic of Digital Electronic Techniqul大气遥感Remote Sensing of Atmosphere模拟电子技术基础Analog Electron Technical Base大气化学Atmospheric Chemistry航空气象学Areameteorology计算机程序设计Computer Program Design数值预报模式与数值模拟Numerical Model and Numerical Simulation接口技术在大气科学中的应用Technology of Interface in Atmosphere Sciences Application海洋气象学Oceanic Meteorology现代实时天气预报技术（MICAPS系统）Advanced Short-range Weather Forecasting Technique(MICAPS system)1) atmospheric precipitation大气降水2) atmosphere science大气科学3) atmosphere大气1.The monitoring and study of atmosphere characteristics in near space as an environment forspace weapon equipments and system have been regarded more important for battle support.随着临近空间飞行器的不断发展和运用,作为武器装备和系统环境的临近空间大气特性成为作战保障的重要条件。

TD-SCDMA和WCDMA区别

• 核心网由三部分构成：电路域、分组域和广播域。核心网内各网络实体及其接口定义与WCDMA的对应部分完全一致。 • 接入网和核心网的接口为Iu接口，遵循3GPP 25.41x 规范的规定。 • 接入网和UE之间的空中接口为Uu接口，遵循3GPP 25.1xx、 25.2xx、25.3xx 的规定。
Iub接口上无线网络层控制面协议（NBAP）的差别
Iub接口上无线网络层用户面协议(Iub FP)的差别
27
Iub接口上无线网络逻辑资源中公共资源的差异
C ell C e l l-Id 1
[F D D 0-i] [T D D 0-1 ]
1
P C P IC H C PC I d
0 -m
S C P IC H C PC I d
U SCH FP
CPCH FP
R a d io N e tw o rk L a yer
N ode B A p p lic a tio n P a r t (N B A P )
D CH FP
ALCAP Q .2 6 3 0 .2
Q .2 1 5 0 .2
T ra n s p o rt L a yer
S S C F-U N I SSCO P A A L T yp e 5
•1 • 60 •6 • 2Mbps • 0.4
TD-SCDMA •1.6MHZ，可同时用于上行和下行的传输，非对称性/对称都能够传输
•1 • 24 • 15 • 2Mbps • 1.25
频率复用系数
•1
每载波同时工作 • 30 信道数频谱利用率（话音） • 12 最大数据传输速率频谱利用率（数据, Mbps/MHz/cell ） • 2.5Mbps • 1.0

Keysight Technologies N4000A, N4001A, N4002A SNS S

Keysight TechnologiesN4000A, N4001A, N4002ASNS Series Noise Sources10 MHz to 26.5 GHzTechnical OverviewNoise Sources Designed to Meet Specific NeedsAutomatically down-loads ENR data from an SNS Series noise source into any NFA Series or any X-Series signal analyzer Advances in Noise Figure AccuracyN4000AUsed for low noise figure devices or devices sensitive to mismatch in the 10 MHz to 18 GHz range N4001AUsed for general purpose measurements in the 10 MHz to 18 GHz rangeN4002AUsed for measurements in the 10 MHz to 26.5 GHz rangeThe Keysight Technologies, Inc. SNS Series of noise sources work inconjunction with–NFA Series noise figure analyzers–X-Series signal analyzersTo simplify measurement set-up and improve accuracy these noise sources automatically download electronically stored calibration data to the compatible Keysight noise figure measuring analyzers. The noise sources also have the capability to automatically mea-sure their own temperature so that compensation can be applied to the calibration data. These capabilities increase the overall reliability and accuracy of noise figure measure-ments.SNS Series key features and benefits–Automatic download of ENR data to the analyzer speeds overall setup time–Electronic storage of Excess Noise Ratio (ENR) calibration data decreases the op-portunity for user error.–Temperature sensing improves measurement accuracy, leading to tighter specifica-tion of device performance.The N4000A and N4001A, which cover the 10 MHz to 18 GHz frequency range, come with an APC 3.5 (m) connector as standard, and offer the option of a Type-N (m) connec-tor.The N4002A, which covers the frequency range 10 MHz to 26.5 GHz, has an APC 3.5 (m)connector as standard.N4000A for Low Noise Figure or Mismatch Sensitive Devices Up to 18 GHzThe N4000A is designed to accurately measure devices with low noise figure, or devices whose gain is especially sensitive to small changes in source impedance. This includes most GaAs FET’s. The N4000A maintains the same impedance whether turned on or off. By maintaining the same impedance at the input to the device under test (DUT) gain changes are reduced. These gain changes can often masquerade as DUT noise and cause noise figure measurement errors.The ENR of this noise source is nominally 6 dB from 10 MHz to 18 GHz. DUTs with noise figures up to 20 dB can be accurately and reliably measured with this device. The N4000A noise source has a choice of connectors, with an APC 3.5 (m) as standard.N4001A for General Purpose Measurements from10 MHz to 18 GHzThe N4001A noise source is ideal for general purpose use with a low reflection coeffi-cient and a nominal ENR of 15 dB from 10 MHz to 18 GHz. DUT’s with noise figures up to 30 dB can be measured accurately and reliably with this device. The N4001A has a selection of connectors, with an APC 3.5 (m) as standard.N4002A for Measurements Up to 26.5 GHzThe N4002A noise source was designed to measure DUT noise figures reliably and accu-rately up to 30 dB from 10 MHz up to 26.5 GHz accurately and reliably. This noise source comes with an APC 3.5 connector as standard.Accurate Noise PowerThe output of a noise source, usually given in terms of Excess Noise Ratio (ENR), mustbe known in order to make accurate noise figure measurements. Any uncertainty in theENR transfers into uncertainty of the measured noise figure, dB for dB. Keysight providesaccurate ENR calibration data with each noise source. ENR uncertainty and reflectioncoefficients at each frequency point are provided as well.The following is an example of calibration data for an N4001A noise source:# ENR Data File# Created by N8975A NFA Series Noise Figure Analyzer# Serial Number GB40390000 Firmware Revision A.01.01# 13:37:07 Mar 28, 2001# Format is: Frequency (Hz), ENR (dB), ENR Unc (dB), # On Refl.Mag (lin), On Refl.Phase (deg),# Off Refl.Mag (lin), Off Refl.Phase (deg) , # On Refl.Mag Unc (lin), On Refl.Phase Unc (deg),# Off Refl.Mag Unc (lin), Off Refl.Phase Unc (deg)[Filetype ENR][Version 1.1][Serialnumber US41240152][Model N4001A][Option 001][Caldate 20000727][Calduedate 20010727][Placeofcal EPSGQ][Trackingnum 10][Temperature 296.5K][Humidity 65%][Current 36272]10000000, 15.281, 0.193, 0.0450, –136.0, 0.0450, –136.0, 0.0030, –6.0, 0.0070, +6.0, 100000000, 15.291, 0.190, 0.0358, +168.0, 0.0358, +168.0, 0.0040, +4.6, 0.0050, –4.6, 1000000000, 15.118, 0.151, 0.0398, +39.6, 0.0398, +39.6, 0.0100, +4.5, 0.0067, +1.5, 2000000000, 14.999, 0.168, 0.0377, 0.168, 0.0377, –85.7, 0.0056, +0.9, 0.0086, +1.9, 3000000000, 14.879, 0.172, 0.0267, +150.6, 0.0267, +150.6, 0.0080, –9.2, 0.0090, –1.2, 4000000000, 14.795, 0.173, 0.0130, –18.1, 0.0130, –18.1, 0.0013, +16.0, 0.0063, +10.0, 5000000000, 14.818, 0.179, 0.0359, +169.5, 0.0359, +169.5, 0.0024, –9.3, 0.0035, –0.3, 6000000000, 14.846, 0.181, 0.0556, +63.7, 0.0556, +63.7, 0.0041, +10.3, 0.0067, –4.3, 7000000000, 14.895, 0.180, 0.0430, –37.0, 0.0430, –27.0, 0.0079, –2.3, 0.0049, –2.3, 8000000000, 15.016, 0.198, 0.0232, –160.3, 0.0232, –160.3, 0.0091, –3.8, 0.0053, –1.8, 9000000000, 15.134, 0.201, 0.0122, +71.4, 0.0122, +71.4, 0.0037, +17.3, 0.0057, +7.3, 10000000000, 15.253, 0.194, 0.0080, +116.2, 0.0080, +116.2, 0.0048, –1.4, 0.0056, –5.4, 11000000000, 15.249, 0.243, 0.0241, +65.7, 0.0241, +65.7, 0.0059, +1.5, 0.0049, +44.5, 12000000000, 15.349, 0.240, 0.0196, +8.8, 0.0196, +8.8, 0.0057, +3.2, 0.0077, +2.2, 130****0000,15.383, 0.188, 0.0217, –5.4, 0.0217, –5.4, 0.0062, –6.9, 0.0045, –1.9, 14000000000, 15.355, 0.178, 0.0228, –66.6, 0.0228, –66.6, 0.0075, +11.2, 0.0065, +1.2, 150****0000,15.367, 0.187, 0.0141, +141.6, 0.0141, +141.6, 0.0036, –3.2, 0.0029, –1.2, 16000000000, 15.421, 0.182, 0.0251, +6.4, 0.0251, +6.4, 0.0030, +7.2, 0.0042, –1.2, 17000000000, 15.418, 0.174, 0.0242, –100.5, 0.0242, –100.5, 0.0048, –2.7, 0.0050, +9.7, 180****0000,15.464, 0.179, 0.0183, +124.4, 0.0183, +124.4, 0.0098, –1.1, 0.0100, +9.1,The Importance of Noise Source Reflection CoefficientTwo aspects of noise source reflection coefficient are important to note:–A non-zero reflection coefficient contributes to re-reflections between the DUT and the source. The reflections cause uncertainty in the noise power emerging from the source. The measured noise figure, furthermore, refers to the actual noise source impedance rather than the desired 50 Ω value. The low reflection coefficient of Key-sight SNS Series noise sources can keep this uncertainty under 0.1 dB.–The change in reflection coefficient between On and Off can cause DUT Gain vari-ations which, in turn, can cause noise figure measurement errors. This problem is effectively eliminated by the N4000A, whose complex reflection coefficient change is specified to be less than 0.01.The key difference between the N4000A and the N4001A noise sources is the nominal 6 dB ENR of the N4000A whereas the N4001A has a nominal 15 dB ENR.Consider the 6 dB ENR noise source when–The DUT is especially sensitive to source impedance changes at its input –There is a need to measure very low noise figures –The noise figure does not exceed 20 dBThe N40001A is well suited to general-purpose measurements up to 18 GHz, whereas the N4000A is better suited to making measurements on lower noise devices or devic-es which are sensitive to changes in input impedance. The N4000A contains additional internal attenuation, which provides greater isolation at its output. It is less affected by the ON/OFF condition that is the output impedance of the N4001A. There is a benefit of using a N4000A rather than a N40001A with an added attenuator. The extra attenuaton in the N4000A is included in its calibration and is fully traceable.Choosing Between the N4000A and the N4001ASNS Series Noise Source SpecificationsSpecificationsThe specifications are performance standards or limits against which the noise source may be tested. These specifications for the noise source are ONLY valid if the analyzer has been allowed to meet its specified warm up time of 60 minutes. Specifications are valid at ambient temperature 23 ± 5°C .Supplemental Characteristics Temperature Sensing AccuracyMaximum change in complex reflection coefficient between noise source ON and OFF states: 0.01Supplemental characteristics are not specifications but are typical characteristics in -cluded as additional information for the user.ENR variation with temperature: < 0.01 dB/°C for 30 MHz to 26.5 GHz Range: 0 to 55°C Resolution: 0.25°CAccuracy: ± 1° at 25°C ± 2° over 0°C to 55°CInstrument model Frequency range ENR range N4000A 10 MHz to 18 GHz 4.5 - 6.5 dB N4001A 10 MHz to 18 GHz 14 - 16 dB N4002A10 MHz to 26.5 GHz12 - 17 dBInstrument model Frequency range Max standing wave ratio (SWR)Reflection coefficient (Rho) (p)N4000A0.01 - 1.51.5 - 3.07.0 - 18.0< 1.04:1< 1.04:1< 1.22:10.030.030.10N4001A0.01 - 1.51.5 - 3.03.0 - 7.07.0 - 18.0< 1.15:1< 1.15:1< 1.20:1< 1.25:10.070.070.090.11N4002A0.01 - 1.51.5 - 3.03.0 - 7.07.0 - 18.018.0 - 26.5< 1.22:1< 1.22:1< 1.22:1< 1.25:1< 1.35:10.100.100.100.110.15Figure 1. Characteristic SWR at 23°CCharacteristic ENR (U(Y)) SpecificationENR values are given at cardinal frequency points over the frequency range of each noise source. These values are stored within the noise sources internal EEPROM and docu-mented in the calibration report.The uncertainty analysis for the calibration of the noise sources is in accordance with the ISO/TAG4 guide. The uncertainty data reported on the calibration report is the expanded uncertainty (U(Y)) with 95% confidence level and a coverage factor of 2. This uncertainty analysis is valid for APC 3.5mm and Type-N (Option 001) connector types.Instrument model Frequency range ENR uncertainty (± dB)1N4000A0.01 - 1.51.5 - 3.03.0 - 7.07.0 - 18.00.16 0.15 0.15 0.16N4001A0.01 - 1.51.5 - 3.03.0 - 7.07.0 - 18.00.14 0.13 0.13 0.16N4002A0.01 - 1.51.5 - 3.03.0 - 7.07.0 - 18.018.0 - 26.50.15 0.13 0.13 0.15 0.221. Characteristic values are met or bettered by 90% of instruments with 90% confidence.The uncertainty for each noise source can be unique to that noise source. The uncer-tainty will typically vary by less than 0.01 dB at any frequency between different noise sources produced in the same year when first produced. Subsequent calibrations must be performed at suitably capable calibration vendors in order to keep the uncertainties similar.The standard level of calibration for the SNS series is Option A1R (calibration against a 1-level removed reference standard). Another choice is Option APR (calibration against a primary reference standard).For Option A1R, performance can only be matched with a Standards Lab Calibration, available from the Roseville Standards Lab at Keysight. For Option APR, performance can only be matched by the National Physical Laboratory (NPL) in the UK.Using the appropriate calibration level should result in similar uncertainties to the orig-inal production uncertainties. These will mostly be within 0.01 dB of the original uncer-tainties, but they will vary with each calibration because they include the repeatability observed on each device. Uncertainties for newly produced devices include population repeatabilities instead of individual device repeatabilities, and thus vary little between devices of the same model and option configuration.Figures 2 and 3 show example uncertainties for standard (option A1R) production noise sources, as of the end of 2013. This time period is after significant changes were made in the uncertainties from better understanding of the error sources and improvementsin the references from the National Metrology Institute used, NPL. If NPL performance changes in the future, Keysight uncertainties will follow those changes.Figure 4. Characteristic ENR plot versus cardinal frequency points.Figure 2. Example ENR versus frequency for the N4000A model.Figure 3. Example ENR versus frequency for the N4001A and N4002A models.E N R U n c e r t a i n t y , d BLate 2013 ENR Uncertainties, N400xA0.160.140.120.100.080.060.040.020.00N4002AN4001AN4000AN4000A-001N4001-00110100100020003000400050006000700080009000100001100012000130001400015000160001700018000190002000021000220002300024000250002600027000Connector Care for the APC-3.5 (m) ConnectorThe APC-3.5 (m) connector is designed for instrumentation applications requiring long life, low reflection coefficient, and good mating capabilities with SMA connectors.The APC-3.5 (m) can achieve a life expectancy of over 1000 connections if precautions as listed below are taken:1. Use a torque wrench set to the recommended torque.2. Tighten the nut only, to prevent the connectors rotating with respect to each oth-er. Friction causes rapid wear of the conducting surfaces.3. Clean connectors after every 10 connections.4. Mate with APC-3.5 connectors in good condition.Casual use of the connector can reduce the life expectancy of APC-3.5 (m) connectors to fewer than 200 connections. Below is a list of several actions that may also reduce the life expectancy of the APC-3.5 (m).5. Estimating the torque with an ordinary wrench.6. Twisting the noise source body (accidentally or otherwise) during final tighteningor when loosening.7. Frequent mating with worn-out SMA connectors. This can be a problem withfrequently used accessories.The APC-3.5 (m) connector used on the SNS Series of noise sources has an extra-large nut to make it easier to tighten without applying torque to the noise source body. A20 mm torque wrench is also available from Keysight for this application. Please contact your local Keysight representative for ordering information.Keysight 20 mm torque wrench 8710-1764Ordering InformationProductsN4000A SNS Series noise source, 10 MHz to 18 GHz, nominal ENR 6 dBN4001A SNS Series noise source, 10 MHz to 18 GHz, nominal ENR 15 dBN4002A SNS Series noise source, 10 MHz to 26.5 GHz, nominal ENR 15 dBAll of these noise sources are provided with an APC 3.5 (m) connector as standardOptionsN400xA-002 5-foot (1.5 m) SNS noise source cable is a default option as it is required to make the SNS function. Unselect this option if you already own a noisesource cable.The following option is available with the N4000A and the N4001A:ConnectorN400xA-001 Type-N (m) connectorN400xA-100 APC 3.5 (m) connectorService optionsWarranty and serviceFor 3 years, order 36 months of R-51B. Standard warranty is 12 months.R-51B Return to Keysight warranty and service planCalibration1For 3 years, order 36 months of the appropriate calibration plan shown below.R-50C-001 Standard calibration planR-50C-002 Standard compliant calibration planRecommended accessoriesThe SNS Smart Noise Source Series requires a compatible cable and adaptor to enable their use. The 11730A is selected as a default option for every SNS; however, customers may choose to unselect this option or order the 11730B or 11730C separately.11730A: 5-foot (1.5 m) power sensor and SNS noise source cable (included as a default option with every SNS)11730B: 10-foot (3.0m) power sensor and SNS noise source cable11730C: 20-foot (6.1m) power sensor and SNS noise source cableA good quality adaptor must be used to connect the SNS Series noise source to the in-put of the NFA Series noise figure analyzer. Keysight provides a suitable connector upon purchasing an NFA. These adaptors are also available separately.83059B precision 35 mm coaxial adaptorKeysight recommends a torque wrench for use with the large sized (20 mm) APC 3.5 (m) connector nut found on the Keysight SNS Series noise sources. Keysight also recom-mends a torque wrench for use with the 5/16” connector on the female to female adaptor. 8710-1764: 20 mm torque wrench8710-1765: 5/16” torque wrenchNoise Figure Literature from Keysight Keysight instruments are backed up with a full spectrum of literature and support offerings. A detailed listing follows.Noise Figure Selection Guide,Literature number 5989-8056ENFundamentals of RF and Microwave Noise Figure Measurements, Application Note 57-1, Literature number 5952-8255ENoise Figure Measurement Accuracy - The Y-Factor Method, Application Note 57-2, Literature number 5952-3706EOptimizing RF and Microwave Spectrum Analyzer Dynamic Range, Application Note 1315, Literature number 5968-4545E10 Hints for Making Successful Noise Figure Measurements, Application Note 57-3, Literature number 5980-0288EKey Web ResourcesFor the latest information on Keysight noise figure solutions,visit our web page at: /find/nfFor the latest news on the component test industry,visit our web page at: /find/component_testThis information is subject to change without notice.© Keysight Technologies, 2009 - 2016Published in USA, January 27, 20165988-0081ENmyKeysight/find/mykeysightA personalized view into the information most relevant to you.Three-Year Warranty/find/ThreeYearWarrantyKeysight’s committed to superior product quality and lower total cost of ownership. Keysight is the only test and measurement company with athree-year warranty standard on all instruments, worldwide. And, we provide a one-year warranty on many accessories, calibration devices, systems and custom products.Keysight Assurance Plans/find/AssurancePlansUp to ten years of protection and no budgetary surprises to ensure your instruments are operating to specification, so you can rely on accurate measurements.Keysight Infoline/find/serviceKeysight’s insight to best in class information management. Free access to your Keysight equipment company reports and e-library.Keysight Channel Partners/find/channelpartnersGet the best of both worlds: Keysight’s measurement expertise and product breadth, combined with channel partner convenience.For more information on KeysightTechnologies’ products, applications or services, please contact your local Keysight office. The complete list is available at:/find/contactus Americas Canada (877) 894 4414Brazil 55 11 3351 7010Mexico001 800 254 2440United States (800) 829 4444Asia Pacific Australia 1 800 629 485China800 810 0189Hong Kong 800 938 693India 1 800 11 2626Japan 0120 (421) 345Korea 080 769 0800Malaysia 1 800 888 848Singapore 180****8100Taiwan0800 047 866Other AP Countries (65) 6375 8100Europe & Middle East Austria 0800 001122Belgium 0800 58580Finland 0800 523252France 0805 980333Germany ***********Ireland 1800 832700Israel 1 809 343051Italy800 599100Luxembourg +32 800 58580Netherlands 0800 0233200Russia 8800 5009286Spain 800 000154Sweden 0200 882255Switzerland0800 805353Opt. 1 (DE)Opt. 2 (FR)Opt. 3 (IT)United Kingdom0800 0260637For other unlisted countries:/find/contactus(BP-01-01-16)/go/quality Keysight Technologies, Inc.DEKRA Certified ISO 9001:2008 Quality Management SystemFrom Hewlett-Packard through Agilent to KeysightFor more than 75 years, we‘ve been helping you unlock measurement insights. Our unique combination of hardware, software and people can help you reach your next breakthrough.Unlocking measurement insights since 1939.1939 THE FUTURE。

Instruction manual.pdf_1693225695.0476854说明书

I. M EASUREMENT OF DC AND AC VOLTAGE AND CURRENT , MEASUREMENTUNCERTAINTY AND ERRORS.M ESUREMENT OF THE PARAMETERS OF DIODES ANDTRANSISTORSTheory:Theory of errors and uncertainty in the measurement. Uncertainty of type A ,type B and C. Definitions of the instrument precision by the producers. Principle of multimeters. Measurement of DC and AC voltage and current. Connection of the multimeter to the tested circuit. Measurement of the effective value of the voltage and current- definitions & principles. Measurement of the effective value alternating voltage/current with or without superimposed direct voltage/current. Shape coefficient, crest factor. Testing of diodes and transistors using the multimeter Principle of the digital frequency measurement. Exercises:1) Get acquainted with Agilent 33220A waveform generator. Set the appropriate load value according tothe resistor used (Utility > Output Setup> Load> 50Ω). ATTENTION: The generator output must be matched to the load impedance for all laboratory tasks.2) Set the generator for harmonic signal output of 2Vpp amplitude and 100 Hz frequency (setting of thegenerator, not measured value on the voltmeter). Connect the rectifier to loaded output according to the schematic. Measure the rectified voltage by available multimeters (using DC mode). Read at least10 measured values. Estimate measurement uncertainty of type A. Estimate the measurementuncertainty of type B based by parameters from datasheets. Determine overall uncertainty of your measurements (type).3) Generate a harmonic, rectangular, triangular, saw tooth and at least one of embedded arbitrarysignals with arbitrary amplitude from the range 1-5 V and frequency from the range 50-300 Hz with the offset equal to zero. Measure voltages for all shapes using both a TRMS voltmeter and simple multimeter with diode rectifier. Explain why the multimeter readings differ for every waveform and amplitude. Use a multimeter also for frequency measurement of every waveform.4) Repeat task 3 for harmonic, rectangular, triangular, saw-tooth waveform with DC offset set to 1V.Measure the output voltage of the generator by TRMS voltmeter in both AC and DC mode. What is the total dissipated power on the resistor load and what is the effective value of the voltage? Hint -Parceval´s theorem.5) Generate a harmonic signal with amplitude 1V and frequency of 5Hz. What is measured by themultimeter? Gradually adjust the frequency 10, 50, 200, 1k, 10k, 25k, 100k, 500kHz and 1MHz. What is measured by the multimeter? Try to explain the multimeter behavior.6) Set the generator for rectangular pulses of 100 Hz repeating frequency and pulse width of 100 s. Setthe low voltage level to 0V. The high level (pulse amplitude) set gradually to 0.02V, 0.2V, 2V. How does the measured rms value change for different peak values of the signal? What voltage value is shown by the multimeter? Is its variation consistent with the changes of the pulse amplitude?Compare your measurement results acquired with other types of multimeters.7) Repeat task 4 for AC and DC current through the load. How can you calculate total power dissipatedon the resistor load from the measured current and resistor’s value? Compare results with those of the task 4.8) Test available diodes using a multimeter and assess whether they passed. What does thismeasurement tell us about the measured diode? Measure also the Graetz bridge9) Measure PN junctions and h21E of available transistors in the active and inverse mode. Comparemeasured results with datasheet values.10) Switch the multimeter to frequency measurement mode. Set the generator to an arbitrary harmonicwaveform of frequency within kHz range. Gradually rise the amplitude from minimum up to 5V.Observe the measured frequency and determine an amplitude threshold, where multimeter starts to measure correctly. Try to explain the results and behavior of the multimerter in frequency measurement mode.Instruments‘ manuals:Multimeter UT 803Multimeter Agilent 34410AMultimeter Agilent 34405AMultimeter Metex 3640Multimeter METEX 3850DGenerator Agilent 33220AStudy materials:Agilent multimeter simulation installation filesWebsite simulating the function of selected instruments - meas-lab.fei.tuke.sk。

Global primary production a remote sensing

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INTRODUCTION availability of remote sens1og 0>曲sure川 ments that provtde complete global cov町age with a high revisit frequency h部 encouraged a new phase in 由己 study 。f tt也 Ero由（NASA, 1988; Gowaro, 1989). f ＂由e 且rst time pr，田esses 由at can only be m帕’阳帽d with high temporal fr吨uency m盹sutemen1s can be studi 创l spatially (Prin<-e & J山川队 1991 ）。 Here we d四cribe a new model of global primary production thal 岭四tirely driven by remo1ely sensed m"1surements. 111• Advaoced Very High Re明lull佣 Radiomclcr (A VHRR) carried on tbe NOAA series of polar-orbiting satellites is a ra由er simple multispe皿rat s阳$啊， h＜＞飞、>ever, tt provid创 a w阅1th of inJ~阳mation relevant to biosphcric g回nitoring (Goward et al.,1994）。 Data from the AVHRR have been used almost exclusively in 由e new model even though several soorces of sa时lite observations are available, and 由ese nught ha四 led to b国胆r te•ul<s (Gum＇町－ Fosier & Par挝时佣. 1993). Recent results with AVHRR observations at various int四sively studi叫自cld sites sugge即由at much of the information needed t。”。nitor 悦。可，benc activlly can be eslitnated f 呻 m 由e sa出Hite data (Goward & Dye, 1995). We have therefore· a1tcmp1cd a 且rst, global-scale model of

男女精力的波动规律

男女精力的波动规律英文回答：Physical Fluctuations.1. Testosterone.Men: Testosterone levels are highest in the morningand gradually decrease throughout the day.Women: Testosterone levels fluctuate during the menstrual cycle, peaking during ovulation.2. Estrogen.Women: Estrogen levels vary during the menstrual cycle, being lowest during menstruation and highest during ovulation.3. Progesterone.Women: Progesterone levels increase after ovulation and remain elevated during the luteal phase of the menstrual cycle.Mental Fluctuations.1. Cognitive Function.Men: Cognitive function is typically better in the morning.Women: Cognitive function may be impacted by fluctuations in hormones during the menstrual cycle.2. Mood.Women: Mood can be affected by hormonal changes, particularly during the premenstrual phase of the menstrual cycle.3. Sleep.Men: Sleep patterns are typically more stable than women's.Women: Sleep quality can be affected by hormonal fluctuations and menstrual cramps.4. Energy Levels.Men: Energy levels tend to be higher in the morning and decrease throughout the day.Women: Energy levels may vary during the menstrual cycle, with some experiencing increased energy during ovulation and decreased energy during menstruation.Cultural and Societal Influences.Cultural and societal norms can also influence perceptions of energy fluctuations. For example, in some cultures, women are expected to be more energetic and productive during menstruation, while in others, they areencouraged to rest and recover.Interindividual Variability.It's important to note that the above patterns are generalizations and there is significant interindividual variability in both physical and mental energy fluctuations. Some individuals may experience more pronounced fluctuations, while others may experience more subtle changes.中文回答：生理周期波动规律。

科技英语翻译教程

CHAPTER THREE1. 2. 3. 4. 5.The inflammation is characterized by red,swelling,fever,and pain.[E.44]Amaterial balance is based on the law of conservation of matter.[E.45]Coating thickness ranges from0.1mm to2mm.[E.46]The new medicine will expire in2years.[E.47]Gases differ from solids in that the former have greater compressibility than the latter.[E.48]6.The molecules continue to stay close together,but do not continue to retain a regularfixed arrangement.[E.49]7.These products tend to react with soap and detergents and produce soapscum.[E.50]8.With this software so available there seems little need for analysts to develop theirown programs.[E.51]9.To design is to formulate a plan for the satisfaction of a human need.[E.52]10.China's successful explosion of its first atom bomb caused tremendous repercussionthroughout the world.[E.53]11.The construction of a scientific theory may be compared to the preparation of aweather map at a central meteorological station.[E.54]12.In a similar wa y,in the theory of light,we use terms like"waves"and"particles"for the description and discussion of the results of experiments.[E.55]13.One of our ways for getting heat is by burning fuels.[E.56]14.An understanding of the laws of friction is important in the designing of modernmachines.[E.57]15.Heating water does not change its chemical composition.[E.58]16.This experiment is an absolute necessity in determining the best processingroute.[E.60]17.I am a stranger to the operation of electronic computer.[E.61]18.His experiment was a success.[E.62]19.I found a lot of difficulties to continue the experiment.[E.63]heat always passes by conduction from the 20.Whenever one body touches another,warmer to the colder.[E.68]21.This workpiece is not more elastic than that one.[E.69]22.In fission processes the fission fragments are very radioactive.[E.70]23.Glass is much more soluble than quartz.[E.71]24.This metal is less hard than that one.[E.72]25.The wide application of electronic computers affects tremendously the developmentof science and technology.[E.81]26.Earthquakes are closely related to faulting.[E.82]27.The electronic computeris chiefly characterized by accuracy and quick computation.[E.83]28.Gasoline is appreciably volatile.[E.84]29.It is demonstrated that dust is extremely hazardous.[E.85]30.The power plant supplies the inhabitants sixty li about with electricity.[E.86]31.The buildings around are mostly of modem construction.[E.87]32.The attractive force between the molecules is negligibly small.[E.88]33.All structural materials behave plastically above their elastic range.[E.89]34.These parts must be proportionally correct.[E.90]35.Chlorine is very active chemically.[E.91]36.Open the valve to let air in.[E.92]37.Their experiment has been over.[E.93]38.In this case the temperature in the furnace is up.[E.94]39.The frequency,wave length,and speed of sound are closely related.[E.106]40.The advantages of the recently developed composite materials are energy saving,performance efficient,corrosion resistant,long service time,and without environmental pollution.[E.107]41.Radiant,electrical and chemical energies can all be turned into heat.[E.108]42.The temperature needed for this processing is lower than that needed to melt themetal.[E.109]43.Oxidation will make metals rusty.[E.110]44.In rapid oxidation a flame is produced.[E.111]45.These principles will be illustrated by the following transition.[E.112]46.The best conductor has the least resistance and the poorest has the greatest.[E.113]47.Forces can be classified as internal and external.[E.114]48.Economic globalization has widened the gap between the North and the South andbetween the rich and the poor.[E.115]49.Matter can be changed into energy,and energy into matter.[E.116]50.The generation plant,transmission lines,and primary substations are shown abovethe dashed line;the load and distribution below the line.[E.117]51.Science demands men of great effort and complete devotion.[E.118]52.The new products will soon be put into use.[E.119]53.There are three larger injection machines in the workshop.[E.120]54.Note that the words“velocity"and"speed"require explanation.[E.121]55.A data processor can issue address and function codes.[E.122]56.Air is a mixture of gases.[E.123]57.For reasons the alternating current is more widely used than the direct current.[E.124]58.These early cars were slow,clumsy,and inefficient.[E.130]59.Science and technology are developing rapidly.[E.131]60.A new kind of computer----small,cheap,attention.[E.132]61.Inflation has now reached a serious level.[E.133]62.It must have been surprising to see a little girl working at a high table,surroundedby maps and ala kinds of instruments.[E.134]fine----is attracting increasing63.Heat from the sun stirs up the atmosphere,generating winds.[E.135]64.In general,all the metals are good conductors,with silver the best and copper thesecond.[E.136]65.In addition to theadvantages.[E.137]speed of erection,these types usually have other66.The level of a liquid rises as its temperature is increased and falls with a decrease intemperature.[E.198]67.The properties of alloys are much better than those of pure metals.[E.199]68.We must check the conclusion in practice,and should not blindly rely on such as wasreached merely by calculations.[E.200]69.Natural water is that which contains impurities.[E.201]70.Other substances,apart from organic ones,burn in air or oxygen.[E.202]71.An electric light bulb is a vacuum,and so is a radio tube.[E.203]72.A transversely stressed fillet weld can sustain higher loads than one stressedlongitudinally.[E.204]73.It takes more power to do a job in two minutes than it does to do the same job in twohours.[E.205]74.We tried in vain to measure the voltage.[E.224]75.Hardened steel is too hard and too brittle for many tools.[E.225]76.Ideal machines which would have an efficiency of100%should be free offriction.[E.226]77.The need for more potassium compounds than could be obtained from plants ledmen to search for other source of these important compounds.[E.227]78.In the absence of force,a body will either remain at rest or continue to move withconstant speed in a straight line.[E.228]79.The structure will prove weak in service.[E.229]80.The precision instrument must be kept free from dust.[E.230]81.The Theory of Relativity worked out by Einstein is above many people'scomprehension.[E.231]82.Better to do well than to say well.[E.233]83.The common gem materials tend to be less ductile and weaker.[E.234]84.As rubber electricity from passing through it,it is used as insulating material.[E.235]85.There are.many other energy sources in store.[E.236]86.In the high altitude snow and ice remain all year.[E.237]87.It was suggested that such devices should be designed and produced withoutdelay.[E.238]88.Sodium is never found uncombined in nature.[E.239]89.In this case we cannot but determine K first.[E.240]90.It's not eas to talk about Dolly in a world that doesn't share a uniform set of ethicalValues.[E.241]91.Such flight couldn't long escape notice.[E.242]92.Crystals do not melt until heated to a definite temperature.[E.243]earthser is the most powerful drilling machine,because there is nothing onwhich cannot be drilled by it.[E.244]94.Both of the instruments are not precision ones.[E.270]95.Both of the substances are not made up of carbons.[E.271]96.We are not familiar with both of the instruments.[E.272]97.Positive ions are not all alike and may differ in charge or weight.[E.273]98.An engine may not all ways do work at its rated horse-power.[E.274]99.Not everyone can be a mathematician,but in order to understand our modern world,it is necessary to know something about mathematics.[E.275]100.Digital oscilloscopes can not be often used in our experiments.[E.276]101.All metals do not conduct electricity equally well.[E.277]102.All these various losses,great as they are,do not in any way contradict the law of conservation of energy.[E.278]103.All the chemical energy of the fuel is not converted into heat.[E.279]104.All isotopes cannot be manufactured in this way.[E.280]105.Mercury,so small and close to the sun that its gases were quickly lost to space,is nearly airless.[E.282]106.The speed of the man-made satellite hardly changes at all.[E.283]107.Rarely do metals occur in nature in a pure form by themselves.[E.284]108.The US has well-developed and successful offensive command and control warfare(C2W),electronic warfare(EW),and other information(1W)capacities,but these can hardly be characterized as"strategic".[E.285]109.Barely any of our present batteries would be satisfactory enough to drive theelectric train fast and at a reasonable cost.[E.286]110.Scarcely ever does the common oyster contain a valuable pearl.[E.287]111.Workers can violate the safety rules on no conditions.[E.316]112.We shall consent to the designing plan under no circumstances.[E.317]113.He was not ready to believe something just because Aristotle said so.[E.318]114.The engine did not stop because the fuel was finished.[E.319]115.This electric motor does not work properly.[E.320]116.If iron is kept in air-free distilled water,its rusting is not so fast.[E.321]CHAPTER FIVE117.Being no cause to change the motion,line.[E.10]ing a transformer,voltage.[E.11]119.Solving (8),we have the following equation.[E.12]120.When iodine crystals are heated to 114°C,they melt,forming liquid iodine.[E.16]121.The propeller of an airplane forces air backward,developing thrust.[E.17]122.The base and acid neutralize each other,forming a new substance.[E.18]123.Electronic computer having many advantages cannot carry out creative work andreplace man.[E.19]124.Not having been discovered,many laws of nature actually exist in nature.[E.20]power at low voltage can be transformed into power at high a body can move uniformly and in a straight 125.The typical problem of circuit and network theory is to determine the currents causedby the application of a given voltage to given circuit or network.[E.33]126.The principle and method taken in the experiment give us goodmessage enlightenment.[E.34]127.The major advantages of the transistor as used in electronic circuits are light weight small space,low power consumption.[E.35]128.Radio continues to find wider application in science.[E.65]129.An electric current begins to flow through a coil,which is connected across a charged condenser.[E.66]130.A machine is just a mechanical device which makes it possible to do work more conveniently by changing the applied force in directions or in magnitude or both.[E.67]131.The basic action of an SCR is to switch power on very rapidly.[E.68]132.The function of a fuse is to protect a circuit.[E.69]133.Arc welding is to make metals together by means of an electric current.[E.70]134.The two contacts at the base of the lamp are to cant'current from the lamp holder.[E.71]135.Loss of control is most likely to occur on inductive loads.[E.86]136.These are liable to occur through hammering or working the metal,or through rapid cooling.[E.87]137.Up to now,copper alloys,according to CDA,have been more expensive to pressure die cast than aluminum and zinc,and a25%reduction in the cost of pressure die casting of copper alloys is expected with the new technique.[E.88]138.Circuit breakers are necessary to deenergize equipment either for normal operation or on the occurrence of short circuits.[E.89]139.We consider heat to be a form of energy.[E.90]140.Conductors allow electricity to pass through more or less freely.[E.91]141.It is to be emphasized that a source of electricity current is simply a device for causing electricity to move around a circuit.[E.92]142.Electricity makes a motor run.[E.93]143.Let F represent force.[E.94]144.Heat is considered to be a form of energy.[E.95]145.The thermal decomposition of ammonium carbamate can be made to occur by the following methods.[E.96]146.Insulators are used to confine a current to the desired path.[E.97]147.The fact that some bodies float on water and other liquids shows also that there exists a force acting against the lower surfaces sufficient to counteract their weight.[E.113]148.Some of the of the charge produces the sound and light which enable us to hear and see the spark.[E.116]149.The purpose is to transmit only a chrominance signal for color and a luminance signal that contains the monochrome information.[E.117]150.The physical dimension of the antenna determines the amount of inductance and capacity existing in the circuit and consequently the resonant frequency of the antenna system.[E.118]151.However,both the theory and the generation of FM are a good deal more complex to think about and visualize than those of AM.[E.119]152.The development greatly extends the range of applications and the reliability of the jet-type filter while retaining its other advantages.[E.120]CHAPTER SIX153.Day light comes from the sun,which is a mass of hot,glowing gas.[E.129]154.The concept of energy leads to the principle of the conservation of energy,which unifies a wide range of phenomena in the physical science.[E.130]155.Another kind of rectifier consists of a large pear-shaped glass bulb from which all the air has been removed.[E.131]156.If you deal with the younger age group,then you will see a lot of the acute infections such as herpes and trench mouth,which is due to bacteria and causes open sores between the teeth.[E.132]157.These waves,which are commonly called radio waves,travel with the velocity of Light.[E.133]158.ISDN is the name given to a network that is able to transmit and switch a wide variety of telecommunication services.[E.134]159.Sulfur melts at a temperature of112.8°C,where it changes to yellow liquid.[E.135] 160.The last big Alaskan earthquake created a tsunami,which could be felt1,500miles away.[E.136]161.The electricity is changed into the radio-frequency power which is then sent out in form of radio waves.[E.137]162.There are some materials which possess the power to conduct heat.[E.138]163.In a conductor there are a large number of electrons than move freely from atom to atom.[E.139]164.OSHA has qualified the noise level in industry which has become a major concern for many digital controls manufacturers.[E.140]165.The factory produced machine tools to which precision instruments were attached.[E.141]166.Good clocks have pendulums,which are automatically compensated for temperature changes.[E.142]167.Gases,the molecules of which are widely separated from one another,have greatcompressibility than liquids.[E.143]168.An improved design of such a large tower must be achieved which results in moreuniformed temperature distribution in it.[E.155]169.A body that contains only atoms with the same general properties is called anelement.[E.156]170.Such liquid fuel rockets as are now being used for space research have to carry theirown supply of oxygen.[E.157]171.Such propellers as we have recently designed for small ships are actually modeledon fish tails.[E.158]172.Many inventors followed the same principles as that French inventor had used in hisInvention.[E.159]173.A color transmission contains the same information as a black and whitetransmission.[E.160]174.Were there no transformers to adjust the voltage,long-distance transmission ofelectricity would be impossible.[E.184]175.Should there be urgent situations,press this red button to switch offelectricity.[E.185]176.The temperature at the sun's center is as high as 10,000,0000C.[E.186]177.The outer portion of the wheel may travel as fast as 600miles per hour.[E.187]178.The oxygen atom is nearly 16times heavier than the hydrogen atom.[E.188]179.Mercury weighs more than water by about 14times.[E.189]180.Solar cells are as different from so called solar heating panels as solid state physicsis from plumbing.[E.190]181.In such occasions we would rather increase the friction of the surface than deceaseit.[E.191]182.The loads which a structure is subjected to are divided into dead loads,thewhichinclude the weights of parts of the structure,and live loads.Which are due to the weights of people,movable equipment,etc.[E.245]183.The resistance of any length of a conducting wire is easily measured by finding the potential difference in volts between its ends when a known current is following.[E.246]184.Fuel cells are devices that when a fuel such as hydrogen or hydrogen-rich compounds and oxygen is supplied to materials arranged like the anode and cathode of a conventional battery,combine to convert chemical energy directly into electrical energy.[E.247]185.With the same number of protons,all nuclei of a given element may have different numbers of neutrons.[E.248]186.The unit of electrical energy is called the joule,which is equivalent to10exp(7) ergs.[E.249]187.The discovery that electrical currents can be produced by magnetism is extremely important in the field of electricity.[E.250]188.Grounding every circuit,however,makes the system susceptible to excessive currents should a short circuit develop between a live conductor and ground.[E.251]189.It is very interesting to note the differently chosen operating mechanism by the different manufacturers,in spite of fact that the operating mechanism has a major influence on the reliability of the circuit-breakers.[E.252]190.The construction of such a satellite is now believed to be quite realizable,its realization being supported with all the achievements of contemporary science,which have brought into being not only materials capable of withstanding severe stresses involved and high temperatures developed,but new technological processes as well.[E.253]191.Various machine parts can be washed very clean and will be as clean as new ones when they are treated by ultrasonic waves no matter how dirty and irregularlyshaped they may be.[E.254]CHAPTER SEVEN192.Theγ-rays are not affected by an electric field.[E.4]193.If the work piece is gabbed directly,it warps due to the body temperature.[E.5]194.If a body is acted on by a number of forces and still remains stationary,the body is said to be in equilibrium.[E.6]195.An oxidation number may be assigned to each atom in a substance by the application of simple rules.[E.7]196.The second group is composed of compounds derived from or related to benzene C6H6.[E.8]197.The crops were washed away by the flood.[E.9]198.The airplane is supported by the wings;it is propelled by the power plant;it is guided by its control surfaces.[E.10]199.This extraction rate was confirmed in batch tank tests.[E.11]200.Other advantages of our invention will be discussed in the following.[E.12]201.These problems must be solved before the test starts.[E.13]202.North China was hit by an unexpected heavy rain,which caused severe flooding.[E.14]203.The hypothesis was not accepted by most chemists until the1970s.[E.15]204.The first car driven by one of these engines was seen on the roads in1894.[E.16]。

The_Brief_Research_on_the_Pitch_Pattern_Comparison

Open Journal of Acoustics, 2013, 3, 36-39doi:10.4236/oja.2013.32006 Published Online June 2013 (/journal/oja)The Brief Research on the Pitch Pattern Comparison ofElectroacoustic Disguised VoiceHongbing ZhangChina Criminal Police University, Shenyang, ChinaReceived November 25, 2012; revised January 1, 2013; accepted January 10,2013Copyright © 2013 Hongbing Zhang. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACTCamouflage voice is the common check material form in judicial voice testing field that brings about many difficulties to speaker identification. Aiming at the electroacoustic disguised voice, we get fundamental frequency variation rule before and after voice change of multiple corpuses by analyzing map and data. The results show that the fundamental frequency before and after voice change exists a linearity relationship, we can realize speaker identification in elec- troacoustic disguised speech field through comparing Chinese pitch pattern.Keywords: Disguised Voice; Pitch Pattern; Normalization; Speaker Identification1. IntroductionFundamental frequency as one important acoustics char- acter in speech check field has indispensable application value about speaker identification work. The pitch dif- ference will not change tone, but the pitch change will change tone. Since every person has different compass, and check material is easy to camouflage, channel and voice extraction methods, etc. factors are different in judicial speech testing process, that speaker fundamental frequency is prone to some degree of variation, so the fundamental frequency data has not comparability. It’s particularly difficult to make speaker identification be- cause of disguised speech which is the common check materiel form in judicial speech testing field, and elec- troacoustic camouflage is a typical individual speech ca- mouflage pattern.The personalized camouflage for speaker’s natural voice realized by voice changing hardware and software technology lead to most listener feel difficult to identify speaker’s identity, age and sex, and seriously affected the identification effect of judicial speech test, which bring great trouble to the judicial identification work. Aiming at the electroacoustic disguised pattern, we focus on the speech character changing rule before or after voice change. According to this variation rule of acoustic fea- ture which combined with the Chinese pitch pattern the- ory and in depth analysis of the change regularity of fun- damental frequency value before and after speaker voice change, we can compare the voice and find whether there are differences between their pitch pattern curves. As result we provide a scientific and effective method for speaker identification of such voice through pitch pattern comparison.2. Chinese Pitch PatternSince Mandarin Chinese pitch changes in different, they form four tones in Mandarin Chinese. The Chinese pitch changes bear rich speech, linguistic information, these complex changes also reflects the speaker’s pitch fea- tures. Generally we use tone shape and tone pitch to de- scribe Chinese tone. Tone shape is a reflection of funda- mental frequency changing morphology when the vocal cords vibrate. The fundamental frequency changing range is from the lowest tone to the highest tone which called tone domain. There are many internal difference existed in Chinese pitch. It is necessary to do a detailed decom- position of pitch change to analyze the various personal- ity characteristics, so we can gain the specific differences from individual tones [1].2.1. Fundamental Frequency Acquisition andProcessingNow there are many methods of pitch extraction, some- one simply adopt to choosing syllable region directly and get the average value or measure harmonic wave fre- quency value sometime and divided by harmonic wave number then make data analysis. Someone use complexH. B. ZHANG37algorithm to extract the fundamental frequency and con- sider the noise resistance performance and other factors. The former method’s operation is simple but has large measurement error, and makes little sense for fundamen- tal frequency comparison. The latter method has higher extraction precision but require complex algorithms and large number of data processing in later stage. However apply either algorithm to get fundamental tone periodic orbit that could not coincide with the true fundamental tone orbit perfectly. Based on this problem the author uses Praat software to make labeling and measuring analysis for fundamental frequency, adjust the curve data at same time to ensure smooth of the curve.Averagely select 10 sampling points from pitch curve which been extraction and smoothed, measure their fun- damental frequency value respectively. About the same tone we use length average value (L) to make normaliza- tion processing, and curve within L + 20% length range as the measuring object, in order to avoid the influence brought by time length of fundamental frequency [2]. The dots in this figure (Figure 1) mean fundamental frequency value of that time point which been analyzed by Praat program. If the fundamental frequency value is neat without sudden flip phenomenon, the analysis result is basically correct. If the fundamental frequency point free on the overall we need pay special attention and modification. Fundamental frequency value extraction errors typically occur near starting and ending position of fundamental frequency band. In addition if the funda- mental frequency is relatively low or periodicity is not clear, that requires prior check about doubtful point of fundamental frequency value to ensure the error within 4 Hz and do the accurate measurement with the help of narrow-band speech map.Direct measurements of the fundamental frequency data have some floating ranges that do not meet the speaker pitch characteristic of overall pronunciation. Now the scientific method is combined with Zhao Yuanren’s “five degree tone-marking method” as well as T value calculation formula of the tone pattern, to normalize the fundamental frequency data within 5 degree range. On fundamental frequency curve smoothing process, we find other types of curves appear the breakpoint region except the high-level tone curve. So consider the average value of high-level tone as the fundamental reference value to form pitch curve model is more accurate [3,4].2.2. Pitch Pattern Curve FittingAfter data measurement and five degrees normalization processing, the fundamental frequency data can been multiple fitted directly through Excel for minimum ra- dius of curvature, etc problems, thereby forming a smooth pitch pattern curve. Through the observation andcomparison of the pitch pattern diagram, we can easilyFigure 1. Praat fundamental frequency label analysis. summarize speaker’s pitch levels and characteristics. In addition to the comparison of their overall morphology change, also can make specific comparison analysis through parameters describe method. Such as, Upper limit value and lower limit value of pitch, average value of high- level tone, initial and ending value of each curve, the slope rate of curves rising section and descending section, etc in the model. Otherwise special attention is need to the “elbow section” and “tail section” of the curve. Con- sidering the starting and end point of pronunciation sta- bility problem, when make comparing analysis we need to make the appropriate correction.3. The Experiment and AnalysisBy selecting different speaker to make normal and cam- ouflage pronunciation from different corpus, we can analysis the fundamental frequency value change before and after camouflage, and use each corpus to fit their pitch model curve. We can research & analysis the pitch pattern curve shape stability and Feasibility using pitch patterns for speaker identification through comparative analysis the curve shape and pattern parameter of pitch. 3.1. The Experiment Corpus and DesignThis experiment select 4 speakers (3 men and 1 women) to do normal and electroacoustic disguised pronunciation about 100 syllables within four tones, that we form 8 corpus including 400 syllables, numbered list is A, B, C, D, AW, BW, CW, DW. Select the professional recording studio as recording environment to ensure a high signal to noise ratio.3.2. The Experiment Result AnalysisThe comparison of pitch model with same corpus con- tents between different speakers. Figure 2 is the pitch pattern curve selected from these four speakers’ normalH. B. ZHANG38(a)(b)(c) (d)Figure 2. Pitch pattern curve of four speakers’ normal pro- nunciation.pronunciation corpus.Comparison of four patterns can see that different speaker’s curve pattern has certain difference. (a) and (c) curved in the end compared with (b) and (d), that shows the former two speakers stop tone in rising tone end. (a) and (c) have obvious difference in the cross point of positive tone and falling-rising tone compared with (b) and (d). The former speaker’s parameter is above 4, es- pecially (c), and the latter speaker’s parameter is under 4, especially (d). This parameter (Table 1) shows their dif- ference in their positive sound rising speed or falling- rising tone falling speed. In addition there is obvious dif- ference in blank area which formed by each speaker’s positive tone, rising tone and falling-rising tone curve crossed. This analysis results show that there is essential difference between each speaker’s pitch pattern curves (Table 2).3.3. Fundamental Frequency Value Analysisbefore and after Disguised.We respectively change the low tone and high tone of these four speaker using voice changer, measure the fun- damental frequency value before and after voice change and make statistical analysis, the statistical standard de- viation is less than 0.05. That result shows that funda- mental frequency value before and after voice change and disguise have strong correlation, and have strong linear ratio relation that fundamental frequency value after voice change can go back to the original voice by multiple relations.Table 1. Pitch pattern parameter of four corpus.CorpusAverage value oflevel toneUpper limit of positive toneDiapason (a) 140.5 5.46 3.66 (b) 164.4 5.32 4.36 (c) 159.2 6.18 4.18 (d) 240.74.494.7Table 2. Pitch pattern parameter of four corpus.CorpusUpper limit of falling-rising toneLower limit of falling-rising tone(a) 6.18 2.45 (b) 6.05 1.74 (c) 5.92 1.78 (d) 5.630.843.4. The Pitch Pattern Comparison of the SameSpeaker’s Corpus before and after DisguisedFigures 3 and 4 are the pitch pattern curves respectively extracts from B and BW corpus. Although there are some differences between the two patterns, but from the over- all shape and each pitch pattern parameters’ comparative analysis, the pitch pattern did not change their quality before and after camouflage, some difference was caused by measurement error. So, the speaker identification method using pitch pattern is applicable to voice change camouflage speech.4. ConclusionsChinese is a tone language, so comparative analysis for its pitch becomes important aspects of Implementation of speaker identification during judicial speech testing pro- cess, especially for speech camouflage, the comparative analysis of Chinese pitch pattern can more objectively and accurately reflect the speaker ‘s pitch variation.This article combines with five degree tone-marking method and tone pattern theory, using Praat and Excel and other conventional software to realization of speaker’s pitch pattern measuring and fitting extraction. Based on statistical analysis of fundamental frequency values be- fore and after voice change about every corpus, we know that speech fundamental frequencies before and after voice change exists strong linear ratio relation, and then respectively compared the pitch pattern of the same speaker in curve shape and model parameter before and after voice change. Comprehensive analysis of experi- mental results, I sum up that pitch patterns exist rela- tively stability of speaker-self, there are obvious differ- ence in pitch pattern between different speakers. We can make speaker identification in electroacoustic disguisedH. B. ZHANG 39speech field in help with comparison of pitch patternscurve shape and parameter difference method.REFERENCES[1] G. Q. Zhang, Y. Z. Jin, H. W. Liu and X. Y. Cui, “Studyon Changing Rules of Electronic Disguised Voice,” Evi- dence Science , Vol. 16, No. 4, 2010, pp. 10-11.[2] W. W. Song and X. Y. Du, “A Simple Method aboutThird-Order Curve Fitting,” Information Technology , 2008, p. 6. Figure 3. Normal pitch pattern.[3] Q. Q. Feng, “Experimental Study on the Pitch Pattern ofHarbin Dialect,” Liaoning Technical University Journal (Social Sciences Version), Vol. 1, No. 2, 2008, pp. 5-7.[4] L. Chen and X. W. Zhang, “A Novel Approach forSpeech Camouflage Communication Based on Speech Quality Evaluation,” Signal Processing , Vol. 19. No. 5, 2003, pp. 23-25.Figure 4. Disguised pitch pattern.。

ideal time-frequency analysis -回复

ideal time-frequency analysis -回复对于信号处理和数据分析领域来说，时间频率分析是一种非常重要的工具和方法。

它可以用来研究信号在时间和频率上的变化特征，揭示信号所蕴含的信息。

在这篇文章中，我们将一步一步地回答关于时间频率分析（TFA）的问题，从基础知识到常用方法和应用案例。

1. 时间频率分析是什么？时间频率分析是信号处理和数据分析领域中一种研究信号在时间和频率上变化特征的方法。

它将信号分解成时间和频率上的成分，以便更好地理解和解释信号的特征。

通过时间频率分析，可以确定信号在不同时刻和不同频率上的能量分布，进而研究信号的时频特性。

2. 为什么需要时间频率分析？在许多实际问题中，信号往往具有时间和频率上的非平稳性质。

传统的时域分析和频域分析往往不能很好地处理这种非平稳信号。

时间频率分析提供了一种更细致的分析方法，可以更好地反映信号的时频特性。

3. 时间频率表示方法有哪些？时间频率表示方法是时间频率分析的核心。

常见的时间频率表示方法有短时傅里叶变换（STFT）、连续小波变换（CWT）和分布式傅里叶变换（DFT）。

不同的方法适用于不同的信号类型和应用场景。

4. 短时傅里叶变换（STFT）短时傅里叶变换是最常用的时间频率表示方法之一。

它将信号分成小段，并对每段进行傅里叶变换，得到在时间和频率上的能量分布。

STFT的主要特点是时间和频率分辨率可以灵活地调整，但是存在时间-频率不确定性的问题。

5. 连续小波变换（CWT）连续小波变换是一种基于小波分析的时间频率表示方法。

它通过将信号与一组小波函数进行卷积，得到在时间和频率上的能量分布。

相比于STFT，CWT具有更好的时间-频率局部化特性，可以更准确地分析信号的瞬态特性。

6. 分布式傅里叶变换（DFT）分布式傅里叶变换是一种基于时间-频率和时间-时间局部性原理的时间频率表示方法。

它将时频平面分成小块，并在每个块内进行傅里叶变换，得到时频局部性能量分布。

时频分析英语作文

时频分析英语作文Title: An Exploration of Time-Frequency Analysis。

Time-frequency analysis is a powerful tool used in various fields such as signal processing, communication engineering, and neuroscience. It provides insights into the time-varying characteristics of signals, allowing researchers to understand their behavior in both the time and frequency domains. In this essay, we will delve into the principles, methods, and applications of time-frequency analysis.### Introduction to Time-Frequency Analysis。

Time-frequency analysis is concerned with analyzing signals in both the time and frequency domains simultaneously. Unlike traditional Fourier analysis, which provides information about the frequency content of asignal over its entire duration, time-frequency analysis focuses on how the frequency content of a signal changesover time. This is particularly useful when dealing with non-stationary signals whose frequency components evolve over time.### Principles of Time-Frequency Analysis。