接收机参数

Receiver Parameters

接收机参数

云南监测站业务室

2011年3月

Content

目录

*Receiver Parameters

*接收机参数

1、Noise Figure

噪声系数

2、MDS

最小可探测信号

3、Sensitivity

灵敏度

4、IP2/IP3

二阶截获点/ 三阶截获点

5、1dB compression

1dB压缩点

6、Oscillator phase noise

振荡器相位噪声

7、2nd / 3rd IFfilter

第2/第3中频滤波器

8、Dynamic range / Spurious free dynamic range

动态范围/无杂散动态范围

* Receiver Operating Modes

*接收机工作模式

1、Low noise mode

低噪声模式

2、Normal mode

常规模式

3、Low distortion mode

低失真模式

Noise

噪声

The physical causes for this effect ultimately lie in irregular electron movements.

有电流的地方就有噪声。这种现象的产生归结为电子的不规则运动。

The following principle applies: The higher the current, the more noise is generated in our receiver.

我们的接收机遵循下面的原则：电流越大，接收机产生的噪声就越大。

We must therefore try a low-current receiver design, although this very quickly conflicts with its linearity.

因此，我们将尽量采用低电流的接收机设计，尽管这与接收机的线性度形成了冲突。（接收机电流越小，接收机的线性度就越低。这就形成了一对矛盾）

The requirements for "low noise" (NF) and "high linearity" (IP3) are opposite in nature.

对于低噪声（NF噪声系数）和高线性度（IP3三阶截获点）的要求在本质上是相反的，是一对矛盾关系。

Noise is understood as the inherent noise of a receiver, which reduces the original signal-to-noise ratio of an input signal.

噪声被理解为接收机的固有噪声（内部噪声），它降低了输入信号的信噪比。

Inherent noise is therefore a measure of the sensitivity of the receiver. It allows conclusions as to the minimum level the signals must have to be detectable save.

所以固有噪声（内部噪声）是衡量接收机灵敏度的尺度之一。由此得出结论：内部噪声是可靠检测小信号的关键。

The inherent noise is usually expressed as a bandwidth-independent value: Noise Figure(NF).

固有噪声通常表示为一个与带宽无关的值：噪声系数（NF）。

MDS-Minimum Detectable Signal = DNL

最小可探测信号

MDS = -174dBm + NF + 10▪log(RBW/1Hz) + 3dB

(RBW/1Hz) →Best MDS-value for RBW =1 Hz

当RBW=1Hz时可以得到最好的MDS.

3dB→important to calculate SFDR2 and SFDR3

对于计算2阶和3阶无杂散动态范围很重要

MDS/dBm = minimum detectable signal

最小可探测信号单位：dBm

-174 dBm = basic noise floor at room temperature(@ 1 Hz BW)

室温下的最小基本噪声

NF / dB = noise figure

噪声系数单位：dB

RBW / Hz = used resolution band width

所用分辨力带宽

3 dB = noise level + equal signal level increase power by 3dB (if signal is in phase with random noise phase )

噪声电平+ 等信号电平增加3dB功率（如果信号相位与噪声相位同相）

Sensitivity

灵敏度

The sensitivity of a receiver is calculated from

接收机的灵敏度计算方法如下：

P in, min(dBm) = -174dBm / Hz + NF + 10·lgBW + S/N

BW →e.g. demod BW=6KHz for AM

带宽例如AM的解调带宽为6KHz

e.g. demod BW= 15KHz for FM

例如FM的解调带宽为15KHz

S/N →e.g. S/N = 12dB for AM

信噪比例如AM信噪比为12dB

e.g. S/N = 20dB for FM

例如FM信噪比为20dB