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Frequency modulated continuous wave (FMCW) radar
• Transmit and receive continuously and simultaneously
• • • • • No blind zones in range Highest possible duty cycle Requires separate transmit and receive antennas for highest sensitivity Simple transceiver Sensitivity is limited by crosstalk between transmit and receive antennas and the stability of the transmitted signal
• Radar
• all-weather conditions • range, azimuth, elevation and range rate measurement • no continuous coverage (until now)
June 17, 2010
Mid-Air Collision Avoidance Volume surveillance with radar
• Linear frequency modulation achieves lowest bandwidth on receive
• Beat frequency
fb =
B ⋅ t B ⋅ 2R = T T ⋅c
• Example: B = 100 MHz (∆R = 1.5 m), R = 15 km, T = 1 ms → fb = 10 MHz • factor 10 sampling rate reduction w.r.t. pulse radar with the same range resolution Sweep time (T) Frequency
Rx
1-D FFT
2-D FFT
Rx Rx Rx
doppler digital digital filter / beam array ranging forming antenna
13 Digital MultiBeam Radar Rx
= receiver incl. ADC
June 17, 2010
June 17, 2010
• Example: t = 100 µs → R = 15 km
• Range resolution : ∆R =
• Example: τ = 10 ns → ∆R = 1.5 m
6 Digital MultiBeam Radar
Radar Fundamentals (2)
Transmitted sweep Echo
Beat frequency (fb) Time
Sweep bandwidth (B)
8
Digital MultiBeam Radar
June 17, 2010
Mid-Air Collision Avoidance Crowded aerospace leads to accidents
1975 1938
4 Digital MultiBeam Radar June 17, 2010
AMBER
Scalable
DIAMOND
Distributed
Radar Technology
EMERALD
5 Digital MultiBeam Radar Multifunction
SAPPHIRE
Airborne Safety Radar
Digital multiple beam radar • continuous coverage (no scanning beams) • (frequency modulated) continuous wave (no blind zone) • planar antenna arrays (easy to integrate in aircraft)
June 17, 2010 Imaging
Radar Fundamentals (1)
Pulse radar
Pulse length (τ)
Peak Power (P) Time delay (t)
Transmitted pulse
Echo pulse
• Range : R =
c ⋅t 2 c ⋅τ 2
2
Digital MultiBeam Radar
June 17, 2010
Why Radar?
• Radar penetrates objects that are opaque for other sensors
• • • • • • fog dust walls clothes soil …
• Radar can measure
Transmit antenna
Crosstalk
Receive antenna Beat signal
7
Digital MultiBeam Radar
Baidu Nhomakorabea
June 17, 2010
Radar Fundamentals (3)
Frequency modulated continuous wave (FMCW) radar
Digital multiple beam radar
• • • • • Floodlight transmit beam Multiple beams on receive Receiver behind each antenna element (continuous coverage) Digital beamforming with 2-D FFT Doppler filtering with FFT Transmitter
TNO Radar Heritage
Active phased array radar PHARUS Passive phased array radar FUCAS
Digital phased array radar AMBER
Electronic listening device
2006 1995
1 km
1.5 km 10 km
1.5 km
11
Digital MultiBeam Radar
June 17, 2010
Volume Surveillance with Radar
Pencil beam scanning
• single transmitter and receiver • long scan time with single pencil beam (no continuous coverage) Mechanical scanning
10 Digital MultiBeam Radar
Non-cooperative systems • Visual flight rules (VFR)
• well-established method • depends on pilot’s eyes • does not work in bad weather
Transmitter
Gimbal
Receiver Reflector antenna
Electronical scanning
Transmitter
Receiver Phased array antenna
12 Digital MultiBeam Radar June 17, 2010
Volume Surveillance with Radar
Airborne Safety Radar Functions
Mid-air collision avoidance Ground proximity warning
Weather hazard detection
High resolution ground mapping
17
Digital MultiBeam Radar
• • • • • range azimuth elevation radial velocity material properties • dielectric constant • temperature
• Non-ionising
3
Digital MultiBeam Radar
June 17, 2010
9
Digital MultiBeam Radar
June 17, 2010
Mid-Air Collision Avoidance
Cooperative systems • Air traffic control (ATC) • well-established method • collision avoidance through transponders and voice communications with aircraft • does not work for aircraft without transponders and/or comms • Traffic Collision Avoidance System (TCAS) • based on interrogation of transponders • independent of ATC • does not work for aircraft without transponders
June 17, 2010
Conclusions
• Novel digital multibeam radar concept for mid-air collision avoidance • Floodlight transmission with (FM)CW waveform → continuous coverage • Planar receive antenna array with (many ) digital receivers • Multiple simultaneous beams created by digital beamforming • No mechanical or electronical scanning • Easy to integrate in aircraft • Radar concept proven during flight trial • Multiple radar functions • mid-air collision avoidance • ground proximity warning • hazardous weather detection • high resolution ground mapping
14
Digital MultiBeam Radar
June 17, 2010
Airborne Safety Radar Demonstrator
• • • • • • 1 transmit channel 256 receive channels scalable front-end: 8 × 32 channels real-time digital beamforming USB 2.0 interface CompactFlash on-board storage
“Frontware”
“Middleware”
15
Digital MultiBeam Radar
June 17, 2010
Airborne Safety Radar Trial
Receive Antenna
Transmit Antenna
16
Digital MultiBeam Radar
June 17, 2010
• Electro-optical cameras
• relatively mature • continuous coverage with wide field-of-view cameras • no range and range rate information • does not work in bad weather
Digital MultiBeam Radar
Bits & Chips Hardware Conference
Albert Huizing
Outline
• • • • Why radar? Radar fundamentals Mid-air collision avoidance Airborne safety radar • Concept • Block diagram • Hardware requirements • Conclusions
• Transmit and receive continuously and simultaneously
• • • • • No blind zones in range Highest possible duty cycle Requires separate transmit and receive antennas for highest sensitivity Simple transceiver Sensitivity is limited by crosstalk between transmit and receive antennas and the stability of the transmitted signal
• Radar
• all-weather conditions • range, azimuth, elevation and range rate measurement • no continuous coverage (until now)
June 17, 2010
Mid-Air Collision Avoidance Volume surveillance with radar
• Linear frequency modulation achieves lowest bandwidth on receive
• Beat frequency
fb =
B ⋅ t B ⋅ 2R = T T ⋅c
• Example: B = 100 MHz (∆R = 1.5 m), R = 15 km, T = 1 ms → fb = 10 MHz • factor 10 sampling rate reduction w.r.t. pulse radar with the same range resolution Sweep time (T) Frequency
Rx
1-D FFT
2-D FFT
Rx Rx Rx
doppler digital digital filter / beam array ranging forming antenna
13 Digital MultiBeam Radar Rx
= receiver incl. ADC
June 17, 2010
June 17, 2010
• Example: t = 100 µs → R = 15 km
• Range resolution : ∆R =
• Example: τ = 10 ns → ∆R = 1.5 m
6 Digital MultiBeam Radar
Radar Fundamentals (2)
Transmitted sweep Echo
Beat frequency (fb) Time
Sweep bandwidth (B)
8
Digital MultiBeam Radar
June 17, 2010
Mid-Air Collision Avoidance Crowded aerospace leads to accidents
1975 1938
4 Digital MultiBeam Radar June 17, 2010
AMBER
Scalable
DIAMOND
Distributed
Radar Technology
EMERALD
5 Digital MultiBeam Radar Multifunction
SAPPHIRE
Airborne Safety Radar
Digital multiple beam radar • continuous coverage (no scanning beams) • (frequency modulated) continuous wave (no blind zone) • planar antenna arrays (easy to integrate in aircraft)
June 17, 2010 Imaging
Radar Fundamentals (1)
Pulse radar
Pulse length (τ)
Peak Power (P) Time delay (t)
Transmitted pulse
Echo pulse
• Range : R =
c ⋅t 2 c ⋅τ 2
2
Digital MultiBeam Radar
June 17, 2010
Why Radar?
• Radar penetrates objects that are opaque for other sensors
• • • • • • fog dust walls clothes soil …
• Radar can measure
Transmit antenna
Crosstalk
Receive antenna Beat signal
7
Digital MultiBeam Radar
Baidu Nhomakorabea
June 17, 2010
Radar Fundamentals (3)
Frequency modulated continuous wave (FMCW) radar
Digital multiple beam radar
• • • • • Floodlight transmit beam Multiple beams on receive Receiver behind each antenna element (continuous coverage) Digital beamforming with 2-D FFT Doppler filtering with FFT Transmitter
TNO Radar Heritage
Active phased array radar PHARUS Passive phased array radar FUCAS
Digital phased array radar AMBER
Electronic listening device
2006 1995
1 km
1.5 km 10 km
1.5 km
11
Digital MultiBeam Radar
June 17, 2010
Volume Surveillance with Radar
Pencil beam scanning
• single transmitter and receiver • long scan time with single pencil beam (no continuous coverage) Mechanical scanning
10 Digital MultiBeam Radar
Non-cooperative systems • Visual flight rules (VFR)
• well-established method • depends on pilot’s eyes • does not work in bad weather
Transmitter
Gimbal
Receiver Reflector antenna
Electronical scanning
Transmitter
Receiver Phased array antenna
12 Digital MultiBeam Radar June 17, 2010
Volume Surveillance with Radar
Airborne Safety Radar Functions
Mid-air collision avoidance Ground proximity warning
Weather hazard detection
High resolution ground mapping
17
Digital MultiBeam Radar
• • • • • range azimuth elevation radial velocity material properties • dielectric constant • temperature
• Non-ionising
3
Digital MultiBeam Radar
June 17, 2010
9
Digital MultiBeam Radar
June 17, 2010
Mid-Air Collision Avoidance
Cooperative systems • Air traffic control (ATC) • well-established method • collision avoidance through transponders and voice communications with aircraft • does not work for aircraft without transponders and/or comms • Traffic Collision Avoidance System (TCAS) • based on interrogation of transponders • independent of ATC • does not work for aircraft without transponders
June 17, 2010
Conclusions
• Novel digital multibeam radar concept for mid-air collision avoidance • Floodlight transmission with (FM)CW waveform → continuous coverage • Planar receive antenna array with (many ) digital receivers • Multiple simultaneous beams created by digital beamforming • No mechanical or electronical scanning • Easy to integrate in aircraft • Radar concept proven during flight trial • Multiple radar functions • mid-air collision avoidance • ground proximity warning • hazardous weather detection • high resolution ground mapping
14
Digital MultiBeam Radar
June 17, 2010
Airborne Safety Radar Demonstrator
• • • • • • 1 transmit channel 256 receive channels scalable front-end: 8 × 32 channels real-time digital beamforming USB 2.0 interface CompactFlash on-board storage
“Frontware”
“Middleware”
15
Digital MultiBeam Radar
June 17, 2010
Airborne Safety Radar Trial
Receive Antenna
Transmit Antenna
16
Digital MultiBeam Radar
June 17, 2010
• Electro-optical cameras
• relatively mature • continuous coverage with wide field-of-view cameras • no range and range rate information • does not work in bad weather
Digital MultiBeam Radar
Bits & Chips Hardware Conference
Albert Huizing
Outline
• • • • Why radar? Radar fundamentals Mid-air collision avoidance Airborne safety radar • Concept • Block diagram • Hardware requirements • Conclusions