Cooperative frequency-modulated continuous-waveform radar systems

Patent metadata

Field	Value
Publication number	US-11061126-B2
Application number	US-201916364868-A
Country	US
Kind code	B2
Filing date	Mar 26, 2019
Priority date	Mar 26, 2019
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

A system and a method that enable two or more dispersed platforms to simultaneously use respective frequency-modulated continuous-wave radar systems in a typical radar application such as synthetic-aperture radar for terrain mapping, moving-target indicator radar to track targets on the ground and air-to-air tracking of other aircraft. The systems use the same RF spectrum in their operation and also communicate through their respective radar systems while simultaneously reducing their interplatform interference through the use of both filters and coded waveforms.

First claim

The invention claimed is:

1. A distributive collaborative radar network comprising first and second radar systems having synchronized respective clocks, wherein each of the first and second radar systems comprises a respective common radar/communications transmitter comprising a transmission antenna and a combined radar and communications receiver comprising a common reception antenna, a radar receiver connected to the common reception antenna and a communications receiver connected to the common reception antenna, wherein:
the common radar/communications transmitters of the first and second radar systems are each configured to convert respective periodic time and position information into respective timing headers representing successive times and respective position prediction sections representing successive positions which are valid for those respective times in a respective packet of data and then transmit frequency-modulated continuous-wave signals representing the respective packet of data; and
the communications receivers of the first and second radar systems are each configured to extract timing and position information from received frequency-modulated continuous-wave signals and compute a respective local position and respective time offset using the timing and position information,
wherein the common radar/communications transmitter of the first radar system is further configured to transmit frequency-modulated continuous-wave signals having a first chirp slope and the common radar/communications transmitter of the second radar system is further configured to transmit frequency-modulated continuous-wave signals having a second chirp slope, and
wherein the radar receiver of the first radar system is further configured to demodulate received frequency-modulated continuous-wave signals to form return signals and then filter out return signals having the second chirp slope when the second chirp slope is different than the first chirp slope.

2. The distributive collaborative radar network as recited in claim 1 , wherein the radar receiver of the second radar system is further configured to demodulate received frequency-modulated continuous-wave signals to form return signals and then filter out return signals having the first chirp slope when the second chirp slope is different than the first chirp slope.

3. The distributive collaborative radar network as recited in claim 1 , wherein:
the radar receiver of the first radar system is further configured to filter out return signals derived from frequency-modulated continuous-wave signals received from beyond a maximum return distance; and
the common radar/communications transmitter of the second radar system is further configured to transmit frequency-modulated continuous-wave signals having the second chirp slope with a start time delay equal to at least a time for the frequency-modulated continuous-wave signals having the second chirp slope to travel the maximum return distance of the radar receiver of the first radar system.

4. The distributive collaborative radar network as recited in claim 3 , wherein the radar receiver of the first radar system comprises a first analog-to-digital converter that converts analog return signals to digital return signals, and the radar receiver of the second radar system comprises a second analog-to-digital converter that converts analog return signals to digital return signals.

5. The distributive collaborative radar network as recited in claim 4 , wherein the radar receiver of the first radar system further comprises a first demod/remod filter that is configured to filter out return signals having the second chirp slope.

6. The distributive collaborative radar network as recited in claim 5 , wherein the radar receiver of the second radar system further comprises a second demod/remod filter that is configured to filter out return signals having the first chirp slope.

7. The distributive collaborative radar network as recited in claim 5 , wherein the radar receiver of the first radar system further comprises a high-pass filter that receives return signals which have passed through the first demod/remod filter and passes return signals having frequencies above a threshold corresponding to the maximum return distance for up chirps.

8. The distributive collaborative radar network as recited in claim 7 , wherein the radar receiver of the first radar system further comprises a low-pass filter that receives return signals which have passed through the first demod/remod filter and passes return signals having frequencies below a threshold corresponding to a maximum return distance for down chirps.

9. The distributive collaborative radar network as recited in claim 8 , wherein the radar receiver of the first radar system further comprises a radar signal processing module configured to find a peak in frequency in the return signals which have passed through the high- and low-pass filters for up and down chirps and estimate a range and a velocity of a target object.

10. The distributive collaborative radar network as recited in claim 1 , wherein the timing headers and position prediction sections are in a form of supersymbols, each supersymbol being a concatenation of pairs of up chirps and down chirps of equal chirp lengths, the up chirps of the concatenation having the same up phase and the down chirps of the concatenation having the same down phase.

11. The distributive collaborative radar network as recited in claim 1 , wherein the data in each packet further includes payload sections made up of multiple symbols and timing header/position prediction slots made up of multiple supersymbols, wherein the payload sections and timing header/position prediction slots alternate in sequence within the packet, and each timing header/position prediction slot includes a respective timing header and a respective position prediction section which is contiguous with the respective timing header.

12. The distributive collaborative radar network as recited in claim 11 , wherein:
supersymbols in timing headers of the timing header/position prediction slots of supersymbols transmitted by the common radar/communications transmitter of the first radar system are phase encoded with time information indicating a duration of time for which a prediction of a position of the first radar system was valid; and
supersymbols in position prediction sections of the timing header/position prediction slots transmitted by the common radar/communications transmitter of the first radar system are phase encoded with position information indicating the prediction of the position of the first radar system.

13. A distributive collaborative radar network comprising first and second radar systems having synchronized respective clocks, wherein each of the first and second radar systems comprises a respective common radar/communications transmitter comprising a transmission antenna and a combined radar and communications receiver comprising a common reception antenna, a radar receiver connected to the common reception antenna and a communications receiver connected to the common reception antenna, wherein:
the common radar/communications transmitters of the first and second radar systems are each configured to convert respective periodic time and position information into respective timing headers representing successive times and respective position prediction sections representing successive positions which are valid for those respective times in a respective packet of data and then transmit frequency-modulated continuous-wave signals representing the respective packet of data; and
the communications receiver of the first and

Assignees

• Boeing Co

Inventors

• Ray Gary A

Classifications

• H04L27/2273

  associated with quadrature demodulation, e.g. Costas loop · CPC title

• H04B1/16

  Circuits · CPC title

• H04L27/3863

  Compensation for quadrature error in the received signal · CPC title

• H03D7/166

  using two or more quadrature frequency translation stages · CPC title

• G01S13/24

  using frequency agility of carrier wave · CPC title