Shaping the spectrum of random-phase radar waveforms

Patent metadata

Field	Value
Publication number	US-9645228-B1
Application number	US-201314102928-A
Country	US
Kind code	B1
Filing date	Dec 11, 2013
Priority date	Dec 14, 2012
Publication date	May 9, 2017
Grant date	May 9, 2017

Abstract

The various technologies presented herein relate to generation of a desired waveform profile in the form of a spectrum of apparently random noise (e.g., white noise or colored noise), but with precise spectral characteristics. Hence, a waveform profile that could be readily determined (e.g., by a spoofing system) is effectively obscured. Obscuration is achieved by dividing the waveform into a series of chips, each with an assigned frequency, wherein the sequence of chips are subsequently randomized. Randomization can be a function of the application of a key to the chip sequence. During processing of the echo pulse, a copy of the randomized transmitted pulse is recovered or regenerated against which the received echo is correlated. Hence, with the echo energy range-compressed in this manner, it is possible to generate a radar image with precise impulse response.

First claim

What is claimed is:

1. A method performed at a radar system, the method being for generating a randomized radar pulse waveform, the method comprising:
determining, at a processing component of the radar system, a waveform spectrum profile, the determining being based on at least one parameter;
assigning, at the processing component, sample frequencies of the waveform spectrum profile to a set of chips;
configuring, at the processing component, an order of chips in the set of chips based upon a randomization key to form a randomized sequence of chips; and
transmitting a pulse signal having a waveform that is based upon the randomized sequence of chips, the signal transmitted from a transceiver of the radar system.

2. The method of claim 1 , wherein a frequency width spacing of a first chip in the set of chips is equal to the frequency width spacing of a second chip in the set of chips.

3. The method of claim 1 , wherein a frequency width spacing of a first chip in the set of chips is disparate to the frequency width spacing of a second chip in the set of chips.

4. The method of claim 1 , wherein the randomization key is a pseudo-random code.

5. The method of claim 1 , further comprising controlling, at the processing component, a duration of transmission of a chip in the randomized sequence of chips to facilitate achieving a desired energy for the chip.

6. The method of claim 1 , further comprising:
receiving, at the transceiver, an echo pulse, wherein the echo pulse is based at least in part on an interaction between the pulse signal and a target;
comparing, at the processing component, the echo pulse to a copy of the transmitted pulse signal; and
based at least in part on the comparing of the echo pulse to a copy of the transmitted pulse signal, determining, at the processing component, at least one characteristic of the target.

7. The method of claim 1 , wherein an energy spectral density of the transmitted pulse signal is equal to one of a linear frequency modulated chirp, a non-linear frequency modulated chirp, a stepped frequency profile chirp, a phase-coded modulation profile chirp, a random noise waveform chirp, or a pseudo-random noise waveform chirp.

8. A radar system comprising:
a chip frequency component configured to slice a radar waveform into a plurality of chips, wherein the plurality of chips have an original sequence;
a chip randomizer component configured to re-sequence the original sequence of chips into a randomized sequence of chips; and
a phase accumulator component configured to accumulate frequencies of the randomized sequence of chips to facilitate production of a phase function for each chip in the randomized sequence of chips.

9. The system of claim 8 , further comprising a read-only-memory (ROM) component configured to convert the phase function for each chip in the randomized sequence of chips into an amplitude to facilitate generation of a transmittable pulse.

10. The system of claim 8 , further comprising a randomization key, wherein the randomization key is utilized by the chip randomizer component to facilitate generation of a randomized sequence of chips.

11. The system of claim 10 , wherein the randomization key is one of a randomly generated code or a code retrieved from a database.

12. The system of claim 8 , further comprising a transceiver configured to transmit a pulse, wherein the pulse comprises the randomized sequence of chips.

13. The system of claim 12 , wherein the transceiver is further configured to receive an echo pulse, wherein the echo pulse is a reflection, from a target, of the transmitted pulse.

14. The system of claim 13 , further comprising a correlator component configured to compare the echo pulse to the transmitted pulse.

15. The system of claim 14 , the correlator component further configured to measure at least one target characteristic based on comparing the echo pulse with the transmitted pulse.

16. The system of claim 8 , wherein the radar waveform's original sequence is one of a linear frequency modulated chirp, a non-linear frequency modulated chirp, a stepped frequency profile chirp, a phase-coded modulation profile chirp, a random noise waveform chirp, or a pseudo-random noise waveform chirp.

17. A method for utilizing a randomized radar pulse waveform at a radar system, the method comprising:
at a processing component of the radar system:
slicing a waveform into an original sequence of chips;
obtaining a randomization key; and
randomizing the sequence of chips with the randomization key to form a transmittable pulse comprising a randomized sequence of chips;

at a transceiver of the radar system:
transmitting the pulse; and
receiving an echo pulse, wherein the echo pulse is based at least in part on an interaction of the transmitted pulse and a target;

responsive to receiving the echo pulse, and at the processing component of the radar system:
comparing the echo pulse with the transmitted pulse; and
determining at least one target characteristic based at least in part on comparing an energy of a first chip in the transmitted sequence of chips with an energy of the first chip in the sequence of chips derived from the echo pulse.

18. The method of claim 17 , wherein the randomization key is one of a randomly generated code or a code obtained from a database.

19. The method of claim 17 , further comprising controlling, at the processing component, a duration of transmission of a chip in the randomized sequence of chips to facilitate achieving a required energy for the chip.

20. The method of claim 17 , wherein a frequency sample spacing of a first pair of frequency samples in the energy spectrum of a waveform is equal to the frequency sample spacing of a second pair of frequency samples in the energy spectrum of the waveform, or the frequency sample spacing of a first pair of frequency samples in the energy spectrum of the waveform is disparate to a second pair of frequency samples in the energy spectrum of the waveform.

Assignees

• Sandia Corp
• General Atomics Aeronautical Systems Inc

Inventors

• Doerry Armin W
• Marquette Brandeis

Classifications

• G01S7/292 Primary

  Extracting wanted echo-signals · CPC title

• G01S13/284 Primary

  using coded pulses · CPC title

• G01S13/0209

  Systems with very large relative bandwidth, i.e. larger than 10 %, e.g. baseband, pulse, carrier-free, ultrawideband · CPC title

• G01S7/282

  Transmitters · CPC title