TECHNIQUES FOR PHASE MODULATED SIGNALS HAVING POOR AUTOCORRELATION

• US 20200136870A1
• Filed: 10/29/2018
• Published: 04/30/2020
• Est. Priority Date: 10/29/2018
• Status: Active Grant

• Current Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Original Assignee: BAE Systems Information and Electronic Systems Integration Incorporated (BAE Systems Plc)
• Inventors: Watson, William D., Basu, Prabahan, Beaudeau, Jonathan P., Couto, David J.
• Granted Patent: US 10,666,475 B2
• Time in Patent Office: Days
• CPC Class Codes: G01S 7/006 using shared front-end circuitry, e.g. antennas G01S13/765, G01S13/825 take precedence
• CPC Class Codes: H04J 13/10 Code generation
• CPC Class Codes: H04L 27/20 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/2278 using correlation techniques, e.g. for spread spectrum signals

Abstract

An electronic transmitter includes: a modulator to phase modulate a carrier signal with a baseband signal using a phase modulation sequence; and an emitter to emit the phase modulated signal. The phase modulated signal has poor autocorrelation, has a corresponding mismatched filter based on the phase modulation sequence, and is configured to demodulate into the baseband signal through poor cross-correlation with the mismatched filter. Sometimes, the transmitter is part of a sensing apparatus, where the emitter emits the phase modulated signal at a target and the emitted signal reflects off the target. The sensing apparatus includes a receiver that has a collector to collect the reflected signal, and a demodulator to demodulate the collected signal into the baseband signal through the poor cross-correlation with the mismatched filter. Sometimes, the transmitter is part of a communication system, where the emitter emits the phase modulated signal to an intended recipient.

Claims

1. An electronic sensing apparatus comprising:

a modulator to phase modulate a carrier signal with a baseband signal using a phase modulation sequence, wherein the phase modulated signal has poor autocorrelation;

an emitter to emit the phase modulated signal; and

a receiver, wherein the receiver includes

a collector to collect the emitted phase modulated signal, and

a demodulator to demodulate the phase modulated signal into the baseband signal through poor cross-correlation with a mismatched filter, wherein the mismatched filter is based on the phase modulated sequence.

2. The electronic sensing apparatus of claim 1, wherein the emitter is further configured to emit the phase modulated signal at a target and the emitted signal is configured to reflect off the target to generate a reflected signal;

and the collector to collect the reflected signal.

3. The electronic sensing apparatus of claim 1, wherein the emitter is further configured to emit the phase modulated signal to an intended recipient;

and the receiver is at the intended recipient.

4. The electronic sensing apparatus of claim 1, wherein the phase modulation sequence is a final phase modulation sequence generated by a sequence generation circuit configured to:

generate an initial phase modulation sequence having an initial autocorrelation sequence;

iteratively adjust the initial autocorrelation sequence having an initial autocorrelation metric to a target autocorrelation sequence having a target autocorrelation metric corresponding to the poor autocorrelation;

generate an intermediate phase modulation sequence corresponding to the target autocorrelation sequence and based on the target autocorrelation metric;

iteratively generate next phase modulation sequences from the intermediate phase modulation sequence, the next phase modulation sequences corresponding to the target autocorrelation sequence and having corresponding autocorrelation metrics successively approaching the target autocorrelation metric; and

output a last of the next phase modulation sequences as the final phase modulation sequence when a last of the corresponding autocorrelation metrics is sufficiently close to the target autocorrelation metric.

5. The electronic sensing apparatus of claim 4, wherein the target autocorrelation metric is sufficiently close to a worst autocorrelation metric.

6. The electronic sensing apparatus of claim 5, wherein the worst autocorrelation metric is the Barankin Bound.

7. The electronic sensing apparatus of claim 4, wherein the sequence generation circuit is further configured to iteratively generate the next phase modulation sequences by iteratively:

generating a next set of frequencies based on a frequency domain expansion of the target autocorrelation sequence and that minimizes differences between the target autocorrelation sequence and the autocorrelation sequence of a current one of the next phase modulation sequences; and

generating a next one of the next phase modulation sequences that minimizes differences between the next set of frequencies and those of the frequency domain expansion of the target autocorrelation sequence.

8. The electronic sensing apparatus of claim 4, wherein the sequence generation circuit is further configured to generate the mismatched filter from the final phase modulation sequence.

9. A method of electronic sensing, the method comprising:

phase modulating a carrier signal with a baseband signal using a phase modulation sequence by a modulator, wherein the phase modulated signal has poor autocorrelation;

emitting the phase modulated signal using an emitter;

collecting the emitted phase modulated signal using a collector; and

demodulating, with a demodulator, the collected signal into the baseband signal through poor cross-correlation with a mismatched filter, wherein the mismatched filter is based on the phase modulated sequence.

10. The method of claim 9, wherein emitting the phase modulated signal comprises

emitting the phase modulated signal at a target to generate a reflected signal;

reflecting the emitted phase modulated signal off the target; and

collecting the reflected signal using the collector.

11. The method of claim 9, wherein emitting the phase modulated signal comprises emitting the phase modulated signal to an intended recipient;

and wherein the collector is at the intended recipient.

12. An electronic receiver comprising:

a collector to collect an emitted or reflected signal, wherein the emitted or reflected signal is from a phase modulated signal generated using a phase modulation sequence, and the phase modulated signal

has poor autocorrelation,

has a corresponding mismatched filter based on the phase modulation sequence, and

is configured to demodulate into a baseband signal through poor cross-correlation with the mismatched filter; and

a demodulator to demodulate the collected emitted or reflected signal into the baseband signal through the poor cross-correlation with the mismatched filter.

13. An electronic sensing apparatus comprising:

the receiver of claim 12, wherein the emitted or reflected signal is a reflected signal off a target; and

a transmitter including

a modulator to phase modulate the baseband signal into the phase modulated signal, and

an emitter to emit the phase modulated signal at the target, wherein the emitted signal is to reflect off the target to become the reflected signal.

14. An electronic communication system comprising:

the receiver of claim 12, wherein the emitted or reflected signal is an emitted signal; and

a transmitter including

a modulator to phase modulate the baseband signal into the phase modulated signal, and

an emitter to emit the phase modulated signal as the emitted signal at the collector.

15. A method of phase modulation sequence generation using a processing circuit, the generated phase modulation sequence being a final phase modulation sequence used to phase modulate a carrier signal with a baseband signal to create a phase modulated signal having poor autocorrelation and a corresponding mismatched filter based on the phase modulation sequence, the phase modulated signal being configured to demodulate into the baseband signal through poor cross-correlation with the mismatched filter, the method comprising:

generating, by the processing circuit, an initial phase modulation sequence having an initial autocorrelation sequence;

iteratively adjusting, by the processing circuit, the initial autocorrelation sequence having an initial autocorrelation metric to a target autocorrelation sequence having a target autocorrelation metric corresponding to the poor autocorrelation;

generating, by the processing circuit, an intermediate phase modulation sequence corresponding to the target autocorrelation sequence and based on the target autocorrelation metric;

iteratively generating, by the processing circuit, next phase modulation sequences from the intermediate phase modulation sequence, the next phase modulation sequences corresponding to the target autocorrelation sequence and having corresponding autocorrelation metrics successively approaching the target autocorrelation metric; and

outputting, by the processing circuit, a last of the next phase modulation sequences as the final phase modulation sequence when a last of the corresponding autocorrelation metrics is sufficiently close to the target autocorrelation metric.

16. The method of claim 15, wherein the target autocorrelation metric is sufficiently close to a worst autocorrelation metric.

17. The method of claim 16, wherein the worst autocorrelation metric is the Barankin Bound.

18. The method of claim 15, wherein iteratively generating the next phase modulation sequences comprises iteratively:

generating a next set of frequencies based on a frequency domain expansion of the target autocorrelation sequence and that minimizes differences between the target autocorrelation sequence and the autocorrelation sequence of a current one of the next phase modulation sequences; and

generating a next one of the next phase modulation sequences that minimizes differences between the next set of frequencies and those of the frequency domain expansion of the target autocorrelation sequence.

19. The method of claim 15, further comprising generating, by the processing circuit, the mismatched filter from the final phase modulation sequence.

20. A computer program product including one or more non-transitory machine-readable storage mediums having instructions encoded thereon for generating the final phase modulation sequence by the method of claim 15 using the processing circuit.

21. (canceled)