System and method using adjunct signals to increase wideband receiver performance

Patent metadata

Field	Value
Publication number	US-11736323-B2
Application number	US-202117397682-A
Country	US
Kind code	B2
Filing date	Aug 9, 2021
Priority date	Sep 30, 2020
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

Systems and methods which use adjunct signals from a remote highly stable clock to enhance performance of a digital wideband receiver equipped with a less stable local clock system. The digital wideband receiver includes an analog-to-digital converter (ADC) and an adjunct receiver system connected to the output of the ADC. The adjunct receiver system includes matched filters and circuitry configured to generate an interpolation coefficient vector based on the matched filter outputs. The adjunct receiver system further includes an interpolating filter which is configured to remove jitter from the digitized samples output by the ADC using the interpolation coefficient vector.

First claim

The invention claimed is:

1. A wideband receiver comprising:
an antenna;
a local clock configured to generate clock signals;
an analog-to-digital converter connected and configured to convert analog signals received by the antenna into digital samples in accordance with the clock signals;
an adjunct processing module connected and configured to match filter the digital samples output by the analog-to-digital converter and derive an interpolation coefficient vector from the clock signals and the match-filtered digital samples;
delay circuitry connected and configured to delay the digital samples output by the analog-to-digital converter and received directly by the delay circuitry without match filtering;
an interpolation filter connected and configured to convolve the digital samples output by the delay circuitry with the interpolation coefficient vector output by the adjunct processing module to remove local clock-induced jitter from the digital samples output by the delay circuitry; and
a wideband receiver processing module connected and configured to process digital samples received from the interpolation filter.

2. The wideband receiver as recited in claim 1 , wherein the adjunct processing module comprises:
a plurality of matched filters connected and configured to pass digital samples representing adjunct signals received from the analog-to-digital converter; and
a noise-free adjunct signal generation module that is connected to receive the clock signals from the local clock and the digital samples representing the adjunct signals output by the matched filters and configured to generate noise-free adjunct signals which are synchronized with the adjunct signals.

3. The wideband receiver as recited in claim 2 , wherein the adjunct processing module further comprises a processor or other circuitry configured to perform operations comprising:
forming a vector T(i) including the noise-free adjunct signals;
forming a matrix MF(i) including the digital samples representing adjunct signals output by the matched filters; and
solving a system of linear equations MF(i)C(i)=T(i) to derive the interpolation coefficient vector C(i).

4. The wideband receiver as recited in claim 2 , wherein the noise-free adjunct signal generation module comprises:
a plurality of noise-free adjunct signal generators configured to generate the noise-free adjunct signals; and
a correlator which is connected and configured to determine a degree of correlation of a sum of the adjunct signals output by the matched filters and a sum of the noise-free adjunct signals generated by the noise-free adjunct signal generators and output a leading/trailing indicator indicative of the degree of correlation.

5. The wideband receiver as recited in claim 4 , wherein the noise-free adjunct signal generation module further comprises a processor or other circuitry configured to perform a signal index process that receives the clock signals from the local clock and produces an index k(i) at sample time i based on an offset from the leading/trailing indicator.

6. The wideband receiver as recited in claim 4 , wherein the noise-free adjunct signal generators are lookup tables.

7. A system comprising a wideband receiver system, a plurality of transmitter systems, and an adjunct transmitter system,
wherein each of the plurality of transmitter systems comprises a respective waveform generator and a respective transmit antenna configured to transmit a respective signal of interest based on waveforms generated by the respective waveform generator;
wherein the adjunct transmitter system comprises a remote clock having a high stability, an adjunct waveform generator, and an adjunct transmit antenna configured to transmit adjunct signals based on adjunct waveforms generated by the adjunct waveform generator; and
wherein the wideband receiver system comprises:
a receive antenna;
a local clock configured to generate clock signals and having a stability lower than the high stability of the remote clock;
an analog-to-digital converter connected and configured to convert the adjunct signals and the respective signals of interest received by the receive antenna from the respective transmit antenna of each of the plurality of transmitter systems and adjunct transmit antenna into digital samples in accordance with the clock signals from the local clock;
an adjunct processing module connected and configured to match filter the digital samples of the adjunct signals and derive an interpolation coefficient vector from the clock signals and the match-filtered digital samples;
delay circuitry connected and configured to delay the digital samples output by the analog-to-digital converter and received directly by the delay circuitry without match filtering;
an interpolation filter connected and configured to convolve the digital samples output by the delay circuitry with the interpolation coefficient vector output by the adjunct processing module to remove local clock-induced jitter from the digital samples output by the delay circuitry; and
a wideband receiver processing module connected and configured to process the digital samples received from the interpolation filter.

8. The system as recited in claim 7 , wherein the adjunct processing module comprises:
a plurality of matched filters connected and configured to pass the digital samples representing the adjunct signals received from the analog-to-digital converter; and
a noise-free adjunct signal generation module that is connected to receive the clock signals from the local clock and the digital samples representing the adjunct signals output by the matched filters and configured to generate noise-free adjunct signals which are synchronized with the adjunct signals.

9. The system as recited in claim 8 , wherein the adjunct processing module further comprises a processor or other circuitry configured to perform operations comprising:
forming a vector T(i) including the noise-free adjunct signals;
forming a matrix MF(i) including the adjunct signals output by the matched filters; and
solving a system of linear equations MF(i)C(i)=T(i) to derive the interpolation coefficient vector C(i).

10. The system as recited in claim 8 , wherein the noise-free adjunct signal generation module comprises:
a plurality of noise-free adjunct signal generators configured to generate the noise-free adjunct signals; and
a correlator which is connected and configured to determine a degree of correlation of a sum of the adjunct signals output by the matched filters and a sum of the noise-free adjunct signals generated by the noise-free adjunct signal generators and output a leading/trailing indicator indicative of the degree of correlation.

11. The system as recited in claim 10 , wherein the noise-free adjunct signal generation module further comprises a processor or other circuitry configured to perform a signal index process that receives the clock signals from the local clock and produces an index k(i) at sample time i based on an offset from the leading/trailing indicator.

12. The system as recited in claim 10 , wherein the noise-free adjunct signal generators are lookup tables.

13. The system as recited in claim 7 , wherein the adjunct signals transmitted by the adjunct transmit antenna are tones.

14. The system as recited in claim 7 , wherein frequencies of the adjunct signals are the same or nearly the same as frequency of respective signals of interest transmitted by each of the plurality of transmitter systems.

15. A method of operating a wideband receiver, the method comprising:
receiving analog signals using an

Assignees

• Boeing Co

Inventors

• Ray Gary A

Classifications

• H04L25/08 Primary

  Modifications for reducing interference; Modifications for reducing effects due to line faults {; Receiver end arrangements for detecting or overcoming line faults} · CPC title

• H04L25/03828

  Arrangements for spectral shaping; Arrangements for providing signals with specified spectral properties (partial response systems H04L25/497) · CPC title

• H04L25/02 Primary

  Details {; arrangements for supplying electrical power along data transmission lines (systems for transmitting signals via power distribution lines H04B3/54)} · CPC title