Two stage radio frequency interference cancellation system and method

• US 9,312,895 B1
• Filed: 03/09/2015
• Issued: 04/12/2016
• Est. Priority Date: 08/07/2008
• Status: Active Grant

• Current Assignee: Hypres, Inc.
• Original Assignee: Hypres, Inc.
• Inventors: Gupta, Deepnarayan, Inamdar, Amol
• Primary Examiner(s): Nguyen, Duc M
• Application Number:
  US14/641,927
• Time in Patent Office: 400 Days
• Field of Search: 455/295, 455/296, 455/304, 455/305, 455310-312, 455/570
• US Class Current: 1/1
• CPC Class Codes: H04B 1/10 Means associated with receiver for limiting or suppressing noise or interference
• CPC Class Codes: H04B 1/109 by improving strong signal performance of the receiver when strong unwanted signals are present at the receiver input
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver
• CPC Class Codes: H04B 7/15585 by interference cancellation
• CPC Class Codes: H04L 27/01 Equalisers baseband equalizers at the transmitter end H04L25/03343; in analogue transmission systems H04B3/04, H04B7/005

Abstract

A radio frequency receiver subject to a large in-band interferor employs active cancellation with coarse and at least one cancellation signals, each with a respective radio frequency combiner, in order to increase the effective dynamic range of the receiver for weak signals of interest. One or both can be digitally synthesized. This is particularly applicable for co-site interference, whereby the interfering transmit signal is directly accessible. A similar system and method may also be applied to external interferors such as those produced by deliberate or unintentional jamming signals, or by strong multipath signals. An adaptive algorithm may be used for dynamic delay and gain matching. In a preferred embodiment, a hybrid technology hybrid temperature system incorporates both superconducting and semiconducting components to achieve enhanced broadband performance.

Claims

1. An interference suppression method, comprising:

receiving a combined signal comprising a signal of interest conveying information and an interfering signal present in a common signal band;

generating an analog signal having a controllable delay and magnitude selectively corresponding to a predicted future state of the interfering signal based on a digitally implemented model, by at least one automated processor;

combining the combined signal with the generated analog signal with the delay and magnitude controlled to at least partially reduce a ratio of a power of the interfering signal and the signal of interest, to produce a model-based interference suppressed signal;

combining the model-based interference suppressed signal with a feedback-controlled cancellation signal to produce an output signal; and

generating the feedback-controlled cancellation signal, based on at least the output signal.

2. The method according to claim 1, wherein the combined signal and the generated analog signal are combined using a first magnetic flux subtractor.

3. The method according to claim 1, wherein the model-based interference suppressed signal is subjected to a limiter before being combined with the feedback-controlled cancellation signal, and the analog signal is generated substantially without feedback from the model-based interference suppressed signal.

4. The method according to claim 1, wherein the model-based interference suppressed signal and the feedback-controlled cancellation signal are combined using a second magnetic flux subtractor.

5. The method according to claim 1, wherein the received combined signal comprises a wirelessly received radio frequency signal.

6. The method according to claim 5, further comprising digitizing the output signal with at least one analog to digital converter to produce a digitized signal.

7. The method according to claim 6, wherein the digitized signal is digitally down converted with a digital down converter, and digitally processed by a digital signal processor to extract the conveyed information from the signal of interest.

8. The method according to claim 1, wherein the feedback-controlled cancellation signal is generated with at least one digital correlator.

9. The method according to claim 8, wherein the digital correlator acts as a waveform correlator to determine a relative delay between a signal derived from a source of the interfering signal and the output signal.

10. The method according to claim 8, further comprising iteratively adjusting at a delay of the feedback-controlled cancellation signal.

11. The method according to claim 1, wherein the digitally implemented model receives information from a source of the interfering signal.

12. An interference suppression system, comprising:

an input configured to receive a combined signal comprising a signal of interest conveying information and an interfering signal present in a common signal band;

an automated digitally-controlled model-based signal generator configured to generate an analog signal having a controllable delay and magnitude selectively corresponding to a predicted future state of the interfering signal;

a first combiner configured to combine the combined signal with the generated analog signal with the delay and magnitude controlled to at least partially reduce a ratio of a power of the interfering signal and the signal of interest, to produce a model-based interference suppressed signal;

a second combiner configured to combine the model-based interference suppressed signal with a feedback-controlled cancellation signal to produce an output signal; and

a cancellation signal generator, configured to generate the feedback-controlled cancellation signal, based on at least the output signal.

13. The system according to claim 12, wherein first combiner comprises a first magnetic flux subtractor and the second combiner comprises a second flux subtractor.

14. The system according to claim 12, further comprising a limiter configured to limit an amplitude of the model-based interference suppressed signal before combination with the feedback-controlled cancellation signal.

15. The system according to claim 12, wherein the received combined signal comprises a wirelessly received radio frequency signal, further comprising at least one analog to digital converter configured to digitize the output signal to produce a digitized signal.

16. The system according to claim 15, further comprising a digital down converter configured to down convert the digitized signal, and a digital signal processor configured to extract the conveyed information from the signal of interest.

17. The system according to claim 12, further comprising at least one digital correlator configured to correlate information from the output signal with information defining the interfering signal, to determine a relative delay.

18. A signal distinguishing method, comprising:

receiving a combined signal comprising a first signal and a second signal present in a common signal band;

predictively modeling future states of the second signal using at least one automated processor;

combining the combined signal with an analog signal representing the predictively modeled future states of the second signal, having a delay and magnitude adjusted to at least partially reduce a ratio of a power of the second signal and the first signal, to produce a model-based interference suppressed signal;

combining the model-based interference suppressed signal with a feedback-controlled cancellation signal to produce an output signal; and

generating the feedback-controlled cancellation signal with at least one digital processor, based on at least the output signal.

19. The method according to claim 18, wherein at least one of the predictively modeling, and the generating are performed with at least one Josephson junction circuit.

20. The method according to claim 18, wherein the received combined signal comprises a wirelessly received radio frequency signal, further comprising digitizing the output signal with at least one analog to digital converter to produce a digitized output signal.