Method and apparatus for cancelling in-band energy leakage from transmitter to receiver

• US 5,444,864 A
• Filed: 12/22/1992
• Issued: 08/22/1995
• Est. Priority Date: 12/22/1992
• Status: Expired due to Term

• Current Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Original Assignee: E-Systems LLC
• Inventors: Smith, Winthrop W.
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): LIN, MARY
• Application Number:
  US07/995,055
• Time in Patent Office: 973 Days
• Field of Search: 455/76, 455/79, 455/80, 455/82, 455/83, 455/295, 455/304, 455/307, 455/84, 455/24, 455/126
• US Class Current: 455/84
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 1/408 the transmitter oscillator frequency being identical to the receiver local oscillator frequency
• CPC Class Codes: H04B 1/525 with means for reducing leakage of transmitter signal into the receiver

Abstract

A method and apparatus system for cancelling a leak-through signal component generated by an interfering transmitter from a received/leak-through signal comprising a multiplier for multiplying the received/leak-through signal by a reference signal provided from the interfering transmitter. The system further includes an integrator for integrating the output of the multiplier to generate an estimate of the gain and phase of the leak-through signal component. A gain and phase adjustor, responsive to the generated gain and phase estimates, is also included for adjusting the gain and phase of the reference signal to generate a cancellation signal that is a substantially gain and phase matched estimate of the leak-through signal. The generated cancellation signal is then subtracted from the received/leak-through signal to substantially cancel the leak-through signal component.

Claims

1. A system for processing a transmitted signal and a received signal to generate an output signal representing an estimate of an undesired signal mixed within the received signal, wherein the undesired signal is a by-product of the transmitted signal, comprising:

means for processing the transmitted and received signals to generate a correction signal, said correction signal comprising estimates of the gain and phase of the undesired signal mixed within the received signal; and

means for processing the received signal and the correction signal according to the gain and phase estimates of the correction signal to generate the output signal substantially gain and phase matched to the undesired signal mixed within the received signal.

2. The system as in claim 1 wherein the means for processing the transmitted and the received signals comprises matched filter computational means for generating the correction signal.

3. The system as in claim 2 wherein the means for processing the received signal and the correction signal comprises means for multiplying the transmitted signal by the correction signal to generate the output signal.

4. The system as in claim 1 wherein the means for processing the transmitted and the received signals comprises:

means for multiplying the transmitted signal by the received signal to generate a multiplied output signal; and

means for integrating the multiplied output signal to generate the correction signal.

5. The system as in claim 1 further including means for subtracting the output signal from the received signal to substantially cancel the undesired signal from the received signal.

6. A method for processing a transmitted signal and a received signal to generate an output signal representing an estimate of an undesired signal mixed within the received signal, wherein the undesired signal is a by-product of the transmitted signal, comprising the steps of:

matched filter processing of the transmitted and the received signals to generate a correction signal including estimates of the gain and phase of the undesired signal mixed within the received signal; and

adjusting the gain and phase of the transmitted signal in accordance with the gain and phase estimates of the correction signal to generate the output signal that is substantially gain and phase matched with the undesired signal mixed within the received signal.

7. The method as in claim 6 wherein the step of matched filter processing comprises the steps of:

multiplying of the transmitted signal by the receiver signal to generate a multiplied signal output; and

integrating the multiplied signal output to generate the correction signal including the gain and phase estimates.

8. The method as in claim 7 wherein the step of adjusting comprises the step of:

multiplying the correction signal by the transmitted signal to generate the output signal.

9. The method as in claim 6 further including the step of:

subtracting the output signal from the received signal to substantially cancel the undesired signal from the received signal.

10. A system for cancelling an undesired signal produced on a receiver line by a source of interference, comprising:

means coupled to the source of interference for sampling a reference signal generated by the source of interference;

means coupled to the receiver line for sampling a receiver signal comprised of the undesired signal and a desired signal;

means for processing the reference signal and the receiver signal to generate a correction signal, the correction signal comprising estimates of the gain and phase of the undesired signal within the receiver signal;

means for processing the reference signal and the correction signal to adjust the gain and phase of the reference signal according to the estimates of the gain and phase in the correction signal and generate a cancellation signal substantially gain and phase matched to the undesired signal; and

means for subtracting the cancellation signal from the receiver signal to cancel the undesired signal produced on the receiver line.

11. The system as in claim 10 wherein the means for processing the reference signal and the receiver signal comprises matched filter computation means.

12. The system as in claim 11 wherein the matched filter computation means comprises:

means for multiplying the reference signal by the receiver signal to generate a multiplied output signal; and

means for integrating the multiplied output signal to generate the estimate signal including the estimates of the gain and phase.

13. The system as in claim 11 wherein the signal adjustor means comprises:

means for multiplying the reference signal by the correction signal comprising estimates of the gain and phase to adjust the gain and phase of the reference signal such that the gain and phase of the generated cancellation signal substantially matches the gain and phase of the undesired signal.

14. The system as in claim 10 wherein the means for processing the reference signal and the correction signal comprises signal adjustor means.