Detecting and measuring interference contained within a digital carrier

• US 20030165205A1
• Filed: 02/26/2003
• Published: 09/04/2003
• Est. Priority Date: 03/04/2002
• Status: Active Grant

• Current Assignee: Glowlink Communications Technology, Inc. (Singapore Technologies Engineering Limited)
• Original Assignee: Glowlink Communications Technology, Inc. (Singapore Technologies Engineering Limited)
• Inventors: Downey, Michael L., Chu, Jeffrey C.
• Granted Patent: US 7,639,761 B2
• Time in Patent Office: Days
• US Class Current: 375/346
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04B 17/345 Interference values signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR] H04B17/336
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

A method and system for measuring noise and or interference in a communications signal without taking the signal out of service. In the present invention the communications signal is converted from an RF signal into an IF signal. The IF signal is then digitized and stored. The stored signal is processed to determine the interference signal. The interference signal is calculated from an error vector produced by a blind equalizer demodulator. The interference signal is extracted and presented to a user.

Claims

1. A method of detecting in-band interference in a carrier signal in a communication system comprising the steps of:

acquiring a signal including the carrier signal and an interfering signal; and

extracting the interfering signal from the carrier without interrupting the carrier.

2. The method according to claim 1, without knowledge of the carriers RF or modulation parameters.

3. The method according to claim 1, with knowledge of the carriers RF or modulation parameters.

4. The method according to claim 1, wherein the interfering signal comprises noise.

5. The method according to claim 1, wherein the communication system performs as a wireless communication system.

6. The method according to claim 1, wherein the communication system performs as a satellite communication system.

7. The method according to claim 1, wherein the carrier comprises an RF signal.

8. A method of detecting in-band interference in a carrier signal in a communication system comprising the steps of:

acquiring a digital signal including receiving the signal, filtering the signal and digitizing the filtered signal;

formatting the digital signal including filtering the digital signal, performing decimation and re-sampling of the digitized signal; and

performing blind equalization and demodulation thereby forming an error vector that is representative of the interference signal.

9. The method according to claim 8, wherein the step of formatting the digital signal is performed without knowledge of the carriers RF or modulation parameters.

10. The method according to claim 8, wherein the step of formatting the digital signal is performed with knowledge of the carriers RF or modulation parameters.

11. The method according to claim 8, wherein the interfering signal comprises noise.

12. The method according to claim 8, wherein the communication system performs as a wireless communication system.

13. The method according to claim 8, wherein the communication system performs as a satellite communication system.

14. The method according to claim 8, wherein the carrier comprises an RF signal.

15. The method according to claim 8, wherein acquiring the digital signal includes converting the carrier signal into an IF signal, wherein the IF signal is representative of the carrier signal.

16. The method according to claim 8, wherein filtering the digital signal includes filtering the carrier signal to limit the bandwidth to a signal of interest.

17. The method according to claim 8, wherein acquiring a digital signal includes storing a digitized filtered signal into memory.

18. The method according to claim 8, wherein formatting the digital signal includes calculating an average baseband and an average bandwidth of the carrier signal.

19. The method according to claim 8, wherein filtering the digital signal includes down-converting the digital signal to the baseband of the carrier signal.

20. The method according to claim 8, wherein the re-sampling of the digital signal occurs at twice the frequency of interest.

21. The method according to claim 8, including removing a M initial samples of the error vector, wherein the M initial samples occur while the blind equalization and demodulation is sill converging.

22. The method according to claim 8, including removing a DC bias from the error vector.

23. A system of detecting in-band interference in a carrier signal in a communication system comprising:

a receiver for acquiring a digital signal

a signal processor for conditioning the digital signal and

a blind equalizer demodulator forming an error vector that is representative of an interference signal included in the carrier signal.

24. The system according to claim 23, wherein the signal processor is without knowledge of the carriers RF or modulation parameters.

25. The system according to claim 23, wherein the signal processor knows of the carriers RF or modulation parameters.

26. The system according to claim 23, wherein the interference signal comprises noise.

27. The system according to claim 23, wherein the communication system performs as a wireless communication system.

28. The system according to claim 23, wherein the communication system performs as a satellite communication system.

29. The system according to claim 23, wherein the carrier comprises an RF signal.

30. The system according to claim 23, wherein the receiver further converts the carrier signal into an IF signal, wherein the IF signal is representative of the carrier signal.

31. The system according to claim 23, wherein the receiver further filters the carrier signal to limit the bandwidth to a signal of interest.

32. The system according to claim 23, wherein the receiver further stores a digitized filtered signal in memory.

33. The system according to claim 23, wherein the signal processor further calculates an average baseband and an average bandwidth of the carrier signal.

34. The system according to claim 23, wherein the signal processor further down-converts the digital signal to the baseband of the carrier signal.

35. The system according to claim 23, wherein the signal processor further decimates the digital signal at twice the symbol rate.

36. The system according to claim 23, including removing a M initial samples of the error vector, wherein the M initial samples occur while the blind equalization and demodulation is sill converging.

37. The system according to claim 23, including removing a DC bias from the error vector.

38. The system according to claim 23, including receiving the signal, filtering the signal and digitizing the filtered signal