METHOD TO DETECT INTERFERENCE IN WIRELESS SIGNALS

• US 20100105346A1
• Filed: 10/24/2008
• Published: 04/29/2010
• Est. Priority Date: 10/24/2008
• Status: Abandoned Application

• Current Assignee: Anritsu Corporation
• Original Assignee: Anritsu Corporation
• Inventors: Huang, Kee-dyi, Lundquist, Randy L., Venugopal, Vaidyanathan, Thiagarajan, Bhaskar
• Application Number:
  US12/258,108
• Publication Number:
  US 20100105346A1
• Time in Patent Office: Days
• US Class Current: 455/226.400
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal

Abstract

A method to detect interference in wireless signals, comprising sampling a received signal; identifying a dominant waveform in the received signal; subtracting the dominant waveform from the received signal to create a modified received signal; and repeating the above steps, recursively substituting the modified received signal for the received signal, until all adjusted reference waveforms have been subtracted.

Claims

1. A method to detect secondary signals in wireless signals, the method comprising:

receiving a signal including a first component and a second component wherein each component is from a different signal source;

identifying the first component of the signal; and

removing the first component of the signal and leaving the second component of the signal.

2. The method of claim 1 wherein the first component of the signal includes at least one predefined component in accordance with a signal type of interest and wherein the second component of the signal includes a portion of the signal not included in the first component.

3. The method of claim 1 further comprising:

analyzing the spectrum of the second component of the signal; and

displaying a spectrum of the second component of the signal on a display.

4. The method of claim 1 further comprising:

analyzing the first component of the signal;

measuring characteristics of the first component of the signal; and

displaying the first component of the signal along with its characteristics on a display.

5. A method to detect interference in wireless signals, the method comprising:

(a) receiving a signal;

(b) identifying a dominant waveform in the received signal;

(c) removing the dominant waveform from the received signal to create a modified received signal; and

(d) repeating steps b-c, recursively substituting the modified received signal from step c for the received signal, until all dominant waveforms have been removed.

6. The method of claim 5 wherein identifying a dominant waveform comprises:

cross-correlating the received signal with a set of ideal reference waveforms; and

identifying a waveform with a highest correlation value as the dominant waveform.

7. The method of claim 5 wherein removing the dominant waveform comprises:

measuring frequency, phase, and time offset and power for the dominant waveform;

adjusting an ideal reference waveform corresponding to the dominant waveform according to the measured frequency, phase, and time offset and power to create an adjusted waveform; and

subtracting the adjusted waveform from the received signal.

8. The method of claim 6 wherein the set of ideal reference waveforms is constructed according to the steps of:

acquiring a standard-defined set of reference sequences;

modulating the reference sequences according to a signal type associated with the reference sequences;

storing the reference waveforms as a set of ideal reference waveforms.

9. The method of claim 8 wherein the modulated reference waveforms are interpolated and over-sampled before being stored.

10. A method to detect interference in wireless signals, the method comprising:

(a) sampling a received signal;

(b) storing the received signal;

(c) cross-correlating the received signal with a set of ideal reference waveforms;

(d) identifying a dominant waveform in the received signal;

(e) measuring frequency, phase, and time offset and power for the dominant waveform;

(f) adjusting an ideal reference waveform corresponding to the dominant waveform according to the measured frequency, phase, and time offset and power to create an adjusted reference waveform;

(g) subtracting the adjusted reference waveform from the received signal to create a modified received signal; and

(h) repeating steps c-g, recursively substituting the modified received signal from step g for the received signal, until all dominant waveforms have been subtracted.

11. The method of claim 10 wherein the received signal is received through an antenna.

12. The method of claim 10 wherein the set of ideal reference waveforms is created by the steps of:

acquiring a standard-defined set of reference sequences in discrete time format;

modulating the reference sequences according to a signal type to which the reference waveforms correspond;

storing the reference waveforms.

13. The method of claim 12 wherein the reference sequences are interpolated and oversampled to an Nx sampling rate, wherein the Nx sampling rate is greater than a rate associated with the standard-defined set of reference sequences.

14. The method of claim 13 wherein the cross-correlation is performed at the Nx sampling rate.

15. The method of claim 14 wherein modulating includes pulse shaping or equalization for reference waveforms as specified in the respective signal standards, e.g. 1×

EV-DO, TD-SCDMA or EDGE/GSM.

16. The method of claim 14 wherein modulating includes performing a discrete inverse Fourier transform for reference waveforms corresponding to OFDM signals.

17. The method of claim 10 further comprising:

performing a Fourier transform on the modified received signal; and

displaying the transformed modified received signal on a spectrum analyzer.

18. The method of claim 10 further comprising:

displaying each dominant waveform along with its measured power and time offset.

19. The method of claim 10 wherein identifying a dominant waveform includes determining which reference waveform generates a highest correlation value in the cross-correlation.

20. The method of claim 10 wherein the received signal is filtered and pulse-shaped.

21. The method of claim 10 wherein the received signal is a cellular or wireless area network signal.