Methods and systems for distinguishing a signal of interest from interference signals

• US 8,532,207 B2
• Filed: 05/27/2011
• Issued: 09/10/2013
• Est. Priority Date: 05/27/2011
• Status: Active Grant

• Current Assignee: Honeywell International Inc.
• Original Assignee: Honeywell International Inc.
• Inventors: Hanson, Colin S., Winstead, Benjamin J.
• Primary Examiner(s): PHU, PHUONG M
• Application Number:
  US13/117,407
• Publication Number:
  US 20120300822A1
• Time in Patent Office: 837 Days
• Field of Search: 375/340, 375/260, 375/316, 375/259, 375/224, 375/228, 455/67.11, 455/206.1, 455/206.2, 455/226.1, 455/226.2, 702 75- 77
• US Class Current: 375/260
• CPC Class Codes: H04B 1/1027 assessing signal quality or detecting noise/interference for the received signal
• CPC Class Codes: H04L 25/03 Shaping networks in transmitter or receiver, e.g. adaptive shaping networks

Abstract

A method for distinguishing a signal of interest from one or more interference signals in a received analog signal comprises receiving an analog signal at a radio front end, and transmitting the received analog signal to an analog-to-digital converter to sample data in the received analog signal and output a digital signal. A sub-channel Fast Fourier Transform (FFT) is performed on the digital signal, and sub-channel FFT bin magnitudes are averaged over a set period of time to determine a shape of the received signal. The shape of the received signal is compared to one or more signal reference patterns by computing a metric for the shape of the received signal, and computing a metric for the one more signal reference patterns. The computed metrics are then compared to a predetermined threshold value to determine the presence, or lack thereof, of a signal of interest in the received signal.

Claims

1. A method for distinguishing a signal of interest from one or more interference signals in a received analog signal, the method comprising:

receiving an analog signal at a radio front end;

transmitting the received analog signal to an analog-to-digital converter to sample data in the received analog signal and output a digital signal;

performing a sub-channel fast Fourier transform (FFT) on the digital signal;

averaging sub-channel FFT bin magnitudes over a set period of time to determine a shape of the received signal; and

comparing the shape of the received signal to one or more signal reference patterns by a method comprising;

(a) normalizing the shape of the received signal;

(b) selecting a next signal reference pattern;

(c) normalizing the next signal reference pattern;

(d) computing a bias correction factor for the normalized received signal and the normalized signal reference pattern;

(e) computing a metric for comparing the shape of the normalized received signal with the normalized signal reference pattern;

(f) determining whether one or more different signal reference patterns are available;

(g) if one or more different signal reference patterns are available, repeating (b) to (f) until a metric has been computed for each of the signal reference patterns; and

(h) determining whether each computed metric has passed a threshold requirement indicating that a signal of interest is present in the received signal.

2. The method of claim 1, wherein the radio front end is a single-channel analog front end.

3. The method of claim 2, wherein averaging the sub-channel FFT bin magnitudes comprises computing sub-channel FFT bin magnitudes by summing the magnitudes of the bins within a channel.

4. The method of claim 2, wherein averaging the sub-channel FFT bin magnitudes comprises:

(a) performing an M-point FFT, where M is a variable representing the number of data points that provide sufficient resolution to provide multiple FFT bins per channel for a data block;

(b) updating a rejection threshold;

(c) determining whether a channel magnitude is greater than the threshold;

(d) if the channel magnitude is not greater than the threshold, adding current sub-channel FFT bin magnitudes to a sum of past sub-channel FFT bin magnitudes for a current sample collection period and determining whether the sample collection period is complete;

(e) if the channel magnitude is greater than the threshold, determining whether the current sample collection period is complete; and

(f) repeating (a) to (e) if the sample collection period is not complete.

5. The method of claim 1, wherein the front end is a wideband analog front end.

6. The method of claim 5, wherein prior to performing a sub-channel FFT on the digital signal, an FFT or filtering is performed on the sampled data to channelize the signal.

7. The method of claim 6, wherein the sub-channel FFT is performed on the channelized signal, and a magnitude of the channelized signal is computed.

8. The method of claim 7, wherein averaging the sub-channel FFT bin magnitudes comprises:

(a) performing an M-point FFT, where M is a variable representing the number of data points that provide sufficient resolution to provide multiple FFT bins per channel for a data block;

(b) updating a rejection threshold;

(c) determining whether a channel magnitude is greater than the threshold;

(d) if the channel magnitude is not greater than the threshold, adding current sub-channel FFT bin magnitudes to a sum of past sub-channel FFT bin magnitudes for a current sample collection period and determining whether the sample collection period is complete;

(e) if the channel magnitude is greater than the threshold, determining whether the current sample collection period is complete; and

(f) repeating (a) to (e) if the sample collection period is not complete.

9. A computer program product, comprising:

a non-transitory computer readable medium having instructions stored thereon executable by a processor to perform a method for distinguishing a signal of interest from one or more interference signals, the method comprising;

receiving an analog signal at a radio front end configured to receive a single channel or multiple channels;

transmitting the received analog signal to an analog-to-digital converter to sample data in the received analog signal and output a digital signal;

performing a sub-channel fast Fourier transform (FFT) on the digital signal;

averaging sub-channel FFT bin magnitudes over a set period of time to determine a shape of the received signal, wherein averaging the sub-channel FFT bin magnitudes comprises;

(a) performing an M-point FFT, where M is a variable representing the number of data points that provide sufficient resolution to provide multiple FFT bins per channel for a data block;

(b) updating a rejection threshold;

(c) determining whether a channel magnitude is greater than the threshold;

(d) if the channel magnitude is not greater than the threshold, adding current sub-channel FFT bin magnitudes to a sum of past sub-channel FFT bin magnitudes for a current sample collection period and determining whether the sample collection period is complete;

(e) if the channel magnitude is greater than the threshold, determining whether the current sample collection period is complete; and

(f) repeating (a) to (e) if the sample collection period is not complete; and

comparing the shape of the received signal to one or more signal reference patterns.

10. The computer program product of claim 9, wherein the radio front end is configured to receive a single channel.

11. The computer program product of claim 9, wherein comparing the shape of the received signal to one or more signal reference patterns comprises:

(a) normalizing the shape of the received signal;

(b) selecting a next signal reference pattern;

(c) normalizing the next signal reference pattern;

(d) computing a bias correction factor for the normalized received signal and the normalized signal reference pattern;

(e) computing a metric for comparing the shape of the normalized received signal with the normalized signal reference pattern;

(f) determining whether one or more different signal reference patterns are available;

(g) if one or more different signal reference patterns are available, repeating (b) to (f) until a metric has been computed for each of the signal reference patterns; and

(h) determining whether each computed metric has passed a threshold requirement indicating that a signal of interest is present in the received signal.

12. The computer program product of claim 9, wherein when the radio front end is configured to receive multiple channels, prior to performing a sub-channel FFT on the digital signal, an FFT or filtering is performed on the sampled data to channelize the signal.

13. The computer program product of claim 12, wherein the sub-channel FFT is performed on the channelized signal, and a magnitude of the channelized signal is computed.

14. A system for distinguishing a signal of interest from one or more interference signals, the system comprising:

a radio front end configured to receive a single channel or multiple channels;

an analog-to-digital converter operatively coupled to the radio front end to receive a signal from the radio front end, the analog-to-digital converter configured to sample data in the received signal and produce a digital signal;

at least one processor operatively coupled to the analog-to-digital converter to receive the digital signal; and

at least one computer readable medium operatively coupled to the processor, the computer readable medium having instructions executable by the processor to perform a method comprising;

performing a sub-channel fast Fourier transform (FFT) on the digital signal;

averaging sub-channel FFT bin magnitudes over a set period of time to determine a shape of the received signal; and

comparing the shape of the received signal to one or more signal reference patterns by a method comprising;

(a) normalizing the shape of the received signal;

(b) selecting a next signal reference pattern;

(c) normalizing the next signal reference pattern;

(d) computing a bias correction factor for the normalized received signal and the normalized signal reference pattern;

(e) computing a metric for comparing the shape of the normalized received signal with the normalized signal reference pattern;

(f) determining whether one or more different signal reference patterns are available;

(g) if one or more different signal reference patterns are available, repeating (b) to (f) until a metric has been computed for each of the signal reference patterns; and

(h) determining whether each computed metric has passed a threshold requirement indicating that a signal of interest is present in the received signal.

15. The system of claim 14, wherein averaging the sub-channel FFT bin magnitudes comprises computing sub-channel FFT bin magnitudes by summing the magnitudes of the bins within a channel.

16. The system of claim 14, wherein averaging the sub-channel FFT bin magnitudes comprises:

(a) performing an M-point FFT, where M is a variable representing the number of data points that provide sufficient resolution to provide multiple FFT bins per channel for a data block;

(b) updating a rejection threshold;

(c) determining whether a channel magnitude is greater than the threshold;

(d) if the channel magnitude is not greater than the threshold, adding current sub-channel FFT bin magnitudes to a sum of past sub-channel FFT bin magnitudes for a current sample collection period and determining whether the sample collection period is complete;

(e) if the channel magnitude is greater than the threshold, determining whether the current sample collection period is complete; and

(f) repeating (a) to (e) if the sample collection period is not complete.

17. The system of claim 14, wherein when the radio front end is configured to receive multiple channels, prior to performing a sub-channel FFT on the digital signal, an FFT or filtering is performed on the sampled data to channelize the signal.

18. The system of claim 17, wherein the sub-channel FFT is performed on the channelized signal, and a magnitude of the channelized signal is computed.