Multichannel non-gaussian receiver and method

• US 5,640,429 A
• Filed: 01/20/1995
• Issued: 06/17/1997
• Est. Priority Date: 01/20/1995
• Status: Expired due to Term

• Current Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Original Assignee: United States Of America As Represented By The Secretary Of The Air Force
• Inventors: Rangaswamy, Muralidhar, Michels, James H.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): Le, Amanda T.
• Application Number:
  US08/376,959
• Time in Patent Office: 879 Days
• Field of Search: 375/229-232, 375/316, 375/345, 375/346, 375/349, 375/350, 375/340, 364/514 R, 364/515.01, 364/516, 364/550, 364/570, 364/572, 364/574, 364/724.01, 364/724.19, 364/734, 342/89, 342/91, 342/93, 342/378, 324/76.11, 324/76.12, 324/76.19, 324/77.11, 324/76.29, 455/296, 455/303
• US Class Current: 375/340
• CPC Class Codes: G01S 7/292 Extracting wanted echo-signals

Abstract

A process and system for improving the detection of signals in additive correlated non-Gaussian noise using multichannel data. This improves detection performance of receivers through the signal processing architecture when the observation data X(n) is first split into an upper and lower path. In the upper path, the known signal is first subtracted from the data and then passed directly to the prediction error filter. The output of the prediction error filters are then input to the zero-mean non-linear processor and their associated estimated variances are used to determine H₀ and H₁ where H₀ denotes the condition where no signal is present in the data and H₁ denotes the signal present case.

Claims

1. A multichannel, non-Gaussian receiver for use with a host system, said host system receiving an observed data signal with a signal vector with a signal of interest obscured by Gaussian noise and non-Gaussian noise, said multichannel non-Gaussian receiver producing a detection signal containing H₀ when the signal of interest is not present in the observed data signal, and H₁ when the signal of interest is present in the observed data signal, said multichannel non-Gaussian receiver comprising:

a means for subtracting the signal vector from the observed data signal from the host system to produce thereby a first subtraction signal;

a means for estimating the signal of interest from the observed data signal to produce an estimate signal;

a first linear prediction error filter which processes the first subtraction signal and the estimate signal to produce thereby a first output signal which has data;

a second linear prediction error filter which processes the observed data signal from the host system with the estimate signal to produce a second output signal which has data;

a means for transforming the first output signal of the first linear prediction error filter based upon the probability distribution function (pdf) of the data of the first output signal;

a means for transforming the second output signals of the second linear prediction error filter based upon the probability distribution function (pdf) of the data of the second output signal;

a means for subtracting a second Gaussian equivalent signal from a first Gaussian equivalent signal to produce thereby a second subtraction signal; and

a means for generating test statistic signals which receives and processes the second subtraction signal to produce thereby said detection signal for said host system via threshold comparison.

2. A multichannel, non-Gaussian receiver, as described in claim 1, wherein said estimating means comprises a data processor element which processes the observed data signal from the host system with a set of estimation algorithms to produce thereby said estimate signal.

3. A multichannel, non-Gaussian receiver, as described in claim 2, wherein said means for transforming the output signal of the first linear prediction error filter using a first zero memory nonlinear transformation unit.

4. A multichannel, non-Gaussian receiver, as described in claim 2, wherein said means for transforming the output signal of the second linear prediction error filter using a second zero memory nonlinear transformation unit.

5. A multichannel, non-Gaussian receiver, as described in claim 2, wherein said means for generating test statistic signals comprises a threshold comparison unit which receives and processes the second subtraction signal to produce thereby said detection signal for said host system.

6. A multichannel, non-Gaussian receiver, as in claim 1, wherein said means for transforming the first output signal of the first linear prediction error filter comprises a first zero memory nonlinear prediction error filter comprises a first zero memory nonlinear transformation unit.

7. A multichannel, non-Gaussian receiver, as described in claim 6, wherein said means for transforming the output signal of the second linear prediction error filter using a second zero memory nonlinear transformation unit.

8. A multichannel, non-Gaussian receiver, as described in claim 6, wherein said means for generating test statistic signals comprises a threshold comparison unit which receives and processes the second subtraction signal to produce thereby said detection signal for said host system.

9. A multichannel, non-Gaussian receiver, as described in claim 1, wherein said means for transforming the second output signal of the second linear prediction error filter comprises a second zero memory nonlinear prediction error filter comprises a second zero memory nonlinear transformation unit.

10. A multichannel, non-Gaussian receiver, as described in claim 9, wherein said means for generating test statistic signals comprises a threshold comparison unit which receives and processes the second subtraction signal to produce thereby said detection signal for said host system.

11. A multichannel, non-Gaussian receiver, as described in claim 1, wherein said means for generating test statistic signals comprises a threshold comparison unit which receives and processes the second subtraction signal to produce thereby said detection signal for said host system.

12. A multichannel, non-Gaussian receiver process for use with a host system, said host system receiving an observed data signal with a signal vector with a signal of interest obscured by either Gaussian noise or non-Gaussian noise,

said multichannel non-Gaussian receiver process producing a detection signal for hypothesis H₀ when the signal of interest is not present in the observed data signal, and H₁ when the signal of interest is present in the observed data signal, said multichannel non-Gaussian receiver process comprising the steps of:

a first subtracting step that comprises subtracting the signal vector from the observed data signal from the host system to produce thereby a first subtraction signal;

estimating the signal of interest from the observed data signal to produce an estimate signal;

a first step which uses a first linear prediction error filter which processes the first subtraction signal and the estimate signal to produce thereby an output signal;

a second step which uses a second linear prediction error filter which processes the observed data signal from the host system with the estimate signal to produce an output signal;

a transforming step that comprises transforming the output signal of the first linear prediction error filter using a first ZMNL transformation unit;

a second transforming step that comprises transforming the output of the second linear prediction error filter using a second ZMNL transformation unit

a second subtracting step that comprises subtracting the second ZMNL transformed signal from the first ZMNL transformed signal to produce thereby a second subtraction signal; and

generating threshold signals from the second subtraction signal to produce thereby said detection signal for said host system.

13. A multichannel, non-Gaussian receiver process as described in claim 12, wherein said estimating step comprises using a data processor to obtain a signal amplitude estimate using ##EQU28## where s_O is a steering vector of the host system and Σ

^-1 is an inverse of an estimated data covariance matrix, and X is the observed data signal received by said host system.

14. A multichannel, non-Gaussian receiver process as described in claim 13, wherein said first and second using steps each comprise producing output signals using Kalman filters as said first and second linear prediction error filters.

15. A multichannel, non-Gaussian receiver process, as described in claim 14, wherein said first and second transforming steps each respectively comprise taking ln on where h_2JN (q) represents the output signals of the first and second linear prediction error filters.

16. A multichannel, non-Gaussian receiver process, as described in claim 15, wherein said generating step comprises using a data processor to calculate ##EQU29## where H₀ denotes the condition where no signal of interest is present in the observed data signal and H₁ denotes that the signal of interest is present in the observed data signals received by the host system and wherein G_j² (k) is the associated estimated variances of the error signals.