Method and apparatus for receiving a geo-location signal

• US 7,778,367 B1
• Filed: 09/23/2005
• Issued: 08/17/2010
• Est. Priority Date: 09/23/2005
• Status: Active Grant

• Current Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Original Assignee: Rockwell Collins, Inc. (Rtx Corporation)
• Inventors: Stockmaster, Michael H.
• Primary Examiner(s): Liu; Shuwang
• Assistant Examiner(s): Yu; Lihong
• Application Number:
  US11/234,660
• Time in Patent Office: 1,789 Days
• Field of Search: 375/347, 375/144
• US Class Current: 375/347
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 5/0215 Interference
• CPC Class Codes: H04K 3/228 Elimination in the received signal of jamming or of data corrupted by jamming interference suppression in receivers H04B1/10
• CPC Class Codes: H04K 3/28 with jamming and anti-jamming mechanisms both included in a same device or system, e.g. wherein anti-jamming includes prevention of undesired self-jamming resulting from jamming

Abstract

A method and apparatus for receiving geolocation signals wherein the geolocation signals are received by receiving a plurality of perspectives of a geolocation signal and a jamming signal; generating a plurality of wavelet transformations corresponding to the plurality of perspectives; determining a covariance between corresponding elements in the plurality of wavelet transformations; weighting each element in each wavelet transformation by weights derived from the determined covariance; generating a nulled wavelet transformation by summing together corresponding weighted elements from each of the plurality of wavelet transformations; and generating a time-domain rendition of the geolocation signal according to the nulled wavelet transformation through use of the inverse wavelet transform.

Claims

1. A method for receiving geolocation signals:

simultaneously receiving a plurality of perspectives of a geolocation signal and a jamming signal;

generating a plurality of wavelet transformations corresponding to the plurality of perspectives;

determining a covariance between corresponding elements in the plurality of wavelet transformations;

weighting each element in each wavelet transformation by weights derived from the determined covariance;

generating a nulled wavelet transformation by summing together corresponding weighted elements from each of the plurality of wavelet transformations; and

generating a time-domain rendition of the geolocation signal according to the nulled wavelet transformation through use of the inverse wavelet transform.

2. The method of claim 1 wherein generating a plurality of wavelet transformations comprises:

collecting a sample set for each perspective of the geolocation signal and the jamming signal; and

applying a discrete wavelet transformation function to each sample set.

3. The method of claim 1 wherein generating a plurality of wavelet transformations comprises:

selecting a basis function according to an anticipated jamming signal type;

collecting a sample set for each perspective of the geolocation signal and the jamming signal; and

applying a discrete wavelet transformation utilizing the basis function to each sample set.

4. The method of claim 1 wherein weighting each element in each wavelet transformation comprises masking an element in a wavelet transformation when the element in the wavelet transformation corresponds to at least one of a friendly jammer or a geolocation signal void.

5. The method of claim 1 further comprising:

characterizing the jamming signal according to the determined covariance;

selecting a basis function used in a subsequent wavelet transformation according to the characterization of the jamming signal.

6. The method of claim 5 wherein characterizing the jamming signal comprises determining at least one of a duty cycle and a bandwidth.

7. The method of claim 1 further comprising:

determining a residual level of the jamming signal represented in the nulled wavelet transformation; and

selecting a basis function used in a subsequent wavelet transformation according to the residual level of the jamming signal represented in the nulled wavelet transformation.

8. A geolocation system comprising:

plurality of signal receivers each configured for simultaneously generating a signal according to a received perspective of a geolocation signal and a jamming signal;

plurality of wavelet transformation units each generating a wavelet transformation according to a signal received from a corresponding signal receiver;

covariance unit that generates a covariance signal for each element in each wavelet transformation generated by the plurality of wavelet transformation units;

plurality of weighting units each of which applies a weight to a wavelet transformation received from a corresponding wavelet transformation unit wherein the weight applied is determined according to a covariance signal received from the covariance unit;

summation unit that generates a nulled wavelet transformation by adding the outputs from each of the weighting units; and

inverse wavelet transformation unit that generates a geolocation signal according to the output of the summation unit.

9. The geolocation system of claim 8 wherein the wavelet transformation unit comprises:

analog to digital converter that converts a signal received from a corresponding signal receiver into a sample-set;

basis function table capable of storing at least one basis function; and

discrete wavelet transformation unit that generates a discrete wavelet transformation comprising a plurality of elements according to the sample set according to a basis function provided by the basis function table.

10. The geolocation system of claim 9 wherein the wavelet transformation unit further comprises a jammer-type register capable of storing a jammer-type indicator for a jamming signal wherein the basis function table provides a basis function according to a jammer-type indicator stored in the jammer-type register.

11. The geolocation system of claim 10 further comprising a jammer-type correlation memory capable of generating a jammer-type indicator according to a plurality of covariances generated for a plurality of corresponding elements in a plurality of discrete wavelet transformations and wherein the jammer-type indicator is stored in the jammer-type register.

12. The geolocation system of claim 11 wherein the jammer-type correlation memory is used to store a jammer profile that is based on at least one of bandwidth of the jamming signal and duty cycle of the jamming signal.

13. The geolocation system of claim 9 further comprising a friendly jammer identification unit that generates a mask signal for an element of a discrete wavelet transform when the element corresponds to at least one of a friendly jammer and a geolocation signal void.

14. The geolocation system of claim 9 further comprising a jammer-residual signal monitor that generates a residual-signal-level for the jamming signal according to the output of the summation unit and wherein each wavelet transformation unit further comprises a residual-signal-level input and wherein the basis function table provides a basis function according to the residual-signal-level signal.

15. A geolocation anti-jamming unit comprising:

plurality of analog-to-digital converters each configured for simultaneously capturing a sample-set of a perspective of a geolocation signal and a jamming signal;

processor capable of executing an instruction sequence;

memory for storing at least one of one or more instruction sequences, a sample set captured by one of the analog-to-digital converters and other data;

one or more instruction sequences stored in the memory including;

discrete wavelet transform module that, when executed by the processor, minimally causes the processor to create and store in the memory a wavelet transformation according to a sample-set stored in the memory;

covariance module that, when executed by the processor, minimally causes the processor to create and store in the memory a set of weights based on a covariance matrix generated according to a plurality of wavelet transformations stored in the memory;

weighting module that, when executed by the processor, minimally causes the processor to create and store in the memory a weighted wavelet transformation according to the weights stored in the memory when the processor executes the covariance module;

summation module that, when executed by the processor, minimally causes the processor to create and store in the memory a nulled wavelet transformation according to a plurality of weighted wavelet transformation stored in the memory; and

inverse discrete wavelet transform module that, when executed by the processor, minimally causes the processor to create and store in the memory a time-domain rendition of a geolocation signal according to a nulled wavelet transformation stored in the memory.

16. The geolocation anti-jamming unit of claim 15 further comprising a basis function cache stored in the memory that includes one or more basis function definitions and wherein the discrete wavelet transformation module minimally causes the processor to create and store in the memory a wavelet transformation according to a sample-set stored in the memory and also according to a basis function stored in the basis function cache.

17. The geolocation anti-jamming unit of claim 15 further comprising a friendly jammer identification module stored in the memory that, when executed by the processor, minimally causes the processor to create and store in the memory a weighted wavelet transformation by masking an element included in a wavelet transformation stored in the memory when the element corresponds to at least one of a friendly jammer and a geolocation signal void.

18. The geolocation anti-jamming unit of claim 15 further comprising a jammer type module that, when executed by the processor, minimally causes the processor to create and store in the memory a jammer type identifier according to a covariance matrix stored in the memory and wherein the discrete wavelet transformation module causes the processor to create and store in the memory a wavelet transformation according to a sample-set stored in the memory and according to a basis function selected according to the jammer type identifier.

19. The geolocation anti-jamming unit of claim 15 further comprising a jammer type module that, when executed by the processor, minimally causes the processor to create and store in the memory a jammer type identifier according to at least one of a bandwidth and a duty cycle of a signal represented in a weighted discrete wavelet transform stored in the memory and wherein the discrete wavelet transformation module causes the processor to create and store in the memory a wavelet transformation according to the sample-set stored in the memory and according to a basis function selected according to the jammer type identifier.

20. The geolocation anti-jamming unit of claim 15 further comprising a jamming signal residual signal module that, when executed by the processor, minimally causes the processor to create and store in the memory a signal level indicator for the jamming signal represented in a weighted discrete wavelet transform stored in the memory and wherein the discrete wavelet transformation module causes the processor to create and store in the memory a wavelet transformation according to the sample-set stored in the memory and according to a basis function selected according to the signal level indicator.