Method and apparatus for acquiring wide-band pseudorandom noise encoded waveforms

• US 6,549,151 B1
• Filed: 11/26/2001
• Issued: 04/15/2003
• Est. Priority Date: 08/21/1997
• Status: Expired due to Term

• Current Assignee: Data Fusion Corp.
• Original Assignee: Data Fusion Corp.
• Inventors: Thomas, John K., Kober, Wolfgang
• Primary Examiner(s): WAMSLEY, PATRICK G
• Application Number:
  US09/995,207
• Time in Patent Office: 505 Days
• Field of Search: 341/155, 341/141, 341/61, 331/78, 375/148, 375/240.11, 375/150, 370/288, 370/290, 370/291, 348/384.1, 382/240
• US Class Current: 341/141
• CPC Class Codes: G01S 1/045 Receivers
• CPC Class Codes: G01S 7/021 Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals
• CPC Class Codes: G01S 7/285 Receivers
• CPC Class Codes: H03M 1/121 Interleaved, i.e. using multiple converters or converter parts for one channel

Abstract

The method and apparatus of the present invention is directed to architectures for signal processing, such as for performing analog-to-digital and digital-to-analog conversions, in which the source signal is decomposed into subband signals by an analysis filter, processed, and the processed subband signals combined to form a reconstructed signal that is representative of the source signal.

Claims

1. A method for acquiring a coded signal having a bandwidth, comprising:

(a) providing a received coded signal having a bandwidth;

(b) decomposing the received coded signal into a plurality of subband signals, each of the subband signals having an associated bandwidth less than the coded signal bandwidth;

(c) forming a plurality of subband correlation signals corresponding to the plurality of subband signals;

(d) combining the plurality of subband correlation signals to form a correlation function corresponding to the received coded signal, the correlation function defining a plurality of peaks;

(e) determining, based on the correlation function, an estimated transmit time and frequency of at least part of the coded signal; and

(f) determining, based on the estimated transmit time and frequency, a replicated code corresponding to the at least part of the received coded signal.

2. The method of claim 1, wherein in step (f) an amplitude and delay for each of the plurality of peaks is determined, and further comprising:

(g) inputting the amplitudes and delays to a RAKE processor to provide a RAKE signal.

3. The method of claim 2, wherein in the providing step (a) the coded signal is received by a plurality of spatially dislocated antennas and further comprising:

summing a plurality of antenna outputs without compensating for a corresponding, relative output delay.

4. The method of claim 3, wherein N is the number of antenna outputs and p is a number of multipath signal segments output by the antenna outputs and wherein the product of N and p is the number of peaks in the correlation function.

5. The method of claim 4, wherein in step (g) the Np peaks are used to realign and scale the inputted signal segments before summation by the RAKE processor.

6. The method of claim 2, further comprising:

(h) correlating the RAKE signal and the replicated code to provide a second estimate of the transmit time and frequency of the at least part of the received coded signal.

7. The method of claim 6, further comprising:

(i) detecting the at least part of the coded signal based on the second estimate of the transmit time and frequency.

8. The method of claim 1, wherein the providing step (a) comprises:

down converting a received signal to an intermediate frequency;

filtering the down converted signal; and

converting the down converted signal from analog to digital form to form the received coded signal.

9. A method for acquiring a coded signal having a bandwidth, comprising:

(a) providing a received coded signal having a bandwidth;

(b) decomposing the received coded signal into a plurality of subband signals, each of the subband signals having an associated bandwidth less than the coded signal bandwidth;

(c) forming a plurality of subband correlation signals corresponding to the plurality of subband signals;

(d) combining the plurality of subband correlation signals to form a correlation function corresponding to at least part of the received coded signal, the correlation function defining a plurality of peaks;

(e) determining, based on the correlation function, an amplitude and time delay for each of the plurality of peaks; and

(f) inputting the amplitudes and delays to a RAKE processor to provide a RAKE signal derived from the at least part of the received coded signal.

10. The method of claim 9, wherein in step (e) an estimated transmit time and frequency are determined for the at least part of the received coded signal;

and further comprising;

(g) determining, based on the estimated transmit time and frequency, a replicated code corresponding to the least part of the received coded signal.

11. The method of claim 10, further comprising:

(h) correlating the RAKE signal and the replicated code to provide a second estimate of the transmit time and frequency of the at least part of the received coded signal.

12. The method of claim 11, further comprising:

(i) detecting the at least part of the received coded signal based on the second estimate of the transmit time and frequency.

13. The method of claim 9, wherein in the providing step (a) the coded signal is received by a plurality of spatially dislocated antennas and further comprising:

summing a plurality of antenna outputs without compensating for a corresponding, relative output delay.

14. The method of claim 13, wherein N is the number of antenna outputs and p is a number of multipath signal segments output by the antenna outputs and wherein the product of N and p is the number of peaks in the correlation function.

15. The method of claim 14, wherein in step (f) the Np peaks are used to realign and scale the input signal segments before summation by the RAKE processor.

16. The method of claim 9, wherein the providing step (a) comprises:

down converting a received signal to an intermediate frequency;

filtering the down converted signal; and

converting the down converted signal from analog to digital form to form the received coded signal.

17. A system for acquiring a coded signal having a bandwidth, comprising:

(a) means for providing a received coded signal having a bandwidth;

(b) means for decomposing the received coded signal into a plurality of subband signals, each of the subband signals having an associated bandwidth less than the coded signal bandwidth;

(c) means for forming a plurality of subband correlation signals corresponding to the plurality of subband signals;

(d) means for deriving from the plurality of subband correlation signals a correlation function corresponding to the received coded signal, the correlation function defining a plurality of peaks;

(e) first means for determining, based on the correlation function, an estimated transmit time and frequency of at least part of the received coded signal; and

(f) second means for determining, based on the estimated transmit time and frequency, a replicated code corresponding to the at least part of the received coded signal.

18. The system of claim 17, wherein the first determining means determines an amplitude and delay for each of the plurality of peaks and further comprising:

(g) RAKE processing means for providing a RAKE signal based on the amplitudes and delays and the at least part of the received coded signal.

19. The system of claim 18, further comprising:

a plurality of spatially dislocated antennas for receiving a corresponding signal and outputting the corresponding signal through a corresponding output and wherein the coded signal is a sum of the plurality of antenna outputs and is independent of a relative output delay associated with each antenna output.

20. The system of claim 19, wherein N is the number of antenna outputs and p is a number of multipath signal segments output by the antenna outputs and wherein the product of N and p is the number of peaks in the correlation function.

21. The system of claim 20, wherein the RAKE processing means uses the Np peaks are used to realign and scale the input signal segments before summation by the RAKE processing means.

22. The system of claim 18, further comprising:

(h) means for correlating the RAKE signal and the replicated code to provide a second estimate of the transmit time and frequency of the at least part of the received coded signal.

23. The system of claim 22, further comprising:

(i) means for detecting the at least part of the received coded signal based on the second estimate of the transmit time and frequency.

24. The system of claim 17, wherein the providing means comprises:

means for down converting a received signal to an intermediate frequency;

means for filtering the down converted signal; and

means for converting the down converted signal from analog to digital form to form the received coded signal.

25. A system for acquiring a coded signal having a bandwidth, comprising:

(a) means for providing a received coded signal having a bandwidth;

(b) means for decomposing the received coded signal into a plurality of subband signals, each of the subband signals having an associated bandwidth less than the coded signal bandwidth;

(c) means for forming a plurality of subband correlation signals corresponding to the plurality of subband signals;

(d) means for deriving from the plurality of subband correlation signals a correlation function corresponding to the received coded signal, the correlation function defining a plurality of peaks;

(e) means for determining, based on the correlation function, an amplitude and time delay for each of the plurality of peaks; and

(f) RAKE processing means for providing a RAKE signal based on the amplitudes and delays.

26. The system of claim 25, wherein the determining means determines an estimated transmit time and frequency for at least part of the received coded signal;

and further comprising;

(g) second means for determining, based on the estimated transmit time and frequency, a replicated code corresponding to at least part of the received coded signal.

27. The system of claim 26, further comprising:

(h) means for correlating the RAKE signal and the replicated code to provide a second estimate of the transmit time and frequency of the at least part of the received coded signal.

28. The system of claim 27, further comprising:

(i) means for detecting the at least part of the received coded signal based on the second estimate of the transmit time and frequency.

29. The system of claim 25, wherein the providing means comprises a plurality of spatially dislocated antennas, each antenna having an associated antenna output, and the RAKE processing means sums the plurality of antenna outputs without compensating for a relative output delay associated with each output.

30. The system of claim 29, wherein N is the number of antenna outputs and p is a number of multipath signal segments received by the antenna outputs and wherein the product of N and p is the number of peaks in the correlation function.

31. The system of claim 30, wherein the RAKE processing means, based on the Np peaks, realigns and scales the inputted signal segments before summation of the segments.

32. The system of claim 25, wherein the providing means comprises:

means for down converting a received signal to an intermediate frequency;

means for filtering the down converted signal; and

means for converting the down converted signal from analog to digital form to form the received coded signal.

33. A system for acquiring a coded signal having a bandwidth, comprising:

(a) an input operable to provide a received coded signal having a bandwidth;

(b) an analysis filter bank operable to decompose the received coded signal into a plurality of subband signals, each of the subband signals having an associated bandwidth less than the coded signal bandwidth;

(c) a plurality of subband correlators operable to form a plurality of subband correlation signals from the plurality of subband signals;

(d) a synthesis filter bank operable to form a correlation function corresponding to at least part of the received coded signal from the plurality of subband correlation signals, the correlation function defining a plurality of peaks;

(e) a pre-detector operable to determine, based on the correlation function, an estimated transmit time and frequency of at least part of the received coded signal; and

(f) a code generator operable to determine, based on the estimated transmit time and frequency, a replicated code corresponding to the at least part of the received coded signal.

34. The system of claim 33, wherein the pre-detector is operable to determine an amplitude and delay for each of the plurality of peaks and further comprising:

(g) a RAKE processor operable to provide a RAKE signal based on the amplitudes and delays and the at least part of the received coded signal.

35. The system of claim 34, further comprising:

a plurality of spatially dislocated antennas operable to receive a corresponding signal and output the corresponding signal through a corresponding output and wherein the coded signal is a sum of the plurality of antenna outputs and is independent of a relative output delay associated with each antenna output.

36. The system of claim 35, wherein N is the number of antenna outputs and p is a number of multipath signal segments output by the antenna outputs and wherein the product of N and p is the number of peaks in the correlation function.

37. The system of claim 36, wherein the Np peaks are used to realign and scale the input signal segments before summation by the RAKE processor.

38. The system of claim 34, further comprising:

(h) a correlator operable to correlate the RAKE signal with the replicated code to provide a second estimate of the transmit time and frequency of the at least part of the received coded signal.

39. The system of claim 38, further comprising:

(i) a detector operable to detect the at least part of the received coded signal based on the second estimate of the transmit time and frequency.

40. The system of claim 33, wherein the input comprises:

a down converter operable to down convert a received signal to an intermediate frequency;

a filter operable to filter the down converted signal; and

an analog-to-digital converter operable to convert the down converted signal from analog to digital form to form the received coded signal.

41. A system for acquiring a coded signal having a bandwidth, comprising:

(a) an input operable to provide a received coded signal having a bandwidth;

(b) an analysis filter bank operable to decompose the received coded signal into a plurality of subband signals, each of the subband signals having an associated bandwidth less than the coded signal bandwidth;

(c) a plurality of subband correlators operable to form a plurality of subband correlation signals corresponding to the plurality of subband signals;

(d) a synthesis filter bank operable to form a correlation function corresponding to at least part of the received coded signal from the plurality of subband correlation signals, the correlation function defining a plurality of peaks;

(e) a pre-detector operable to determine, based on the correlation function, an amplitude and time delay for each of the plurality of peaks; and

(f) a RAKE processor operable to provide providing a RAKE signal based on the amplitudes and delays and the received coded signal.

42. The system of claim 41, wherein the pre-detector determines an estimated transmit time and frequency for the at least part of the coded signal and further comprising:

(g) a code generator operable to determine, based on the estimated transmit time and frequency, a replicated code corresponding to the at least part of the received coded signal.

43. The system of claim 42, further comprising:

(h) a correlator operable to correlate the RAKE signal with the replicated code to provide a second estimate of the transmit time and frequency of the at least part of the received coded signal.

44. The system of claim 43, further comprising:

(i) a detector operable to detect the at least part of the received coded signal based on the second estimate of the transmit time and frequency.

45. The system of claim 41, wherein the input comprises a plurality of spatially dislocated antennas, each antenna having an associated antenna output, and wherein the RAKE processor sums the plurality of antenna outputs without compensating for a relative output delay associated with each output.

46. The system of claim 45, wherein N is the number of antenna outputs and p is a number of multipath signal segments received by the antenna outputs and wherein the product of N and p is the number of peaks in the correlation function.

47. The system of claim 46, wherein the RAKE processor, based on the Np peaks, realigns and scales the inputted signal segments before summation of the segments.

48. The system of claim 41, wherein the input comprises:

a down converter operable to down convert a received signal to an intermediate frequency;

a filter operable to filter the down converted signal; and

a converter operable to convert the down converted signal from analog-to digital form to form the received coded signal.