Adaptive Correlation for Detection of a High-Frequency Signal

• US 20100135367A1
• Filed: 12/02/2008
• Published: 06/03/2010
• Est. Priority Date: 12/02/2008
• Status: Active Grant

• Current Assignee: Infineon Technologies AG
• Original Assignee: Infineon Technologies AG
• Inventors: Schmid, Andreas
• Granted Patent: US 8,477,828 B2
• Time in Patent Office: Days
• US Class Current: 375/150
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: H03J 7/04 where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant

Abstract

Embodiments related to acquisition, detection, and processing of a high-frequency signal are described and depicted.

Claims

1. A receiver, comprising:

a coherent integration stage configured to coherently integrate a signal downconverted using a downconversion frequency, wherein the coherent integration is performed over a first period of integration to produce a pre-detection sample;

a phase error detection stage configured to produce a phase error signal dependent on a phase error of the pre-detection sample; and

a correction stage configured to output a downconversion frequency adjustment signal in response to the phase error signal.

2. The receiver as claimed in claim 1, wherein the received signal is a CDMA signal.

3. The receiver as claimed in claim 1, further including a detection stage coupled to the coherent integration stage, the detection stage configured to produce a decision statistic employing the pre-detection sample.

4. The receiver as claimed in claim 3, wherein the phase error detection stage is configured

to delay a plurality of the pre-detection samples,

to form a complex conjugate of the plurality of the delayed pre-detection samples,

to form a sum of products over a second period of integration of the plurality of the pre-detection samples with the plurality of the delayed and complex conjugated pre-detection samples, and

to produce the phase error signal dependent on an angular coordinate of the sum of products.

5. The receiver as claimed in claim 4, wherein the delayed pre-detection samples of the plurality of delayed pre-detection samples are each delayed by the first period of integration of the coherent integration stage.

6. The receiver as claimed in claim 4, wherein a sequence of magnitudes is formed in the detection stage from the sum of products, and the sequence of magnitudes is summed to form the decision statistic.

7. The receiver as claimed in claim 4, wherein the correction stage is configured to adjust at least one of a duration of the first period of integration and a duration of the second period of integration employing the phase error signal.

8. The receiver as claimed in claim 1, further comprising a baseband signal downconverter stage configured to produce a downconverted baseband signal using the downconversion frequency and a despreading code.

9. A receiver comprising a coherent integration stage configured to coherently integrate a received signal over a first period of integration to produce a pre-detection sample, wherein the pre-detection sample is employed to adjust a duration of the first period of integration during acquisition of the received signal.

10. The receiver as claimed in claim 9, further including a detection stage coupled to the coherent integration stage, the detection stage configured to produce a decision statistic employing the pre-detection sample, wherein the receiver is further configured

to delay a plurality of the pre-detection samples,

to form a complex conjugate of the plurality of the delayed pre-detection samples,

to form a sum of products over a second period of integration of the plurality of the pre-detection samples with the plurality of the delayed and complex conjugated pre-detection samples, and

to produce a phase error signal dependent on an angular coordinate of the sum of products,

wherein the phase error signal is employed to adjust the first period of integration during the acquisition of the received signal.

11. The receiver as claimed in claim 10, wherein the delayed pre-detection samples of the plurality of delayed pre-detection samples are each delayed by the first period of integration of the coherent integration stage.

12. The receiver as claimed in claim 10, wherein a sequence of magnitudes is formed in the detection stage from the sum of products, and the sequence of magnitudes is summed to form the decision statistic.

13. The receiver as claimed in claim 10, wherein the receiver is further configured to adjust at least one of the first period of integration and the second period of integration employing the phase error signal.

14. The receiver as claimed in claim 9, further comprising a baseband signal downconverter stage, the baseband signal downconverter stage configured to produce a downconverted baseband signal using a downconversion signal having a downconversion frequency, wherein the downconverted baseband signal comprises the received signal, and wherein the pre-detection sample is further used to adjust the downconversion frequency.

15. A method of processing a received signal, the method comprising:

integrating a signal downconverted by a downconversion frequency over a first period of coherent integration to produce a pre-detection sample;

producing a phase error signal dependent on a phase error of the pre-detection sample; and

producing a downconversion frequency adjustment signal in response to the phase error signal.

16. The method as claimed in claim 15, further comprising producing a decision statistic employing the pre-detection sample, wherein producing the decision statistic comprises:

delaying a plurality of the pre-detection samples;

forming a complex conjugate of the plurality of the delayed pre-detection samples;

forming a sum of products over a second period of integration of the plurality of the pre-detection samples with the plurality of the delayed and complex conjugated pre-detection samples; and

producing the phase error signal dependent on an angular coordinate of the sum of products.

17. The method as claimed in claim 16, wherein the delayed pre-detection samples of the plurality of delayed pre-detection samples are each delayed by the first period of integration of the coherent integration stage.

18. The method as claimed in claim 16, further comprising forming a sequence of magnitudes from the sum of products, and summing the sequence of magnitudes to form the decision statistic.

19. The method as claimed in claim 16, further comprising adjusting at least one of a duration of the first period of integration and a duration of the second period of integration employing the phase error signal.

20. A method of processing a signal in a receiver, the method comprising:

integrating the signal over a first period of coherent integration to produce a pre-detection sample; and

adjusting a duration of the first period of integration during acquisition of the received signal employing the pre-detection sample.

21. The method as claimed in claim 20, further comprising:

producing a decision statistic employing the pre-detection sample;

delaying a plurality of the pre-detection samples;

forming a complex conjugate of the plurality of the delayed pre-detection samples;

forming a sum of products over a second period of integration of the plurality of the pre-detection samples with the plurality of the delayed and complex conjugated pre-detection samples;

producing a phase error signal dependent on an angular coordinate of the sum of products; and

employing the phase error signal to adjust the first period of integration during the acquisition of the received signal.

22. The method as claimed in claim 21, wherein the delayed pre-detection samples of the plurality of delayed pre-detection samples are each delayed by the first period of integration of the coherent integration stage.

23. The method as claimed in claim 21, further comprising:

forming a sequence of magnitudes in the detection stage from the sum of products; and

summing the sequence of magnitudes to form the decision statistic.

24. The method as claimed in claim 21, further comprising adjusting at least one of the first period of integration and the second period of integration employing the phase error signal.

25. The method as claimed in claim 20, further comprising:

producing a downconverted baseband signal using a downconversion signal having a downconversion frequency;

employing the pre-detection sample to adjust the downconversion frequency; and

employing a despreading code to demodulate the signal.