Spread spectrum signal processing

• US 8,422,601 B2
• Filed: 09/28/2007
• Issued: 04/16/2013
• Est. Priority Date: 10/15/2002
• Status: Active Grant

• Current Assignee: Qualcomm technologies international, ltd. (Qualcomm, Inc.)
• Original Assignee: Nordnav Technologies AB (Qualcomm, Inc.)
• Inventors: Sthlberg, Christian, Normark, Per-Ludvig
• Primary Examiner(s): Bocure, Tesfaldet
• Application Number:
  US11/864,342
• Publication Number:
  US 20080095272A1
• Time in Patent Office: 2,027 Days
• Field of Search: 375/316, 375/343, 375/130, 375/140, 375/141, 375/147, 375/150, 342/357.2, 34235722-35724, 342/357.4, 34235741-35744, 701/207, 701/213, 340/426.19, 340/539.11, 340/539.13
• US Class Current: 375/343
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 2201/70715 with application-specific features

Abstract

The present invention relates to processing of spread spectrum signals, where a continuous signal of a comparatively high frequency is received. This signal is sampled at a basic sampling rate whereby a resulting sequence of time discrete signal samples is produced, which are in turn quantized into a corresponding level-discrete sample value. A plurality of data words are formed, which each includes one or more consecutive sample values. Information obtained from these data words is correlated with at least one representation of a signal source specific code sequence, which has been pre-generated in the form of a code vector. The correlation step specifically involves correlating at least each vector in a sub-group of the code vectors with at least one vector that has been derived from the data word. Thereby resulting data is produced.

Claims

1. A software receiver comprising:

a receiver capable of receiving a radio signal;

means for digitizing the radio signal; and

a software correlator capable of mixing the digitized radio signal to form a baseband signal using bit-wise parallelism.

2. The software receiver of claim 1 wherein said software correlator comprises:

means for computing correlations between the baseband signal and at least one pseudo-random number (PRN) code using the bit-wise parallelism.

3. The software receiver of claim 2 wherein said software correlator further comprises:

means for computing accumulations from the correlations using the bit-wise parallelism.

4. The software receiver of claim 3 further comprising:

application-specific code capable of computing navigation data using the accumulations.

5. The software receiver of claim 1 wherein said means for digitizing comprises:

means for down-converting the radio signal to an intermediate frequency; and

a digitizer capable of digitizing the intermediate frequency.

6. The software receiver of claim 5 wherein said digitizer produces at least one bit/sample.

7. The software receiver of claim 5 wherein said digitizer is an analog to digital converter.