Claims
- 1. A method for improving the sensitivity of a navigation receiver, the method comprising the steps of:
opening up the radio frequency (RF) and intermediate frequency (IF) passband of RF and IF receiver stages substantially wider than a desired-signal bandwidth; sampling a desired signal after superheterodyne conversion at a first sample-rate; averaging samples obtained in the step of sampling to zero-out noise and increase the signal-to-noise ratio of said desired signal; and outputting averaged samples obtained in the step of averaging at a second sample-rate substantially slower than said first sample-rate; wherein a digital signal processor provides for position solutions from said averaged samples obtained at said second sample-rate.
- 2. The method of claim 1, wherein:
the step of opening up includes the use of L-band microwave signals transmitted from orbiting global positioning system (GPS) navigation satellites.
- 3. The method of claim 1, wherein:
the step of opening up includes the use of bandpass filters with passbands at least twenty times the bandwidth of said desired signal.
- 4. The method of claim 1, wherein:
the step of sampling is such that said first sample-rate is more than ten times higher than said second sample-rate.
- 5. A navigation receiver, comprising,
a first radio-frequency bandwidth filter having a passband at least twenty times the bandwidth of an expected signal, wherein sample averaging is improved; a high-rate sampler for taking high-rate samples of the signal and noise that pass through the first radio-frequency bandwidth filter; a summer for summing up high-rate samples and providing for sample averages; and a converter for converting said sample averages to a low-rate sample.
- 6. The receiver of claim 5, wherein:
the first radio-frequency bandwidth filter has a passband centered on the L1-carrier of a microwave signal and is about 20-MHz wide.
- 7. The receiver of claim 5, wherein:
the high-rate sampler operates at least ten times the frequency of said low-rate samples output from the converter.
- 8. The receiver of claim 5, wherein:
the converter digitally removes a DC-offset than was injected in an earlier stage of the receiver and thus provides for further improved receiver sensitivity.
- 9. The receiver of claim 5, further comprising:
a selector for choosing between high-rate sampling and low-rate sampling.
- 10. The receiver of claim 9, further comprising:
a digital signal processor with a low-rate sample input that is connected to the converter such that it inputs samples at a constant rate independent of the state of the selector.
RELATED PATENT APPLICATION
[0001] U.S. patent application Ser. No. 09/687,044, filed Oct. 11, 2000, and titled SATELLITE NAVIGATION RECEIVER AND METHOD is incorporated herein by reference.