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Method and apparatus for improved L2 performance in dual frequency semi-codeless GPS receivers

a semi-codeless gps receiver and dual-frequency technology, applied in the field of acquisition and tracking of signals, can solve the problems of not being able to track y-code by conventional procedures in civilian gps receivers, w-code is secret and not available for civilian use, and no reference applied to the timing pattern of w-code known information, so as to improve the performance of semi-codeless l2 tracking

Inactive Publication Date: 2007-10-04
LENNEN GARY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

This approach significantly improves the signal-to-noise ratio when tracking the GPS L2 signal, leading to enhanced code and carrier measurement capabilities, as confirmed by experiments and analysis, particularly when using a high-gain antenna and optimized GPS receiver designs.

Problems solved by technology

The W-code is secret and is not available for civilian use.
Because the W-code is unknown, the Y-code cannot be tracked by conventional procedures in a civilian GPS receiver.
However, none of these references apply known information about the timing pattern of the W-code.

Method used

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  • Method and apparatus for improved L2 performance in dual frequency semi-codeless GPS receivers
  • Method and apparatus for improved L2 performance in dual frequency semi-codeless GPS receivers
  • Method and apparatus for improved L2 performance in dual frequency semi-codeless GPS receivers

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Embodiment Construction

[0035]FIG. 1 is a high-level illustration of a GPS receiver 10 in accordance with one embodiment of the invention. Key aspects of the invention are provided primarily in the L1 / L2 digital channel processors (channel processors) 12. Although other portions of this GPS receiver 10 can be similar to conventional receivers, see for example, U.S. Pat. No. 5,541,606 to Lennen, aspects of this invention can be incorporated elsewhere, for example, the software which runs on the microprocessor system 14.

[0036] In operation, the antenna 16 receives the GPS L1 and L2 signals transmitted from GPS satellites and other GPS sources. The antenna 16 outputs a corresponding antenna signal 18 which is filtered and amplified by filter / low-noise-amplifier (LNA) 20. The resulting filtered signal 22 is then translated (downconverted and digitized) by a radio frequency (RF) module 24 to generate intermediate frequency signals 26. Thus, for example, the GPS L1 signal is frequency translated to 420 kilohert...

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Abstract

This invention relates to improving the signal-to-noise ratio of semi-codeless tracking by presenting a method and apparatus which employs an optimal W-code timing pattern, and / or provides signal-to-noise gain by adding L1 and L2 W-code bit timing estimate signals before combining the L1 W-code estimate signal with the L2 W-code estimate signal.

Description

CROSS REFERENCE TO RELATED APPLICATIONS [0001] This application claims the benefit of U.S. Provisional Application No. 60 / 157,298 filed Oct. 1, 1999.FIELD OF THE INVENTION [0002] This invention relates to the acquisition and tracking of signals transmitted in accordance with the Global Positioning System (“GPS”), and in particular, using information from the GPS signal transmitted in the frequency band about 1575.42 Megahertz (MHz) (“L1”) to improve the signal-to-noise ratio (“SNR”) for acquiring and tracking the GPS signal transmitted in the frequency band about 1227.6 MHz (“L2”). BACKGROUND OF THE INVENTION [0003] Tracking the GPS L2 signal plays a significant role in high-end GPS receivers and especially for civilian applications such as machine control and survey equipment. The GPS L2 signal, like the GPS L1 signal, contains-three or more separate components: (1) a carrier signal (such as a 1227.6 MHz sinusoidal waveform); (2) a code signal; and (3) a data signal. The code signa...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): H04B1/00G01S1/00H04B1/69H04B1/707
CPCG01S19/32H04B2201/70715H04B1/7077
Inventor LENNEN, GARY
Owner LENNEN GARY