Oscillator frequency correction in GPS signal acquisition

A technology of GPS signal and oscillator frequency, which is applied in the field of global positioning system and can solve problems such as complex calculations

Inactive Publication Date: 2008-04-23
GOOGLE TECH HLDG LLC
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  • Description
  • Claims
  • Application Information

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However, these solutions require additional hardware systems and are computationally complex

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  • Oscillator frequency correction in GPS signal acquisition
  • Oscillator frequency correction in GPS signal acquisition
  • Oscillator frequency correction in GPS signal acquisition

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Embodiment Construction

[0028] The present invention provides an improved system and method for assisting GPS signal acquisition. Significant signal detection improvements are achieved with improved oscillator accuracy by acquiring and coherently operating on acquired GPS satellite signals. In this way, weaker signals can also be detected in the same pre-detection integration interval previously used for stronger signals. Depending on the predictability of the satellite signal data pattern, the correlation can be further improved. By applying the improved technique described below, positioning data can be obtained in weak signal areas without increasing the correlation time. This allows energy saving - an important feature of portable devices, and makes E911 service feasible in portable products.

[0029] Before delving into specific examples, an overview of several aspects of the improved method and the teachings of the systems approach is provided. The method and system includes a wireless commu...

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Abstract

A method (50) for correcting oscillator frequency error in GPS signal acquisition includes a first step (52) of receiving at least one broadcasted GPS signal. A next step (54) includes estimating a plurality of Doppler offsets. A next step (56) includes correlating the signal to produce a Doppler modulation for each of the plurality of Doppler estimates. A next step (58) includes calculating a magnitude separation of peak and null states of each modulation. A next step (60) includes searching the peak and null separation to finding the Doppler estimate producing the largest magnitude separation in peak and null states. The found Doppler estimate defines a frequency error estimate for the at least one broadcasted GPS signal, which will be common across all satellites.

Description

technical field [0001] The present invention relates generally to the Global Positioning System (GPS), and more particularly to improved signal detection acquisition time and low level signal detection for GPS receivers. Background technique [0002] According to the Federal Communications Commission (FCC), cellular radiotelephone calls must be geographically locateable. This capability is desired for emergency services systems such as E911. The FCC requires stringent accuracy and availability performance goals and requires cellular radio phones to be localizable 67% of the time within 50 meters, 95% of the time at 150 meters for handset-based solutions, and 67% of the time at 100 meters. of the time and 95% of the time at a range of 300 meters can be used for web-based solutions. Even when using conventional TOA / TDOA (Time of Arrival / Time Difference of Arrival) infrastructure technologies, it is difficult to achieve the relaxed threshold of this network-based solution. ...

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Application Information

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IPC IPC(8): H04B7/185G01S5/14G01S19/25G01S1/00G01S19/20G01S19/28
CPCG01S19/30G01S19/29G01S19/256G01S19/20G01S19/28
Inventor 托马斯·M·金乔治·J·盖尔赛弗·基埃依
Owner GOOGLE TECH HLDG LLC
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