发明名称 |
High accuracy low power GPS time source |
摘要 |
A global positioning system (GPS) receiver and high accuracy low power time source (HAL) are disclosed. The HAL provides a time source having an accuracy which is high enough for the receiver to achieve fast direct Y-code acquisition. The HAL includes an oscillator adapted to provide an uncompensated frequency signal at a desired frequency. Frequency conversion circuitry receives the uncompensated frequency signal and a control signal as inputs, and provides as an output a compensated frequency signal having an average compensated frequency which is closer to the desired frequency than is the average uncompensated frequency. A temperature sensor provides an output indicative of a temperature of the oscillator. Frequency error determining circuitry determines an error value, as a function of the temperature sensor output, which is indicative of a quantity of frequency error over time in the uncompensated frequency signal. The frequency error determining circuitry generates the control signal as a function of the determined quantity of frequency error in the uncompensated frequency signal. A counter receives the compensated frequency signal from the frequency conversion circuitry and provides as an output a digital representation of a time period based upon the compensated frequency signal.
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申请公布号 |
US5940027(A) |
申请公布日期 |
1999.08.17 |
申请号 |
US19970940634 |
申请日期 |
1997.09.30 |
申请人 |
ROCKWELL INTERNATIONAL CORPORATION |
发明人 |
FORSETH, DANIEL C.;JAGNOW, PAUL G.;JOHNSON, MARK W.;SNODGRASS, F. BRITT;VITTORINI, LARRY D. |
分类号 |
G01S1/00;G04G3/02;(IPC1-7):G01S5/02;H04B7/185 |
主分类号 |
G01S1/00 |
代理机构 |
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代理人 |
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主权项 |
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