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    • 3. 发明授权
    • High accuracy low power GPS time source
    • 高精度低功耗GPS时间源
    • US5940027A
    • 1999-08-17
    • US940634
    • 1997-09-30
    • Daniel C. ForsethPaul G. JagnowMark W. JohnsonF. Britt SnodgrassLarry D. Vittorini
    • Daniel C. ForsethPaul G. JagnowMark W. JohnsonF. Britt SnodgrassLarry D. Vittorini
    • G01S1/00G04G3/02G01S5/02H04B7/185
    • G01S19/235G04G3/022H03L1/027
    • 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.
    • 公开了一种全球定位系统(GPS)接收机和高精度低功率时间源(HAL)。 HAL提供了具有足够高的准确度的时间源,用于接收机实现快速的直接Y码采集。 HAL包括适于以期望的频率提供未补偿的频率信号的振荡器。 频率转换电路接收未补偿的频率信号和控制信号作为输入,并且提供具有平均补偿频率的补偿频率信号作为输出,其平均补偿频率比平均未补偿频率更接近期望频率。 温度传感器提供指示振荡器的温度的输出。 频率误差确定电路确定作为温度传感器输出的函数的误差值,其表示在未补偿的频率信号中随时间的频率误差量。 频率误差确定电路根据所确定的未补偿频率信号中的频率误差量产生控制信号。 计数器从频率转换电路接收经补偿的频率信号,并根据经补偿的频率信号提供时间周期的数字表示作为输出。