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公开(公告)号：US4014166A
公开(公告)日：1977-03-29
申请号：US657918
申请日：1976-02-13
摘要： A method and apparatus are provided for maintaining and correcting a time ference in a satellite controlled digital clock system. A time code message including time-of-year information and satellite position information is transmitted in a data stream from a transmitter on earth to a satellite orbiting the earth to be relayed back to receivers located around the world. The data is transmitted at a precise data rate. According to the invention, a local clock oscillator is phase locked with the precise data rate, thereby providing the clock system with time-of-year information by counting the pulses produced by the local oscillator. At the same time, the digital clock system assembles the time code message from the received data stream and compares the message with the time accumulated by counting the pulses produced by the oscillator. After a predetermined number of errors are detected by such comparisons, the clock system resets itself to coincide with the received time code message. If transmission of the time code message is interrupted, the clock continues counting pulses produced by the local oscillator and thereby continues keeping time undisturbed. In a preferred embodiment, the digital clock system is implemented with a firmware programmed micro-computer and the time-of-year and satellite position information is displayed on light emitting diode digital displays.
摘要翻译： 提供了一种用于在卫星控制数字时钟系统中维持和校正时间基准的方法和装置。 包括时间信息和卫星位置信息的时间码消息在数据流中从地球上的发射机发射到绕地球运行的卫星，以被传送回世界各地的接收机。 以精确的数据速率传输数据。 根据本发明，本地时钟振荡器以精确的数据速率锁相，从而通过对本地振荡器产生的脉冲进行计数来为时钟系统提供时间信息。 同时，数字时钟系统从接收到的数据流中组合时间码消息，并将消息与通过对由振荡器产生的脉冲进行计数而累积的时间进行比较。 在通过这样的比较检测到预定数量的错误之后，时钟系统重置自身以与接收到的时间码消息一致。 如果时间码消息的传输中断，则时钟继续对本地振荡器产生的脉冲进行计数，从而继续保持时间不受干扰。 在优选实施例中，数字时钟系统由固件编程的微型计算机实现，并且时间和卫星位置信息被显示在发光二极管数字显示器上。
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公开(公告)号：US5274545A
公开(公告)日：1993-12-28
申请号：US864167
申请日：1992-04-03
申请人： David W. Allan , Judah Levine , Dicky D. Davis , Marc A. Weiss
发明人： David W. Allan , Judah Levine , Dicky D. Davis , Marc A. Weiss
摘要： A device and method provide for an accurate output from a unit, such as an oscillator and/or clock providing an output indicative of frequency and/or time. The device includes a processing section having a microprocessor that develops a model characterizing the performance of the device, including establishing predicted accuracy variations, and the model is then used to correct the unit output. An external reference is used to provide a reference input for updating the model, including updating of predicted variations of the unit, by comparison of the reference input with the unit output. The ability of the model to accurately predict the performance of the unit improves as additional updates are carried out, and this allows the interval between the updates to be lengthened and/or the overall accuracy of the device to be improved. The accuracy of the output is thus adaptively optimized in the presence of systematic and random variations.
摘要翻译： 设备和方法提供来自单元的准确输出，例如提供表示频率和/或时间的输出的振荡器和/或时钟。 该装置包括具有微处理器的处理部分，该微处理器开发表征装置的性能的模型，包括建立预测的精度变化，然后使用该模型来校正单位输出。 通过比较参考输入和单位输出，外部参考用于提供用于更新模型的参考输入，包括更新单元的预测变化。 随着执行额外的更新，模型准确预测单元性能的能力得到改善，这样可以使更新之间的间隔延长和/或改进设备的整体精度。 因此，在存在系统和随机变化的情况下，输出的精度被自适应地优化。
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公开(公告)号：US3958269A
公开(公告)日：1976-05-18
申请号：US499102
申请日：1974-08-20
申请人： Dicky D. Davis
发明人： Dicky D. Davis
CPC分类号： H04N17/04
摘要： Apparatus for measuring the frequency of a reference signal which utilizeshe color subcarrier signal of a television receiver as a standard frequency signal. In a first embodiment, the reference signal controls a circuit to develop bursts of a synthesized color subcarrier signal, gated at the horizontal line rate of a color television receiver. The synthesized signal is superimposed on the broadcast television signal and applied to the receiver to produce a modulation bar on the screen. Any frequency/phase difference between synthesized and broadcast color subcarrier signals will cause the modulation bar to move laterally across the screen, and/or cause the sequence of colors within the modulation bar to vary. Movement of the modulation bar is a coarse indication of frequency difference and change of the color sequence within the bar is a precise indication of phase difference.In a second embodiment, the locally synthesized color subcarrier signal and the color subcarrier signal of the television receiver are compared in a linear phase comparator to develop a signal having an instantaneous voltage proportional to the phase difference between the two signals. The phase signal controls a generator which develops a cursor line on the screen. Movement of the line across the screen provides a coarse indication of phase difference between the subcarrier signals. The phase signal is also applied to a digital counter which affords a precise readout of the phase difference between the signals.
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