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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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