| 摘要 |
A fixed network automatic meter reading system, with up to 5km range between meters 4 and node 6, uses a common reference source 2 for the frequency reference of meter transmitters 12 and system receiver 18. By using a publicly available reference frequency, synchronisation of the transmitter and receiver frequencies is possible without the need for an additional data exchange between the node and the meters. Using this system, frequency stability can be obtained in order to provide a signal to noise bandwidth of the order or 32Hz. Suitable public transmissions include MSF Rugby (60kHz), BBC Droitwich (198kHZ), any FM station carrying RDS data, or the LF/MF services from WWV in Boulder Colorado.
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