| 摘要 |
A method for automatically selecting optimum frequencies for transmitting data from remote terminals upstream to a system manager is provided. The system manager initially selects a set of frequencies from a larger set of available frequencies and transmits a command downstream to each remote terminal indicating which frequencies to use. Each remote terminal transmits data messsages on each selected frequency in response to addressed commands generated by the system manager. The system manager receives and counts the data messages on each of the frequencies, and after a statistically significant number of messages are received, removes from use the frequency with the lowest number of data messages received. This frequency is replaced with either (1) a previously untried frequency, or if all frequencies have been tried, (2) a previously tried frequency with the highest number of data messages received. In a preferred embodiment, new frequencies are removed from use and added to use only when the number of data messages received and the received signal level on a particular frequency falls within certain predetermined ranges. In another embodiment, the transmission level for a particular frequency is recalibrated when the number of data message received and the received signal level falls within other predetermined ranges. In a further embodiment, two or more sets of optimum frequencies are automatically chosen for different times during the day and the system manager is able to immediately switch between these sets at the appropriate times.
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