Transceiver capable of sensing a clear channel

摘要

A transceiver receives electronic input signals comprised of a plurality of frequency bands lying within a plurality of non-overlapping frequency channels. A mixer frequency shifts a selected band to a predetermined center frequency in response to a first clocking signal of a first selectable frequency. A charge transfer device filter is coupled to the mixer output to filter the band of the predetermined center frequency in response to a second selectable frequency clocking signal. The clocking signals are generated by clocking means which receive digital microcommands identifying the selectable frequencies. Signal level measuring means are coupled to the output of the charge transfer device filter and generate digital level signals indicating the signal level present in the filtered band. Microprocessor means are coupled to send microcommands to the clocking means for sequentially filtering various channels from the plurality, and for monitoring the resulting digital level signals.