| 摘要 |
A radio modulator and method with a radio band scan function. The apparatus consists of a frequency selectable RF signal transmitter, a switch that couples the RF signal to an antenna, and a demodulator coupled to mix a received antenna signal with the RF signal to produce an indicia of signal strength at the receive frequency resulting from that mix. A channel memory is coupled to store plural indicia of signal strength values corresponding to plural receive frequencies. A controller is coupled to the transmitter, the switch, the channel memory, and a display. In operation, the controller enables the frequency scan function by decoupling the switch, tuning the transmitter RF signal to plural frequencies, which causes the demodulator to receive plural receive frequencies within the radio band. The controller also stores the resultant plural corresponding indicia of signal strength in the channel memory, and then compares the stored plural indicia of signal strength to select a present transmit frequency that has a low signal interfering level. Next, the controller couples the transmitter to the antenna, tunes the RF signal to the present transmit frequency, and displays the present transmit frequency on the display.
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