| 摘要 |
Received signals are converted into IF signals by a frequency converter. The IF signals are caused to pass through a band-pass filter having a pass band width including a receiving channel and adjacent channels of higher- and lower-frequencies. The resultant signals are then converted into digital signals by an A/D converter. The digital signals are stored in a memory. The pass band of a variable frequency digital filter serving as a digital processing circuit is sequentially switched to the receiving channel and the adjacent channels, and the received signal data stored in the memory are read out and caused to pass through the variable frequency digital filter for each channel. The electric field levels of the received signals from the receiving channel and the adjacent channels are sequentially calculated by an electric field level measuring circuit by using outputs from the variable frequency digital filter or a demodulator connected to the output terminal of the filter. |
