Radio receiving device for measuring an electric field level of a receiving channel and adjacent channels using common components

DETAILED DESCRIPTION The present invention has been made to eliminate the above drawbacks, and has as its object to provide a radio receiving device which can measure the electric field levels of electric wave on a receiving channel and adjacent channels with a small number of electric components and a simple circuit arrangement.
According to the present invention, there is provided a radio receiving device including a frequency converter for converting received signals into IF signals, a band-pass filter for passing the IF signals, and demodulation means for demodulating signals transmitted through a receiving channel and adjacent channels of higher- and lower-frequencies than the receiving channel by using output signals from the band-pass filter, characterized in that the band-pass filter and the demodulation means are commonly used for the receiving channel and the adjacent channels, and the device comprises an analog/digital converter for converting output signals from the band-pass filter into digital signals, a digital filter for processing the digital signals, and a control circuit for switching a pass band of the digital filter substantially to the receiving channel and the adjacent channels.
The band-pass filter and the demodulation means, which filter and demodulate IF signals from the first frequency converter, respectively, are commonly used for the receiving channel and the adjacent channels.
Output signals from the band-pass filter are converted into digital signals.
Switching control is performed for the receiving channel and the adjacent channels by using a digital processing circuit as the demodulation means to filter and demodulate the signals corresponding to the respective channels, thereby measuring the electric field levels of the respective channels.
Therefore, the electric field levels of the receiving channel and the adjacent channels can be measured with a small number of electric components and a small-scale arrangement.