Patent ID: 9692466
Date: 2017-06-27
CPC Classifications: H04B

Claim:
1. A radio reception circuit which demodulates and outputs a received signal received by an antenna, comprising: a variable bandpass filter for passing a particular frequency and a particular bandwidth from the received signal and a demodulation circuit for demodulating the received signal passed through the variable bandpass filter and outputting as an ultimate output signal; a frequency characteristic table which stores in advance a plurality of kinds of parameters regarding the frequency and the bandwidth for passing through the variable bandpass filter; an S/N ratio measurement circuit which calculates an S/N ratio of the output signal in a case where one of the plurality of kinds of parameters is applied to the variable bandpass filter; and a control unit which controls the S/N ratio measurement circuit to calculate the S/N ratio for all of the plurality of kinds of parameters and sets, to the variable bandpass filter, the parameter with which a maximum S/N ratio among those can be acquired, wherein the control unit comprises: a plurality of operation modes with the different bandwidths; and a function which controls the S/N ratio measurement circuit to calculate the S/N ratio after setting, to the variable bandpass filter, a first operation mode with the bandwidth that is wider, and sets a second operation mode with the bandwidth that is narrower to the variable bandpass filter to operate with the parameter with which the maximum S/N ratio among those can be acquired.