Patent ID: 6122493
Filing Date: 2000-09-19
Classification: H03J

Abstract:
A radio receiver comprising:a radio frequency tuning circuit including a tuning element having a variable frequency characteristic for receiving radio frequency broadcasting signals;a mixing circuit for converting a signal output from the radio frequency tuning circuit to an intermediate-frequency signal using a local oscillation signal;a local oscillation circuit for generating the local oscillation signal;a frequency control circuit coupled to an automatic broadcasting-station selection start signal for changing the frequency of the local oscillation signal;a storing circuit for storing control data corresponding to the frequency characteristic of the tuning element; andan arithmetic circuit coupled to the frequency control circuit for generating, in response to the frequency control circuit changing the frequency of the local oscillation signal, a tuning control signal based on the control data and data corresponding to a received frequency and the changed local oscillation frequency to control the frequency characteristic of the tuning element; anda broadcasting-station detecting circuit coupled to the mixing circuit for detecting the presence of a broadcasting station in the received RF signal;wherein the frequency control circuit stops changing the frequency of the local oscillation signal in response to the broadcasting-station detecting circuit detecting the presence of a broadcasting-station, andwherein the interval between the control data values is narrowly set in an area in which the frequency characteristic of the tuning element has a large dispersion and widely set in an area in which the frequency characteristic of it has a small dispersion.