초록 ▼

The object of the present invention is to provide a radio receiver, having a high reception sensitivity, that can limit cross-modulation even during the transmission of a signal that is related to frame synchronization and that has a signal strength different from that of another channel, and that c

The object of the present invention is to provide a radio receiver, having a high reception sensitivity, that can limit cross-modulation even during the transmission of a signal that is related to frame synchronization and that has a signal strength different from that of another channel, and that can take into consideration the deterioration of a received signal caused by thermal noise. A gain controller is provided that employs the quality of received data detected by an error detector and the magnitude of a signal output by a band-pass filter in order to determine whether cross-modulation has occurred, and that controls the degree of attenuation provided by a variable gain attenuator provided at the front end of a reception unit.

대표청구항 ▼

[ What is claimed is:] [1.] A radio receiver for receiving a modulated digital signal comprising:variable gain attenuation means for limiting a signal level of a high frequency signal that is received;high frequency amplification means for amplifying said high frequency signal output by said variabl

[ What is claimed is:] [1.] A radio receiver for receiving a modulated digital signal comprising:variable gain attenuation means for limiting a signal level of a high frequency signal that is received;high frequency amplification means for amplifying said high frequency signal output by said variable gain attenuation means;frequency conversion means for converting into an intermediate frequency signal said high frequency signal that is amplified;a band-pass filter for permitting a passage only of predetermined frequency band of said intermediate frequency signal;variable gain intermediate frequency amplification means for amplifying a signal passed through said band-pass filter and for exercising automatic gain control to output an amplified signal having constant average power;demodulation means for demodulating a signal output by said variable gain intermediate frequency amplification means to obtain a baseband signal, and for outputting received data;error detection means for detecting an error in said received data and for outputting a quality deterioration index representing deterioration of quality of said received data; andgain control means for employing the magnitude of a signal output by said band-pass filter and said quality deterioration index to control the degree of gain attenuation performed by said variable gain attenuation means, said gain control means ascertaining, when deterioration in quality of said received data is detected based on said quality deterioration index, that said quality of said high frequency signal that is received has been deteriorated, and increasing said degree of gain attenuation provided by said variable gain attenuation means when said magnitude of said signal output by said band-pass filter is equal to or greater than a predetermined value, and reducing said degree of gain attenuation when said magnitude of said signal is smaller than said predetermined value.