a delay characteristic particular to the tuning circuit 16c as shown in fig4 as fig4 indicates the delay time of a signal caused by the single tuning circuit 16c sequentially decreases as the frequency is detuned from the center frequency on the other hand fig5 is a graph showing a delay time characteristic of the four element ladder type ceramic filter 16a as shown in fig5 the ladder type ceramic filter 16a increases the delay time as the frequency is detuned from the center frequency as far as the frequency band thereof is concerned eventually the tuning circuit 16c operates in such a manner as to reduce though not completely the deviations of delay time ascribable to the filter 16a hence the delay time of a signal occurring in the data amplifying section 16 is noticeably reduced the second agc amplifier 16d amplifies the output signal of the single tuning circuit 16c while automatically controlling the gain in response to an agc voltage which is also fed back from the detector 17 the detector 17 is connected to the output of the data amplifying section 16 to detect the output signal of the agc amplifier 16d an equalizer 18 is connected to the output of the detector 17 to reduce the deviation of the group delay time for each of the frequencies at the output of the detector 17 i e baseband signal a data processing circuit 19 is connected to the output of the equalizer 18 the output of the data processing circuit 19.