Abstract: A reception circuit receives a digital modulated high frequency signal and is equipped with a plurality of reception systems for receiving the same reception frequency. At least two reception systems share a voltage controlled oscillator of a frequency converting portion that performs frequency conversion of a signal based on the digital modulated high frequency signal, a reference signal oscillator, and a PLL circuit that generates a control voltage based on an output signal of the voltage controlled oscillator and a reference signal delivered from the reference signal oscillator and controls the voltage controlled oscillator based on the control voltage. The frequency converting portion delivers an intermediate frequency signal. The reception circuit includes an intermediate frequency variable gain amplifier that receives a signal based on the intermediate frequency signal.

Abstract: A high-frequency receiving apparatus includes a phase pull-in circuit controlling an oscillator so as to eliminate a phase difference, a frequency pull-in circuit controlling the oscillator so as to eliminate a frequency difference, a frequency shift circuit shifting an oscillation frequency of the oscillator by a prescribed frequency when the frequency difference is large, and a control signal generation circuit controlling those circuits according to an algorithm selected from a plurality of algorithms corresponding to, for example, a symbol rate. Therefore, a wide range of frequency can rapidly be pulled regardless of the level of the symbol rate.

Abstract: A high-frequency receiving apparatus includes a phase pull-in circuit controlling an oscillator so as to eliminate a phase difference, a frequency pull-in circuit controlling the oscillator so as to eliminate a frequency difference, a frequency shift circuit shifting an oscillation frequency of the oscillator by a prescribed frequency when the frequency difference is large, and a control signal generation circuit controlling those circuits according to an algorithm selected from a plurality of algorithms corresponding to, for example, a symbol rate. Therefore, a wide range of frequency can rapidly be pulled regardless of the level of the symbol rate.

Abstract: In the high-frequency receiving device, a frequency dividing circuit of ×1/N divides a sampling clock signal of both A/D converters by the dividing ratio based on a controlling signal outputted from a controlling signal generator, and generates a constant current reference signal whose frequency is equal to a cut-off frequency of a low-pass filter which is to be set. Based on the constant current reference signal, a phase shift circuit, a mixer, a low-pass filter, a DC amplification circuit, and a constant current source perform loop back control so that an output of the mixer is 0, and input an output signal of the DC amplifying circuit as the output signal of a controlling circuit to a constant current source. Thus, the constant current source does not adjust the scale factor, so that a current according to the cut-off frequency which is to be set is inputted to the low-pass filter.

Abstract: In the high-frequency receiving device, a frequency dividing circuit of ×1/N divides a sampling clock signal of both A/D converters by the dividing ratio based on a controlling signal outputted from a controlling signal generator, and generates a constant current reference signal whose frequency is equal to a cut-off frequency of a low-pass filter which is to be set. Based on the constant current reference signal, a phase shift circuit, a mixer, a low-pass filter, a DC amplification circuit, and a constant current source perform loop back control so that an output of the mixer is 0, and input an output signal of the DC amplifying circuit as the output signal of a controlling circuit to a constant current source. Thus, the constant current source does not adjust the scale factor, so that a current according to the cut-off frequency which is to be set is inputted to the low-pass filter.