Abstract: A radio receiving system, which receives an input signal in a direct conversion receiving mode through the use of a plurality of cascaded channel filters, each including a complex coefficient filter, to obtain a desired waveform, wherein a center frequency of a preliminary channel filter corresponds more closely with the frequency of the desired waveform than a center frequency of a subsequent channel filter.

Abstract: A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the fist and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of &ohgr;o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8.

Abstract: A radio receiving system includes an orthogonally-modulated waveform detection/channel filter section 4, an I signal root Nyquist filter 20, a Q signal root Nyquist filter 21, and a signal detection/demodulation section 25. The orthogonally-modulated waveform detection/channel filter section 4 further includes a first filter (a band pass filter) 2 which permits passage of only a signal at a frequency band assigned to a communications system from which the radio receiving system receives a signal; a sample-and-hold circuit 5; a Hilbert transformer 6; a first channel filter 7 through N-th channel filter 9; and a clock signal shaping/controlling section 15. The band pass filter 2 is provided with the characteristics which cancel the aperture effect due to a sampling operation, thus compensating for the aperture effect due to a sampling operation.

Abstract: A radio receiving system, which receives an input signal in a direct conversion receiving mode through the use of a plurality of cascaded channel filters, each including a complex coefficient filter, to obtain a desired waveform, wherein a center frequency of a preliminary channel filter corresponds more closely with the frequency of the desired waveform than a center frequency of a subsequent channel filter.

Abstract: A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of &ohgr;o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8.

Abstract: A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Abstract: A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of &ohgr;o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8.

Abstract: A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Abstract: A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Abstract: A receiving circuit includes a first antenna 1, a second antenna 2, units 10 and 11 for generating a sum signal or a difference signal from signals of two paths received by the respective antennas, a unit 12 for giving delay to either an output of the sum signal generating unit or an output of the difference signal generating unit, a unit 13 for summationally combining an output of the delay unit and the signal of the not-delayed path, a desired-wave pass filter unit 14 for receiving an output of the summationally combining unit, a dividing unit 15 for receiving an output of the desired-wave pass filter unit, an orthogonal detection unit 16-19 for receiving an output of the dividing unit, and a filter unit 20 and 21 for receiving an output of the orthogonal detection unit to extract a base band signal therefrom, wherein the receiving path including the summationally combining unit and the following are made into one path to thereby attain miniaturization and low power consumption.

Abstract: A received signal obtained from an antenna is subjected to high-frequency amplification. The amplified signal is supplied to a first bandpass filter, which extracts only signals of all the channels of a communications system concerned while filtering out other radio signals. The extracted signals are frequency-converted by using a local oscillation frequency, and only a desired wave is passed by a second bandpass filter. The desired wave is supplied to a sample-and-hold circuit, which performs sampling according to the bandwidth-limiting sampling theorem. A resulting discrete signal is supplied to an I-axis-component and Q-axis-component separating circuits, where the polarity of sample values is inverted for every other clock pulse with respect to each of the I and Q axes to thereby effect Hilbert transform. Resulting two orthogonal components on a phase plane are supplied to a complex coefficient filter.

Abstract: A receiving circuit mainly available in a digital modulation type communication system having a plurality of channels, which is capable of reducing power in a receiving system, simplifying the circuit and reducing the power consumption. Upside and downside frequencies corresponding to a central value between channels are separately supplied from a local frequency signal generating circuit 4 to first and second frequency converting circuits 2, 3 so that two output signals are developed with respect to one of a desired wave, upside channel and downside channel. The desired wave present in common in the first and second frequency converting circuits 2, 3 is extracted in a common wave extracting circuit 5, and a frequency offset of .omega.o existing in the output of the common wave extracting circuit 5 is removed a frequency offset circuit 6 and further an unnecessary frequency component is filtered by a filter 8.