Abstract: A reference local oscillation signal transmission station 1 radiates a reference local oscillation signal to a service zone. A portion of the signal received by each radio slave station terminal 2 is branched and fed to an injection locked oscillator 6. As a result, a local oscillation signal which is synchronized with the reference local oscillation signal is obtained. In the slave station terminal 2, the thus-obtained local oscillation signal is fed to a transmission frequency converter (mixer) 7 and a reception frequency converter (mixer) 8. An IF band transmission modulated signal is fed to the mixer 7 for frequency conversion to a radio frequency band, and the thus-obtained radio-frequency modulated signal is transmitted. Meanwhile, a received radio-frequency modulated signal is fed to the mixer 8 for down conversion, and the thus-obtained signal is fed to an IF band demodulator 10 so as to restore an information signal.

Abstract: A transmitter 1 transmits from a transmission antenna 7 a mixture signal containing a radio-frequency (RF)-band modulated signal, and a portion of power of a local oscillation signal used for frequency conversion. Meanwhile, a receiver 8 detects the transmitted signal by means of a reception antenna-detection section 9. In the reception antenna-detection section 9, a plurality of base unit reception circuits 11 are disposed. Each base unit reception circuit 11 includes a planar printed antenna 12 such as a patch antenna, an amplifier circuit 13 formed on a very small planar circuit by means of an MMIC technique, and a mixer circuit 14 serving as a square-law detector. Respective outputs of the base unit reception circuits 11 are power-mixed and fed to the IF signal demodulation section. The IF signal demodulation section 10 demodulate reception data.

Abstract: In a radio communication apparatus and method, on the transmitting side, an input signal is modulated in an intermediate frequency band to produce a modulated intermediate frequency band signal, a local oscillation signal is used to up-convert the modulated intermediate frequency band signal to a modulated radio frequency band signal, and the local oscillation signal and the modulated radio frequency band signal are simultaneously transmitted as a radio signal, and, on the receiving side, the radio signal from the transmitter is received, the received signal is down-converted by multiplying the local oscillation signal component and the modulated radio frequency band signal component contained in the received signal to generate a multiplication component and thereby produce a modulated intermediate frequency band signal, and the modulated intermediate frequency band signal is demodulated.

Abstract: A line quality characteristic evaluation system for estimating a line quality characteristic under an interference environment including nonlinear interference for a wireless communication system including at least one interfering wireless line, including a line quality estimating unit estimating the line quality of a wireless communication line under a nonlinear interference wireless line in an area in which wireless communication lines and interfering wireless lines are present together based on nonlinear distortion included by all wireless lines and expressed by an intercept point input level (IIP), a reception equivalent band limitation expressed by attenuation of the intercept point input level (IIP), reception side thermal noise of the wireless communication lines, and leakage power from other interfering wireless lines leaking into the reception equivalent band.

Abstract: An interference measurement and evaluation system for accurately estimating an interference characteristic of a receiving side including nonlinear interference for a wireless communications system, having a transmission signal for wireless communication and an interference signal between a transmitting means and receiving means, provided with a nonlinear interfering means for giving an interference signal having a level unable to be neglected compared with the level of the modulated carrier transmitted from the transmitting means, and provided with an interference characteristic estimating means for estimating an interference characteristic including a nonlinear interference characteristic possessed by a receiving means in accordance with a received signal level and a received level when a nonlinear interference theoretical curve given in relation with the line quality satisfies a predetermined line quality.

Abstract: The present invention provides a radio communication device, a transmitter and a receiver capable of handling a plurality of signal waves. A radio communication device has a millimeter-wave transmitter (15) and a millimeter-wave receiver (29). Millimeter-wave transmitter (15) includes a multiplexing circuit (1), a millimeter-wave up-converter (4) and an antenna (3), and the millimeter-receiver includes an antenna (31), a millimeter-wave down-converter (32) and an output processing circuit (45). The signal waves dedicated to the user are modulated by a modulation circuit (121 to 124) so as to be allocated between the ground broadcast waves and satellite broadcast waves. The frequencies are multiplexed in an intermediate frequency band, after that, the multiplexed frequencies are converted into a millimeter-wave band and the resultant is transmitted. On the reception side, the multiplexed waves are down-converted, separated to signal waves and demodulated.

Abstract: This invention includes a wireless transmitter comprising an IF-signal generator that modulates input signals into those of an intermediate frequency band, signal distributors that distribute signals from the IF-signal generator, and a plurality of signal-transmission units that convert the signals distributed by the signal distributors into those of a radio frequency band, and then transmit the converted radio signals. The invention also includes a wireless receiver that receives the radio-frequency-band modulated signals and restores the signals of the intermediate frequency band. In this way, effective diversity is realized and signal interruptions are prevented. In addition, a handy, low-cost wireless communications system is provided.

Abstract: Only a first radio station is equipped with a local oscillation signal source. A signal transmitted to a second radio station includes local oscilaation signal components used to up-convert a modulated intermediate frequency band signal in addition to intermediate frequency band signal components. The second radio station that receives the signal from the first radio station extracts and regenerated the local oscillation signal used at the first radio station using a local oscillation signal regenerator. The extracted and regenerated local oscillation signal is used to down-convert modulated radio signal components to the intermediate frequency band and simultaneously up-convert to the radio frequency band the modulated intermediate frequency band signal to be transmitted to the first radio station.

Abstract: A communications system of the type having a normal operating system and a back-up standby system includes a branching circuit which supplies an output signal at a high power and at a lower power, respectively. The high power signal is supplied to the system which is presently operating as the normal operating system. Controlled switching means are provided to direct the high power signal to the back-up system when the back-up system is to operate as the normal operating system, and to couple the output of the back-up system to the communications system output upon this occurrence.