Abstract: Band-pass filters BPF1, BPF2, and BPF3 correspond to the reception frequency band for FDD, the transmission band for FDD, and the band for TDD, respectively. An antenna A1 is used in common for transmission and reception in the FDD and TDD systems. Another antenna A2 is used for diversity reception in the FDD system. A controller 20 controls switches SW1 through SW4. When the FDD system is selected, the reception signal is sent from the antenna A1 or A2 through the filter BPF1 to a reception amplifier RA, and the transmission signal is sent from the transmission amplifier TA through the filter BPF2 to the antenna A1. When the TDD system is selected, the reception signal is sent from the antenna A1 through the filter BPF3 to the reception amplifier RA, and the transmission signal is sent from the transmission amplifier TA through the filter BPF3 to the antenna A1.

Abstract: An FM radio receiver, particularly for mobile receivers, reduces the effects of multipath distortion. It selects either an adaptive process (constant modulus algorithm or CMA) or a antenna diversity process depending on the circumstances of the instantaneous reception. The receiver reduces both the decline of the level of received signals with the diversity process and waveform distortion with the CMA process.

Abstract: A diversity apparatus for a global positioning system antenna capable of selectively using a better receiving sensitivity antenna among antennas is disclosed. The invention includes at least two antennas; first and second amplification comparing means for amplifying signals received from the antenna through a low noise amplifier and a coupling line and for comparing a direct current with a base voltage; selection means for selecting one antenna among the antennas by activating an impedance line; and first and second connection means for determining from the amplified signals, which of the antenna signals to output, and outputting the alternating current signal from that antenna.

Abstract: A mobile receiver for satellite broadcast comprises directive antennas, a navigation unit for generating a navigation signal representing a position and an attitude of an airplane, a control unit for generating a control signal for controlling the antennas, on the basis of the navigation signal from the navigation unit and prestored information indicating a position of a broadcasting satellite, and a drive unit for driving the antennas in response to the antenna control signal from the control unit to orient the directivity of the antennas toward the broadcasting satellite.

Abstract: An antenna switching circuit comprises a first amplifier including a first FET receiving a first receive signal from a first antenna at a gate of the first FET, and amplifying the first receive signal, and outputting the amplified signal via a drain of the first FET to an output terminal, and a second amplifier including a second FET receiving a second receive signal from a second antenna at a gate of the second FET, and amplifying the second receive signal and outputting the amplified signal via a drain of the second FET to the output terminal. The first and second FETs are coupled to receive, at their sources, first and second control signals complementary to each other so that one of the FETs is made active while the other is made inactive, depending on values of the first and second control signals. The consumption current is reduced, and in addition, an amplifier in a receiver provided to receive the output of the antenna switching circuit may be omitted.

Abstract: A diversity FM receiver of the antenna switching system type which includes first and second antennas, an antenna switching circuit, an FM receiving unit and a sample hold circuit. The receiving unit functions to demodulate the wave signal input thereto and to output a wave detection signal. The switching circuit switches the signal received from one antenna or the other antenna to the receiving unit in accordance with the amplitude of the wave detection signal. The sample hold circuit maintains the voltage of the wave detection signal during switching at the value of the signal immediately before switching.

Abstract: Two or more signal paths are provided for receiving a radio frequency signal. One or more signal paths include conventional bandpass filters for eliminating interference and noise signals. One or more remaining signal paths include reduced filtering devices for increasing the sensitivity of a radio frequency receiver to the desired signal. Each of the receiving paths is coupled to a respective radio frequency amplifier. Provided that each radio frequency amplifier has equivalent current-source output impedances, the output signals from each amplifier are added constructively if they are in-phase. If the output signals are out-of-phase, a phase inverter inverts the phase of one signal so that the signals may be added constructively. The combined signals of the two or more radio frequency amplifiers pass through various signal processing components associated with conventional superheterodyne receivers. A control unit produces gain variation signals for controlling the gain of each radio frequency amplifier.

Abstract: A system intended for the simultaneous reception of several TV channels retransmitted by satellites. This system comprises a multi-frequency microwave frequency head, installed in an external unit, whose inputs are connected to the satellite antennas. Wide band demodulation is made possible by a microwave frequency source controlled by a synthesizer. Digital signals transmitted by a link cable ensure programming of the synthesizer and therefore of the selected TV channels. A remodulation in amplitude modulation is performed for supplying signals in the 40-860 MHz band, carried by an existing link cable for terrestrial antennas. The system finds particular application to the simultaneous reception of several TV channels.

Abstract: A diversity receiver has distributors each of which is connected with each of a plurality of antennas, and as many antenna switches as there are receivers. Each of the antenna switches has as many contacts as there are distributors. The distributor distributes a radio frequency signal from the antenna into as many signal paths as there are receivers. Each of the antenna switches is connected with each of the distributors via the contact connected with the signal path. A demodulated signal selecting circuit has as many contacts as there are said receivers. The demodulated signal selecting circuit receives the demodulated output of the receivers via each of said second contacts to selectively output the demodulated outputs of the receivers.

Abstract: The invention relates to a signal diversity arrangement for a mobile reception, comprising a receiver and a diversity processor, which receives the input signals and applies a different input signal to the receiver when interference occurs. The diversity processor comprises an interference detector operating in the analog mode and a comparator, to whose first input is applied the output signal of the interference detector and to whose senond input is applied a suitably set voltage V1. The comparator shows on its output the occurence of interference by way of a binary signal when the threshold voltage V at the second input is exceeded.

Abstract: There is disclosed an antenna and coupling system for use in frequency hopping communication systems. The system includes a dual antenna configuration wherein the antennas are coupled in parallel to a tunable broadband coupler which provides a VSWR which is nominally less than 2:1 over the full hopping bandwidth of the system. The antenna and coupling system are so constructed that the coupler is operated over a plurality of passbands defining a broadband frequency range and each passband is of sufficient width such that several hopping band center frequencies can fall within a given passband. The passbands also overlap to permit continuous frequency coverage over the frequency range of the system.

Abstract: A space diversity reception system which minimizes the inband amplitude and/or phase dispersion by controlling the phase shifter is described. According to the present invention, the interference waves in the two antenna outputs are combined in anti-phase condition. The phase shifter control direction is decided by the sign of the two parameters. One of them is difference between two antenna levels at the center frequency of the pass-band, and the other is the difference of the combined signal levels at the extreme edges of the pass-band. The control means comprises four detectors for detecting said levels, two subtractors for providing said level difference between them, and the control circuit for deciding the phase shifter control direction.