Abstract: A multiplexer receives a message from a first bus and a message from a second bus, wherein a preamble is received at the head of each message, compares the preamble from each bus against an ideal preamble and, prior to receiving the next bit in either message, provides to a transceiver the message which is least noisy as indicated by the comparison; if the preamble in the message on the bus presently selected for reception by the transceiver does not compare favorably with the ideal preamble, the message from the other bus is selected.

Abstract: A radio communication device (600) comprises a microstrip antenna (300) having a planar antenna element (302) and a ground plane (314) coupled to the planar antenna element (302). The microstrip antenna further comprises a dielectric material (304) positioned between the planar antenna element (302) and the ground plane (314), and a primary receiver element (325, 326, 328) mechanically coupled to the ground plane (314). The microstrip antenna (300) further comprises a feeder (308, 310) electrically coupled between the planar antenna element (302) and the primary receiver element (325, 326, 328) for feeding an intercepted radio signal therebetween for down conversion by the primary receiver element (325, 326, 328). The radio communication device (600) also comprises a secondary receiver element (828) coupled to the primary receiver element (325, 326, 328) for demodulating the intercepted radio signal after down conversion by the primary receiver element (325, 326, 328).

Abstract: Earth-fixed cell beam management methods which may be employed to allocate beams generated by a constellation of low Earth orbit satellites (12) flying in orbits below geosynchronous altitudes are disclosed. These beams (19) are electronically steered so that they illuminate "Earth-fixed cells" (26) as opposed to "satellite-fixed cells." In a system that employs satellite-fixed cells, the "footprint" of the beams propagated by a spacecraft defines the zone on the ground called a "cell" which is illuminated by the spacecraft. This satellite-fixed cell moves constantly as the spacecraft moves around the globe. In sharp contrast, an "Earth-fixed cell" (26) is a stationary region mapped onto the surface of the Earth (E) that has permanent fixed boundaries, just like a city or a state.

Abstract: In a time division multiple access (TDMA) system (10), a method (50, 60) of recovering a data signal of a transmission burst commences by obtaining the frequency transmission codes for the transmitters to be monitored (52, 62). The data signal is then received in separate transmission bursts from a first transmitter in a first time period (53, 65) and from a second transmitter in a second time period (56, 65). The data signal of one of the received transmission bursts is then selected or a plurality of the data signals are combined (58, 69) to be used by the receiver as the received data signal.

Abstract: A receiving circuit, which prevents spikes included in reproduced clock signals, caused by a time slot change in the division multiplex wireless communication or by the switching of diversity antenna, from being transmitted to the following circuits, and thereby eliminates errors in the determination of the received data, has a demodulator coupled to an antenna for demodulating signals received therefrom, a selector coupled to the demodulator for selecting from a plurality of clock signals reproduced from the data of the respective time slots, one of the reproduced clock signals. A time division timing control circuit is coupled to the selector and to a switching circuit, which control circuit is supplied with an internal clock signal from an internal clock generation circuit. The switching circuit is coupled to the output terminal of the selector and selects and outputs either the internal clock signal or the selected reproduced clock signal.

Abstract: A satellite communications system includes a feed array and reflector receiving antenna coupled to a dual-mode network, for generating two channels, with independent signals representing two beams, one for each channel. Each output channel of the dual-mode network contains redundant information relating to a plurality of information channels. In the absence of an interfering signal or intrusion, the combined signals are amplified and block frequency-converted, then de-multiplexed into separate channels, which are each applied through selection switches to a transmitter multiplexer for retransmission. An alternate signal is tapped from each of the two received signal channels, phase controlled, and combined, to produce a combined signal representing a receive antenna beam with a null controllable in position in response to phase. The combined signal is demultiplexed into separate information channels.

Abstract: An operation control system includes a GPS receiver unit and a radio telephone unit. The GPS receiver unit includes a GPS antenna and a GPS signal receiver circuit connected thereto. The radio telephone unit includes a telephone antenna and a transmitter circuit connected thereto. The transmitter circuit transmits a call channel signal through the telephone antenna during the radio telephone unit being in an ON-CALL MODE and a control channel signal during an OFF-CALL MODE. The system is designed to set the transmitter circuit operative and the GPS signal receiver circuit inoperative during the ON-CALL MODE. On the other hand, the system allows alternate operations of the transmitter circuit and the GPS signal receiver circuit during the OFF-CALL MODE.

Abstract: A reference voltage (V.sub.ref) is set to a received signal level corresponding to an anticipated data error rate and compared with outputs of intermediate frequency amplifiers (3-1, 3-2) by comparators (7-1, 7-2). When the outputs of the intermediate frequency amplifiers (3- 1, 3-2) are lower than the reference voltage (V.sub.ref), operation of receiving circuits (A12-1, B12-2) is stopped. At inter symbol interference amount calculating sections (6-1, 6-2), inter symbol interference amounts are calculated from auto-correlation parameters of preamble signal bit trains included in received signal data, and selectors (9-1, 9-2) are controlled so that a diversity branch having the least residual inter symbol interference amount or the highest S/N ratio is selected and the received signal data of the selected branch are inputted to an equalizing section (11). When a signal having a high data error rate is received, operation of the corresponding receiving circuit is stopped.

Abstract: A multichannel communication system carries signals having a different frequency range in each channel. In order to achieve a particular output power level from each channel, an amplifier is associated with each channel to boost the signal level. For reliability, a switching arrangement switches amplifiers among the channels in accordance with a priority, or substitutes a redundant amplifier for a degraded or failed unit in a channel. The amplifier is subject to distortion at the desired output level, and is cascaded with a distortion equalizer or linearizer for reducing the total distortion. In accordance with the invention, each distortion equalizer is fixedly connected in one channel, and is optimized for the relatively narrow frequency range of that channel, rather than being switched together with the amplifier and being optimized over the total or cumulative bandwidth of all the channels.

Abstract: An antenna selecting diversity receiving apparatus utilizes linear modulation with information about the envelope of a modulating wave included therein and is employed in a radio communication system using TDM. An integrating circuit serves to integrate electric-field levels received by respective antennas over a predetermined period of time before a start in a time slot allotted to a radio receiver. Then, a comparing circuit makes a comparison among respective time-integrated values corresponding to the respective antennas. In addition, a changeover control circuit serves to select an antenna corresponding to the maximum time-integrated value as the antenna used during the period of the time slot allotted to the radio receiver.

Abstract: A radio receiver with two receiving systems includes a CPU for selecting the appropriate ranges of local signal generators in the two receiving systems so that local signals generated by the local signal generators do not fall into the frequency range of a received RF signal.

Abstract: A receiver system for a mobile telephone system comprises two or more antenna spaced a distance apart from each other greater than the wavelength of incident radiation, and a receiver. Each antenna is coupled to a respective receiver channel of the receiver, each receiver channel comprising an RF means for processing the received signals, and equaliser means for equalising and/or decoding the signals from the RF means. The equaliser means includes metric generating means for generating metric information which provides probability measures for a sequence of time intervals and for a multiplicity of possible states of the receiver within each time interval that the received signal has put the receiver into the respective states, and selector means for comparing the values of corresponding metrics from respective receiver channels for selecting received data from the receiver channel having the higher probability of accuracy.

Abstract: An antenna selection diversity receiver system for TDM signals that switches antennas for every assigned time slot so that the best receive signal quality is obtained in the assigned time slot according to the prediction made by using the signal quality just before the assigned time slot. The prediction of signal quality is carried out according to the receive level (R.sub.1, R.sub.2), and the slope of the same of each of the antennas just before the assigned time slot. The signal quality may be determined by the average code error rate, receive level at the center of the assigned slot, or the minimum receive level in the assigned slot. The prediction is carried out either through linear prediction or non-linear prediction.

Abstract: Fixed radio equipment serving as a base station includes a transmitter, a plurality of antennas, and a selective control circuit. The antennas are spaced apart from each other by a distance which minimizes a correlation of interferential fading. The transmitter modulates a carrier by identical signals to be transmitted during periods associated in number with the antennas and feeds the resulting bursts of the carrier time-serially to a selective control circuit. The selective control circuit delivers one of the successive bursts of the carrier fed from the transmitter to one of the antennas and then delivers another burst following the above-mentioned burst to another one of the antennas. Mobile radio equipment or station has a single antenna for receiving the identical signals transmitted time-serially from the base station. The mobile station selects and outputs either one of the received signals which has higher quality than the other.

Abstract: In the diversity receiver which switches between receiver branches to receive phase modulated signals, this invention can achieve a diversity effect with a circuit of simple construction which by switching between receiver branches based on relative modulation phase error, and can attain diversity effect not only against fading but also against any factor which might affect the transmission lines.

Abstract: A combiner for a radio receiving signal which receives signals having various signal paths of a digital radio transmitter, particularly a mobile transmitter. The combiner is designed so it allows maximum power gain in broadband systems and can also be used in systems which have pulse or discontinuous transmission. A correlator is provided at the receiver in every signal path. Frequency converters are also in each signal path. Following the frequency converter and following each of the correlators there is provided a metric table in each path which had been calculated in accordance with the respective line model obtained at the receiver. The output values formed from the metric tables and individual signals are combined and supplied to a Viterbi demodulator which produces the corrected output signal.

Abstract: A Voice Guard digital voter system for a multi-site public service trunking (PST) digitally trunked RF communications system operates on the principle that it is highly likely that messages received during a system redundancy removal period are redundant messages. For a given RF channel, digital receiver is associated with each of multiple sites and receives digital messages reported to it by its associated sites. The multiple digital receivers are connected to a digital selector via a service request line (FSL) and a serial data line (BSL). Digital receivers calculate a bit error rate code (BERC) for each message they receive. All digital receivers receiving a version of a message are synchronized by the digital selector in response to a request to transmit by one of the digital receivers. The digital receivers wait a delay time corresponding to the BERC they calculates and also responsive to a fixed slot assignment associated with each digital receiver.

Abstract: A digital voter system for a multi-site public service trunking (PST) digitally trunked RF communications system operates on the principle that it is highly likely that messages received during a system redundancy removal period are redundant messages. For a given RF channel, digital receiver is associated with each of multiple sites and receives digital messages reported to it by its associated sites. The multiple digital receivers are connected to a digital selector via a service request line (FSL) and a serial data line (BSL). Digital receivers which have messages to transfer to the digital selector attempt to seize the service request line and, if they successfully seize it, maintain the line in its seized state for the redundancy removal period. Digital receivers which have messages but discover the service request line is already seized simply discard their messages.

Abstract: An antenna selection technique is used in an RF communication system in which user modules (UM) communicate with at least one node. The UM's and nodes each have multiple antennae. The combination of each UM and node antenna is evaluated at the UM. Based on both signal quality and strength, the UM selects its antenna and the best node antenna for use.

Abstract: A digital voter system for a multiple site digitally trunked RF communications system includes an improved voting arrangement which tests for actual redundancy before removing redundant messages--thereby decreasing retransmission traffic in simulcast and other large coverage area RF trunking systems. Status messages indicating ongoing call reception are generated periodically by each receiver site which receives a given call. The status messages are received by a digital voter, which in a clear voice mode is used to determine (in responses to the status messages) whether an analog voter should maintain a clear voice call.

Abstract: In an antenna-selection diversity transmission and reception equipment which is in digital communication with a transmission and reception equipment having a single antenna, and performs transmission and reception with time division by using the same radio frequencies, the antenna-selection diversity transmission and reception equipment comprises a plurality of antennae, a receiving part having a receiving unit, comparing unit and selecting unit which are adapted for a receiving-antenna selection diversity, and a transmitting part having a memory unit for storing antenna information that was selected by the receiving part. An antenna for transmission is selected from the plurality of antennae at the time of transmission in accordance with the information of the memory unit.

Abstract: A diversity system comprising two receiving branches for receiving a radio signal including a data signal portion and a training signal portion propagating through a multipath, wherein, in each branch, a transmission property of a propagating path thereto is estimated from the training signal portion received, the transmission property comprising components significant to an equalizer and the remaining insignificant components, a blanch selectors selects, as a selected branch, a specific one of the branches providing the maximum value of a power ratio of the significant components to the insignificant components, and the equalizer equalizes the data signal portion received at the selected branch to produce an equalized signal as a resultant signal of the system.

Abstract: A diversity receiving apparatus includes first and second antennas and circuitry for selecting one antenna or the other. Control circuitry analyzes signal strength received from the selected antenna and determines when the antennas should be switched.

Abstract: A mobile electric accessory apparatus for mounting on a vehicle equipped with a wireless transceiver unit such as a mobile radiotelephone and a separate wireless receiver unit such as a television receiver is adapted to limit operation of the wireless receiver unit, as by cutting off power thereto or inhibiting reception of a signal from the corresponding receiving antenna, when the wireless transceiver unit is being used, thereby preventing interference in the reception of the wireless receiver unit. If a receiving antenna nearest the transceiver antenna of the transceiver unit, when the latter is in use, is excluded from the antennas in a diversity reception system, good reception can be obtained. By disposing antenna for the transceiver unit and the antenna for the receiver unit on a single windshield glass adjacent mutually opposing edges thereof, the receiver unit will not have its reception disturbed by electric waves from the transceiver unit.

Abstract: A switching system in a digital radio-communication system including a plurality of main radio-communication systems and a plurality of stand-by radio-communication systems provided for backing-up the main radio-communication systems. The switching system includes a plurality of switches independently operable from one another, the number of which is equal to the number of the stand-by radio-communication systems. Each switch switches between a stand-by radio-communication system defined in connection with the switch and a failed main radio-communication system, in a predetermined time.

Abstract: A microwave receiver self-test capability which includes at least two channels with each channel including an amplifier and an IF receiver, the microwave receiver, also including a local oscillator capable of mixing with either of said channels for providing an IF signal and a data modulated signal source capable of coupling with said local oscillator through one channel of said microwave receiver and thereby, generating a microwave test signal for the other of said channel of said microwave receiver.

Abstract: An FM receiver includes a first antenna and a second antenna. A first pulse generator produces a first pulse according to a noise signal included in the signal received by the first antennas, and a second pulse generator produces a second pulse according to a noise signal included in the signal received by the second antennas. A calculation circuit including shift registers is provided for shifting data, which is either one of the first and second pulses, in one direction in accordance with the first pulse from the first pulse generator and for shifting the switch data in another direction in accordance with the second pulse from the second pulse generator. Also, a switch circuit is provided for switching on a transmission line for a signal received at either one of the first and second antenna in response to the data produced from the calculation circuit.

Abstract: A portable radio communication apparatus includes a first antenna that can extend away from, or be retracted towards, an apparatus housing. The apparatus includes a second, usually flat antenna mounted within or around the outer periphery of the housing. When the first antenna is extended away from the housing, it is connected via a switch to a node, in turn, connected via respective filters to both a transmitter and a diversity receiver. At this time, the second antenna is connected to the diversity receiver via a respective filter. When the first antenna is sufficiently retracted towards the housing, a switch, mechanically coupled to the first antenna, disconnects the first antenna from the node, connects the second antenna to such node, and disconnects the second antenna from the diversity receiver.

Abstract: In a digital radio communication system using at least two regular channel and two or more standby channels for transmitting a test signal therethrough in the standby condition thereby permitting the regular channel to be synchronously switched to one of the standby channels, the improvement wherein a channel switching system for monitoring the standby channels is provided at the receiving side of the digital communication system with: control signal generator means operating so that when two or more standby channels are in standby condition, it generates a control signal to designate them in turn, and when only one standby channel is in standby condition, it generates a control signal to designate the channel; synchronizing switching means for selectively outputting the test signal transmitted via each of the standby channels designated by the control signal; and standby channel monitoring means for detecting an output from the synchronizing switching means to monitor the communication quality of the standby

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: A portable transceiver has a narrow band square microstrip antenna connected to a first radio receiver, a wideband sleeve or whip antenna connected to an associated duplexer, and a second radio receiver and a transmitter both connected to the wideband antenna via the duplexer. The square microstrip antenna if formed of a conductive emission plate and a conductive ground plate joined by a conductive connector plate. A housing enclosing the transceiver has an earphone and microphone set in its front side, the microstrip antenna under its back side, and the wideband sleeve or whip antenna mounted upright on its top side.

Abstract: An aircraft navigation system supporting a plurality of navigation modes. An error estimator for each navigation mode provides an estimated navmode error signal representative of an estimate of the error in the position signal generated by the associated navmode. A navigation mode selector enables the navmode having the smallest estimated navmode error signal that is consistent with procedure specified navaid criteria. The navmode computed position signal is processed through a low pass position filter. The estimated navmode error signal associated with the selected navmode is processed through a low pass position error filter having the same time constant as the low pass position filter to provide an estimated position error. The estimated position error is utilized in providing the INS and DEAD RECKONING navigation as well as to set a threshold for estimated navmode error signals sensor data validation.

Abstract: A channel switching system without an instantaneous signal loss in a data communication system such as a digital microwave multiple radio communication system. The channel switching system includes a control unit for generating a switching control signal in response to a fault detecting circuit; a unit for receiving a phase adjustment signal from the active receiver unit of an active transmission channel and another signal from the standby receiver, for adjusting the phases between both received signals in response to the switching control signal, and for outputting a switch energizing signal; a high speed switching unit, including a unipolar high speed switching circuit, for switching signals from the phase adjustment unit in response to the switch energizing signal. The switching system further includes a compulsory switching unit, for compulsorily switching the signals supplied to the switching unit.

Abstract: A diversity reception radio receiver has a two-receiver system incorporating first and second receivers. A wave envelope detector is provided for each receiver to generate an output voltage corresponding to the strength of the electromagnetic signal wave which is picked up by the receiver. A hysteresis comparator compares the outputs of the two wave envelope detectors and generates a switching control signal. A switching device responds to the switching control signal by selecting between the signals which are repoduced by the first and second receivers. Because the amount of hysteresis in the comparator is automatically adjusted in accord with the strength of the signal wave, there is a minimum of hunting between the outputs of the two receivers.

Abstract: An antenna diversity system for the mobile reception of frequency-modulated oscillations having a receiver, antennae and a diversity processor. An optimum system according to the invention includes an FM tuner with intermediate frequency part (2) and at least two antennae, while the diversity processor (3) receives an intermediate frequency signal or high-frequency signal, which corresponds to a given linear combination derived from the antenna signals. The diversity processor (3) further includes an FM demodulator (32) with a succeeding frequency sweep threshold detector (31) and a device by which, in dependence upon the occurrence of an interference-dependent frequency sweep pulse exceeding the frequency sweep threshold of the frequency sweep threshold detector (31) in the intermediate frequency of high-frequency signal, another linear combination derived from the antenna signals is supplied to the input side of the tuner with intermediate frequency part (2).

Abstract: An improved polarity switch for connection between a dual antenna system and a satellite television reception system has a first embodiment which utilizes a pin diode switch between the dual antenna system and each of a plurality of receivers to permit use of the receiver to select one of the two antenna feeds for decoding and display at that television set. A second embodiment is also disclosed which utilizes an electromechanical relay to isolate the antenna feeds from each receiver.

Abstract: A diversity system of the selection type for correcting phase ambiguities among a plurality of differentially encoded digital signals while retaining the digital encoding of those signals. With this system, no differential decoding/encoding means are needed in relay units of the system. Thus, differentially encoded digital signals may be sent through relay systems containing error correcting MODEMs without the additional complication of differential decoding/encoding circuitry.

Abstract: A first multi-port hybrid coupler is formed by n2.sup.n-1 (where n is an integer equal to or greater than 2) hybrid couplers alone, which are divided into n stages, each including 2.sup.n-1 hybrid couplers. A signal input to any one of N (=2.sup.n) input terminals of the first stage is distributed equally to N output terminals of the nth stage. The N output terminals of the nth stage of the first multi-port hybrid coupler are connected to N amplifiers at the input side thereof, respectively, and the N amplifiers are connected at the output side to a second multi-port hybrid coupler. The second multi-port hybrid coupler is identical in construction with the first multi-port hybrid coupler, but its input terminals and output terminals are reverse from those of the latter and the input terminals of the second multi-port hybrid coupler are connected to the N amplifiers in an order reverse from the order of arrangement of the output terminals of the first multi-port hybrid coupler.

Abstract: An improved data transmission system has a transmitter which includes a modulator responsive to a synthesized modulating signal, which provides for transmission of data substreams on parallel subchannels, for example, by using subcarrier frequencies. At the receiver the subcarriers are received and data is selected from the received subcarriers at two diverse receivers. In addition, there are provided signals added to the transmitted data for retiming the data at the receiver.

Abstract: An input circuit is provided for a television receiver for amplifying and transforming the input signals into an intermediate frequency signal. The output of the mixers is fed via intermediate-frequency bandpass filters to respective decoupling diodes, which are switched on depending on the selected receiver frequency range. The output of the decoupling diodes is fed to an impedance transformer such as an emitter follower and its output in turn is entered into an intermediate-frequency amplifier.

Abstract: A novel signal synthesizer provides high frequency synthesized waveforms for the user. By converting phase information into digital outputs in parallel and by selectively coupling these digital outputs, an ordered digital output is formed to provide the high frequency waveforms. This ordered digital output, which represents points on a sine function, is converted to an analog signal for the synthesizer output. Furthermore, frequency and phase modulations of the synthesized waveforms are easily implemented with this novel signal synthesizer; the modulation information is simply added to the digital outputs prior to selectively coupling. Thus when the ordered digital output is converted to an analog signal, the analog signal contains the modulation information.

Abstract: RF switching diodes in the antenna transfer switch of a video disc player are reverse biased by means of a bias supply when the main power supply of the player is turned off. The reverse bias counteracts any tendency for RF signals applied to the player antenna input connector from forward biasing the diodes which otherwise could result in intermodulation distortion of antenna input signals coupled to the player RF output connector. The effect of the reverse bias is augmented by a high pass filter in the antenna transfer switch which attenuates RF input signals at frequencies below the lowest assigned television channel frequency.

Abstract: A control arrangement for a radio communication system in which mobile users communicate with one another and with a central dispatcher via repeaters. In a first embodiment, the repeater station providing the best quality received signal from a mobile station is caused to re-transmit that signal without the signal traversing lengthy telephone lines to and from a central station. A second embodiment, a repeater station having a local and plural satellite receivers selects the best quality signal among those received by its local receiver and its satellites for re-transmission.

Abstract: Device for receiving radio call messages, preferably on board ships, which device comprises a number of receivers (1) for different frequencies from various stations and/or transmitters and means for processing the messages. The output of each receiver is connected to the input of a shift register (4) of which the output signal is a binary signal having the value "1" or "0" and each output is fed to the input of an identifier (11) for determining the pertinence of the messages to the relevant ship. The outputs of the identifier or of the identifiers (11) are connected to a switching unit (14), which, in case the identifier means (11) has identified a message pertinent to the relevant ship, connects the appropriate shift register to a store (13) available at that moment. A cyclic scanner (18) then quickly and successively reads out the completed and stored messages and transfers them to a terminal station for further storing and processing.