Abstract: An adaptive, recursive frequency offset tracking system for effectively acquiring and tracking coherent as well as noncoherent electromagnetic data signals transmitted with or without countermeasure protection. The invention includes circuitry for eliminating the carrier frequency and generating complex samples of the baseband signal. The invention compares the phase of a sample to that of the previous sample to extract signals representing the phase difference between the two. The signals representing the phase difference are then converted to phasor signals and filtered to eliminate any noise component. The phase difference signals are derived from the phasor signals and accumulated to derive signals representing the frequency offset of the received data signal. The frequency offset signal is then provided to a phase shifter to correct for the effect of Doppler shift on the received data signal.

Abstract: The mixer comprises a microelectronic circuit composed of one or a number of active electronic elements having a nonlinear characteristic and carried on a substrate, the elements being supplied by waveguide lines placed on the substrate. The microelectronic circuit is fixed within a closed casing and connected to terminals placed on the casing in order to mix an incident wave S having a frequency F.sub.S applied to a first terminal of the casing with a mixing wave OL having a frequency F.sub.L applied to a second terminal of the casing and in order to restitute a mixed wave OR having a frequency F.sub.O on a third terminal. The cavity formed by the internal space of the casing is tuned to a "sum" frequency representing the sum of the frequency of the mixing wave F.sub.L and of the frequency of the incident wave F.sub.S.

Abstract: The invention is a high frequency hetrodyne receiver front end for receiving a communications signal comprising a desired information frequency and an undesired image frequency. The receiver comprises a bandpass filter, a preamplifier responsive to the bandpass filter, a mixer and a coupler means between the preamplifier and the bandpass filter. The coupler means defines a reactive short at the undesired image frequency due to impedance characteristics of the coupler means. The coupler means thereby eliminates the image frequency noise at the input of the preamplifier. Preferrably the coupler means is a transmission line of a length L where L equals .eta..pi./.beta. and .eta. is an integer and .beta. is proportional to the wavelength of the image frequency.

Abstract: A simulcast communication system for permitting the same audio signal to be simultaneously broadcasted from a plurality of base stations located remotely from a dispatch station used to transmit this audio signal to each of the base stations over conventional telephone lines is described. The simulcast communication system generally comprises first circuit means for equalizing the audio signal transmission characteristics from the dispatch station to each of the base stations in response to at least one test signal broadcasted from each of the base stations, and second circuit means for generating a synchronized squelch signal at each of the base stations in response to a pilot signal transmitted to each of the base stations with the audio signal and a phasing signal transmitted to each of the base stations at the beginning of the audio signal.

Abstract: Expanded multiplexed noise codes including code mate pairs having autocoration functions which upon detectionprovides an impulse autocorrelation function are generated by delaying the inverse of one of the code mate pairs (code b) by a value .tau. and adding it to the other code mate pair (code a) to form a first expanded code mate (code A) while a second expanded code mate (code B) is generated by delaying the inverse of said other code (code a) also by a value .tau., forming the complement thereof and adding it to said one code mate (code b). Such an expansion enables each expanded code to begin with each different code of a mate pair.

Abstract: A radio receiver suitable for use in a spaced carrier area coverage system in which two or more carriers are transmitted.In order to reduce the overall noise which is present in existing systems and to enable carriers to be spaced more regularly and/or closer, the radio receiver is adapted to measure the strength of each signal, in turn, and to determine which of the received signals has the greatest strength. A local oscillator, conveniently in the form of a frequency synthesizer is adjusted so that the output frequency to the mixer of the RF section is such as to enable the signal having the greatest strength to be received. The system remains locked on to the selected signal unless or until the incoming signal decreases in amplitude by more than a predetermined amount.

Abstract: The present invention relates to a space diversity combiner which includes two branches wherein separate multipath signals received from a remote source are propagated. The branch signals are combined and the combiner output signal is used for obtaining noncoherent spectrum measurements which are in turn used to account for both dispersion and noise in controlling the relative amplitudes and phases of the two branch signals to provide a maximum performance measure for the combiner.

Abstract: A switching element is inserted in a power supply line to a transmission circuit in the portable unit of a cordless telephone. The charge potential which is supplied from the base unit to the portable unit actuates the switching element to break the power supply line when the portable unit is replaced on the cradle of the base unit.

Abstract: In a power supply system for use in a radio communication system comprising a base station for transmitting and receiving radio signals, one or more repeater stations for repeating the radio signals, and a terminal station communicating with the base station through the repeating stations, the base station comprises means for transmitting synchronizing signal pulses at a predetermined period for effecting a battery saving type power supply. Each of the repeater station and terminal station comprises means, responsive to successive reception of a predetermined number of the synchronizing signal pulses, for effecting intermittent battery saving at a period substantially equal to the period of the synchronizing signal pulses during occurrence of the synchronizing signal pulses.

Abstract: An integrated planar antenna-mixer device for microwave reception utilizes a slot-ring antenna and a diode quad connected thereto. The device comprises a planar metallic sheet backed on one side by a dielectric layer. A circular ring pattern is cut from the metallic sheet forming a slot ring antenna with a central disc and a surrounding ground plane. Diodes of a diode quad are connected between the central disc and the ground plane with adjacent diodes being separated by 90.degree.. The incoming microwave signal is directed perpendicular to the device plane and polarized in a direction orthogonal to a local oscillator signal similarly directed. Operation is quasi-optical without waveguides.

Abstract: Radio-receiver having a frequency-locked loop which comprises, arranged one after the other, a tunable voltage-controlled oscillator, a mixer stage, a filtering element, as well as a frequency-voltage converter which is connected to the tunable voltage-controlled oscillator, several stable tunings being possible for each transmitter. An unambiguous selection is made from these stable tunings of a tuning to a desired station by muting the radio receiver in the other stable tuning frequency ranges. To this end the radio receiver according to the invention comprises a muting circuit as well as a control circuit for the muting circuit in which use is made of a further frequency voltage converter comprising an all-pass frequency-dependent 180.degree. phase shifting network, a phase detector and a limiter.

Abstract: A UHF tuning system for providing linear high gain operation over the entire UHF band comprises a field effect transistor (FET) amplifier coupling a received RF signal to a mixer for developing an IF signal, the IF signal being coupled to an IF processing stage by a signal regulating diode. An AGC control signal is derived from the IF stage for controlling the gain of the FET amplifier which, in turn, is utilized to control the conduction of the regulating diode so as to provide a substantially constant level IF signal to the IF processing stage. The novel arrangement of the present invention permits the field effect transistor to operate at a lower voltage for more efficient thermal operation and increased reliability while providing a high, flat gain characteristic over the entire UHF band.

Abstract: The invention relates to a multicarrier signal receiver protected against unwanted signals. Between the high frequency circuit and the intermediate frequency circuit, it has a frequency-selective attenuation and preselection circuit, while a circuit for detecting the disturbed channels is coupled to the demodulation circuit and supplies control signals characteristic of the appearance and disappearance of the unwanted signals. The receiver also comprises a control circuit eliminating the disturbed channel for processing demodulated signals and for the automatic control of the intermediate frequency amplifier circuit, and controlling the attenuation of the disturbed channel in the selective attenuation circuit.

Abstract: A satellite broadcast signal receiving system for receiving a plurality of signals of individual transmission bands, which are mutually different in frequency and/or polarization angle, transmitted through an artificial satellite, wherein the signals picked up by an antenna or antennas are first applied to a plurality of outdoor units each corresponding to one transmission band and comprising a convertor for converting the incoming signal into an IF signal, and the converted IF signals are then applied through a change-over switch to a common indoor unit including a demodulator to be demodulated for application to a conventional television set or the like.

Abstract: Disclosed is an antenna monitor for a diversity communication system having the capability of detecting differences in reception characteristics between a plurality of reception paths or modes and storing that failure information in a non-volatile memory store. Subsequently, the memory is read to determine if the antenna systems are functioning improperly.

Abstract: The invention is a synchronized communication system for effectively transmitting messages to a remote mobile receiver where the system includes a plurality of transmitters operating on a single RF communication channel. The system includes a central wide area transmitter which transmits messages over a wide area. The system also includes a plurality of local transmitters which transmit messages over a local area within the wide area served by the wide area transmitter. The transmitters of the system are coordinated by a synchronization link which allows the central wide area transmitter to be keyed only when the local transmitters are not keyed. Correspondingly the synchronization link only allows the local transmitters to be keyed when the central wide area transmitter is not keyed. Normally the synchronization link keys and dekeys the central wide area transmitter and local transmitters in a normal timing cell pattern.

Abstract: An electrical device in a buoyant, watertight housing, with electrical circuitry, including a battery, to illuminate an incandescent lamp to project either dispersed light or a beam through the translucent bottom of the housing, and to power a radio, as well as a water temperature thermometer. A handle is provided so that the device may be used as a portable lantern and/or radio.

Abstract: To monitor the operability of a radio receiver which has special recognition circuitry to recognize warning or emergency announcements, a modulation detector (11) is provided, sensing the change in degree of modulation of a region recognition (RR) signal, which changes its degree of modulation when an announcement recognition (AR) signal is radiated, the degree-of-modulation signal being stored in a memory (flip-flop 12), the output of which controls a transfer switch (6). The transfer switch transfers output from a muting stage (5) in the receiver, which is disabled upon detection of the AR frequency to a tone generator, for application to the amplifier of a warning tone if no change in the degree of modulation of the RR signal has been detected within a predetermined time period, as determined by a timing stage (15). A suitable timing interval is, for example, 24 hours. If such timing signals are received, the tone generator is not enabled, however.

Abstract: A system for enhancing the quality of a signal received by a mobile FM transmitter by reducing the adverse effects of multipath transmission to the receiver. A pair of antennas is provided, and each antenna is arranged to receive transmitted signals that traverses a different path. The signal produced in the receiver by one antenna is compared with a reference threshold and when the amplitude of the signal falls below the reference threshold, the receiver switches to the other antenna. The signal amplitude is sensed in a high frequency portion of the receiver, i.e. before detection or demodulation, so that switching between antennas occurs rapidly and is normally not perceived by the user of the receiver.

Abstract: A scanning receiver is provided with a pause detector which causes the receiver to tune to a priority channel during pauses in the transmission on a nonpriority channel. If a priority transmission is present, the receiver remains on the priority channel until the priority transmission ends. If no priority transmission is present, the receiver is tuned back to the former nonpriority channel.