Abstract: A transmission system (10). The transmission system communicates data to a number of subscribers (14a, 14b). The transmission system includes a transceiver (12) that has a number of highly directional antennas (28). A number of digital repeaters (16a, 16b, 16c) are disposed in a geographic region serviced by the transceiver. The repeaters include a sectorized antenna that communicates with subscribers in a number of sectors of the geographic region of the repeater. The repeater also includes an upstream demodulator/modulator circuit (19). The upstream demodulator/modulator circuit demodulates data from signals from subscribers that were modulated with a first modulation technique, and generates a re-modulated signal with the data using a second modulation technique.

Abstract: A system for redistributing a broadband audio-visual-data signal to a multiplicity of receiver units within a multiple dwelling unit (MDU) includes a main receiving antenna that receives a broadband video/audio/data signal having a number of individual program multiplex signals therein and a transmodulator device that transmodulates the individual program multiplex signals associated with the broadband signal from a first modulation scheme to a second modulation scheme to reduce the bandwidth of the broadband signal. The transmodulated signals are broadcast over a cable network, along with terrestrial signals, to individual receiver units at the MDU. The receiver units demodulate the transmodulated and/or terrestrial signals and provide user-specified channels to television sets for display.

Abstract: A satellite payload having d transparent channels, a first plurality d of band-pass channel filters IMUX of bandwidth .delta. that filter received signals, frequency converters, a plurality k of channel amplifiers (k.gtoreq.d), power amplifiers and a second plurality p of channel filters OMUX that filter the signals amplified by the channel amplifiers and the power amplifiers, d amplifiers assigned to said d channels, the frequency converters including at least one mixer and at least one source of a conversion frequency signal, wherein the g band-pass channel filters IMUX filter the received signals before frequency conversion by the converters.

Abstract: An analog processor for use with digital satellites. The analog processor is connected between the receiving circuitry of the satellite and a pool of digital on-board processors, and segments the bandwidth of uplink RF beams into sub-bands that can be processed more readily with standard, low-risk, low-power digital processors. Using the present invention, the risk of employing a particular digital processor technology can be managed and optimized. The present invention also provides for the dynamic allocation and reallocation of the available on-board digital processing bandwidth based on the anticipated traffic pattern and changes in the traffic pattern. In addition, the present invention facilitates the use of standard and non-standard redundancy schemes at minimal hardware expense.

Abstract: Individual channels are centrally and tunably selected for emission in a distributed wireless communications system. A high-frequency signal received at a central antenna is down-converted such that a selected channel corresponds to a predetermined frequency range. Non-selected channels are filtered out. The selected channel is transmitted to remote locations over commonly available transmission lines, up-converted, and re-emitted. The transmitted channel is chosen by tuning the frequency of the local oscillator used for down-conversion. A high-stability global tuning signal is used to tune and stabilize the local oscillators used for up-conversion. The global tuning signal is generated by frequency-dividing the down-conversion local oscillator signal by a fixed number, while the up-conversion local oscillator signals are generated by frequency-multiplying the global tuning signal by the same fixed number. Phase-locked loops are used for frequency multiplication and stabilization.

Abstract: Transponder systems are disclosed for routing signals from a plurality of input frequency channels at each of a plurality of receive antennas to a plurality of output frequency channels at each of a plurality of transmit antennas. The routing is preferably processed at an intermediate frequency. A plurality of bandpass filters are coupled to each receive antenna to define input signal paths. First and second mixers are positioned in series with each bandpass filter. A mixing signal at the first mixer adjusts the frequency of a selected one of the input signals to pass it through the bandpass filter and onto the respective input signal path. A mixing signal on the second mixer translates the frequency of that input signal to have a frequency order in the intermediate frequency band that corresponds with the frequency order of a selected one of the output frequency channels at its respective transmit antenna. Each of the transmit antennas is coupled to a common signal path of an adder.

Abstract: An improved repeater for receiving and re-transmitting radio signals for a cell in a cellular telecommunication system. The repeater raises the levels and is capable of converting the frequencies of the radio signals used in the telecommunication system. Due to the power amplifiers being provided between the channel selecting means and combiner, the power amplifier needs only to amplify one frequency band. In this way the repeater gets a simpler design, demands less maintenance, and gets a higher degree of efficiency in combination of high power capacity and generation of low levels only of intermodulation products.

Abstract: An apparatus and method for use in receiving radio frequency (RF) signals having varied frequency bands from a n-sector base station antenna, and converting the RF signals to intermediate frequency (IF) signals for allocation to all available receiver radio channels. By employing a combiner and power splitter/divider, the IF signals from the converters in each sector of the receiver can be accessed by every receiver radio channel. Accordingly, remote communications users placing calls in high traffic sectors will have access to all available radio communications channels.

Abstract: A system and method for transmitting a radio frequency (RF) signal in a RF bandwidth over a low bandwidth medium, e.g., in-building cabling, which has a transmission bandwidth below the RF bandwidth. The system has a unit for receiving the RF signal and a global reference oscillator for distributing a global reference tone of high stability to the entire system. Local oscillators are controlled by adjustment signals derived from this global reference tone to deliver RF reference tones of high stability required for mixing the RF signal to obtain an intermediate frequency (IF) signal which is fed through the low bandwidth medium. The global reference tone is preferably delivered through the same low bandwidth medium to desired locations, such as remote coverage sites in a network for cellular communications, cordless telephony, local RF communications, interactive multi-media video, high bit-rate local communications.

Abstract: Input RF signals to a transponder, such as a communications satellite, are down converted to a lower intermediate frequency (IF) that is common for each different channel. The channel signals are all processed at the common IF, and then up converted to different respective transmission frequencies. This allows for a down conversion/signal processing/up conversion unit design that is the same for each channel (except for frequency and gain values), and facilitates the use of inexpensive available standard components as well as low bandwidth channel filters. An improved phase noise cancellation phase lock loop (PLL) is preferably used to generate tuning signals used in the up and down conversion processes. The PLL includes two loop mixers, with the down and up conversion mixing signals taken respectively from the inputs to the first and second loop mixers. The first and second loop mixers receive mixing signals at frequencies (T-R) and (T-IF-N.multidot.

Abstract: Apparatus for simultaneously receiving a plurality of AM signals of widely differing strengths on a set of carrier frequencies and for re-broadcasting the AM signals at equalized strengths at either the original carrier frequencies or at a set of carrier frequencies that are offset from the original from the received frequencies by a constant difference. Regardless of whether the re-broadcast carriers are offset, the system includes provision for interrupting the re-broadcast signals by an audio message of general interest or public safety.

Abstract: A dual frequency cellular radiotelephone system, having different service providers, serving mobile subscribers at first and second distinct frequency ranges, uses frequency conversion techniques, to serve both frequency ranges with a minimum of equipment duplication. A first service group is serviced by a first system including a mobile switching center (MSC), a first transmission unit, a first base station controller (BSC), a first base transceiver, a first linear amplifier and first antenna. The entire train of components is designed to support air interface transmissions at the first frequency band at which the first group is served. A signal frequency converter, connected to a transceiver of the first frequency band, converts downlink signals from the first frequency range to the second frequency range and uplink signals from the second frequency range to the first frequency range.

Abstract: An automatic repeater station, sometimes called a relay system, is disclo. The relay system receives signals, preferably at one band of frequencies, then filters and restores their inherent information, and finally transmits the restored information, preferably at another band of frequencies. Unlike the prior art systems utilizing transceivers and electronically tunable filters, the present invention uses separate receivers and transmitters and is devoid of electronically tunable filters.

Abstract: A repeater system in a communication system including a base station and a mobile unit provides a communications link between the base station and the mobile unit when the mobile unit is located in an environment that is substantially closed off to high radio frequency communication between the base station and the mobile unit. The repeater system has a first linear two-way frequency converter including a high frequency port for two-way coupling to the base station and a low frequency port for two-way coupling to a low frequency signal that is capable of distributing radio frequency power through the closed environment. The low frequency port is connected to a cable which propagates and receives low radio frequency power within the closed environment.

Abstract: Linking of radio paging transmitters is accomplished through the utilization of TDM transmission on the same channel as that assigned to the paging service, thus eliminating the necessity of a separate channel for linkage of the remote transmitting sites to a central originating location. For data transmission, real time data is broadcast via a direct RF link to buffer storage at each of the remote transmitting sites, with the data being read out to each of the paging transmitters from the local buffers in a phase-adjusted synchronized fashion under control of sync signals generated at and broadcast from the central originating location. The data transmission rate from the central originating location to the remote sites may be made significantly higher than the radio paging data rate in order to minimize link time to minimize linkage overhead by reducing the amount of time the channel is used for linkage as opposed to paging.

Abstract: In a cellular system, including at least one cell site located within a corresponding geographic sector, an apparatus and method provides for expanding cellular system capacity through subdivision of the geographic sector by use of a cell site transceiver and a remote site transceiver to extend said cell site to a remote location within said geographic sector. Each transceiver provides duplex operation and includes a cellular band transmitter and receiver portion for local communication with the cell site or remote site mobile units, as the case may be; and a link frequency transmitter and receiver portion for communicating cellular band information, after conversion to an appropriate baseband frequency, between the cell site and the remote site transceivers.

Abstract: A regenerative RF bi-directional communications system is provided for establishing RF coverage within a RF block tunnel area. The system uses a plurality of cascaded amplifier stages for periodically regenerating signals which are transmitted and received along a series of radiating cable length which link base station transceivers to hand-held or like mobile communication units. An intermediate frequency distribution system is used so that the required level of amplification is achieved through the several cascaded amplifier stages at the level of low-power IF signals generated from the original RF signals in conjunction with the appropriate oscillator and pilot signals. The IF distribution system restricts the cascading effect occurring due to the plurality of cascaded amplifier stages on the relatively low-power IF signals, thereby producing a negligible amount of intermodulation.

Abstract: A signal repeater assembly (1) for a spacecraft, includes a channel selectivity network (CSN) (2) having a plurality of first input ports (4-13) connected by selectively operable filter circuits (14-23) to a plurality of first output ports (24-31) to enable a signal at any selected first input port (4-13) to be passed to any selected first output port (24-31). The CSN (2) is connected to a shared power amplification module (SPAM) (3) having a plurality of second input ports (44-51) for receiving signals from the first output ports (24-31), a plurality of second output ports (52-59) and a network (60) of balanced amplifier devices (61) operable to couple the second input ports (44-51) to the second output ports (52-59) so that any amplification of a signal received at any one of the second input ports (44-51) is shared by all the amplifier devices (61) to allow the total available amplification power to be used by any one or a combination of second output ports (52-59).

Abstract: A high-frequency signal booster which has at least one channel unit including a down-converter for converting input signals into intermediate-frequency signals and an up-converter for converting time into output signals. The respective up- and down-converters are separately equipped with station-originating signal oscillators. Further, the station-originating signal oscillator provided for the up-converter has a function of effecting the modulation with out-of-voice-band signals.

Abstract: A split band filtering scheme to reduce adjacent band interference in a communications network, such as a cellular mobile radio system, is disclosed. A repeater, interposed between a base or cell site and a mobile/portable radio, includes a down converter for converting a system operating frequency to a lower frequency signal. The lower frequency signal represents a communications band. The signal is presented to a split band filter having a narrow passband with steep skirts. The processed signal is coupled to an up converter where it is restored to the system operating frequency. In this way, the passband of the repeater is restricted to that of the desired communications band and adjacent band interference is reduced or eliminated.

Abstract: Direct relay equipment includes a first antenna, a second antenna, an up direction circuit connected from the first antenna via a first circulator to the second antenna via a second circulator, and a down direction circuit connected from the second antenna via the second circulator to the first antenna via the first circulator. In the up direction circuit and the down direction circuit, the received signal having a frequency f.sub.1 from the first (or second) antenna is amplified by a microwave amplifier, the output of the microwave amplifier is converted to a signal having a frequency f.sub.2 (sending frequency), the signal having the frequency f.sub.2 is amplified by the same amplifier, and the amplified signal having a frequency f.sub.2 is sent from the second (or first) antenna.

Abstract: A system for maintaining an accurate frequency source in a single sideband repeater employs an ultra stable station control reference (SCR) frequency generator. A first frequency synthesizer for a local oscillator of the repeater phase locks to the output of the SCR normally, but is free running upon failure of the SCR. A second frequency synthesizer for another local oscillator phase locks to the output of the first synthesizer. Upon failure of the SCR, the system of synthesizers can provide a satisfactory frequency reference for the repeater. Disclosed are phase lock loop filter time constant design considerations for achieving proper operation.

Abstract: An apparatus for minimizing the spillover signal from the transmitter to the receiver in a same frequency repeater includes a mechanism for generating a receiver first injection signal carrying the modulation component of the transmitter signal, and a first mixer for mixing the received signals and the first injection signal to produce a first IF signal having one unmodulated IF component signal and another modulated IF component signal. A correlation and cancellation circuit is utilized to cancel the unmodulated IF component signal. A mechanism is provided for generating a second injection signal which carries the modulation component of the transmitter signal. A second mixer mixes the first IF signal and the second injection signal to produce a second IF signal such that the modulation component of the spillover signal is substantially cancelled.

Abstract: A service channel signal transmission system in which a service channel signal is constantly fed to at least two radio channels in parallel. Each intermediate repeater station has a service channel demodulator which is constantly connected to either one of the radio channels. A combining and switching circuit automatically switches over the service channel demodulation to the other radio channel in response to an alarm output which indicates an abnormality in a received signal at a receiver associated with the one radio channel. The service channel is completely switched from one to the other without resorting to line switchover control signals from terminal stations.

Abstract: A same-frequency repeater used in a system that has at least one other same-frequency repeater is protected against oscillation resulting from feedback of signals broadcast by the same-frequency repeater, either directly or after reception and rebroadcast by another same-frequency repeater. A tag is added to the signal to be broadcast from the first SFR, and one tag detection and canceling system is added to the first SFR for each SFR, in the system. Each tag detector senses the presence of tagged signal received by the first SFR and adjusts amplitude and phase of an appropriately delayed signal that is fed back to cancel the signal containing tag.

Abstract: Simulcast distortion in a receiver when using a same-frequency repeater is minimized by applying double modulation to a signal that is broadcast to the same-frequency repeater. A voice signal is applied without delay as AM on a carrier to a modulation index of up to 30%, and the same signal is also applied as FM on the same carrier with a time delay equal to the time delay in the same-frequency repeater. The same-frequency repeater detects the AM and applies the detected signal as FM on a carrier that is rebroadcast. Received FM signals are thus delayed by substantially the same amount whether they are received from the original broadcast or the same-frequency repeater.

Abstract: A carrier recovery network for QPSK modems employs a synchronous oscillator which may be used as a frequency multiplier, divider and tracking bandpass filter. A preferred embodiment of the carrier recovery network includes a multiply-by-four circuit to remove QPSK data modulation, and a synchronous oscillator tuned to one-fourth the input frequency to thereby act as a frequency divider and tracking bandpass filter to provide a recovered carrier signal.

Abstract: In order to compensate for nonlinearities introduced by a transmission member in a radio relay transmission system by means of a distortion converter stage, the converter stage is supplied with an intermediate frequency signal modulated with the useful signal, and with a local oscillator signal, a desired high frequency signal with its desired level is provided by a first mixing diode included in a first converter, a desired high frequency signal with a level below its desired level and with a phase shift is provided by a second mixing diode included in a second converter, the two high frequency signals are combined in a summing member, and the high frequency signal provided by the second converter is set by a level and phase controller so that the combined high frequency output signal has a distorted component whose amplitude coincides with the amplitude of the distorted signal component introduced by the transmission member but whose phase is in phase opposition with the latter.

Abstract: Spillover of RF signal from the output of a same-frequency repeater to the input is reduced by attaching a tag to the output signal. The tag is double-sideband, suppressed carrier to place two spectral spikes, one above and one below the carrier. The tag is applied to the signal in the IF. A tagged signal of variable amplitude and phase is added to the received signal so as to cancel the tag and hence the spillover signal, leaving only the desired signal. A feedback system controls the amplitude and phase of the cancelling signal.

Abstract: A system of frequency-shifting of frequency modulated signals, continuously above or below a pre-established frequency, the shift being possibly also null. The system includes a source of frequency modulated signals, the frequency of which is to be shifted; a reference oscillator; a first phase locked loop to which is applied the signals from the signal source and the output of the reference oscillator, the arrangement being such that the first phase locked loop will be locked to a conversion frequency above or below the frequency of the signal source.

Abstract: Frequency modulators for use in microwave link transmission systems include acoustic surface wave (ASW) oscillators. Each frequency modulator comprises two voltage control quadripole ASW oscillators. Control inputs of the two ASW oscillators receive modulation signal in opposite phase. Outputs of ASW oscillators are mixed in a mixer for delivering an IF signal. Thus frequency deviation is larger than in a conventional arrangement. Moreover, surface wave oscillators make it possible to directly insert a service channel signal in a microwave link repeater, without demodulation and modulation operations.

Abstract: A method and means for translating frequencies, as for example, to correct a frequency error .DELTA.f.sub.d introduced into a carrier signal of frequency f.sub.c, comprising means for dividing the resultant signal frequency (f.sub.c +.DELTA.f.sub.d) by N, resulting in a divided-down frequency (f.sub.c /N+.DELTA.f.sub.d /N), with .DELTA.f.sub.d being reduced to .DELTA.f.sub.d /N, and then heterodyning the divided-down frequency with signal of frequency (f.sub.c +f.sub.c /N) to produce a resultant signal of frequency (f.sub.c +.DELTA.f.sub.d /N), the frequency error remaining at its low, divided level .DELTA.f.sub.d /N.

Abstract: Frequency bands in spot beams received by a satellite transponder are selectively routed to transmitted spot beams. The total band width from each spot beam receiver is divided among a plurality of independently adjustable variable bandpass filters, and the outputs from the selected bandpass filters at each receiver are combined at the spot beam transmitters so that each downlink spectrum is made up of a frequency multiplex of selected bands from each uplink spot beam.

Abstract: In radar apparatus for actively enhancing and retransmitting a received radar signal, the incoming signal is mixed with the output of a first local oscillator, the resulting signal being supplied to a frequency lock loop which varies the frequency of the first local oscillator until the frequency of the resulting IF signal is equal to a first reference IF frequency. The first local oscillator output is mixed with the output of a second local oscillator, the frequency of which is varied until the frequency of the resulting second IF signal is equal to a second reference IF frequency. The output from the second local oscillator is retransmitted. The first and second reference IF frequencies are identical if the frequency to be retransmitted is the same as the incoming RF carrier frequency.