Abstract: The present invention describes a resynthesized DRFM and method thereof. A conventional DRFM is utilized with the addition of a computer device. Once the digital pattern signals are stored they are utilized to generate a digital pattern which fills the interpulse period between the pair of signals. The interpulse digital pattern is then adjusted so that the digital pattern phases of the first and second signals match. In general the interpulse period digital pattern is not a uniform replication of the pulsed signal digital pattern because the adjustments have been made in order to accomplish pattern phase between the two pulses. These are then stored in memory until recalled.

Abstract: In a time division multiple access radio communication system constituted by a plurality of repeater stations and a plurality of terminals, only when the time slot in both the upward and downward directions is identical in a repeater station, the repeater station repeats data in the time slot. Downward data of a time slot used by a subscriber in an upward zone is not repeated to downward repeater stations, thereby saving power.

Abstract: In a radio paging system wherein paging calls are initiated by a central radio station and sent over lines to subordinate radio stations for transmission to paging devices, the subordinate stations are synchronized to transmit paging messages by introducing time delays between reception of a message from the central radio station before transmission, the time delays being functions of the message transmit times via the lines to the various other stations as well as the radio propogation time between the other stations.

Abstract: An "avalanche" relay communication network is configured of a plurality of transceiver stations spread out over a geographic area of interest to establish multipath communication diversity among the stations. The transceiver equipment at each station has the capability of simultaneous transmission over the same frequency through a "common knowledge" network timing scheme such as TDMA and has the capability of taking advantage of received multipath signals. Communications between an originating station and an intended recipient station are achieved by the originating station modulating onto an HF carrier a digital packet formatted to contain the number of times the message is to be repeated and a means of establishing the quality of the received message. All stations which have correctly received the packet repeat that same message on the same carrier frequency at the same preestablished future absolute time (or times, based on the number of repeats).

Abstract: A portable advertising sign is positioned in proximity to a street and includes a message board. A low power transmitter is physically secured to the sign and generates a modulated RF output signal at a predetermined frequency within the broadcast band. An antenna colocated with the sign is coupled to the transmitter and radiates the transmitter output signal. A cassette tape player is positioned in a secure area physically spaced apart from the sign by a substantial distance and includes a colocated power supply for supplying a DC voltage. A cable conveys the audio output signal from the tape player and the DC voltage from the power supply to the transmitter. The sign message board displays the operating frequency of the transmitter to vehicles passing by the sign.

Abstract: A memory system adapted to store samples of a finite portion of a periodic signal and produce an output signal having the same frequency as the periodic signal for a relatively longer time duration. The system includes a network for comparing the initial and terminal portions of the finite portion of the stored signal to determine the relative phase shift therebetween. Portions of the samples of the stored periodic signal and of the phase delayed replicas which extend from the first sample to the next to the last sample thereof are sequentially coupled to an output selectively in accordance with the determined relative phase shift to produce the output signal.

Abstract: In a repeater station for use in a repeater station to repeat a sequence of downward time slots and a succession of upward time slots, a detector (40) detects a synchronizing signal included in a particular one of the downward time slots. A timing circuit (41) produces a first timing signal when a first predetermined duration lapses after detection of the synchronizing signal. The first predetermined duration is preferably predictively determined in consideration of a reception time instant of a particular one of the upward time slots that corresponds to the particular downward time slot. Signals included in each upward time slot are memorized in a memory section (60) with reference to the first timing signal. The timing circuit further produces a second timing signal after the first timing signal to transmit the memorized signals to an upward station. The second timing signal is produced in consideration of a deviation with which the upward time slots reach the upward station.

Abstract: This invention is directed to a same frequency repeater (SFR) for use in a multiple SFR system in which only one SFR at a given time is allowed to retransmit a received signal thereby preventing simulcast distortion which could occur due to multiple SFR retransmissions. The SFR includes a receiver for receiving a signal carrying information at a given frequency and a transmitter for rebroadcasting the received signal at the given frequency. A mechanism is provided for keying the transmitter upon the reception of a received signal. A detector senses if a predetermined pilot tone is carried by the received signal. A mechanism responsive to the detection of the pilot tone inhibits the keying of the transmitter if the pilot tone is detected before the transmitter is keyed. A tone generator encodes the output signal of the transmitter with the pilot tone.

Abstract: A satellite repeater for a digital satellite communication system for use on board of satellites. Receivers are provided with respective antennas for receiving radio-frequency signals from a plurality of ground stations. A signal processing circuit switches signals received in synchronism with stable clock timings. Transmitters receive the switched outputs of the signal processing circuit to provide radio-frequency signals for transmission through respective antennas of the transmitters. Timing detectors receive the outputs of the receivers and detect the frame timings of the output signals of the receivers. Signal storage circuits are provided between respective outputs of the receivers and the signal processing circuit for storing the respective output signals of the receivers by respective amounts.

Abstract: A method and apparatus for increasing the capacity of present and future satellite communication systems transmits signals from correspondent pairs of earth stations simultaneously in channels that have at least a partial overlap in bandwidth. Each receiver at each earth station subtracts from the received composite signal the portion of the composite signal which was transmitted by the receiving earth station. This leaves a desired signal which corresponds to the signal transmitted by the other earth station of the correspondent pair and which is then demodulated. Each receiver at each earth station thus reconstructs an estimated target signal which has the amplitude, delay, frequency and phase of the signal as transmitted from the earth station and retransmitted by the satellite. The reconstructed target signal provides a very precise estimate of the portion of the composite signal transmitted by the earth station.

Abstract: The system comprises two terminal stations connected through a two-wire transmission line including bidirectional repeaters. The duration of each half-duplex cycle between successive emissions of two digital packets from a terminal station is independent of the length or range of the line. In particular, the half-duplex cycle duration is less than the transmission duration of two packets along two opposite transmission directions for a line having a great length. The system is characterized in that at least one of repeaters comprises a memorizing circuit for delaying each packet which is received along one of the transmission directions, with at least two times the duration of a packet, thereby retransmit it after the transit of another packet along the other transmission duration through the repeater.

Abstract: An apparatus is provided for communicating to a transmitter or sender of an emergency message a response indicating that the message was received. The communicating apparatus operates in conjunction with a portable alarm unit carried by the sender, a continuous-loop magnetic tape recorder-player, and a local CB radio (i.e., a CB radio located within the range of the portable alarm unit). In response to a signal from the portable alarm unit, the apparatus activates the communicating recorder-player causing it to play a pre-recorded emergency message and to apply this message, in the form of a message signal, to the local CB radio. The local CB radio transmits the message to a listener at a remote CB radio station. In response to a selected acknowledgement message received from a listener via the local CB radio, the communicating apparatus detects the acknowledgement message and transmits a signal to the portable alarm unit indicating receipt by a listener of the emergency message.

Abstract: A digital memory system is provided wherein a received radio frequency signal is separated into a pair of quadrature signal channels, the signals in each one of the channel being sampled and stored in a digital memory at a rate substantially lower than the Nyquist sampling rate. During recall the stored samples are sequentially read from the memories at the rate at which they were stored. The samples read from the memories in each of the channels are sampled at the relatively low sampling rate and are then combined into a single channel after shifting the phase of the signals in one of the channels 90 degrees, to form a composite signal having a plurality of radio frequency signal components, each one being separated in frequency from another one by an amount having a predetermined relationship to the pulse repetition frequency of the sampling pulses; one of such radio frequency signal components having the frequency of the received signal.

Abstract: In a relay station for use in a radio telephone network, which relay station includes a time storage unit composed of a time delay member connected to be switched, in response to recognition of a calling signal by its associated evaluator, from a reset state in which it is inactive to a set state in which it triggers emission of an identification signal after a delay period which is characteristic of the relay station and which differs from that of all other relay stations in the network, a member responsive to detection of such selective calling signal by its associated evaluator subsequent to recognition of a calling signal and prior to emission of a resulting identification signal for returning the time delay member to its reset state and preventing emission of that identification signal, and a member for automatically returning the time delay member to its reset state at the end of a time interval which follows recognition of a calling signal and is longer than the longest delay period characteristic of a

Abstract: Monitoring system for a forward and backward link equipped with two way repeaters-regenerators comprises a monitoring station including means for transmitting through the forward link information data and a low frequency control signal and for receiving through said backward link information data and supervisory words respectively monitoring the performance of the repeaters-regenerators and identifying errors made therein. In each repeater regenerator a supervisory word is stored in a shift register and advance pulses for said shift register are obtained by frequency division of the low frequency control signal. The supervisory word is completed by a start bit and a stop bit, and modulates the low frequency control signal. The modulated start stop supervisory word is transmitted to the monitoring station through the backward link.

Abstract: A digital memory system adapted to store samples of a received radio frequency signal and enable retransmission of a radio frequency signal from such stored samples, such retransmitted radio frequency signal having a frequency related to the frequency of the received radio frequency signal. The received signal is heterodyned to a periodic sinusoid video frequency signal having a predetermined average level. A sequence of one-bit logical signals representative of the amplitude of the video signal relative to a predetermined level other than the predetermined average level is stored. The stored samples are returned and converted to a radio frequency signal having a frequency of the received signal. By using a non-average level as the threshold voltage, the spectrum of the signal retrieved from the memory will have reduced harmonic components relative to the fundamental frequency component.

Abstract: A digital memory system adapted to store a sequence of one bit quantized samples of an input signal having a frequency within a predetermined band of frequencies and to produce a replica of such input signal from such stored one bit samples. A control signal is produced indicative of the particular portion of the band of frequencies which includes the frequency of the input signal. A plurality of filters is provided, each one tuned to a different portion of the band. In response to the control signal the sequence of bits read from memory passes through the filter which is tuned to the portion of the band which includes the frequency of the input signal. With such arrangement many unwanted harmonics produced because of the one bit quantization of the input signal are removed.

Abstract: A memory system adapted to receive a radio frequency signal and produce a signal having a frequency related to the frequency of the received signal for an extended, predetermined period of time. The received signal is heterodyned to an intermediate frequency signal. The intermediate frequency signal is sampled and digitized by an analog-to-digital converter. One bit of each digitized sample has a logic state related to the polarity of the intermediate frequency signal. The bits associated with the samples are stored for a time interval beginning at a time the intermediate frequency signal changes polarity with a predetermined sense, i.e. the start of a complete cycle of the signal. A control signal is produced providing an indication of the portion of the bits stored in the shift register at the end of the time interval which is associated with complete cycles of the stored signal and the portion of the stored bits which is associated with an incomplete cycle of the stored signal.

Abstract: An improved method and apparatus for automatically monitoring objects, such as vehicles, for example, wherein signpost units are positioned at predetermined locations and each signpost unit transmits a binary signpost code for reception via units installed in the objects being monitored and the objects being monitored receive the signpost codes and store object location information. In one aspect, the present invention contemplates a method and an apparatus which has a multi-mode operation capability wherein the location of the monitored objects is reported when the monitored object enters a different coverage region in an automatic reporting mode, wherein only those monitored objects within a predetermined region or on a predetermined route report to the base station in a region or route reporting mode, and wherein only the locations of predetermined monitored objects are reported to the base station in a polling mode.

Abstract: All messages broadcast through a two-way radio by a police officer from his vehicle, are recorded on an endless tape loop of a playback recorder. An alerting signal generated by a pretuned oscillator is simultaneously recorded on the tape with each message. Playback operation of the recorder is initiated by a remote radio trigger device so as to replay and transmit the recorded message and altering signal through the vehicle radio for a timed duration.