Abstract: A serial-type data transmission channel employing a transmitter and a receiver and a plurality of coaxial cables interconnected therebetween with optical coupling being provided at the receiver. One of the coaxial cables is used to transmit data comprised of messages interposed with identifying data indicating whether a next following message is a data message or a control message. Another coaxial cable is used to transmit a clock at one repetition rate when a message is being transmitted and at another repetition rate when identifying data is being transmitted. The receiver employs the received clock to extract the message and identifying data from the received signals, and to also provide indications of message availability and of the type of message received.

Abstract: In a closed-loop multiple data terminal data transmission system, each message includes in addition to a message portion, a prefix portion having at least the address of the terminal for which the message is intended. When such a message reaches a data terminal its address is checked, and if not for that terminal, the prefix and the message portions are repeated along the loop. If the message is for the terminal only the prefix is repeated along the loop, the message portion being retained at the intended terminal. The prefix with no attached message eventually reaches the originating data terminal where its arrival indicates that the message has reached its destination and that the loop is intact.

Abstract: A time division multiplex transmission system for communication of a data signal in a time-multiplex fashion over a data signal transmission path comprises a clock pulse generator for generating two-phase clock pulses including a first train of one phase and a second train of opposite phase. The system further comprises a plurality of transmitters and receivers, each including a wave shaper for demodulating the two-phase clock pulses and producing a single-phase clock pulse train, and a station selection circuit for processing the single-phase clock pulse train to identify that period of time during which the particular transmitter or receiver is selected for transmission or reception. Each transmitter and receiver also comprises a reset signal detector circuit, responsive to the detection of an intermission period in the clock pulse train, to reset the station selection circuit of the particular transmitter or receiver, thus achieving overall synchronization of the transmitters and receivers in the system.

Abstract: A pulse form restorer (pulse repeater) which detects that it is not passing pulse bit steam inserts a fixed resistor in series with the constant current cable power supply, and isolation of the faulty unit is accomplished by measurement of the voltage drop through the cable system. In a test mode the near end driver modulates the digital data at a slow alternating rate. A cable fault locator coupled to the power supply output comprises a peak detector, an A/D converter and a numerical display, which convert the change in voltage between data-on and data-off intervals to a number, which by a table look up designates the faulty restorer.

Abstract: This invention relates to a switching system for time-division multiplexed PCM channels. The system possesses essentially an incoming time-division switching device, a space-division switching device and an outgoing time-division switching device. The invention proposes to produce these time-division switching devices in the form of memories organized in pages enabling them to be manufactured in the form of hybrid monolithic integrated circuits. Application: time-division telephone switching.

Abstract: Disclosed is an apparatus for and a method of complex signal generation and transmission having particular application in a time assigned speech interpolation or TASI system. Samples of the amplitudes of a plurality of signalling status and test signals are stored in a digital code in a digital memory. These samples are retrieved as needed without the need for a plurality of time base signal generating means. The signal to noise ratio of the signals to be transmitted is increased by statistically predicting the n equally likely amplitude ranges of the entire set of signals. Each character of the digital code employed identifies one of these ranges. The more likely occurring amplitudes are thus defined by more code characters than are the less likely amplitudes.

Abstract: A synchronous digital transmission system (12), operating over a prescribed range of bit rates, is interfaced with subscribers (10, 11) whose data sources and receivers have different bit rates by means of transmitter and receiver interface networks (13, 14). The transmitter interface network (13) comprises means (20, 21, 23, 24) for phase-locking an integral subharmonic f.sub.o /N of a variable frequency oscillator (22) to an input clock signal, f.sub.1, associated with an input data stream, and means (25, 27) for encoding the data stream for operation at a bit rate corresponding to the fundamental frequency, f.sub.o, of the local oscillator (22) and including one code violation at a prescribed rate, f.sub.1 /M, related to the input clock frequency f.sub.1. The receiver interface network (14) includes means (30, 31, 32) for decoding the received signal and for recovering the input data stream and clock signal.

Abstract: A television tuning system employs a frequency synthesizer system for establishing the tuning of the receiver. A first programmable frequency divider controlled by a reversible counter is connected between the output of a reference oscillator and a phase comparator to which the output of the local oscillator, after passing through another programmable frequency divider, also is applied. The phase comparator output is a tuning voltage used to control the tuning of the local oscillator. A logic circuit responsive to characteristics of the received signals changes the count in the reversible binary counter to adjust the first programmable frequency divider to compensate for channel frequency offsets which may occur in excess of the pull-in range of the AFT discriminator circuit. To permit operation of the receiver as a signal seek receiver, a pair of signal seek push buttons for the "up" and for the "down" direction, respectively, are provided.

Abstract: An FM wave received by an antenna is fed via an AGC circuit to a first FM demodulator and to a compensation signal generator which includes an envelope signal generator, a capacitor, a function generator, an analog multiplier, an SSB modulator, and a second FM demodulator so that the output signal of the compensation signal generator is added to the output signal obtained by the first FM demodulator to offset the multipath distortion contained in the received FM wave.

Abstract: The invention relates to a movement detector, more particularly a sensor comprising a container partially filled with a liquid into which three electrodes extend. An input alternating signal is applied to two of the electrodes and an output signal amplitude modulated in accordance with movement of the liquid in the container, is detected from another two of the electrodes by means of a sensing circuit which includes a demodulator for detecting the amplitude modulation and a circuit arrangement which provides a container movement signal in response to successive peaks in the demodulated signal which are in excess of a given threshold value being spaced apart in time from one another by a time dependent upon the peak magnitudes of the demodulated signal.

Abstract: An unslotted radio frequency multiple access bus communications system employing a contention listen-while-talk (LWT) protocol. The system includes a plurality of remotely located terminals coupled to a communications bus. The bus includes a pair of oppositely directed, unidirectional signal paths which are connected at one end so that one path is an inbound path to that end and the second is an outbound path from that end. Each of the remote terminals includes a bus interface unit (BIU) coupled to both the inbound and outbound paths at the remote location. Each BIU is adapted to transmit and receive modulated carrier signals on the inbound and outbound paths, respectively.When a terminal wishes to send a message to another terminal, the terminal's BIU initially performs an rf carrier sensing operation to make an initial determination as to whether or not any other subscriber is transmitting on the inbound path.

Abstract: A remote control system and method therefor is disclosed that includes a control station coupled by a two-wire line to a base station having a transmitter for providing simplex radio communications to mobile radios. The control station utilizes digital pulsed DC signalling to select a radio channel of the base-station transmitter for transmission of each message. In response to activation of a transmission switch, the control station applies a DC voltage to the two-wire line and thereafter applies a command pulse train having a predetermined number of pulses corresponding to the selected radio channel. The base station is responsive to the DC voltage on the two-wire line for receiving the command pulse train. The pulses in the received command pulse train are totalized, and the base station transmits the message on the radio channel corresponding to the totalized number of pulses.

Abstract: A method and apparatus are disclosed for the emergency control of model aircraft. The incoming signals to the model are screened and, if missing or outside acceptable limits, the screened signals are replaced with a sequence of preprogrammed emergency signals which control the model into an emergency procedure.

Abstract: A time-division switching system for switching data words from data word sources received in channels of a time-multiplex line where a first plurality of data word sources uses a channel only once every n channels and a second plurality of data word sources uses a channel once every m channels where m is less than n and n is not an integer multiple of m. The switching system operates in response to control words sequentially provided by a control word source. The control word source of the disclosed embodiment comprises a first storage arrangement having n storage locations for storing control words and a second storage arrangement having m storage locations for storing control words. A storage reading circuit substantially simultaneously reads the contents of one storage location of both storage arrangements sequentially.

Abstract: A modem capable of achieving essentially 9600 bit per second information transfer rate through the switched telephone network. The high bit rate is achieved notwithstanding the variations in the characteristics of the switched telephone network by phase and amplitude modulating a plurality of sub-carriers at a relatively low baud rate. Correlation detection is employed at the receiver to extract or demodulate the information contained in the various sub-carriers. To allow correlation detection with orthogonal signals, each of the sub-carriers is harmonically related to a fundamental which fundamental is, however, slightly higher than the baud rate. This allows the receiver to delay correlation for a "gap" time, which reduces the effect of transients produced by modulation and also provides greater tolerance to inter-symbol distortion.

Abstract: A system and method for improving the spectrum utilization of voice communications channels by increasing the number of voice conversations a given number of lines can service. This invention can be used to improve the reliability and efficiency of conventional TASI (Time Assignment Speech Interpolation) systems and allow such systems to provide good performance when utilizing a mixture of types of telephone lines; including, microwave, cable, satellite, and two wire configuration lines.

Abstract: A digital communication system employs a technique of effectively controlling the size of the bytes making up a field of data to be serially transmitted from one station to another, particularly one wherein the byte size may be selectively changed during the transmission of the data field. Assembly of a transmitted data field is controlled so that it includes an encoded data byte, termed a first pre-header byte, which contains information as to whether or not a change in the byte size of the data field is to occur. If the first pre-header byte indicates the occurrence of a byte size change, it also will contain a code representative of the size of the change. In addition, for a change in byte size, a second encoded data byte, termed a second pre-header or count byte is generated and immediately follows the first pre-header byte. The count byte contains information which specifies the length of that portion of the data field which precedes the occurrence of the change in byte size.

Abstract: Different ones of a plurality of sounds or tones are digitally signaled selectively in the different time slots of recurring frame cycles by initially storing a group of PCM samples for each sound in addressable memory. As each given time slot recurs one sample of a sound preselected for that time slot is read out to a common bus, and as successive cycles occur the address signals applied to the memory during any given time slot are progressively changed to cause repeated scanning of the samples of the preselected sound. After address signals for one time slot have been pulled from a read/write memory, they are replaced by writing "next sample address" signals into the same location of that memory, the latter having a word location for each time slot and being addressed for reading and writing by control signals which exist during and uniquely identify the successive time slots of each cycle.

Abstract: The present invention relates to a method for use in a communcation system of providing efficient access by low traffic stations while keeping the buffering requirements for high traffic stations at a minimum. The method provides a TDMA architecture which includes a plurality of different frame rates which is dependent on the traffic requirements between station pairs. In operation, a sequence of a plurality of s switching frames are used to form a super frame and each communication burst of a switching frame is divided into a plurality of q subbursts representative of q transmission channels so that a maximum of (q.multidot.s) transmission channels are available for assignment in corresponding bursts during a super frame. When traffic demands require n.multidot.

Abstract: A noise detector circuit for radio receivers is disclosed. The circuit includes a delay circuit for slightly delaying a received signal. A comparator compares the level of the received signal with the delayed signal to generate a pulse sequence having a number of pulses per unit that is proportional to the level of said noise. A counter counts the number of pulses to detect the level of the noise in the received signal.