Abstract: An adaptive differential pulse code modulation system includes an adaptive quantizer and an adaptive predictor which have a coding characteristic optimized to a voice signal, and a quantizer and a predictor which have a coding characteristic optimized to a voice band MODEM signal. This system is normally used as a coding system optimized to the voice signal, and when this system detects a MODEM training signal, it becomes a coding system optimized to the MODEM signal.

Abstract: A music delivery arrangement permitting a subscriber to select from among a plurality of available music selections, particular selections that he wishes to hear at any time. The plurality of music selections are "played" at a central "jukebox" facility. They are frequency multiplexed onto one or more communication channels that are typically used to carry video information, such as cable television channel. The video channel information is distributed to individual subscribers either via unused channels of a cable television system, by direct broadcast at commercial television frequencies, by direct satellite transmission to a subscriber, or by some other means. The subscriber uses a converter box to demultiplex and thereby select a desired musical selection for demodulation. Demodulation can take place in the subscriber's FM broadcast receiver or in some other apparatus.

Abstract: In a frequency division multiple access (FDMA) communication system, a plurality of carrier frequencies relating to a predetermined frequency band for transmitting a PSK (phase shift keying) signal are provided on a frequency scale. When a service is a low bit rate signal, it is transmitted by using a single carrier frequency and its related frequency band. When a service is a high bit rate signal which can not be transmitted in a single carrier signal, the service signal is divided in to a plurality of low bit rate PSK signals, each of which is transmitted by using a single carrier frequency and the related frequency band.

Abstract: Using the inventive method and apparatus, two scanning sequences can be synchronized with small signal delays and at the smallest possible apparatus expense. The time differences between associated scanning values or signals of the two scanning sequences are compensated by alternatingly delaying relative to each other the scanned values or signals and interpolating between the scanned values or signals of one of the two scanning sequences. The apparatus for carrying out the synchronizing operation comprises a storage for producing the delays and a filtering device for performing the interpolation.

Abstract: The digital samples (An) representing the components in phase (X) and quadrature (Y) of data signals, are digitally integrated by the assembly comprised of multipliers (14 and 15) and an adder (16). The energy signal (Bn) which is obtained, is loaded into a register (17) so as to be provided with the energy signal obtained on the preceding sampling time. The value (Bs) of the energy signal from which the energy signal decrease rate exceeds a predetermiined value, is loaded into a register (21). Then a comparator (23) provides a binary 1 signal transmitted on the output line (25) as the energy drop signal when the value of the energy signal (Bn) has fallen below a predetermined fraction of the value (Bs) stored in register (21).

Abstract: A method for changing the data transmission rates in a synchronous data communication system including a first modem and a second modem coupled together through a transmission channel, the transmission channel including a first path for transmissions from the first modem to the second modem and a second path for transmission from the second modem to the first modem, includes the steps of determining, at the first modem, that the second path of the transmission channel is adequately high in quality to support an increase in transmission rate. Next it is determined, at the second modem, that the first path of the transmission channel is adequately high in quality to support an increase in transmission rate. A training sequence is then transmitted at an increased transmission rate from the second modem to the first modem. Next, a training sequence is transmitted at the increased transmission rate from the first modem to the second modem.

Abstract: Methodology, and associated circuitry, for encoding and decoding signals utilize optimizing orthogonal code techniques that effect autonomy of communications and simplified signal processing, thereby improving reliability.Encoder (121) processes an incoming data stream by associating an optimizing orthogonal code with each binary one in the input stream and then by transmitting a series of rate-increased pulses over a path during intervals determined by the code for each of the binary ones.Decoder (131) is generally arranged as a correlation detector in that the decoder only responds to the particular optimizing orthogonal code for which it is configured. Sensors in energy transfer relation to the path are positioned at detection points on the path in correspondence to an assigned code. The outputs of the sensors are processed to produce a rate-decreased detected signal at the rate of the input stream whenever a rate-increased stream corresponding to the decoder configuration is propagating along the path.

Abstract: Methodology, and associated circuitry, for encoding and decoding signals utilize bistate orthogonal code techniques that effect autonomy of communications and simplified signal processing, thereby improving reliability.Encoder (121) processes an incoming data stream by associating a bistate orthogonal code with each binary one in the input stream and then by transmitting a series of rate-increased pulses over a path during intervals determined by the code for each of the binary ones.Decoder (131), in synchronism with encoder (121), is generally arranged as a correlation detector in that the decoder only responds to the particular bistate orthogonal code for which it is configured. Sensors in energy transfer relation to the path are positioned at detection points on the path in correspondence to an assigned code.

Abstract: A retroreflective optical communication system in which a laser at a control station is aimed at a retroreflector at a second position or station whose reflectivity can be varied so as to impress a signal onto the retroreflected beam, and then back to the first station for detection. The communication link is such that the laser and aiming capability are at the receiving or control station and, greatly reducing the aiming and power requirements and cost at the retroreflector end of the link. The retromodulator optical communication system provides a high data rate, secure, non-jammable line-of-sight communication link between the second station, which may be a remotely piloted vehicle (RPV) and its control station. The retromodulator maybe entirely passive and thus would not give its presence away as would RF transmitting and receiving stations.

Abstract: A binary transversal filter (200) in which the delay line of flip-flops (A-L, A'-L') is driven by timing signals (CLK, CLK*, CLKD, CLKD*) that are the same clock rate as the clock rate (CLK) of the encoded binary signals (IMPULSE 0, IMPULSE 1) being introduced into the delay line forming the binary transversal filters (200). The timing signal (CLK, CLK*, CLKD, CLKD*) that time or clock the stages of the delay line (A-L, A'-L') are phases of the clock (CLK) that introduces the encoded binary signals (IMPULSE 0, IMPULSE 1) into the delay line (A-L, A'-L'). Two substantially identical binary transversal filters (200a, 200b) are used to convert two encoded binary data streams (IMPULSE 0, IMPULSE 1) into a duobinary signal. The output of the two binary transversal filters (200a, 200b) are summed (Q2) and passed to a programmable amplifier (210), the gain of which is turned on when there is data in the encoded binary signals (IMPULSE 0, IMPULSE 1) to be converted and transmitted and is turned off otherwise.

Abstract: A method of transmitting signalling along a bidirectional digital transmission link consists in transmitting from an intermediate equipment of the link a signalling message in two parts. One is a characterizing part the form of which depends on the signalling type and which is substituted for data of one of the digital bit streams carried by the link in the direction from one of the terminals referred to as the processing terminal. The other is a localizing part whose form is independent of the signalling type and which is substituted for data of the digital bit stream carried by the link in the direction towards the other, so-called relay terminal. The relay terminal responds by sending an acknowledgement message to the processing terminal, the time-delay of this relative to the characterizing part being used to identify the sending equipment. A signalling message transmission circuit controls switching circuits inserted into the paths of the digital bit streams carried by the link.

Abstract: An adjustable positioning plate for aligning a communications laser transmitter or receiver station. The cabinet is anchored to a flat mounting plate by a three point suspension consisting of a ball fulcrum at the cabinet bottom front center and fixtures at the lower rear corners of the cabinet. Each rear fixture includes a horizontal adjustment relative to a block attached to the mounting plate and a vertical screw to furnish vertical adjustment. Four springs straddling the cabinet sides and cross rods across the top hold the cabinet tightly against the three point suspension.

Abstract: Delay time variation in an optical fiber digital communication system which includes optical regenerative repeaters is measured at one of terminal ends having reference clock signal. A monitor signal which depends upon the delay time variation is provided at the farthest repeater in an area where delay time is subject to secular change by dividing reference clock signal from said terminal end, and said monitor signal is returned to the terminal end from said farthest repeater, and the terminal end compares the returned monitor signal with the divided reference signal by using a phase comparator to provide measure of delay time variation.

Abstract: A capacitive type coupling data transmission system for portable electronic apparatus is comprised of an input circuit, a capacitance changing circuit, a transmitting circuit capacitively coupled to, a receiving circuit, and a detecting circuit for detecting any change in the capacitance changing circuit. A data signal to be transmitted is inputted into the input circuit. Based on the value of an inputted binary digital data signal, the capacitance of the capacitance changing circuit is changed. The capacitance change is capacitively transmitted from the transmitting circuit to the receiving circuit and detected thereat. The detecting circuit may be an oscillator circuit, a an RC differentiating circuit, or an RC integrating circuit.

Abstract: A PCM difference data is obtained from an original data, and an absolute data having a lower bit number than the original data is obtained at every data block, each data block comprising a plurality of the difference data. The transmission data includes the difference data and absolute data which is transmitted. The received data is separated into the difference data and the absolute data and the received difference data is integrated to provide the demodulated data. The integrated data is refreshed by the received absolute data only when the difference between the integrated data and absolute data is more than a predetermined value.

Abstract: A technique is presented for simplifying the recovery of two synchronous data signals having a common symbol rate after each signal has respectively modulated a different one of a pair of quadrature-related carrier signals. In the transmitter, the data signal which modulates one of the quadrature-related carrier signals is delayed relative to the data signal which modulates the other quadrature-related carrier signal. This delay is related to an IF frequency chosen at the receiver. After passing through a noisy transmission channel, the quadrature-related carrier signals are coupled in the receiver to a serial combination of an equalizer and analog-to-digital converter. This combination outputs multiple, substantially distortion-free samples of the data signals each symbol interval. The two data signals are then recovered by selecting a subset of the samples provided each symbol interval.

Abstract: An equalizer is provided with a branching device for branching a digitally modulated signal into two outputs. A series of weighting devices weights one of the outputs of the branching means, and a series of second weighting devices equal to or fewer in number than the first weighting devices weights the remaining output of the branching means. Combining elements equal in number to the first weighting devices combine two or three inputs, and delaying means fewer in number than the combining elements are interconnected with the combining elements in a sequential, alternating manner. The outputs of the first weighting devices are respectively applied to the combining elements while those of the second weighting devices are respectively applied to selected ones of the combining elements. The invention provides a construction where the number of taps of the equalizer may be easily increased without creating the necessity of combining circuits having an increased number of inputs.

Abstract: A method and apparatus for synchronizing a digital data signal from a first location, such as a digital telephone station, and which is transmitted to a second location, such as the station interface of a telephone switching system common equipment input, with a digital data signal at the second location, is disclosed. The method includes transmitting a data signal to the second location from the first location, receiving the data signal at the second location and determining if the data signal is present at a selected time. Digital coded data is sent to the first location from the second location for selecting successive delay times at the first location. When the delayed data signal is present at the second location at the selected time, the optimum value of the delay time is determined at the second location, preferably by averaging the values of the delay times at which the data signal was first detected and last detected at the second location.

Abstract: A FM signal demodulating apparatus with a timing pulse generator with a fixed periodic interval, a pulse deletion gate circuit whose pulse deletion ratio in a train of successive timing pulses being set in the range of 0.4 to 0.16, a edge pulse generator, a deletion delay circuit which delays edge pulses, a first counter, a second counter, a detection gate circuit, a first flip flop circuit, a second flip flop circuit and a gate circuit which receives output from the first flip flop circuit and output from the edge pulse generator, the gate circuit detecting the state in which said second counter contains all "1's" or said second counter contains all "0's".

Abstract: The input digital signal is applied to a transition detector which causes an up/down counter to increment or decrement each time a transition is detected. The output of the counter is utilized to address a read only memory (ROM) which, in turn, generates binary words representing first and second integers. These binary words are used to control a programmable divider to generate an output having a frequency which moves between two values corresponding to the digital input. The rate at which the frequency changes between the two values is controlled by the ROM contents. In the implementation, the frequency changes with a raised cosine shape.