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Showing papers on "Digital signal published in 1969"


Book
01 Jan 1969

612 citations


Patent
30 Jul 1969
TL;DR: In this paper, the authors proposed a digital FSK/PSK detector for moderate data rates including at least 1200 bits per second and is capable of operating over switching networks, which consists of a binary amplitude quantizer, a clock, a digital time quantizer and a digital delay coacting with an Exclusive-OR circuit for detecting the digital data signal from the frequency shift keyed modulation signal.
Abstract: The digital FSK/PSK detector demodulates digital data from a frequency shift keyed modulation signal (FSK) or a phase shift keyed modulation signal (PSK) for moderate data rates including at least 1200 bits per second and is capable of operating over switching networks. The digital FSK/PSK detector comprises a binary amplitude quantizer, a clock, a digital time quantizer, a digital delay coacting with an Exclusive-OR circuit for detecting the digital data signal from the FSK/PSK modulated signal and a digital filter and smoothing circuit for eliminating undesirable noise from the digital data signal.

37 citations


Patent
21 Apr 1969
TL;DR: In this paper, an adaptive data shift register is used to store received data bits and cross-correlate these with the signal being received to obtain the impulse response of the transmission channel to provide compensation therefor, where residual distortion is detected by comparison of the sampling of the received signal after compensation and the signal for the most recent data bit to provide a residual signal.
Abstract: An adaptive-type system which provides improved arrangements for correction of distortion of digital data sent over a transmission channel. The system includes a data shift register which stores received data bits and cross-correlates these with the signal being received to thereby obtain the impulse response of the transmission channel to provide compensation therefor. Crosscorrelation networks produce a correction signal for compensation by digitally multiplying each of the n most recently received data bits by any residual distortion remaining in a sampling of the received signal after compensation and integrating the respective products. Residual distortion is detected by comparison of the sampling of the received signal after compensation and the signal for the most recent data bit to provide a residual signal. This residual signal is applied to the correlation circuits to produce a final correction signal which eliminates any distortion causing errors in transmission of the digital data. Another embodiment of the invention also compensates for cross-channel distortion arising in a quadrature modulation system.

32 citations


Patent
16 Sep 1969
TL;DR: In this paper, the decoding logic in the other transceiver must recognize both an acceptable digital word and the complement of that word before machine operations will be ordered or initiated, so that unsafe machine operation may result from distorted digital code words representing commands or conditions.
Abstract: For reducing the possibility that unsafe machine operation may result from distorted digital code words representing commands or conditions, a communications system in which both the machine and a central control unit include transceivers which repetitively transmit a digital word sequence consisting of a digital word and its complement. Decoder logic in the other transceiver must recognize both an acceptable digital word and the complement of that word before machine operations will be ordered or initiated.

23 citations


Patent
01 May 1969
TL;DR: In this paper, a circuit for multiplying a known digital signal by a variable multiplying factor for use in correcting actual fluid volume measurements to a standard volume is presented, where a digital pulse generator cooperating with the digitizing circuit generates at least a pair of time-spaced digital signals and a multiplying circuit receives the discrete series of digital signals.
Abstract: This application discloses a circuit for multiplying a known digital signal by a variable multiplying factor for use in correcting actual fluid volume measurements to a standard volume. In one exemplar embodiment, a digitizing circuit generates a discrete series of digital signals proportional to the variable multiplying factor, a digital pulse generator cooperating with the digitizing circuit generates at least a pair of time-spaced digital signals and a multiplying circuit receives the discrete series of digital signals and the pair of time-spaced digital signals and provides a product of the discrete series of digital signals and the known digital signal.

21 citations


Patent
Roger F Salava1
16 Apr 1969
TL;DR: In this article, a shift register in a receiving unit uses a feedback to develop a digital code and the digital code is compared with an incoming digital code used to synchronize a digital communication signal.
Abstract: A shift register in a receiving unit uses a feedback to develop a digital code and the digital code is compared with an incoming digital code used to synchronize a digital communication signal. Initially the shift register is fed the incoming digital code signal. If the received and generated signals are in agreement an output signal is added in an integrator for each agreement. If the signals do not agree the output signal is subtracted from the signal stored in the integrator. When the signal stored in the integrator reaches a predetermined level a switching action occurs which connects the feedback output of the shift register to the input of the shift register so that the code is selfgenerating and errors in the incoming code will not be coupled into the shift register.

17 citations


Patent
03 Mar 1969
TL;DR: In this article, a scanner focuses a beam of radiant energy, in the order of one micron diameter, and this beam is scanned over a graphic representation, such as a photographic negative or film positive.
Abstract: A scanner focuses a beam of radiant energy, in the order of one micron diameter, and this beam is scanned over a graphic representation, such as a photographic negative or film positive. The amount of radiant energy passing through the graphic representation varies with the density of the image at any given spot and is sensed by a transducer. This variable signal is converted to a digital signal which is recorded at regular intervals. The scanning movement and the recording frequency are both clocked from a crystal controlled oscillator, resulting in a precisely controlled digital signal output which is recorded for subsequent reproduction of the image represented.

16 citations


Patent
Max R Cannon1
24 Nov 1969
TL;DR: In this paper, a digital slow scan video conversion method and system for wide band composite video signals generated by a television camera including an encoder with sampling means to progressively sample instantaneous amplitudes of the video signal, and a digital timer generates digital timing pulses quantitized in time in discrete steps relative to the wide band signal frequency.
Abstract: A digital slow scan video conversion method and system for wide band composite video signals generated by a television camera including an encoder with sampling means to progressively sample instantaneous amplitudes of the video signal, and a digital timer generates digital timing pulses quantitized in time in discrete steps relative to the wide band signal frequency to regulate the sampling for producing digital sampling pulses which form a narrow band signal that may be recorded on magnetic tape or transmitted over lines such as telephone lines. A decoder includes a disc-type storage medium storing or recording the digital sampling pulses in series, and a second digital timer generates digital timing pulses to regulate sequence and position of storage of the sampling pulses so as to gradually assemble the sampling pulses in the proper relation over a longer time interval for subsequent readout. Pulse width modulation of the narrow band video signal prior to storage improves the image detail, and pulse code modulation prior to storage provides for a totally digital form of video conversion to afford accurate timing between sampling and reproducing positions of the sampling pulses.

14 citations


Patent
17 Mar 1969
TL;DR: In this article, a digital differential angle demodulator for high bit rate digital data transmission system utilizing randomly selected voice grade telephone lines is disclosed, where a clock signal from an information-representing phase shifted intermediate frequency modulated signal is employed to synchronously gate a high frequency counter output into a detector circuit.
Abstract: A digital differential angle demodulator for use in a high bit rate digital data transmission system utilizing randomly selected voice grade telephone lines is disclosed The demodulator derives a clock signal from an information-representing phase shifted intermediate frequency modulated signal This clock signal is employed to synchronously gate a high frequency counter output into a detector circuit which samples a precise portion of an intermediate frequency signal containing the phase shift information to be ascertained The high speed counter is phase locked to the intermediate frequency carrier so that the zero crossing of the squared intermediate frequency signal will occur at an odd multiple of 225* in the phase value of the output of the binary counter Two separate storage registers in the detector circuit receive the most significant bits of successive counter output values depending upon the phase sampled from the precise portion of the information-containing signal A parallel adder determines the difference between successive counts, each count of which is characteristic of the information-representing phase change originally received during the interval in question Phase locking of the high speed counter assures that random phase changes caused by system noise will not adversely affect the detection operation An encoder converts the phase change signal as emitted by the parallel adder back to its original digital data level format

13 citations


Book
01 Jan 1969

10 citations


Patent
21 Jan 1969
TL;DR: In this article, a plurality of channels, one channel for each phase of the multiphase clock source, are jointly responsive to the incoming digital signal and to any one of the phases to actuate the channel to an active condition.
Abstract: An incoming digital signal having a pulse repetitive frequency within a given range of frequencies is compared with multiplephase clock signals, all within such given range of frequencies. In the receiver, a plurality of channels, one channel for each phase of the multiphase clock source, are jointly responsive to the incoming digital signal and to any one of the phases to actuate the channel to an active condition and simultaneously inhibit all other channels from being jointly responsive to such digital signal and respective clock phase. Upon completion of receipt of a predetermined number of digital signals, the receiver is reset to again permit any channel to be jointly responsive to an incoming digital signal and any clock phase for actuating a channel. Detection of incoming digital signals by a channel in an active condition includes comparing the incoming digital signal with a clock phase other than the clock phase used to activate the channel. Such other clock phase is selected on the basis of a change of signal state of the incoming digital signal. The resultant detected signal is then supplied to a data processing circuit.

Patent
Brian H Claxton1
16 Jun 1969
TL;DR: In this article, a data signal and a timing signal are combined and transmitted over a single pair of wires to an apparatus for separating data signals and timing signals from the combined signal.
Abstract: A data signal and a timing signal are combined and transmitted over a single pair of wires to apparatus for separating data signals and timing signals from the combined signal. The apparatus for separating data signals and timing signals from a combined signal has means for differentiating and rectifying the combined signal. The rectified signal applied to a one-shot causes the one-shot to produce a timing signal identical to the original timing signal. The timing signal and the combined signal applied to a flip-flop causes the flip-flop to produce a data signal identical to the original data signal.

Patent
Keizo Nakayama1, Yutaka Ohno1
29 Jan 1969
TL;DR: In this paper, a carrier pilot relaying system in which the current flowing through the power transmission line in each electrical station is detected by a current transformer to be converted into a phase signal and a digital signal representing the magnitude (scalar quantity) of the current, these signals being transmitted from one station to another station in the form of a train of pulse signals.
Abstract: A carrier pilot relaying system in which the current flowing through the power transmission line in each electrical station is detected by a current transformer to be converted into a phase signal and a digital signal representing the magnitude (scalar quantity) of the current, these signals being transmitted from one station to another station in the form of a train of pulse signals. In each station, detection of the phase difference between the phase signals and detection of the difference between the magnitude of the currents are carried out independently of each other so that a circuit breaker can be tripped when a predetermined condition is satisfied.

Patent
21 Jan 1969
TL;DR: In this article, the authors describe a line scan signal generator with a comparator that compares the timing signal with the reference signal and, when the two are in phase, provides a signal to enable a first gate to pass a synchronizing signal from a counter to a vertical or frame scanning generator to synchronize the same.
Abstract: A continuously moving film has recorded thereon a succession of frames and a timing track adapted when scanned to produce a timing signal periodically varying at a frequency in fixed relation to the horizontal line scanning frequency and of one phase during part of each frame scan and of the opposite phase during a succeeding part of the frame scan. The timing signal is converted to a signal at the line scanning rate which is used to synchronize a line scan signal generator and from which is derived a reference signal at the timing signal frequency and of fixed phase. A comparator compares the timing signal with the reference signal and, when the two are in phase, provides a signal to enable a first gate to pass a synchronizing signal from a counter to a vertical or frame scanning generator to synchronize the same. The synchronizing signal also initiates a flip-flop which disables the first gate and jointly with the comparator enables a second gate a predetermined number of scanning lines after occurrence of the synchronizing signal to pass a signal from the counter to reverse the phase of the reference signal. For interlaced scan, there is recorded in the timing track a signal which effects a half line (90*) delay in the timing signal at the beginning of each film frame.

Patent
29 Oct 1969
TL;DR: In this paper, a closed-loop system with a binary shift register and a pair of accumulator registers is described. But the binary register is not used for the generation of digital signals.
Abstract: Digital signals are generated representative of successive positions on a sinusoidal curve by means of a pair of accumulator registers and a pair of binary shift registers with the registers being alternately positioned and serially connected in a closedloop system and activated by a split-phase clock so that each accumulator register alternately receives an incremental number from one of the adjacent shift registers representing the number in the other accumulator register multiplied by a predetermined factor. The output of one of the accumulator registers defines a new positional signal at each clock pulse which order can then be processed to provide a corresponding digital velocity signal.

Patent
08 Jul 1969
TL;DR: In this paper, a first and second state pulse trains respectively corresponding to one of the binary states of the digital signal were utilized and the output pulse trains of the asynchronous digital signal are represented by corresponding mode pulse trains in respective time slots.
Abstract: In transmitting a digital signal, e.g. a digital signal on a PCM transmission line which is asynchronous with a clock signal, a first and a second state pulse trains respectively corresponding to one of the binary states of the digital signal are utilized and the output pulse trains of the asynchronous digital signal are represented by corresponding mode pulse trains in respective time slots. When the state of the pulse train of the asynchronous digital signal changes an indicating pulse representing the time of transition of the state of the asynchronous digital signal is inserted in a time slot following the time slot in which the state has changed. On the receiving terminal the mode pulse trains are constructed by utilizing the framing pulse as the reference signal.

Patent
12 Nov 1969
TL;DR: In this article, a gated logic circuit is used as an antijitter circuit in a transponder system with a delay line chain having multiple signal connections from various locations before, between, and after at least three serially connected shift register units of the delay line.
Abstract: Gated logic circuit used as an antijitter circuit in a transponder system with a delay line chain having multiple signal connections from various locations before, between, and after at least three serially connected shift register units of the delay line. The logic circuitry is arranged to gate an output coincident with the leading edge of the second pulse of a twopulse input, however, should a predetermined signal not have been developed within the logic circuitry prior to appearance of the leading edge of the second input signal pulse, the appearance thereof immediately initiates an inhibit signal through logic circuitry preventing the development of a decoder trigger output for that signal cycle.

Patent
James W Conley1
30 Jul 1969
TL;DR: In this paper, an asynchronous analog to logic level signal converter is described, which consists of a first differential amplifier with means for integrating an input analog signal and applying the integrand signal to a second differential amplifier to produce a logic level output signal having a period, T1, inversely proportional to the amplitude of the input signal.
Abstract: An asynchronous analog to logic level signal converter is described as comprising a first differential amplifier with means for integrating an input analog signal and applying the integrand signal to a second differential amplifier to produce a logic level output signal having a period, T1, inversely proportional to the amplitude of the input signal. A reference signal controllably applied to the other differential inputs of the first and second differential amplifiers produces a changed logic level having a period, T2, inversely proportional to the difference in amplitudes between the reference signal and the input signal. The amplitude of the input analog signal is obtained by computing the product of the reference voltage and the ratio of T2 to T1 plus T2.

Patent
06 Oct 1969
TL;DR: In this article, the analog output signals from the converter are connected as inputs to a position measuring device to trigonometrically define the position between two members of the position measuring devices.
Abstract: Digital and analog converter method and apparatus for generating trigonometrically related signals suitable for use with position measuring and position controlling systems. Two or more converter analog output signals are formed as a function of the digital input. The digital input generates a digital count difference between the counts in two digital counters. The two counters are both stepped by synchronously derived stepping pulses to produce counter output signals, exhibiting a phase difference proportional to the digital count difference. The counter output signals are logically combined to form analog output signals. Those analog output signals are pulse-width modulated rectangular waveforms which each include a fundamental sinusoidal frequency component having an amplitude proportional to a trigonometric function of the digital input. The analog output signals from the converter are typically connected as inputs to a position measuring device to trigonometrically define the position between two members of the position measuring device. The position measuring device is typically an transducer or other data element which responsively forms an analog output signal having a magnitude which indicates the relative position of the two members. The analog output signal is typically converted to a digital signal, in the form of a train of pulses, where each pulse represents an incremental distance. That digital signal, derived from the analog output signal, is typically supplied as an input to the converter which converts the digital input to the analog output, thereby forming a closed loop system.

Patent
Duane E Mcintosh1
30 Jun 1969
TL;DR: In this article, a system is presented for broadcasting a TRANSMITTED SIGNAL with an alternate UPPER and LOWER VOLTAGE levels from a RECEIVED Signal this article.
Abstract: A SYSTEM IS PROVIDED FOR REPRODUCING A TRANSMITTED SIGNAL HAVING ALTERNATE UPPER AND LOWER VOLTAGE LEVELS FROM A RECEIVED SIGNAL REPRESENTING THE TRANSMITTED SIGNAL CONTAMINATED WITH HIGH AND LOW FREQUENCY NOISE. A REFERENCE SIGNAL IS DEVELOPED HAVING A VOLTAGE LEVEL WHICH IS NOMINALLY MIDWAY BETWEEN THE UPPER AND LOWER VOLTAGE LEVELS OF THE TRANSMITTED SIGNAL, AND WHICH IS SHIFTED IN RESPONSE TO THE LOW FREQUENCY NOISE WITHIN THE RECEIVED SIGNAL. A LOCAL SIGNAL IS PRODUCED HAVING THE UPPER VOLTAGE LEVEL WHEN THE VOLTAGE LEVEL OF THE RECEIVED SIGNAL IS ABOVE THE VOLTAGE LEVEL OF THE REFERENCE SIGNAL, AND HAVING THE LOWER VOLTAGE LEVEL WHEN THE VOLTAGE LEVEL OF THE RECEIVED SIGNAL IS BELOW THE VOLTAGE LEVEL OF THE REFERENCE SIGNAL. THE LOCAL SIGNAL DUPLICATES THE TRANSMITTED SIGNAL.

Patent
31 Jul 1969
TL;DR: In this article, the operation of an electronic circuit is checked by prerecorded waveforms that are converted into electrical signals, and a reject indicator, which includes switching circuitry operatively responsive to the check signals and the output from the circuit being tested, is energized to indicate when a circuit does not perform to certain operational specifications.
Abstract: The operation of an electronic circuit is checked by prerecorded waveforms that are converted into electrical signals. One of the electrical signals resulting from the processing of the prerecorded waveforms is connected to the input terminal of the circuit being checked. Another of the prerecorded waveforms is processed into a check signal and subsequently characterized into individual synchronizing pulses. A reject indicator, which includes switching circuitry operatively responsive to the check signals and the output from the circuit being tested, is energized to indicate when a circuit does not perform to certain operational specifications.

Patent
09 Jun 1969
TL;DR: In this article, an apparatus and process is provided for controlling delay devices in antenna elements of antenna arrays for controlling the direction of propagation of electromagnetic radiation. But the delay devices are arranged in sequential relation and are successively operated by a clock.
Abstract: According to the present disclosure, apparatus and process is provided for controlling delay devices in antenna elements of antenna arrays for controlling the direction of propagation of electromagnetic radiation. An analog signal is developed from a digital signal and operates on a first control device in a predetermined manner. The analog signal is subsequently altered, as by altering the digital signal in a binary adder, and the altered analog signal operates on the next control device. The control devices are arranged in sequential relation and are successively operated by a clock.

Patent
17 Nov 1969
TL;DR: In this paper, the frequency components of the laser emission are spatially separated inside the generator cavity, and each component is separately pulse-code modulated according to a digital input signal.
Abstract: A laser generator for producing a single laser beam carrying several channels of digital information simultaneously is disclosed. The frequency components of the laser emission are spatially separated inside the generator cavity, and each component is separately pulse-code modulated according to a digital input signal. A simple receiver is also disclosed.

Patent
27 Feb 1969
TL;DR: In this paper, a data terminal consisting of readily portable components is adapted to be interconnected by voice grade telephone lines to a remotely located computer or other data processing equipment, where the data terminal comprises data input means (e.g., a magnetic tape reader or a manually operated keyboard) for generating a coded digital signal, a data set for converting the digital signal of the data input mean to a coded modulated signal that can be transmitted over a telephone line and for converting a modulated message received from said telephone line into coded digital signals, and translator means for converting digital signals received
Abstract: A data terminal comprising readily portable components is adapted to be interconnected by voice grade telephone lines to a remotely located computer or other data processing equipment. The data terminal comprises data input means (e.g., a magnetic tape reader or a manually operated keyboard) for generating a coded digital signal, a data set for converting the digital signal of the data input means to a coded modulated signal that can be transmitted over a telephone line and for converting a modulated signal received from said telephone line into a coded digital signal, and translator means for converting digital signals received from the data input means and from the data set into coded electrical signals capable of operating a data printout device (e.g., a paper tape printer or an electric typewriter).

Patent
Jack T Murray1
27 Jun 1969
TL;DR: In this article, the authors present a method for the analysis of the frequency shifted signal by sampling contiguous epochs of the signal, converting the sampled signal to a digital representation, storing the digital signal in a buffer, reading the stored digital signal a number of times at different reading rates to effect multiple frequency multiplications, and passing the different analog signals through a fixed band-pass filter detector.
Abstract: Contiguous frequency domain analysis of signals is achieved by sampling contiguous epochs of the signal; converting the sampled signal to a digital representation; storing the digital signal in a buffer; reading the stored digital signal a number of times at different reading rates to effect multiple frequency multiplications; converting the different digital signals red read analog equivalents; and passing the different analog signals through a fixed band-pass filter detector to effect an accelerated analysis of the frequency shifted signal.

Patent
22 Oct 1969
TL;DR: In this article, an electrical-signal synthesizer for converting digitally coded information associated with at least one electrical signal, whose frequency, amplitude or phase may vary, to analog signals whose frequency or amplitude varies in substantially the same manner as that of the first electrical signal.
Abstract: Disclosed is an electrical-signal synthesizer for converting digitally coded information associated with at least one electrical signal, whose frequency, amplitude or phase may vary, to analog signals whose frequency, amplitude or phase varies in substantially the same manner as that of the at least one electrical signal. More specifically, the synthesizer is operative to convert a digital signal representative of a first analog signal, such as a voice signal, having varying parameters, such as frequency or amplitude, into an analog output signal which varies in substantially the same manner as the first signal, and where the digital signal is composed of consecutive frames of words, and one word of each frame is representative of a fundamental frequency associated with the first signal at an instant of time, and successive words in the respective frame are representative of the energy associated with at least one of a plurality of successive bands or spectrum segments of the first signal to be reproduced, at the given instant in time, each of the successive bands bearing a predetermined frequency relationship and wherein the synthesis of the output signal is accomplished by generating from the word representative of the fundamental frequency in each respective frame, a stream of digital words representative of the frequency and each of its harmonics at each instant of time and producing therefrom a second stream of digital words which is indicative of the frequency components of the original sound and modulating the second stream with amplitude data corresponding to discrete periods of time and adding the respective digital signals so produced for a discrete period of time and converting the same to an analog signal which is representative of the original voice signal.

Patent
28 Apr 1969
TL;DR: In this paper, a signal generator capable of generating triangular and sine functions in a bipolar mode is described, where the combination of a counter, adder and accumulator register make up a computing unit which is controlled by timing pulses added accumulatively.
Abstract: A signal generator capable of generating triangular and sine functions in a bipolar mode. The combination of a counter, adder and accumulator register make up a computing unit which is controlled by timing pulses added accumulatively. When an accumulator register fills, the overflow pulses are accumulated in another register. By combining the outputs of the various registers, the desired functions are produced.

Patent
29 Oct 1969
TL;DR: In this article, a television system for transmitting a video signal on a narrow-bandwidth base was proposed. But the video signal was not considered. And it was not shown that the video signals can be transmitted at a non-integral factor times the line rate of the video.
Abstract: A television system for transmitting a video signal on a narrow-bandwidth bases. A driven sampling-rate generator is responsive to the video signal for developing a control signal having a frequency equal to a non-integral factor times the line rate of the video signal. A sampling circuit is responsive to the control signal for producing a narrow-bandwidth transmission signal. A second sampling circuit located at the receiver derives a representative video signal from the narrow-bandwidth signal and synchronizes the representative signal with the control signal.

Patent
03 Mar 1969
TL;DR: In this article, the binary signals are integrated by the frequency characteristic of a transmission line of narrow bandwidth, and the transmission line converts the binary pulses to a multilevel signal and converts it to analog signals.
Abstract: Multilevel digital signals are converted to binary signals and are transmitted as such. The binary signals are integrated by the frequency characteristic of a transmission line of narrow bandwidth. The transmission line converts the binary pulses to a multilevel signal. The receiver receives the transmitted multilevel signal and converts it to analog signals.

Patent
27 Feb 1969
TL;DR: In this article, a recurrent signal consisting of pulses which can be identified in time is analyzed in order to extract the signal from the background noise; samples of a first pulse are taken at instants which are separated by predetermined time intervals and digitalized, the result is written in an addressable digital memory channel by a digital adder-subtracter, a zero level determined by sampling by the same sampling circuit at a selected instant is subtracted from the contents of each channel of the digital memory and the same sequence is carried on a large number of pulses that come later than the
Abstract: A recurrent signal consisting of pulses which can be identified in time is analyzed in order to extract the signal from the background noise; samples of a first pulse are taken at instants which are separated by predetermined time intervals Υ, and digitalized, the result is written in an addressable digital memory channel by a digital adder-subtracter, a zero level determined by sampling by the same sampling circuit at a selected instant is subtracted from the contents of each channel of the digital memory and the same sequence is carried on a large number of pulses which come later than the first pulse the samples being added in the digital memory channels. The successive samples of a same pulse are stored in a plurality of time delaying channels each having an analogue storage capacitor. A single lengthening channel may be used and an intermediate memory device fed by the coder stores the zero level and applies it to the input of the adder-subtracter.