Abstract: A coding process, given a total number of available bits per unit time, allocates to each of a plurality of signal channels a number of bits proportional to information in the channel. The process is useful for transcoding BCPCM (Block Coded PCM) voice signals for lower bit rate and conserving transmission channel bandwidth.

Abstract: An adaptive phase detection method and apparatus is described which provides an estimated value .phi..sub.n of the phase .phi..sub.n transmitted at a signalling instant nT in a data transmission system using a M-phase PSK modulation technique. The system compensates for the effects of the intersymbol interference created by not more than one leading lobe of a succeeding signal and an arbitrary number of trailing lobes of preceding signals caused by the impulse response of the transmission channel. The method of the present invention mainly comprises the steps of:Determining at least two residual errors, each of which is obtained by subtracting from the phase .psi..sub.n received at signalling instant nT the sum of one of the possible values which can be taken on by the transmitted signal at each signalling instant, i.e.

Abstract: This invention relates to a new clock synchronizing arrangement for use in the receiving device of a data transmission system employing PSK modulation.In PSK systems, the received signal x(t), for a given carrier angular frequency .omega..sub.c can be defined by its envelope and its phase r (t) and .phi.(t), respectively. r(t) and .phi.(t) can be expressed by:r(t) =.sqroot.x.sup.2 (t) + x.sup.2 (t) and .phi.(t) = arctan x(t)/x(t)where x(t) is the Hilbert Transform of x(t).At the optimum signalling instant t.sub.opt, r(t.sub.opt) and .phi.(t.sub.opt) normalized (without the data) exhibit the minimum variance. The clock adjustment signal is derived from the variance of the envelope or the variance of the phase of the received signal.

Abstract: A method and circuit for finding the beginning of valid coded information from a scanner reading a label such as the Universal Product Code (UPC) label establishes a plurality of counting gates based on a predetermined sequence of discrete signal transitions and counts a plurality of related pulse frequencies during the gating periods under control of the established counting gates. The accumulated counts are compared in a predetermined sequence to determine whether selected counts when compared bear a predetermined relationship to each other and a code generated indicative of the relationship which indicates the beginning of valid label data or invalid label data on a continuous basis.

Abstract: A circuit for filtering positive and negative glitches (i.e., dropouts and noise spikes) in a pulse-like signal to be processed, utilizes a single timing element which introduces a uniform delay in both the leading and trailing edges of the pulse-like signal, thus eliminating pulse-width distortion of the signal. A single adjustment may be made which has the same effect on both the leading and trailing edges making a uniform adjustment of both delays easily achieved.

Abstract: A new adaptive digital tuning filter for tracking a sinusoidal signal within a frequency band is described. The input signal representative of both said sinusoidal signal and noise is fed to a Hilbert transformer which provides the in-phase and quadrature components, x.sub.k and x.sub.k, respectively, of said sinusoidal signal. These components are applied to the input of a filter having a transfer function K where ##EQU1## WHERE .phi. = 2.pi.FT, f is the tuned frequency of the filter,T is the signal sampling period and a is a constant close to unity.The output signals y.sub.x and y.sub.x of the filter are applied to a computing means which provides a frequency control signal e.sub.k such thate.sub.k = x.sub.k y.sub.k - y.sub.k x.sub.kThe above value of .phi. is adjusted through a conventional gradient method where.phi..sub.k + 1 = .phi..sub.k + .mu.e.sub.kand controls are provided to adjust .phi. in a direction to change e.sub.k toward zero.

Abstract: The test circuit disconnects the active elements of the coupler from the input and output and applies a test signal to the input of the active elements. The output of the active elements is first compared with a first threshold which if exceeded or equaled provides a first indication. Within a predetermined time period the output of the active elements is compared with a second threshold to determine if the control function of the active element has reduced the input to the second threshold within the time period. If this condition prevails, the indication previously provided is removed; otherwise, the indication remains and a faulty coupler is indicated.

Abstract: This invention concerns a carrier synchronization system for a four-phase coherent PSK demodulator. The four-phase PSK signal is demodulated by an in-phase reference carrier and a quadrature reference carrier both of which are locally generated by a reference carrier source. The in-phase and quadrature components of the four-phase PSK signal that result from these demodulation operations are delayed a time interval substantially equal to T/2 seconds, T being the signaling period. The product of the delayed in-phase component and the sign of the quadrature component is compared with the product of the delayed quadrature component and the sign of the in-phase component, to produce a phase error signal. This error signal is used to control the adjustment of the reference carrier source.

Abstract: A control language using conventional text characters and a unique command and instruction delimiter whereby the commands and instructions which use conventional text characters may be detected and presented to a utilization device is shown. The control language facilitates the transmission of commands and instructions through existing data communication networks without alterations thereto. In addition, a structure suitable for scanning coded signals, detecting the unique delimiter and providing an indicia of commands and instructions is shown.

Abstract: In a receiver for PSK modulated signals, carrier phase tracking is achieved by a feedback loop comprising a phase error predictor. Means are provided for adaptively setting the gain factor in the phase error predictor to an optimum value, in response to successive residual phase errors.

Abstract: The invention provides a carrier detector for use in a multipoint communication system. In these systems a common communication link interconnects a master modem to a plurality of remote slave modems and a slave modem has to initialize itself without disturbing transmission of data between the master modem and another slave modem. Initialization is to be performed on such data, and the slave modem must be provided with a detector capable of detecting when data is being transmitted. The invention describes such a detector which is independent of the received signal power.The input signal is sampled at rate 6/T, T being the baud rate, and passed into two narrow band filters F1 and F2, centered at Nyquist frequencies f.sub.1 and f.sub.2, respectively.The sum of the outputs from filters F1 and F2 is sampled at a rate of 1/T for each of six different phases of the sampling rate 1/T. The energy of the six samples so obtained is measured.

Abstract: A method and circuit for decoding coded electric signals from a scanner reading a coded label such as the Universal Product Code (UPC) label, establishes a plurality of counting gates based on a predetermined sequence of discrete signal transitions and counts a plurality of related pulse frequencies during the gating periods under control of the established counting gates. The counts are compared in a predetermined sequence to determine the relationship between their magnitudes (e.g., A < B; A > B) and a coded signal generated indicative of the relationship. The said coded signals indicate the value of the coded information.

Abstract: This invention comprises a telephone hybrid circuit having two opto-coupler arrangements for transferring voice signals from the two-wire line to a port of the switching system on one hand and from a port of the switching system to the two-wire line on the other hand. In addition, a pair of feeder circuits in the form of current sources comprising active elements are provided for feeding a constant positive direct current to one wire of the two-wire line and a negative direct current of equal magnitude to the other wire of the two-wire line. Each of the current sources includes control circuitry for maintaining a constant ratio between the current furnished by the current source and a control current common to both current sources. A control current path is connected to the output of one of the opto-coupler arrangements for generating a common control current in response to a dc signal and a superimposed voice signal received from a port of the switching system.

Abstract: A method and structure for converting a sequence of binary digits into a sequence of discrete signal values, e.g., phase values, of a modulated carrier signal for data transmission. By introducing additional redundant signal values and coding information in a state-dependent sequential manner, enlarged minimum Euclidian distance between possible signal value sequences is achieved which results in a reduced error probability when maximum-likelihood decoding is applied in the receiver.

Abstract: An ink jet copier is provided with a document scanner which scans a document to be copied one line at a time producing non-coded binary data. The binary data is inserted in storage in a predetermined arrangement. Stored data is removed from selected predetermined locations in accordance with an algorithm and applied to a plurality of ink jet nozzles arranged in multiple linear arrays about the circumference of a rotating paper drum. The data signals selectively applied to the ink jet printers control the deposition of ink on the paper supported on the rotating drum to cause the reproduction of the original scanned image on a predetermined interlaced basis.

Abstract: A method for accessing and storing data in randomly assigned storage locations in a memory associated with a processor under the control of external circuits connected to the processor I/O bus, said external circuits being provided with registers for storing several assigned addresses in the memory which contain the starting addresses in the memory of a control list stored in a plurality of sequential addresses and five or more storage areas, each including a plurality of contiguous storage locations and further provision being made within the said processor for incrementing the addresses stored in the said assigned addresses each time they are accessed for performing a reading or writing operation in the memory location designated therein.

Abstract: An ink jet copier is provided with a document scanner which scans a document to be copied one line at a time producing non-coded binary data. The binary data is inserted in storage in a predetermined arrangement. Stored data is removed from selected predetermined locations in accordance with an algorithm and applied to a plurality of ink jet nozzles arranged in multiple linear arrays about the circumference of a rotating paper drum. The data signals selectively applied to the ink jet printers control the deposition of ink on the paper supported on the rotating drum to cause the reproduction of the original scanned image on a predetermined interlaced basis.

Abstract: A pair of detectors provide signals coincident with the circumferential and axial edges of a print medium mounted on a rotating media support drum. These signals are used to control counters which respond to an emitter circumferentially disposed with respect to the drum to generate a preset or offset signal value and a gate signal to accommodate axial and circumferential misalignment of the print medium on the drum.

Abstract: A companded digital delta modulator which can encode both voice and voice band modem signals over a wide range of input levels is shown. The companding method or algorithm is based on measuring bit stream correlation and can be scaled to give substantially maximum performance over a wide range of signal types. The algorithm has a low sensitivity to digital channel errors, thus making it suitable for signal coding for satellite channels and the like. In addition, the digital design permits common hardware to simultaneously serve a large number of lines, thus permitting the substantial savings in the hardware cost per line. A further aspect of the invention concerns the ability to handle multiple bit delta modulation as well as single bit delta bit modulation in the above environment.

Abstract: An ink jet copier is provided with a document scanner which scans a document to be copied one line at a time producing non-coded binary data. The binary data is inserted in storage in a predetermined arrangement. Stored data is removed from selected predetermined locations in accordance with an algorithm and applied to a plurality of ink jet nozzles arranged in multiple linear arrays about the circumference of a rotating paper drum. The data signals selectively applied to the ink jet printers control the deposition of ink on the paper supported on the rotating drum to cause the reproduction of the original scanned image on a predetermined interlaced basis.