Showing papers on "Encoder published in 1989"

Optimal pruning with applications to tree-structured source coding and modeling

Abstract: An algorithm introduced by L. Breiman et al. (1984) in the context of classification and regression trees is reinterpreted and extended to cover a variety of applications in source coding and modeling in which trees are involved. These include variable-rate and minimum-entropy tree-structured vector quantization, minimum expected cost decision trees, variable-order Markov modeling, optimum bit allocation, and computer graphics and image processing using quadtrees. A concentration on the first of these and a detailed analysis of variable-rate tree-structured vector quantization are provided. It is found that variable-rate tree-structured vector quantization outperforms not only the fixed-rate variety but also full-search vector quantization. The successive approximation character of variable-rate tree-structured vector quantization permits it to degrade gracefully if the rate is reduced at the encoder. This has applications to the problem of buffer overflow. >

Decoding of trellis-encoded signals in the presence of intersymbol interference and noise

Abstract: A novel receiver for data-transmission systems using trellis-coded modulation is investigated. It comprises a whitened-matched filter and a trellis decoder which combines the previously separated functions of equalization and trellis-coded modulation (TCM) decoding. TCM encoder, transmission channel, and whitened-matched filter are modeled by a single finite-state machine with combined intersymbol interference and code states. Using ISI-state truncation techniques and the set-partitioning principles inherent in TCM, a systematic method is then developed for reducing the state complexity of the corresponding ISI and code trellis. A modified branch metric is used for canceling those ISI terms which are not represented by the trellis states. The approach leads to a family of Viterbi decoders which offer a tradeoff between decoding complexity and performance. An adaptive version of the proposed receiver is discussed, and an efficient structure for reduced-state decoding is given. Simulation results are presented for channels with severe amplitude and phase distortion. It is shown that the proposed receiver achieves a significant gain in noise margin over a conventional receiver which uses separate linear equalization and TCM decoding. >

Model-based analysis synthesis image coding (MBASIC) system for a person's face

Abstract: The initial conception of a model-based analysis synthesis image coding (MBASIC) system is described and a construction method for a three-dimensional (3-D) facial model that includes synthesis methods for facial expressions is presented. The proposed MBASIC system is an image coding method that utilizes a 3-D model of the object which is to be reproduced. An input image is first analyzed and an output image using the 3-D model is then synthesized. A very low bit rate image transmission can be realized because the encoder sends only the required analysis parameters. Output images can be reconstructed without the noise corruption that reduces naturalness because the decoder synthesizes images from a similar 3-D model. In order to construct a 3-D model of a person's face, a method is developed which uses a 3-D wire frame face model. A full-face image is then projected onto this wire frame model. For the synthesis of facial expressions two different methods are proposed; a clip-and-paste method and a facial structure deformation method.

Signal identification system

Abstract: A signal identification system, suitable for producing an identification code on a sound track recording is described. The system includes an encoder 209 effective to eliminate a variable sequence of frequency bands from an audio signal and insert a sequence of code signals into the frequency bands. As the sequence of frequency bands varies throughout the sound track recording, the presence of the code is difficult to detect.

A receiver-compatible enhanced definition television system

Abstract: A television encoder for generating a receiver-compatible signal from a production video signal containing enhancement information which cannot be displayed on a standard receiver, the receiver-compatible signal being compatible with the standard receiver, the encoder including a filter bank for dividing the video signal into at least two groups of spatial frequency components including a first group and a second group, the first group containing members which when combined together form a standard video signal which is displayed by the standard receiver and the second group containing the enhancement information; a quantizer for quantizing at least one member of the first group; a combiner for adding at least one member of the second group to a quantized member of the first group to produce a modified first group; and a synthesizer for combining the members of the modified first group to generate the receiver-compatible signal.

Data compression with dynamically compiled dictionary

Abstract: A data compression system in which a dictionary stored strings of characters and an encoder matches the longest of the stored string with a current string of a data stream input to the encoder. The index of the longest matched stored string is output by the encoder and the dictionary is updated by a new string consisting of the previous match concatenated with the first two characters only of the present match. If the present match has only one or two characters, it is added without reduction.

Method and apparatus for adaptively superimposing bursts of texts over audio signals and decoder thereof

Abstract: An apparatus is disclosed for adaptively superimposing bursts of text over audio signals comprising an encoder and a decoder wherein said encoder comprises means for separating unencoded audio signals into discrete passbands; means for measuring power levels contained in each discrete passband; a time delay; a plurality of power level comparators; means for generating concatenated bursts of digital header, digital text and digital footer signals; a frequency modulator; a modulator output power adjusting means; means for combining time delayed unencoded audio signals with modulator output level; and, means for transmitting or recording resultant encoded sound signals; wherein said decoder comprise means for separating received encoded sound into discrete passbands; an FM demodulator; a text separator; a television modulator; and sound reproduction means.

Magnetic recording and/or reproducing apparatus

Abstract: OF THE DISCLOSURE In a system for recording digital data obtained based on an information signal on a magnetic tape and/or reproducing digital data obtained based on an information signal from a magnetic tape, a magnetic recording apparatus comprises an encoder for producing, based on the information signal, one of plural kinds of digital data which have different transmission rates respectively, a time base processor for selectively converting a time base of digital data obtained from the encoder so as to produce modified digital data having a predetermined transmission rate, a recording modulator for producing a recording signal corresponding to the modified digital data, a recording portion provided with a rotary magnetic head device to which the recording signal is supplied and a tape guide for guiding the magnetic tape and operative to cause the rotary magnetic head device to contact with the magnetic tape for forming oblique record tracks on the magnetic tape, a head driver for rotating the rotary magnetic head device at a predetermined speed of rotation, and a tape driving device for causing the magnetic tape to run at a speed corresponding to the transmission rate of the digital data obtained from the encoder.

An alternative approach to reduced-complexity CPM-receivers

Abstract: By separating the two complexity problems connected with optimum coherent CPM (continuous phase modulation) receivers, namely, the number of linear filters and the number of memory states required, a straightforward procedure for reducing the complexity is proposed and its usefulness is evaluated. A concise analysis of the inherent trellis encoder associated with CPM is given. It is then demonstrated that for almost all schemes of interest in practice, it is quite sufficient for the receiver to implement only four or six linear filters which represent proper reference signals. For a reduction in the number of memory states, decision-feedback sequence estimation together with minimization of the unprocessed intersymbol interference is proposed. Modifications of this procedure allow a state reduction without losses or with only negligible losses because only error events with large distances are affected. Combinations of these methods make possible an almost continuous tradeoff between receiver complexity and SNR (signal/noise ratio) losses. Several examples are considered for which evaluations of minimum Euclidean distances and simulation results are given. >

Remote-control security system and method of operating the same

Abstract: A security system has a remote-control unit, a receiving unit and an operating unit connected to the receiving unit and designed to perform a security function. The remote-control unit comprises a keyboard, an encoder and a transmitter. The encoder is programmed with an algorithm and a base code and, in response to consecutive actuations of the keyboard, operates consecutively with the algorithm, beginning from the base code, to generate a series of modified codes. The encoder also produces a corresponding series of encoded signals containing the base code and a respective modified code. The encoded signals are sent to the receiving unit by the transmitter. The receiving unit includes a receiver for the signals and a decoder which is activated in response to an incoming signal. The decoder is programmed with the same algorithm and base code as the encoder and, similarly to the encoder, generates a series of modified codes in response to consecutive incoming signals. After the decoder generates a modified code upon being activated by an incoming signal, the decoder compares its base code and modified code, respectively, with the base code and modified code of the signal. The decoder sends a control signal to the operating unit if and only if the two base codes are identical and the two modified codes are identical.

Image compression coding system

Abstract: An image coding apparatus includes an image dividing circuit for dividing an image signal of one frame into a plurality of blocks, an amount-of-data calculator for computing the amount of data representing fineness of a picture included each block, a bit-assignment determining circuit for distributing all coding bits usable for encoding the image signal of one frame to the individual blocks, to each block a number of bits which has been determined by the amount of data of the block, a quantizer for quantizing the image signal for each block and outputting a quantization signal, and an encoder for encoding the quantization signal in accordance with the number of bits of each block determined by the bit-assignment determining circuit.

Design of coded CPFSK modulation systems for bandwidth and energy efficiency

Abstract: Consideration is given to the problems related to the design of M-ary continuous-phase frequency-shift keying (CPFSK) systems with modulation index h=J/M, combined with eternal rate r binary convolution encoders. The following questions are raised and answered: (1) how should different encoder-modulator systems be compared and how can comparable systems be recognized from the system parameters, i.e. M, h, and r?; (2) what are the limits on the information rate per unit bandwidth, versus signal-to-noise ratio, when reliable transmission is required?; (3) how does one choose the system parameters M, h, and r when the overall system has to achieve a specified performance?; and (4) how does one design the external rate r binary convolutional encoder to put in front of the M-ary CPFSK modulation system with h=J/M? A simple approximation for the bandwidth of a CPFSK signal is given and shown to be sufficiently accurate for system design purposes. The design of the external convolutional encoder is carried out in a novel way that leads to fewer states in the combined encoder-modulator system and thus yields improved performance for a given demodulation-decoding complexity compared to previous approaches for the design of coded CPFSK systems. >

Data transmission and reception apparatus and method

Abstract: A data transmission and reception apparatus and method capable of selecting either of two modes having the same sampling frequency in which the bit numbers of one data unit are either m or n (which are integral numbers and m>n), while using the same error correction encoder and decoder for the two modes, by inserting m-n bits of dummy data bits into the n-bit data so as to handle it as m-bit data during the processes of error correction encoding and decoding.

Automatic assist for swing-door operator

Abstract: A manual power assist control employs a magnetic encoder which is mounted to a shaft of the door operator. The encoder generates pulse trains which are indicative of an attempt to open the door in a given direction. The pulses are processed to generate a signal for opening the doors in the event a manual attempt to open the doors is detected.

Multiterminal source encoding with encoder breakdown

Abstract: When separate encoders are assigned to each of two correlated sources, it is in general true that the rate sum required is less when decoding is done by a single decoder than when separate decoders are used. However, if either encoder breaks down, system performance ordinarily degrades severely in the single-decoder case when one tries to recover the sources based solely on the output of the remaining encoder. The authors determine the admissible rate region for this situation, which is related to the multiple description problem. Some of the implications of the general result are unintuitive. >

Fixed distortion subband coding of images for packet-switched networks

Abstract: A subband image codec is presented that approximately attains a user-prescribed fidelity by allowing the encoder's compression rate to vary. The fixed distortion subband coding (FDSBC) system is suitable for use with future of packet-switched networks. The codec's design is based on an algorithm that allocates distortion among the subbands to minimize channel entropy. By coupling this allocation procedure with judiciously selected subband quantizers, an elementary four-band codec was obtained. Additional four-band structures may be nested in a hierarchical configuration for improved performance. Each of the configurations tested attains mean square distortions within 2.0 dB of the user-specific value over a wide range of distortion for several standard test images. Rate versus mean-square distortion performance rivals that of fixed-rate systems having similar complexity. The encoder's output is formatted to take advantage of prioritized packet networks. Simulations show that FDSBC is robust with respect to packet loss and may be used effectively for progressive transmission applications. >

Absolute position detection encoder

Abstract: An absolute position detection encoder includes a coder having a track provided with first graduations of an absolute pattern and second graduations of an incremental pattern, plural sensors movable relative to the coder along the longitudinal direction of the track, and a signal processing circuit for processing detection pulse trains, obtained upon reading the first graduations by the sensors, in synchronism with the time point corresponding to approximately the mid position of the minimum reading unit of the first graduation. The encoder outputs the relative position between the coder and the sensors in the form of parallel code signals as the absolute position read out from the absolute pattern graduations on the coder. By detecting the absolute pattern in synchronism with the time point corresponding to substantially the middle of the minimum reading unit of the first graduations, an absolute position detection signal of the correct code contents free of readout errors may be taken out for both the forward and reverse directions of the relative movement. On account of the signal selection function by the binary repetitive rectangular signal obtained from the incremental pattern reading results, the absolute position detection signal of the correct code contents may be taken out simultaneously with turn-on of the power source. The binary repetitive rectangular signal may also be used for generating a sub-scale signal for substantially improving the resolving power.

Rotating seal with integrated magnetic encoder for a bearing with information sensors

Abstract: An encoder is mounted on a seal of a bearing having a fixed ring and a radially spaced rotating ring. The encoder ring has circumferentially separated teeth on one of its radial surfaces which embed into an elastomer portion of the seal.

Hierarchical vector quantisation

Abstract: We present a method of vector quantisation which trades off accuracy for speed of encoding. We achieve this by hierarchically structuring a multistage encoder so that each stage encodes low dimensional input vectors. Such hierarchical encoders may easily be realised as a set of fast table look-up operations. We demonstrate how the Euclidean distortion in such a multistage encoder is approximately minimised by using Kohonen's topographic mapping learning algorithm from neural network theory. We also demonstrate the performance of the technique on various stochastic time series. We find that there is little loss in encoding accuracy, when compared with the exact nearest neighbour encoding using an equivalent single stage encoder.

Satellite communications network

Abstract: A satellite communication network includes an encoder for encoding a signal including message, addressing, and command information and a transmitter connected with the encoder for transmitter the encoded signal to a satellite. The message information may comprise video and/or audio information. A plurality of receivers located at a remote location from the transmitter are operable to receive selected portions of the encoded signal from the satellite in response to the addressing information contained in the encoded signal. A decoder is connected with each receiver for decoding the received portion of the encoded signal. The decoder includes a control device which is operable to control peripheral recording devices including one or more video tape recorders and a printer to record the video information from the decoded signal in response to command information contained in the encoded signal. The satellite communications system according to the invention provides an automatic system for downlinking and recording programming during low usage times for subscribing television stations.

Data compression system and method with buffer control

Abstract: In a digital encoder, truncation is controlled by the fullness of the output rate-smoothing buffer A signal compression system is shown for processing a stream of fixed length digital sample signals, such as audio signals, which system includes a linear digital compression filter for compression filtering the sample signal stream and generating a stream of compression-filtered signals The compression-filtered stream is encoded by an encoder which implements a variable word length truncated code The encoder output is supplied to a buffer for transmission to a communication channel The encoder is controllably operable in a normal mode and in an out of range (OOR) mode In the OOR operating mode an OOR code word together with the compression filtered signal is sent to the buffer Buffer underflow is controlled by operation in the OOR mode when the buffer is empty or near empty Buffer overflow is controlled by truncating sample signals supplied to the compression filter in response to a measure of buffer fullness when the fullness of the buffer exceeds a predetermined level The level of truncation increases as buffer fullness increases With a decrease in buffer fullness, a measure of the rate of change of buffer fullness may be used to accelerate the decrease in truncation for improved audio signal quality Additionally, a measure of variance of the compression-filtered signal stream may be used in conjunction with control based upon a measure of buffer fullness in the control of truncation for improved audio signal quality

Method and apparatus for phase synthesis for speech processing

Abstract: A speech decoder apparatus for synthesizing a speech signal from a digitized speech bit stream of the type produced by processing speech with a speech encoder. The apparatus includes an analyzer for processing the digitized speech bit stream to generate an angular frequency and magnitude for each of a plurality of sinusoidal components representing the speech processed by the speech encoder, the analyzer generating the angular frequencies and magnitudes over a sequence of times; a random signal generator for generating a time sequence of random phase components; a phase synthesizer for generating a time sequence of synthesized phases for at least some of the sinusoidal components, the synthesized phases being generated from the angular frequencies and random phase components; and a synthesizer for synthesizing speech from the time sequences of angular frequencies, magnitudes, and synthesized phases.

Pcm data transmitting apparatus and method

Abstract: A data transmission and reception apparatus and method capable of selecting either of two modes having the same sampling frequency in which the bit number of one data unit are either m or n (which are integral numbers and m>n), while using the same error correction encoder and decoder for the two modes, by inserting m-n bits of dummy data bits into the n-bit data so as to handle it as m-bit data during the processes of error correction encoding and decoding and eliminating from the error correction encoded data the dummy data and a redundant code of the error correction code formed by the dummy data so that the data transmission rate can be lowered.

Subband decoding method and apparatus

Abstract: An subband coding system encoder is provided for improving the quality of a reconstructed speech signal Briefly, the improved subband coding system encoder includes means for improving the selection of the waveform/noise fill gain factor The improved selection method, according to the invention, is based on the quasi-stationary characteristic of speech, that is, that the short-time frequency spectrum of a speech signal varies slowly with time Moreover, the amount of fill energy is adaptively determined for each subband according to the shape of the frequency spectrum for each speech frame

High data rate BCH encoder

Abstract: An encoder for selected linear error correcting codes, such as a BCH code, uses relatively low-speed circuitry to generate parities for correcting the code. A parity matrix derived from the BCH generator matrix is provided as data to a generator vector whereby the generator vector is used as a logical shift function generator. When the logical shift function is applied to the rows of the parity matrix, columns of parity are shifted into an EXCLUSIVE-OR tree to produce the parity bit of the column. The parity bit of the column is then injected into a data stream forming the encoded symbol for transmission, attaching the parity word following the data word. The apparatus may be constructed making maximum use of the standard, commerically available, relatively low-cost integrated circuits, but it is nevertheless capable of operating at speeds in excess 1 GBPS.

Bit-serial VLSI implementation of vector quantizer for real-time image coding

Abstract: A practical high-throughput architecture and its implementation for real-time coding of television-quality signals are presented. The architecture is directed toward the implementation of multistage vector quantization (VQ), as the authors' simulation results show that the latter is more suitable for real-time coding. However, the implementation is suitable for both single-stage and multistage VQ. The functional blocks of the VQ encoder system have been designed and implemented in VLSI technology. The VQ encoding scheme designed has an encoding delay of 25 clock cycles and is independent of the codebook size. >

Multiplexed encoder and decoder with address mark generation/check and precompensation circuits

Abstract: A two-level multiplexed encoder/decoder based on a novel technique of code table compression is disclosed. By means of comparing various code conversion tables such as well-known tables for use in NRZ-MRM, NRZ-RLL conversion schemes, separate code word condition sets are obtained. In accordance with the code word condition sets thus obtained, a two-level multiplexed encode and decode logic can be easily constructed. The code word condition sets representing the compressed code relations are sensed in the first level and are used further to set up the operation of a connected network of a multiplexed logic circuit in the second level. The AM generation/check and precompensation circuit necessary for the encoder and decoder are incorporated as an integral part. This method is applicable when more than two code tables are needed to be integrated in a single encoder/decoder.

Reflective optical rotary encoder disc

Abstract: A reflective optical rotary encoder device detects an angular speed or position of a rotatable member with a light beam applied to and reflected from a reflective optical encoder disc. The reflective optical rotary encoder disc has an annular encoder track for reflecting the light beam, the encoder track being composed of an annular pattern of angularly spaced pit units each including a plurality of radially spaced arcuate pits, and a pit-free annular focus servo track for focusing the light beam onto the encoder track, the focus servo track extending along and being disposed radially substantially centrally in the annular encoder track. The reflective optical rotary encoder disc further includes at least one arcuate reference pit for reflecting the light beam to produce a reference signal, the reference bit being positioned in the focus servo track and radially aligned with one of the pit units, and an annular tracking servo pit for keeping the light beam applied thereto, the annular tracking servo pit extending along and being disposed radially substantially centrally in the annular focus servo track.

Optical sensor using concave diffraction grating

Abstract: An optical WDM sensor and sensing system for determining a value of a measurand, such as an encoder position. An optical source produces a composite input signal that includes a plurality of different wavelength component signals. The sensor includes an encoder and a concave diffraction grating. The encoder has a plurality of tracks, each track being responsive to the value of the measurand for modulating the intensity of light incident thereon to produce a modulated signal. The grating demultiplexes the composite input signal to produce separate component signals that are directed to an incident upon the respective tracks. Each track produces a modulated signal, and the modulated signals are multiplexed, preferably by the grating, to produce a return signal that may be demultplexed and detected to determine the measurand value. Preferably, the sensor comprises a planar optical waveguide having the grating formed on one side surface. The encoder may be positioned adjacent to the waveguide, or coupled to the waveguide via optical fibers.

Image signal compression encoding apparatus and image signal expansion reproducing apparatus

Abstract: A compression encoder uses an arbitrary normalization coefficient and a preset table to achieve a compression of image signal with a desired compression rate. Since the normalization coefficient and the table data are sent to an image signal decoding and reproducing apparatus together with the compressed image data, the reproducing apparatus can restore the original image from those data items. Furthermore, in the encoder, when an amplitude value of the data exceeds a predetermined value, an overflow sensor means the condition so as to produce normalized data in addition to the Huffman-encoded data. The reproducing apparatus achieves the image signal decoding and reproducing operations by use of the normalized data and the Huffman-encoded data. With these apparatuses, the picture quality can be prevented from being lowered due to an overflow in the encoding operation.