Abstract: Various embodiments are described to provide for the transmission and reception of data in an improved manner. Data transmission is improved by including in a transmitter a null generator (110) to generate an output data symbol sequence that exhibits nulls in the frequency domain at particular frequencies that an input data symbol sequence does not. A pilot inserter (120) then adds a pilot symbol sequence to this output data symbol sequence to create a combined symbol sequence. Since the pilot symbol sequence exhibits pilot signals corresponding to the nulls of the output data symbol sequence in the frequency domain, the combined symbol sequence exhibits pilots that are orthogonal to the data in the frequency domain.

Abstract: Substantial improvements in frequency reuse in microwave communications systems is achieved by canceling co-channel interference and transmitter leakage. Interferometric beam-narrowing reduces beamwidth without reducing peak magnitude of the beam pattern. Frequency-dependent beam-shaping compensates for frequency-dependent distortions of the beam pattern thereby improving bandwidth. A spatial demultiplexing technique utilizes spatial gain distributions of received signals to separate signals, even from co-located transmit sources, and uses microwave lensing to enhance received spatial gain distributions. Predetermined cross-polarization interference is used to separate differently-polarized receive signals. A reference branch provides a cancellation signal to a receiver to cancel transmitter leakage signals. An error signal controls an impedance-compensation circuit that is responsive to changes in antenna impedance but not to receive signals.

Abstract: An analog/digital gain control device avoid some of the requirements associated with the nature of a closed-loop AGC circuits and which meets the remaining requirements without much difficulty uses an analog to digital conversion method that increases the number of effective ADC bits by compressing the baseband input analog signal using a logarithmic circuit. After the compressed analog signal is converted into a digital signal, a digital anti-log process or look-up table (LUT) is used to expand the digital signal back to the original linear scale. The word size of the output of the anti-log process is larger than the input word size due to the nature of the anti-log function. To reduce the word size of the digital signal an open loop normalization technique can be applied.

Abstract: A soft demodulation method and apparatus including calculating partial sums for a unit of each predetermined number of bits of a codeword received from a channel; calculating a value of each entry of the decoding table by referring to the partial sums; and detecting a maximum among values of all entries of the decoding table and calculating a log-likelihood ratio (LLR) using the detected maximum. Accordingly, it is possible to reduce the amount of computation required to perform a soft demodulation process using run-length limited (RLL) codes and to simplify the soft demodulation process.

Abstract: A communication system including a transmitter, a receiver, and a serial link, in which encoded data (e.g., encoded video data and encoded auxiliary data) are transmitted from the transmitter to the receiver. The serial link can but need not be a TMDS or TMDS-like link. In typical embodiments, alternating bursts of encoded video data and encoded auxiliary data are transmitted over each of one or more channels of the link. Other aspects of the invention are transmitters for use in encoding data for transmission over a serial link, and methods for sending encoded data over a serial link. In accordance with the invention, the data to be transmitted are encoded using a subset (sometimes referred to as a selected set of code words) of a full set of code words.

Abstract: With audio data reduction on the basis of ISO/IEC standard 11172-3, a frame length varying by 8 bits is used at a sampling frequency of 44.1 kHz in order to arrive, on average, at a particular fixed data rate. The lengthening of a data frame is signalled by a padding bit in the header of the frames. The invention dispenses with evaluation of the padding bit. Instead, the mean frame length L is calculated, L is rounded down to the next integer, for the subsequent frame it is first established whether the expected sync word for this frame appears, and, if this is so, this frame is decoded without taking into account the padding bit, but if the expected sync word for this frame does not appear, the decoding of the frame is started one 8-bit later without taking into account the padding bit.

Abstract: According to some embodiments, an input symbol may be received, and a hard symbol may be generated from the input symbol. A probability associated with the hard symbol may be calculated along with a probability associated with a previous hard symbol. An enhanced symbol may then be determined as a function of a comparison between the probability associated the hard symbol and the previous hard symbol.

Abstract: A method and apparatus reliably encode and decode information over a communication system. The method includes transforming two coefficients into two pairs of random variables, one random variable in each pair having substantially equal energy as one random variable in the other pair. The method further includes quantizing each of the pairs of random variables and entropy coding each quantized random variable separately creating an encoded bitstreams. The encoded bitstreams are received by a decoder which first determines which channels of the communication system are working. The encoded bitstream is entropy decoded, inversed quantized and inversed transformed. An inverse transform performs three different transformations depending upon which channels are working, i.e., whether the first, second or both channels are working.

Abstract: A device for performing predetermined processing on an input signal that may have a signal amplitude of more than one bit. The input signal is obtained by subjecting one-bit serial signals to predetermined signal processing, wherein the signal amplitude of more than one bit is converted to a one-bit serial signal by accumulating the signal amplitudes that exceed one bit, delaying the accumulated signal on the basis of the input signal, and outputting the accumulated signal.

Abstract: A sequence of input information items is space-saving-encoded into variable-length code bit groups. Each information item is mapped on an associated code bit group of a set of bit groups, wherein the bit groups have particular lengths that are non-uniform in the set. The code bit groups are chained into a chaining configuration of bit groups while allowing progressive delimiting of successive bit groups. For regressive delimiting of successive bit groups, each bit group as divided into an idiosyncratic sequence of subgroups. In each sequence, the subgroups are assigned to a respective sub-chainings. The sub-chainings are configured into respective sub-chaining configurations, while maintaining pointer information regarding each respective sub-chaining configuration to preserve mutual synchronization among the various sub-chaining configurations regarding the associated in formation items.

Abstract: An analog/digital gain control device avoid some of the requirements associated with the nature of a closed-loop AGC circuits and which meets the remaining requirements without much difficulty uses an analog to digital conversion method that increases the number of effective ADC bits by compressing the baseband input analog signal using a logarithmic circuit. After the compressed analog signal is converted into a digital signal, a digital anti-log process or look-up table (LUT) is used to expand the digital signal back to the original linear scale. The word size of the output of the anti-log process is larger than the input word size due to the nature of the anti-log function. To reduce the word size of the digital signal an open loop normalization technique can be applied.

Abstract: The multilevel data encoding and modulation technique uses a pair of complementary logic sets. In its most basic form, the sets are binary sets each containing a line level for a logical one and a line level for a logical zero for a total of four logic levels. The encoding technique requires a polar change in the line level after every bit. An optional fifth level may be used in order to skew the frequency or to enable automatic gain control circuitry to ensure consistent level discrimination. The encoding technique may be used in a bipolar device, or a bias level may be applied to the signal for unipolar transmission. The encoding technique involves inverting the polarity of alternating bits, filtering out all odd harmonics, transmitting and receiving the waveform, and decoding the demodulated waveform by comparing the absolute value of the half-cycle peak-to-peak voltage gain to a predetermined table.

Abstract: A data-demodulating method for demodulating a variable-length code (d, k; m, n; r) having a basic code length of n bits to data having a basic data length of m bits. A train of codes is received, and a sync signal having a pattern that breaks a maximum run is detected. The pattern is repeated twice continuously and the minimum run is repeated no more than six times. The first bit of the sync signal is “1” when the train of modulated codes that immediately precedes the sync signal is included in a termination table used to terminate, at a desired position, a code when less than a predetermined number of variable length codes are available.

Abstract: A method of modulating data having a basic data length of m bits, to a variable-length code (d, k; m, n; r) having a basic code length of n bits. A sync signal is added to a received train of codes after a minimum run. The sync signal has a pattern that is repeated twice continuously. The minimum run is repeated no more than six times; and the sync signal exhibits seven types of sync signal IDs, with any adjacent two bits of a sync signal ID being spaced apart by a distance of 2.

Abstract: Apparatus for modulating data having a basic data length of m bits, to a variable-length code (d, k; m, n; r) having a basic code length of n bits. A sync signal is added to a received train of codes after a minimum run. The sync signal has a pattern that is repeated twice continuously. The minimum run is repeated no more than six times; and the sync signal exhibits seven types of sync signal IDs, with any adjacent two bits of a sync signal ID being spaced apart by a distance of 2.

Abstract: A data-demodulating apparatus for demodulating a variable-length code (d, k; m, n; r) having a basic code length of n bits to data having a basic data length of m bits. A train of codes is received, and a sync signal having a pattern that breaks a maximum run is detected. The pattern is repeated twice continuously and the minimum run is repeated no more than six times. The first bit of the sync signal is “1” when the train of modulated codes that immediately precedes the sync signal is included in a termination table used to terminate, at a desired position, a code when less than a predetermined number of variable length codes are available.

Abstract: Method and system for implementing digital filters in the data path of a Pulse Code Modulated (PCM) modem to allow efficient transition of a second analog to digital conversion process in a communication system including monitoring the upstream data path of the communication system to decode the V.34 portion of the data transmission which occurs during the handshake phase of the modem call, where the information contained in the upstream data channel during the handshake phase allows the communication system to determine the manner in which the PCM modem is training and transmitting data to the client modem.

Abstract: An insertion-based error concealment method and apparatus are provided whereby, instead of directly inserting white noise, a filter is created to shape the white noise. The filtered white noise is then used to replace lost data. The method of the present invention is implemented by first estimating the power spectrum of the previous frame; then designing a filter with transfer function H(f), where |H(f)|2=the estimated power spectrum; and finally generating the replacement packet using noise which has been spectrally modified by the filter. The resulting filtered noise has the same power spectrum as the previous packet but is not highly correlated with it.

Abstract: A communication system for performing transmission and reception of a signal over a communication channel assesses a state of the communication channel and produces channel state information accordingly. A block length selector selects block lengths that are dependent on the channel state information and that are selected from a group of block lengths having an integral multiple relationship to produce a schedule of block lengths. Encoding and decoding is performed based on the schedule of block lengths.

Abstract: A method comprises determining a plurality of time intervals Tp and Tn within a variable bit rate (VBR) representation of an image sequence. The time intervals Tp are those in which a number of blocks of information per unit time is greater than a baseline value. The time intervals Tn are those in which a number of blocks of information per unit time is less than the baseline value. A second representation of the image sequence is created in which some blocks of information Bp are removed from the time intervals Tp and interlaced with blocks of information Bn in the time intervals Tn to reduce a variation in a number of blocks of information per unit time between the time intervals Tp and Tn.

Abstract: A coding assisting equipment is provided in which transmission information is fed in such a manner as to be divided into words having a predetermined word length and is coded collectively through a computing unit that is formed as a combinational circuit. A decoding assisting equipment is provided in which a received sequence is fed in such a manner as to be divided into words having a predetermined word length and is decoded collectively through a computing unit that is formed as a combinational circuit. A radio transmitter and a radio receiver are provided that incorporates the above coding assisting equipment and the decoding assisting equipment, respectively. In a transmission system to which the invention is applied, the service quality and the transmission efficiency are increased in an inexpensive manner, resources are utilized effectively, and flexible application of a variety of systems is enabled.

Abstract: An adapter configured to automatically detect and compensate for differential signal inversion is herein disclosed. In one embodiment, the adapter is part of a computer network having differential conductor pairs conveying differential signals between network devices. The network devices include adapters coupled to transmit and receive signals via the differential conductor pairs. The adapter preferably includes a lane receiver, a decoder, and a synchronization circuit. The lane receiver is configured to receive a single differential signal and to convert the differential signal into a sequence of code symbols. The decoder decodes the code symbols to produce a sequence of received symbols. The synchronization circuit examines the sequence of received symbols to determine if it is incorrect due to inversion of the differential signal, and if so, it causes the lane receiver to correct for the differential signal inversion.

Abstract: Disclosed is a method for wireless signal transmission of signals from an array of two or more antennas, in which each signal to be transmitted is selected from a constellation of unitary space-time signals. Each unitary space-time signal is a unitary matrix, in which each column represents a respective antenna, each row represents a respective time interval, and each element represents a complex amplitude to be transmitted by a given antenna during a given time interval. In specific embodiments of the invention, the matrices of the signal constellation form a non-Abelian group having a positive diversity product, or a coset of such a group. In other embodiments, the signal constellation is a subset of such a group, and its multiplicative closure forms a finite non-Abelian group having a positive diversity product.

Abstract: A communication mode determination section 201 determines the communication mode based on the CIR measured by a CIR measurement section 219; a DRC signal creation section 202 creates a DRC signal with a number corresponding to the communication mode; and a DRC power controller 205 refers to a transmission power table 206 showing the correspondence between DRC numbers and transmission power, and, based on the transmission power of the pilot signal output from a pilot power controller 209, increases transmission power in proportion as the DRC signal indicates that downlink channel quality is good.

Abstract: A device and associated method for processing a digital information signal from a channel signal. The digital information signal is runlength limited with one or more constraints. The device comprises receiving means for receiving the channel signal and means for comparing a detected runlength with a predetermined value indicative of a minimum runlength constraint or a maximum runlength constraint of the channel signal and for generating a control signal when the detected runlength violates said constraint. The device further comprises substitute means for in response to the control signal deleting or inserting an element in the channel signal.

Abstract: A method of providing time tracking between a first signal and a second signal in a communication device. In one embodiment, a first signal is generated by the communication device and a second signal is received from an outside source. Then correlation data between a first signal, at a plurality of timing conditions, and a second signal is generated by hardware. Next, the correlation data is filtered by software or firmware at a plurality of timing conditions. Afterward, the correlation data is compared to a threshold value to evaluate accuracy of a system timing for the first signal to obtain a result. Finally, the system timing for the first signal is corrected based upon said result of the comparing step.

Abstract: A low-cost data communication system using modems is disclosed. In the proposed system and method, a binary incoming data stream is split into several parallel sub streams by an encoding modem. These parallel sub streams are mapped into a set of unique orthogonal short-codes and then modulated by a bank of modulators. Thereafter, the modulated data are combined and transmitted through a wired communication channel such as a cable or optical fiber channel. Since there are no multipath components in cables or fiber optical communication channel, the composite outgoing data stream from the encoding modem remains orthogonal during the transmission and maximizes CDMA capacity. A decoding modem can receive encoding information from the encoding modem and appropriately decode the transmitted information.

Abstract: Systems and methods for transcoding a video stream. An incoming video stream is spatially transcoded to reduce the bit rate of the video stream. The incoming video stream is decoded and the stream parameters are saved for use in generating the output video stream. The decoded video stream is resampled and the images are spatially reduced. Using the stream parameters of the incoming video stream, an outgoing video stream is generated. Some of the stream parameters are unchanged while others are re-computed for the outgoing video stream.

Abstract: In order to transmit variable length encoded data in low signal to noise ratio environments, a first data pattern is added to a beginning portion of encoded data to signify a beginning of the encoded data. Further, a second data pattern is added to end portion of the encoded data to signify and end of the encoded data. Additionally, since the encoded data may naturally include the second data pattern and thereby mistakenly indicate an end of the encoded data, the encoded data is first checked for such a pattern. If the pattern is found within the encoded data, a new pattern is substituted therefore. In order to counter errors, patterns similar to the first data pattern are also substituted with new patterns. As such, a variable length encoded data can be transmitted in a low signal to noise ratio environment, and can thereafter be easily decoded.

Abstract: A complex spreading and/or scrambling code sequence generation system uses a first complex code sequence having at least two components and a second complex code sequence having at least two components. The components of the first complex code sequence are respectively mixed with the corresponding components of the second complex code sequence to generate the complex scrambling code sequence. In doing so, an offset between the components of the complex scrambling code sequence is achieved for the same and/or different users. The complex scrambling code sequence can be used for spreading, scrambling, de-spreading or descrambling an information signal.

Abstract: A method and system of operating a digital data decoder. In accordance with this method, a first stream of encoded data is transmitted to the decoder, and a second stream of encoded data is stored in a memory device. One of the first and second streams of encoded data is selected, and the decoder is used to decode that selected stream of encoded data. This second stream of data could have been placed in the memory device by other devices or processes present in an STB system. In this case, all the decoder needs to process the data is a pointer to it and some additional information about, for example, its size. Since the processor has access to all memory, it can do any necessary parsing/manipulation required by the stream format. This provides a large degree of flexibility in this area. The processor can then pass location and attributes of data to the decoder. This also minimizes data movement to/from memory, reducing bandwidth requirements.

Abstract: A method and device for generating a pseudorandom electrical signal for enabling spread spectrum communication scrambling by directing data entry into pseudorandom number generator integrated circuit chip controlling registers using a length selectable feedback logic data sequence and either computer programmable selector means or manual selector means to communicate the logic data sequence characters to buffers. The logic data sequence characters are clocked to a pseudorandom number generating register of an integrated circuit chip and the pseudorandom electrical signal is generated by selectively tapping a signal code therefrom. The method and device features a pseudorandom electrical signal length varying capability and is portable to various laboratory applications without a change in hardware configuration.

Abstract: The subtracter performs subtraction processing between a pointer outputted from the pointer register and code words candidate outputted from the code word count storing circuit, and in accordance with whether the result is negative or positive, determines the code words of input data words. Code word candidates stored in the code word count storing circuit are created according to a finite-state transition diagram stored in the state transition storing circuit. An encoder and a decoder are thus made compact and faster.

Abstract: The present invention provides a pulse modulating method which ensures demodulation of bit data without being affected by a change in the pulse width and permits high-speed transmission, pulse modulating equipment for the pulse modulating method and pulse demodulating equipment. The pulse modulating equipment divides an input signal into n-bit words and converts it into a pulse unit signal which represents the state of the bit data for each word by time intervals i and j between odd-numbered transitions and between even-numbered transitions. The respective time intervals i and j are free from the influence of the transmission line used, for example, and remains unchanged in the pulse demodulating equipment, so that no demodulation error arises. Further, since the bit data is represented by the time intervals i and j between the odd-numbered transitions and between the even-numbered transitions, the coding efficiency increases, permitting high-speed transmission.

Abstract: A run length encoder for encoding DCT coefficients obtained in a DCT, a quantization, and a scanning steps in block units to output an encoded (run, level) symbol, and outputting a predetermined (run, level) symbol if the obtained DCT coefficients of the block unit are all zero, comprises a run length encoding core for receiving the DCT coefficients and outputting the (run, level) symbol; a zero coefficient detector for detecting whether the DCT coefficients are `0` or not; a zero block detector for receiving an output from the zero coefficient detector to detect whether all of the DCT coefficients of each block are `0` or not; and an output selector for selecting the 2-dimensional symbol outputted from the run length encoding core to output a (run, level) symbol or a predetermined (run, level) symbol, if the block determined in the zero block detector is non-zero or zero block, respectively.

Abstract: The invention is a process and apparatus for estimating a bit budget in a circuit for compressing digital data, especially digitized television signals. Signals represented by N-bit coded samples, are estimated based upon the probability of a bit of given order having a given value (0 or 1) out of M binary words representing M samples of the signal. An entropy calculation is performed on the basis of the probabilities corresponding to the N bits with the sum of all the entropies corresponding to the desired estimate.

Abstract: An encoder which counts the length of a data produced by the variable-length encoding, and time-division-multiplexes information of the data length to the variable-length encoded data. An encoder which time-division-multiplexes information of the number of bits after a fixed partition used in the error-correction encoding to the initial bit of a variable-length code to a variable-length encoded data, and transmits them. An encoder which, when a variable-length code for one symbol of the variable-length encoding extends over a partition used in the error-correction encoding, inserts a special code before the partition, or guarantees that the top of the partition is always at the top of the variable-length code. An encoder which obtains the sum of fields and the difference between fields, and performs on these values the orthogonal transform to encode them.

Abstract: A compressive encoding-decoding system is provided specifically for the realization of the lossless encoding system having a good efficiency. Herein, input signals are subjected to analog-to-digital conversion to generate a series of linear PCM data. Then, the system generates a series of difference value data, each representing a difference between adjacent samples of the linear PCM data, which are then combined with respect to each frame. Requantization is performed on the difference value data on the basis of a word length. In a first mode, the word length is determined to coincide with a minimum number of bits which are required to represent the difference value data having a maximum absolute value within the difference value data contained in each frame.

Abstract: Disclosed is a system for selectively enabling intermediate data processing of digital signals external to an integrated circuit (IC). The system comprises a transcoder, a codec connected to the transcoder, and a data processor located externally to the IC. In response to a strobe signal, a programmable switch diverts digital signals between the transcoder and the codec to a data path from the IC to the external processor. The digital signals are formatted within the IC for processing by the external processor. The externally processed digital signals are returned to the IC via a data path from the external processor. The digital signals are then reformatted within the IC for further processing by the IC.

Abstract: A digital information signal is channel encoded into a channel signal. Data sequences in the channel encoded information signal that give rise to an analog signal, upon reproduction or reception, with a single frequency component at f.sub.b M, are limited in length. M being an integer constant larger than 2 and f.sub.b being the bit frequency in the channel encoded information signal.

Abstract: Data items associated with different locations in a spatial field of locations are written in a memory. The memory comprises a length memory in which for each location there is stored a length code which indicates the memory length required for the data item. For the reading of a data item associated with a location, the address of the data item is calculated by reading the length codes for the data items of preceding locations from the memory and by summing the lengths indicated.

Abstract: An encoder counts the length of a data produced by the variable-length encoding, and time-division-multi-plexes information of the data length to the variable-length encoded data. Art encoder time-division-multiplexes information of the number of bits after a fixed partition used in the error-correction encoding to the initial bit of a variable-length code to a variable-length encoded data, and transmits them. An encoder, when a variable-length code for one symbol of the variable-length encoding extends over a partition used in the error-correction encoding, inserts a special code before the partition, or guarantees that the top of the partition is always at the top of the variable-length code. An encoder obtains the sum of fields and the difference between fields, and performs on these values the orthogonal transform to encode them.

Abstract: Disclosed is a system for selectively enabling intermediate data processing of digital signals external to an integrated circuit (IC). The system comprises a transcoder, a codec connected to the transcoder, and a data processor located externally to the IC. In response to a strobe signal, a programmable switch diverts digital signals between the transcoder and the codec to a data path from the IC to the external processor. The digital signals are formatted within the IC for processing by the external processor. The externally processed digital signals are returned to the IC via a data path from the external processor. The digital signals are then reformatted within the IC for further processing by the IC.

Abstract: A digital video signal encoder for coding a block of a digital video signal first converts the block of the digital video signal into a set of quantized transform coefficients having a low and a high frequency zones and scans the set of quantized transform coefficients to produce a first and a second subsets of scanned coefficients. The scanned coefficients of the first and the second subsets are converted into a first and a second sets of one or more RLC codes, respectively. The digital video signal encoder performs the coding each RLC code of the first and the second sets to generate a first and a second sets of one or more variable length codewords.

Abstract: The method for executing coding subprocesses and decoding subprocesses calculates a first time interval from a current point to a variable output point of the coded output signals. Similarly, a second time interval from the current point to an output point of the decoded output signals is calculated. Second, a total processing time of a subsequent coding and decoding subprocesses is calculated. The subsequent subprocesses are both allowed to be subsequently executed. Finally, one subprocess to be subsequently executed is selected from the subsequent coding and decoding subprocesses by comparing the total processing time with a smaller one of the first and the second time intervals.

Abstract: The present invention includes software and hardware components to enable digital data communication over standard telephone lines. The present invention converts analog voice signals to digital data, compresses that data and places the compressed speech data into packets for transfer over the telephone lines to a remote site. A voice control digital signal processor (DSP) operates to use one of a plurality of speech compression algorithms which produce a scaleable amount of compression. The rate of compression is inversely proportional to the quality of the speech the compression algorithm is able to reproduce. The higher the compression, the lower the reproduction quality. The selection of the rate of compression is dependant on such factors as the speed or data bandwidth on the communications connection between the two sites, the data demand between the sites and amount of silence detected in the speech signal. The voice compression rate is dynamically changed as the aforementioned factors change.

Abstract: Before transmitting signals to a receiver, the signals are subjected to adaptive prediction to generate a residual signal for transmission, and the residual signal is then transformed into frequency domain coefficients, the coefficients are grouped together to form vectors, and the vectors are then quantized.

Abstract: Disclosed herein is a system which is capable of providing a high efficient bit rate reduction by selectively employing two or more variable length code tables, depending on the magnitude of the quantization parameter employed in the digitalization process. The system includes a transmitter having a differential pulse code modulator for producing differential signal samples quantized by employing two or more quantization parameters and a variable length coding circuit. The variable length coding circuit for performing a variable length coding process comprises four variable length coding lockup tables for storing variable length code words, each of the variable length coding lockup tables reflecting a statistic of the signal words quantized by each of the quantization parameters; and switching circuit responsive to each of the quantization parameters for selecting one variable length coding lookup table so as to carry out a variable length coding operation.