Patents Assigned to Comsis
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Patent number: 6944242Abstract: An apparatus for and method of converting soft symbol decision information into soft bit decision information that overcomes the disadvantages of the prior art. The invention is adapted to receive M soft symbol values where each symbol represents m bits (M=2m). The output for each symbol comprises m soft values of bits representing the symbol. The invention is operative to convert the soft symbol values to soft bit values using the log likelihood ratios (LLRs) of a bit and a symbol expressed as conditional probabilities. The method of the invention is presented which can be performed in either hardware or software. A computer comprising a processor, memory, etc. is operative to execute software adapted to perform the soft symbol to bit conversion method of the present invention.Type: GrantFiled: January 4, 2001Date of Patent: September 13, 2005Assignee: Comsys Communication & Signal Processing Ltd.Inventors: Evgeny Yakhnich, Ehud Reshef
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Patent number: 6907092Abstract: A novel and useful apparatus for and method of determining the channel order and channel estimate in a communications system such as a wireless communication system including cellular and cordless. Such channels are typically characterized by rapidly changing impulse response and their taps can be modeled as zero-mean, complex, Gaussian random processes. A sufficiently long, initial channel estimate of length is performed so as to ensure that the actual channel taps will be contained in the estimated taps thus making certain that the equalizer will effectively eliminate intersymbol interference. Channel estimation is performed during each burst using the training sequence transmitted in the middle of the burst. The tap energies are averaged so as to track slow variations in the pattern of resultant channel taps. A noise floor is calculated using the lowest averaged taps and a threshold is computed based thereon and applied to the average taps.Type: GrantFiled: July 14, 2000Date of Patent: June 14, 2005Assignee: Comsys Communication & Signal Processing Ltd.Inventors: Evgeny Yakhnich, Ron Cohen
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Patent number: 6901121Abstract: A novel and useful apparatus for and method of DC offset compensation for use in a communications receiver. The invention is operative to calculate an estimate of the DC offset which is subsequently subtracted from each input sample to generate compensated samples. The training sequence portion of the uncompensated input samples is used to generate an estimate of the DC offset. The vector used in calculating the offset estimate is pre-calculated for several channel lengths and stored in memory. An estimate of the channel is generated which provides the channel length and the location in the input sample buffer of the first training sequence sample to be used in calculating the offset estimate. The channel length is used to determine the number of training sequence samples to be used and to select one of the previously calculated vectors.Type: GrantFiled: February 20, 2001Date of Patent: May 31, 2005Assignee: Comsys Communication & Signal Processing Ltd.Inventors: Andrew Dubrovin, Evgeny Yakhnich, Ehud Reshef
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Patent number: 6873608Abstract: The system utilizes host signal processing techniques applicable to cellular communication system devices which are integrated with a system incorporating a general purpose CPU running a multitasking operating system. A RF receiver processes the signals to generate a receive signal, the RF module performs RF transmit processing on a transmit signal and generates the transmit wireless signal from it. A host processor communicates data, status and control information with the RF device via a bus, the host processor includes host based software application and a host based modem application. The receive signal generated by the RF module over the bus and generates receive data in response to it input to the software application at a output by the software application is received and generates the transmit signal in response to it, sending the transmit signal to the RF module over the bus. The figure shows a block diagram illustrating an analog cellular communications systems tuned for data communication.Type: GrantFiled: August 6, 1998Date of Patent: March 29, 2005Assignee: Comsys Communication & Signal Processing LTDInventors: Eli Plotnik, Ophir Shabtai
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Patent number: 6862326Abstract: A novel and useful whitening matched filter (WMF) for use in a communications receiver. The WMF is constructed by cascading a matched filter and a noise-whitening filter. The response of the matched filter is derived from the time reversed complex conjugate of the channel impulse response. The whitening filter is derived by extracting the minimum phase portion of the mixed phase channel impulse response using homomorphic deconvolution. The whitening filter is implemented using either an FIR or IIR filter adapted to process the data received before and after the training sequence using a minimum phase system in a direction in time opposite to that of the direction of corresponding data sample processing performed by the equalizer.Type: GrantFiled: February 20, 2001Date of Patent: March 1, 2005Assignee: Comsys Communication & Signal Processing Ltd.Inventors: Alon Eran, Ophir Shabtay, Alexander Kleinerman, Ariel Zaltsman
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Patent number: 6859434Abstract: A novel data transfer scheme for efficiently transferring data between multiple data generating processing units in a processing element wherein each processing unit may generate data at different rates. The data output of each processing unit is multiplexed into a single data stream and written to a memory buffer. A centralized software processor such as a CPU or DSP implements a demultiplexer operative to read the contents of the input buffer, demultiplex the data and distribute it to individual unit buffers thus recreating the original data streams generating by each of the processing units. The multiplexed data stream is generated by partitioning the outputs of the data generating processing units into multiple multiplexer groups based on individual data rates. The outputs of the various groups are collected by a multiplexer and used to build a single data stream having a well-defined structure.Type: GrantFiled: October 1, 2002Date of Patent: February 22, 2005Assignee: Comsys Communication & Signal Processing Ltd.Inventors: Oren Segal, Yaniv Avital, Moshe Moshe, Ehud Reshef
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Publication number: 20040199557Abstract: A method and apparatus for performing a radix-4 fast Hadamard transform (FHT) with reduced complexity that and for directly determining the maximum output of a fast Hadamard transform using either a radix-4 transform or radix-2 transform without actually generating the outputs. The radix-4 fast Hadamard transform is implemented using only seven operations. To find the maximum value of the output of a fast Hadamard transform and its corresponding index, the N−1 stages of a conventional N stage fast Hadamard transform are computed while a find-maximum stage is inserted in place of the Nth stage. The invention also provides a methodology for constructing fast Hadamard transforms of the form H2N using radix-4 FHTs and permuting the results to achieve the correct outputs.Type: ApplicationFiled: April 19, 2004Publication date: October 7, 2004Applicant: Comsys Communication & Signal Processing Ltd.Inventors: Ehud Reshef, Idan Alrod
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Patent number: 6731700Abstract: An apparatus for and method of generating soft decision information from a sequence of hard symbol decisions output from a decoder in a concatenated communications receiver. Soft symbol decisions are computed given hard symbol decisions from the equalizer, channel estimation information (i.e. FIR filter taps used to estimate the channel), and the input samples received from the channel. The log likelihood ratio (LLR) for all symbol possibilities is calculated by computing the conditional probability of the input sample sequence given the hard symbol decision sequence. The noise variance is optionally used in computing the soft output values, thus improving the overall performance of the receiver. In one embodiment, symbol vectors are calculated beforehand and stored in a table. An error vector calculator functions to calculate an error vector that is applied to soft output calculation units. Each soft output calculation unit functions to generate a soft output value for a particular symbol candidate.Type: GrantFiled: January 4, 2001Date of Patent: May 4, 2004Assignee: Comsys Communication & Signal Processing Ltd.Inventors: Evgeny Yakhnich, Ehud Reshef
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Publication number: 20040066765Abstract: A novel data transfer scheme for efficiently transferring data between multiple data generating processing units in a processing element wherein each processing unit may generate data at different rates. The data output of each processing unit is multiplexed into a single data stream and written to a memory buffer. A centralized software processor such as a CPU or DSP implements a demultiplexer operative to read the contents of the input buffer, demultiplex the data and distribute it to individual unit buffers thus recreating the original data streams generating by each of the processing units. The multiplexed data stream is generated by partitioning the outputs of the data generating processing units into multiple multiplexer groups based on individual data rates. The outputs of the various groups are collected by a multiplexer and used to build a single data stream having a well-defined structure.Type: ApplicationFiled: October 1, 2002Publication date: April 8, 2004Applicant: Comsys Communication & Signal Processing Ltd.Inventors: Oren Segal, Yaniv Avital, Moshe Moshe, Ehud Reshef
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Publication number: 20040034676Abstract: A method and apparatus for performing a radix-4 fast Hadamard transform (FHT) with reduced complexity that utilizes only seven operations and for directly determining the maximum output of a fast Hadamard transform using either a radix-4 transform or radix-2 transform without actually generating the outputs. To find the maximum value of the output of a fast Hadamard transform and its corresponding index, the N−1 stages of a conventional N stage fast Hadamard transform are computed while a find-maximum stage is inserted in place of the Nth stage. The invention also provides a methodology for constructing fast Hadamard transforms of the form H2N using radix-4 FHTs and permuting the results to achieve the correct outputs.Type: ApplicationFiled: August 15, 2002Publication date: February 19, 2004Applicant: Comsys Communication & Signal Processing Ltd.Inventors: Ehud Reshef, Idan Alrod
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Publication number: 20030235238Abstract: A method and apparatus for estimating channel tap delays of multipath components in a CDMA received signal. The search for the tap delays are split into two phases namely, a phase 1 and a phase 2 search. The phase 1 search is a coarse resolution quick search adapted to generate a rough estimate of the location of the tap delays. During this phase, the candidate codes are summed and the input signal correlated with the code sum creating an ambiguity in the code associated with the multipath. A finer resolution slower phase 2 search resolves the code ambiguity present in the initial rough estimates of the phase 1 search. Additional phase 2 correlations may be performed to implement a code-tracking loop.Type: ApplicationFiled: June 24, 2002Publication date: December 25, 2003Applicant: Comsys Communication & Signal Processing Ltd.Inventors: Jacob Schelm, Ophir Shabtay, Yaniv Avital, Ehud Reshef
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Patent number: 6529559Abstract: An apparatus for and method of reducing the soft output information packet to be computed by a soft symbol generator. The reduced soft output information packet generated by the soft symbol generator is subsequently used by a soft symbol to soft bit mapper which functions to convert soft symbol decision information into soft bit decision information. A symbol competitor table is constructed that includes the most likely symbol competitors for each bit of the symbol. The table is populated with m entries for each possible symbol value, where m represents the number of bits per symbol. Symbol competitors am retrieved from the table in accordance with hard decisions. Soft symbol information is generated only for symbol competitors rather than for all possible symbols thus substantially reducing the size of the information packet.Type: GrantFiled: January 12, 2001Date of Patent: March 4, 2003Assignee: Comsys Communication & Signal Processing Ltd.Inventor: Ehud Reshef
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Patent number: 6470047Abstract: A novel and useful apparatus for and method of interference reduction in a communications receiver. The invention first finds the channel estimate and the noise vector from the receive signal. An interference detector is then used to choose an appropriate compensation filter and select between adaptive and deterministic moving average models for noise prediction. After compensation filtering, a new channel estimate and noise vector is calculated. The new noise vector is used to determine noise whitening coefficients if the adaptive model is used. In the deterministic model case, the coefficients do not need to be calculated since they are already known, having been calculated a priori. The noise whitening coefficients are then used in an equalizer such as a Viterbi algorithm based equalizer.Type: GrantFiled: February 20, 2001Date of Patent: October 22, 2002Assignee: Comsys Communications Signal Processing Ltd.Inventors: Alexander Kleinerman, Ariel Zaltsman, Edo Navon, Yuval Bachar
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Patent number: 5892980Abstract: An apparatus for and method of implementing a novel buffer based fall duplex communication system is disclosed. The disclosed invention is particularly useful in native signal processing systems wherein heavy contention of processor resources typically exist, such as in systems running multi-tasking operating systems. The communication system of the present invention includes a receiver, transmitter, CODEC and telephone hybrid. The major components of the system operate on a buffer of input samples consisting of a set of input bits. The communication system operates to generate a buffer of output samples consisting of a set of output bits. The invention utilizes a novel dynamic buffer size mechanism to optimize the tradeoff between buffer delay and processing time period, on one hand, and robustness to interrupt latency and processor availability on the other hand. Small buffers provide the communication system with short, accurate response times in addition to short processing times.Type: GrantFiled: February 28, 1997Date of Patent: April 6, 1999Assignee: Comsys Communication and Signal Processing Ltd.Inventors: Nir Tal, Ron Cohen, Zeev Collin
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Patent number: 5864714Abstract: An apparatus for and method of implementing a novel buffer ba full duplex communication system is disclosed. The disclosed invention is particularly useful in native sign processing systems wherein heavy contention of processor resources typically exist, such as in systems running multi-tasking operating systems. The communication system of the present invention includes a receiver, transmitter, echo canceler. CODEC and telephone hybrid. The major components of the system operate on a buffer of input samples consisting of a set of input bits. The communication system operates to generate a buffer of output samples consisting of a set of output bits. The invention utilizes a novel buffer switching mechanism to optimize the tradeoff between processing response time, on one hand, and robustness to interrupt latency and processor implementation on the other hand.Type: GrantFiled: April 16, 1996Date of Patent: January 26, 1999Assignee: Comsys Communication & Signal Processing Ltd.Inventors: Nir Tal, Ron Cohen, Zeev Collin
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Patent number: 5609525Abstract: A television or video game data reception apparatus receives a data signal of television games transmitted from a base station in a wireless manner or through wire on a local station side so that the received data signal is used to play a game. The reception apparatus is provided, in addition to a game operation memory for storing a data signal of a predetermined game, a save memory for storing a predetermined state of a game, for example, at the time of termination of the game. The save memory is write protected when the save memory does not perform save operation so that for example when a game is terminated in the midway thereof, the data of the state at that termination can be saved in accordance with necessity.Type: GrantFiled: May 22, 1995Date of Patent: March 11, 1997Assignees: NEC Mobile Communications, Ltd., Comsys Corporation, Sega Enterprises, Ltd.Inventors: Yugo Ohno, Shunichi Shoji, Atsushi Kitahara
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Patent number: 5217265Abstract: A child-resistant latch release mechanism which requires operation of two control members which are separated by a distance greater than that which can be effectively spanned by a preschool child. The two control members must be operated first in a certain sequence and then simultaneously in order to permit operation of the latch release mechanism. Conventional self-latching upon closure is retained by the invention latch release mechanism.Type: GrantFiled: May 8, 1992Date of Patent: June 8, 1993Assignee: Comsis CorporationInventors: Neil D. Lerner, Richard W. Huey, Jr.