Abstract: The present invention discloses communications devices which improves communications of pulse code modulation modems which use communications lines with multiple digital-to-analog conversions. One embodiment of the present invention includes a plurality of codecs (312) which receive analog signals through multiple communications channels (310). Digital data streams generated by the codecs (312) from the analog signals is transmitted to an associated one of a plurality of digital signal processors (214). The digital signal processors (214) process the decoded data and then transfers the data to a digital modem (216) for further transmission.

Abstract: A bit-interleaved encoder for a CATV upstream channel is provided having a convolutional encoder for receiving data values, a bit-interleaver interconnected with said encoder, and a symbol mapper interconnected with said bit-interleaver.

Abstract: This invention is particularly useful as a system for digital communications over channels that suffer from impulse noise, and particularly over return cable TV channels, downstream cable TV channels, and digital subscriber loops (DSL) channels for high speed communications over twisted pair copper lines.

Abstract: In a cable television (CATV) data communication network, channel throughput and communications robustness are increased in a manner that improves speed of data transmission while maintaining compatibility with existing specifications and equipment. Enhanced throughput can be realized using the return channel of the CATV network. Alternatively, data retransmission and/or diversity techniques can be used to improve throughput.

Abstract: A system is provided to automatically estimate performance of a receiver for receiving input signals, the input signals having a carrier frequency and a baud rate, from a channel in a communication system and the effect of highly correlated noise cancellation on performance of the receiver, while no active transmission is occurring on the channel, comprising: a digital front end in the receiver for receiving samples of the input signals; a predictor coupled to the digital front end for predicting highly correlated noise in a second sample of the input signal; and a subtraction unit coupled to the predictor for subtracting the predictor output from the second sample to determine residual noise in the second sample. Other systems and methods are disclosed.

Abstract: A method is disclosed for providing data for automatically estimating channel performance if different parameters of a Reed-Solomon (RS) code are used in a communication system while transmission is occurring in the communication system without changing the current Reed-Solomon (RS) code parameters comprising the steps of: receiving an input signal from the channel; processing the input signal in a receiver in the communication system, the receiver having a Reed Solomon decoder having an output of RS symbols; choosing a virtual RS block code size; determining a RS number of errors data by determining how many RS symbols in a sequence of RS symbols the size of the virtual RS block code size are erred RS symbols; determining a RS sequence of errors data by determining how many occurrences there are of erred RS symbols that occur sequentially in the sample and the number of sequential erred RS symbols in each occurrence; and outputting the RS number of errors data and RS sequence of errors data.

Abstract: A method is provided for automatically improving throughput of an active channel in a communication system comprising: receiving input from one or more modules that identify and characterize impairments in the active channel; monitoring the input to track changes in the impairments; and changing channel parameters to improve throughput on the channel based on the changes in the impairments. Other systems and methods are disclosed.

Abstract: A method is provided for automatically optimizing parameter selection in a communication system having one or more channels for transmitting and receiving signals comprising the steps of: receiving a signal from a channel; characterizing impairments in the channel while gathering statistics using the received signal; analyzing the impairments to obtain recommendations for parameter modifications for improved performance; and modifying the parameters based on the recommendations. Other systems and methods are disclosed.

Abstract: A method is provided to automatically identify noise events in a channel of a communication system comprising the steps of: receiving an input signal from the channel; determining the mean energy of the input signal; determining the recent energy of the input signal; identifying a beginning of the noise event when the recent energy is greater than the product of the mean energy and a predefined first threshold; identifying an end of a noise event when the recent energy is less that the product of the mean energy and a predefined second threshold; and providing for output the beginning of the noise event and the end of the noise event. Other systems and methods are disclosed.

Abstract: A method is provided to provide data to automatically estimate channel performance in a communication system if a different order constellation is used comprising the steps of: receiving an input signal from the channel; passing the input signal to a slicer having an output signal; determining signal noise by taking the difference between the input signal and output signal; identifying a beginning of a noise event when the signal noise is greater than a predefined first threshold; identifying an end of a noise event when the signal noise is less than a predefined second threshold; and providing for output the beginning of the noise event and the end of the noise event. Other systems and methods are disclosed.

Abstract: A method is provided for automatically allocating a channel, in a communication system, having a total data rate for transmitting and receiving signals, each of the signals having a carrier frequency, a baud rate and a constellation size, the channel comprising a frequency band comprising a plurality of carrier frequencies, comprising the steps of: receiving a noise sample from the channel; determining a channel noise estimate for the noise sample; receiving a parameter indicating a maximum allowed bit error rate; scanning one or more possible combinations of carrier frequency and baud rate for the channel; determining the bit error rate for each combination based on the channel noise estimate; determining what constellation sizes can be used for each combination such that the bit error rate for that combination does not exceed the maximum allowed bit error rate; determining a data rate for one or more of the combinations; and allocating the channel such that the total data rate is maximized.

Abstract: A method and device for combating logarithmic quantization and Robbed Bit Signaling (RBS) impairments that..are typical to PCM telephone lines is descried. An apparatus is described which includes a front-end unit which receives samples of the digital PCM line, an impairment identifier unit which identifies samples that have a high likelihood to have, large impairments due to the PCM line, an impairment estimator unit which estimates the value of impairment caused by the digital line, a samples reconstructor unit which fixes received samples by subtracting from them the value of the estimated impairment and an output unit transfers the reconstructed samples to a receiver. The method allows improving signal quality at the output of the PCM line, and thus improving data rates and robustness of digital communication receivers, and particularly of V.34 receivers, or V.90 transceivers that are digitally linked to the PCM, line.