Abstract: A system for use in connecting broadband voice and data signals to communications systems such as the telephone system. Due to the low pass filtering characteristics of a standard twisted pair used in conventional telephone access loops data band signals are attenuated more than voice band signals. The present invention provides apparatus and methods for interfacing data and voice band signals to a common communications medium, such as a twisted pair, while significantly reducing the influence of one frequency band on the other.

Abstract: In a method for performing a fast-Fourier transform (FFT), input data samples are written to a storage instance in a data input step, then subjected to a processing step in which the stored input samples are read out of the storage instance and processed in accordance with a transformation algorithm. The resulting output data samples are written back to the storage instance and, in a transformed data output step, read out of the storage instance, successively received batches of the input data samples being fed cyclically to a plurality of such multiple-function storage instances. Each batch is fed to a respective storage instance such that, at any given time during performance of the method, the input, processing and output steps are being performed simultaneously in respect of different batches using different respective storage instances.

Abstract: A method and apparatus for decoding convolutional codes used in error-correcting circuitry for digital data communication. To increase the speed and precision of the decoding process, the branch and/or state metrics are normalized during the soft decision calculations, whereby the dynamic range of the decoder is better utilized. Another aspect of the invention relates to decreasing the time and memory required to calculate the log-likelihood ratio by sending some of the soft decision values directly to a calculator without first storing them in memory.

Abstract: A method of determining cross channel interference in an Discrete Multitone (DMT) implementation of a Digital Subscriber Line (DSL) system. The cross channel interference is determined utilizing a residual impulse spectrum after implementation of a Time Equalization (TEQ) algorithm. In one application the cross channel interference value is used in a bit allocation algorithm to improve such that more bits are allocated to the channels with low interference and fewer bits are allocated to those channels having high interference. In this application the bit allocation algorithm is run twice, once before the interference measurement and once after.