British Telecommunications Public Limited Company

Andrew P Heron

David G Morrison

David O Beaumont

Stephen Richard Gunby

Neil E MacDonald

A transmitter (20) having means (206, 207) to encode an input signal to form coded data, each element of said coded data having one of at least two discrete signal magnitude levels, the encoding means including in the coded data a periodic training sequence of data (T); and a receiver (30) to receive the coded data and, on the basis of the received training sequence, to adapt a threshold or thresholds to allow the discrete levels to be distinguishable from each other. The training sequence T may comprise a plurality of elements at least one of which, in turn, represents each one of the discrete signal levels. The receiver generates a look-up-table to store the adapted thresholds.

Data transmission

Buffer allocation to repeated information blocks in data transmission,

Values, such as a set of coefficients in a transform-based video coder are to be transmitted sequentially in any one of a number of possible preset orders. The order to be selected is the one that results in the largest number of consecutive zeros (or low values) at the end of the sequence. Values are supplied (in an arbitrary sequence) with addresses, in parallel to a bank of assessment sections--one for each preset order--each of which translates the addresses into addresses representing a position in the respective order and records the highest for which the associated value is non-zero. The outputs of the sections are then compared to identify the lowest, and hence the optimum order of transmission.

Data encoding

Video coder

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Ipswich, United Kingdom

Andrew P Heron