The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 05, 1995
Filed:
May. 20, 1994
Chang-Tsou Liu, Fremont, CA (US);
Sierra Semiconductor Corporation, San Jose, CA (US);
Abstract
An efficient data storage scheme for an echo canceller for a high-speed modem provides for storing in bulk memory, instead of a trellis-encoded codewords, unencoded words of lesser length in bits. For a v.32terbo modem operating at 19,200 bps, for example, the unencoded word has only eight bits as compared to nine bits for the trellis-encoded codeword. Therefore, one memory word (16 bits) can be used to store two unencoded words, resulting in memory savings of 50%. More particularly, in accordance with one embodiment of the invention, full-duplex, high-speed data communications using echo cancellation is performed by storing in memory transmit data represented in a first form, at predetermined intervals substantially equal to a round-trip delay time, reading out transmit data from memory and trellis-encoding the transmit data to produce trellis-encoded transmit data, and performing echo cancellation using data derived from the trellis-encoded transmit data. In accordance with another embodiment of the invention, an apparatus for high-speed data communications includes first circuitry, having a first encoder, for producing first signal element data from multi-bit data symbols, an echo canceller, circuitry for storing the multi-bit data symbols and outputting delayed multi-bit data symbols each after a predetermined time, and second circuitry for producing from the delayed multi-bit data symbols second signal element data substantially identical to the first signal element data and for applying the second signal element data to the echo canceller.