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:
Mar. 28, 2006
Filed:
Apr. 03, 2000
Robin Paul Rickard, Harlow, GB;
John Christopher Greenwood, Nr Chippenham Wiltshire, GB;
Philip Athelstan Wainman, Ongar, GB;
Robin Paul Rickard, Harlow, GB;
John Christopher Greenwood, Nr Chippenham Wiltshire, GB;
Philip Athelstan Wainman, Ongar, GB;
Nortel Networks Limited, St. Laurent, CA;
Abstract
In a frequency division multiplexed (FDM) telecommunications system, data is encoded on carriers stepped in frequency within each of a sequence of symbols. The carriers may be arranged in groups between which there are frequency bands in which interference may be expected. The symbols are of predetermined length and are transmitted at a predetermined frequency, and synchronisation to the symbols is needed at a receiver in order to decode the received symbols. During a synchronisation time, a sequence of synchronisation symbols carrying predetermined data is transmitted. The receiver performs unsynchronised Fast Fourier Transforms (FFTs) on the received symbols, starting successive FFTs at about the predetermined symbol frequency. The output of each FFT is evaluated by removing the predetermined data coding from the detected carriers and summing the detected phase differences between the carriers. If the sum exceeds a predetermined threshold, synchronisation between the FFT and a symbol is declared and used to synchronise subsequent FFTs to subsequent symbols.