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:
Oct. 29, 2002
Filed:
Sep. 30, 1992
Robert G. Wilkinson, Portsmouth, GB;
Abstract
A high frequency communications system comprises eight multiplexed ( ) spread spectrum channels with data in each channel transmitted using, for example, 32 semi-orthogonal codes to enable 5 bits of data to be sent for every coded symbol transmitted. The multiplexed data is connected to a phase shift key (PSK) modulator ( ) to modulate an hf carrier. At the receiver, inband interference is removed by frequency excision ( ) or weighting, making use of the facts that the interference is generally narrow-band and the spectrum of the frequency components of the received signal should be symmetrical about the carrier frequency. The detected signal is Fourier transformed by an FFT processor ( ) and then connected to an interference exciser ( ) where signal samples symmetrical about the carrier frequency are compared and any sample which exceeds the respective symmetrical sample by more than a predetermined threshold is excised or given a low weighting. After interference excision the remaining signal is connected to a bank ( ) of 32 cross-correlation detectors before connection to a maximum likelihood detector and decoder ( ).