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:
Feb. 09, 1993
Filed:
May. 06, 1992
Nader Farahati, Cambridge, GB;
Technophone Ltd., Surrey, GB;
Abstract
A method of estimating a digitized data signal transmitted as a sequence of data symbols. The received signal is generally distorted by transmission through a dispersive communications channel. The received symbols can exist in a plurality of different states depending on the number of symbols in the data alphabet and the extent of intersymbol interference. In the present method a near-instaneous soft decision is made (without the need for memory storage) for each estimated symbol using the following main steps. 1) Determine for each state at a given time increment k the respective partial path metric (M.sub.A) in respect of the state transition corresponding to the transmission of a first symbol type (A). 2) Determine for each state at the same time increment k the respective partial path metric (M.sub.B) in respect of the state transition corresponding to the transmission of a second symbol type (B). 3) Select the maximum value (M.sub.Amax and M.sub.Bmax) of the first and second symbol type partial path metrics. 4) Difference the two maximum values at step 3 to yield an estimate of the transmitted data symbol in the form of a soft decision. The soft decision has the advantage that it conveys confidence level information about the estimate or decision made.