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, 1989
Filed:
Mar. 02, 1988
Jan Boer, AN Utrecht, NL;
Wilhelmus J Diepstraten, VL Diessen, NL;
NCR Corporation, Dayton, OH (US);
Abstract
A multipoint data modem communication system includes a control modem (12) and a plurality of tributary modems (14, 16, 18). During an initial training mode, receiver parameters and equalizer coefficients are determined and stored in a storage device (156) in the control modem receiver at addresses associated with the tributary modems. During subsequent relatively short training signals, the stored parameters are accessed. The remote modems transmit identification address tones in parallel with the subsequent training signals, at frequencies separated by 200 Hz intervals from the training signal spectrum frequencies. A plurality of Discrete Fourier Transform (DFT) filter circuits (190) are utilized to determine the transmitted addresses by measuring the correlation of the received signal with locally-generated frequencies.