H - Electricity – 04 – B
Patent
H - Electricity
04
B
325/16
H04B 3/14 (2006.01)
Patent
CA 1182526
Abstract of the Invention Modem apparatus comprising circuitry featuring two loosely coupled microprocessors; and a receiver featuring means for inhibiting the updating of adaptive equalizer coefficients in the presence of periodic data, improved automatic gain control and carrier detect/loss circuitry, improved circuitry for filtering and demodulating received signals, and improved timing recovery and timing initialization circuitry. Background of the Invention This invention relates in several aspects to modem apparatus in which a modulated carrier signal represents digital bits, and in one aspect to modem apparatus in which a received, modulated double sideband carrier signal, representing digital bits, is converted to a stream of digital samples which are then filtered and demodulated. Recently, efforts have been made to use programmable microprocessing circuitry to carry out certain modem functions, e.g., as described in Walsh et al. U.S. Patent No. 4,085,449. P. J. Van Gerwen, N.A.M. Verhoeckx, H. A. Van Essen and F.A.M. Snijders, "Microprocessor Implementation of High-Speed Data Modems", IEEE Transactions on Communica- tions, Vol. COM-25, No. 2, February 1977, pp. 238-250 shows a microprocessor implemented modem receiver wherein an incoming QAM signal passes through two digital phase- splitting filters prior to demodulation.
374535
Codex Corporation
Smart & Biggar
LandOfFree
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