Abstract: An improved method for Time Division Multiple Access (TDMA) communications particularly applicable to a network comprising transmitters having significantly different transmission paths to a common receiver. The common receiver measures the response time from each transmitter, relative to a common time reference, then instructs each transmitter to delay all subsequent responses by an amount specific to each transmitter, as determined from these measured response times. This imposed delay results in a more time efficient TDMA protocol, improved error detection capability, and improved security capabilities. This invention is particularly applicable to bi-directional communications to and from a provider of Cable TV, Telephony, and Data Services.

Abstract: An improved method for signal demodulation, based upon the assessment of an error statistic which is independent of the content of the data stream. To determine the appropriate sampling point within a data period, multiple sampling points are utilized to generate a set of alternative decodings of the data stream. Associated with each of these alternative sets is an error statistic which is computed based upon a known characteristic of the transmitted stream. For example, in Differential QPSK, the encoded phase change is known to be a multiple of 90 degrees. The error statistic would be a function of the difference between each sampled phase and the nearest multiple of 90 degrees. This error statistic provides a quantifiable measure of quality and noise margin associated with each sampling point. The decoded stream associated with the error statistic of highest quality is then selected as the proper decoding of the transmitted data stream.