Digital signal detection with signal buffering and message insertion

Abstract

An improved digital signal detector for indicating the presence of digital data used in a communication system. While attempting to detect valid data, the detector buffers an incoming signal in a first-in, first-out buffer and allows locally generated data, instead of the buffered signal, to be coupled to an output. After detecting valid data, the detector estimates where in the buffer valid data commenced and either releases data from that point or further delays the signal up to the maximum length of the buffer before releasing it to the output. The invention provides high sensitivity and rapid detection, reduces variation in detection time over previous methods, and allows locally generated data to be inserted into the signal path without loss of valid data. The invention would find application in digital systems that require detection at high bit-error-rates without losing valid data and without relying on a particular message format to assist detection or in systems that locally insert preamble sequences for synchronization and control.