Error rate measusrement using a comparison of received and reconstructed

Abstract

Input data symbols are written to a synchronization (sync) adder, which appends a pseudo randomly (PN) generated sync bit to generate a sync word. Sync words are sent to a receiver where synchronization is recovered. The receiver re-generates the same PN sequence that was generated at the transmitter. Synchronization recovery apparatus conceptually looks at each bit position to locate the appended PN sequence. When the sync bit position is found, the data stream is assembled into fixed length sync words and the data symbols of the sync words are written into a buffer at an address determined by the position of the sync bit in the PN sequence. Error rates in the data stream of sync words are measurable using a correlator network for reading the bit in the sync bit position of a sync word and for comparing that bit with its expected value in a reconstructed PN sequence to provide a difference value where the difference is a measure of the error rate in the data stream. Stated alternatively, the error rate can be measured by comparing the difference between the received PN sequence, as read from the received data stream, and the reconstructed PN sequence, as generated by the PN generator at the receiver. The error rate measurement does not expressly measure errors in the data symbols but rather uses the known PN sequence that is used for synchronization (recovery) purposes for yet another purpose, i.e. to provide a measure of the channel error rate.