United States Patent [is>] [ii] Patent Number: 4,791,653
McFarland et al.  Date of Patent: Dec. 13, 1988
 PSEUDORANDOM WORD SEQUENCE SYNCHRONIZER
 Inventors: William J. McFarland, Mountain
View; Richard C. Walker, Palo Alto, both of Calif.
 Assignee: Hewlett-Packard Company, Palo Alto, Calif.
 Appl. No.: 89,291
 Filed: Aug. 25,1987
 Int. Q." H04L 7/00
 U.S. CI 375/115; 375/116;
 Field of Search 375/106, 115, 114, 116;
371/42, 46, 47; 370/107
 References Cited
U.S. PATENT DOCUMENTS
4,442,527 4/1984 Munday 375/115 X
4,663,766 5/1987 Bremer 375/114 X
John J. O'Reilly, "The Radio and Electronic Engineer", vol. 45, No. 4, pp. 171-176, Apr. 1975. I. Rampaigul and J. J. O'Reilly, "Series-Parallel Bit— Error-Ratio Measurement for High Digit Rate Transmission Systems", paper presented at an International Conference on Measurement for Telecommunication, 1985.
Primary Examiner—A. D. Pellinen
Assistant Examiner—Derek S. Jennings
Attorney, Agent, or Firm—John A. Frazzini; Edward Y.
A bit-error-rate tester provides for testing of links with different numbers of channels without replacing or reconfiguring an included pseudorandom word sequence (PRWS) generator. The tester includes a transmitter and a receiver, each with generators for parallel evenly staggered pseudorandom bit sequence (PRBS) replicas collectively constituting the PRWS. The receiver generator is a copy of the transmitter generator so that it can predict the PRWS received from the transmitter. Comparators are provided so that incoming and locally generating sequences can be compared to determine bit error rates. Synchronization of the receiver generator is effected using a pattern detector coupled to at least one reception line. When a predetermined pattern is detected, an injector injects registers of the receiver generator with a predetermined bit pattern. Afterwards, the receiver generator autonomously generates its PRWS synchronously with the PRWS received from the transmitting generator. A further embodiment provides for rerouting of crossed transmission channels as well as synchronization. In either case, there is no requirement that all available channels be active to effect synchronization.
5 Claims, 3 Drawing Sheets