a bit - error - rate tester provides for testing of links with different numbers of channels without replacing or reconfiguring an included pseudorandom word sequence generator . the tester includes a transmitter and a receiver , each with generators for parallel evenly staggered pseudorandom bit sequence 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 .