Abstract: A method for validating Manchester Encoded Gray Coded serial binary signals wherein the Manchester Encoded, Gray Coded data word is first tested for missing data bits by constructing first and second copies of the data word wherein the first copy has a one inserted in a position where a missing data bits is detected and the second copy has a zero inserted in a position where a missing data bit was detected. Thereafter, the first and second copies of the data word are then converted from Gray Code into corresponding coded binary words and the second binary word is subtracted from the first binary word to obtain an absolute value. Only when the absolute value is one is the missing bit the least significant and the received data word valid information.

Abstract: In systems requiring multiple identical digital correlators the original m-bit counter for each correlator can be replaced by an n-bit multi-channel counter. The most significant bit of each n-bit counter is sampled every 2.sup.n-1 clock cycles and the results are stored in dual port memory. Stored input counter samples are converted into a series of binary words which are multiplexed to one of two signal outputs. The dual port memory allows current samples from the input counters to be written on port A, while previously written samples are time multiplexed and read to the output counters on port B. This design not only reduces the number of parts needed for counters but also the buffers needed for so many counters to appear on the same computer bus. In addition, the maximum delay between the sampling of any correlator is greatly reduced.