Apparatus for comparing two binary signals
AssigneeNational Research Development Corporation
InventorsJames Redmon Jordan, Robert Graham Kelly
Life of this patent
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Abstract
In known correlation apparatus for identifying the delay between two signals, the current polarity of the lagging signal is repeatedly compared with sets of successively earlier samples of the polarity of the leading signal which are temporarily stored in a binary word register, the results are counted for each digit position of the word, and a signal is generated indicating the position for which the count first reaches a given value. Such apparatus is improved by using as the register a plurality of serially connected shift registers which are operated at different integrally related speeds.
Claims8
An apparatus for comparing two binary signals, comprising:
- a binary word register comprising a plurality of binary shift registers each having a serial input and each comprising a set of serially connected stages, said shift registers being connected in a serial chain so that the stages of all said shift registers form a sequence defining the sequence of digit positions of a binary word stored in said binary word register;
- means for operating said binary word register so that it stores temporarily, in respect of each of a series of regularly recurrent instants, a binary word the digits of which correspond in sequence to the states of a first one of said two binary signals at times earlier by successively greater amounts than the relevant one of said series of instants, said means comprising means for operating said shift registers individually so that those digits of the binary word temporarily stored in the first of said shift registers in said chain can change state for each of the instants of said series while those digits of the binary word temporarily stored in any other of said shift registers can change state only for each Nth one of the instants for which those digits of the binary word temporarily stored in the preceding one of said shift registers in said chain can change state, N being a small integer;
- means for effecting a sequence of comparison operations in each of which the state of the second of said two binary signals is compared with each of the digits of the binary word temporarily stored in said binary word register;
- means for counting the results of the comparisons separately for each of said digit positions;
- and
- signalling means for generating a signal in response to the reaching of a given value by the count for any one of said digit positions, said signalling means comprising means causing the signal to have a form indicating for which of said digit positions the count first reached said given value.
Dependencies are inferred from the claim text.