Auto-correlation arrangement

Claim 1

An auto-correlation apparatus for producing N auto-correlation values R(k), (k=0, . . . N-1) of an auto-correlation function of a sequence of digital samples x(n), (n=-∞ . . . , 0, . . . p) of a received input signal, such sample being encoded as words of "b" binary bits, each value R(k) being defined by the formula: ##EQU4## where M is the number of samples from which each value R(k) is to be determined; such apparatus comprising: a random access memory for storing at respective addresses therein a plurality of words each of which is a concatenation of a respective one of said digital sample words and a digital word representing a respective one of said auto-correlation values, such memory having a first input and a first output for signal sample words and a second input and second output for auto-correlation words; processing means having first and second inputs respectively coupled to said first and second outputs of said memory, a third input for receiving signal sample words, and an output coupled to said first input of said memory; such processing means comprising a multiplier for multiplying signal sample words received at the first and third inputs thereof and an adder for adding the products so produced to auto-correlation words received from the second output of said memory so as to derive further auto-correlation words, such further auto-correlation words being supplied by said adder to the second input of said memory for storage therein; and memory addressing and sequencing means for supplying said received signal sample words to said first and third inputs of said processing means, such addressing and sequencing means providing read and write cycles of address codes to said memory for storing therein and reading out therefrom signal sample words and auto-correlation words in accordance with said formula; whereby the auto-correlation values R(k) are stored in said memory and can be read therefrom at the second output thereof, said second output being the output terminal of the auto-correlation apparatus.