Patent ID: 7379957

Claim:
A method of demodulating a square root for processing digital signals, suitable for finding an approximate root-mean-square value of a pair of input signals having values I and Q through a formula aX+bY such that X=|X|, Y=|Q| and a and b are the coefficients of X and Y, the method comprising the steps of: defining the larger one of the absolute values |I| and |Q| to be |l arg e| and the smaller one of the absolute values |I| and |Q| to be |small|; defining a first determining form A|small|≦A|l arg e|≦B|small| and A|l arg e|=A|small|, wherein A and B are positive numbers; defining a second determining form A|small|≦A|l arg e|≦B|small| and A|l arg e|≠B|small|; outputting a first signal having a value |l arg e|+2 −5 |l arg e| as an approximate root-mean-square value for the input signals having values I and Q when the relation between |l arg e| and |small| conforms to the first determining form; and outputting a second signal having a value |l arg e|+2 −6 |l arg e| as an approximate root-mean-square value for the input signals having values I and Q when the relation between |l arg e| and |small| conforms to the second determining form.