| 摘要 |
<p>PURPOSE:To omit a multiplier for reduction of the scale of circuits by using the difference between coefficients W<n> and W<n-1> as a coefficient W<n> which is multiplied by the time signal of a relational formula of discrete Fourier transform. CONSTITUTION:A calculation order is changed as follows in order to obtain a difference coefficient in place of a coefficient W<ik> for a Fourier transform equation (1). That is, N pieces of X(k) and 0<=k<=N-1 are first calculated to a single x(i). The calculation order related to the (k) of the X(k) is decided so that the coefficient W<ik> to be multiplied is set in the order of W<0>, W<1>-WN<-1>. For this purpose, the X(k) is stored in a 2nd memory 7 and the address signal is changed when the X(k) is read out of the circuit 7. This address signal is obtained from the value of a sample number (i) of the x(i) through calculation of the residue. In this case, the number N of samples N is set at a prime number approximate to 1,000 and therefore a secondary difference is equal to 0 and + or -1. Thus it is possible to calculate the Fourier transform X(k) with no use of a multiplier.</p> |
