| 摘要 |
PROBLEM TO BE SOLVED: To bring into play the characteristics of a high-speed Hadamard transformation in a back diffusion circuit, while processing at an operation amount equal to or less than a case, where back diffusion is carried out for each channel, even when the number of channels to be demodulated is small. SOLUTION: When the number of channels to be demodulated is small, not all operations of a high-speed Hadamard transformation are carried out, and a specific channel is demodulated in a back diffusion. When a channel n, in correspondence with an n-th diffusion system, is demodulated, the calculations xi(m)=xi-1(m)+xi-1(m+2i-1), mmod 2i<2i-1, xi(m)=xi-1(m-2i-1)-xi-1(m), m mod 2i>=2i-1 are carried out only for m with m mod 2i=n mod 2i and to i=1,..., log2, and the inverse diffusion demodulation of the channel n is carried out. Since the number of times of addition and subtraction in this case is L/2i in the i-th step operation, and the total of all steps becomes L-1, this becomes identical in number of times, as when the back diffusion is carried out for each channel. |
