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From: alex65111 on 19 May 2010 14:39 Let's assume at us is available 1024 discrete samples. Further it is carried out FFT. Whether probably from received 1024 spectral samples to receive 256 spectral samples which are equivalent as if we have executed FFT only on 256 input discrete samples?
From: Jerry Avins on 19 May 2010 15:19 On 5/19/2010 2:39 PM, alex65111 wrote: > Let's assume at us is available 1024 discrete samples. Further it is > carried out FFT. Whether probably from received 1024 spectral samples to > receive 256 spectral samples which are equivalent as if we have executed > FFT only on 256 input discrete samples? I'm sorry. I can decode the first two sentences, but not the last one. I simply can't imagine what you are trying to ask. Jerry -- "I view the progress of science as ... the slow erosion of the tendency to dichotomize." --Barbara Smuts, U. Mich. �����������������������������������������������������������������������
From: alex65111 on 19 May 2010 15:42 >On 5/19/2010 2:39 PM, alex65111 wrote: >> Let's assume at us is available 1024 discrete samples. Further it is >> carried out FFT. Whether probably from received 1024 spectral samples to >> receive 256 spectral samples which are equivalent as if we have executed >> FFT only on 256 input discrete samples? > >I'm sorry. I can decode the first two sentences, but not the last one. I >simply can't imagine what you are trying to ask. > >Jerry >-- >"I view the progress of science as ... the slow erosion of the tendency > to dichotomize." --Barbara Smuts, U. Mich. >??????????????????????????????????????????????????????????????????????? > Let's assume there are 1024 samples X = [X1...X1024]. Y=FFT(X), Y =[Y1...Y1024]. It is required from Y to receive Z, where Z=FFT(X1...X256) or Z=FFT((X1...X256 + X257...X512 + X513...X768 + X769...X1024)/4).
From: Jerry Avins on 19 May 2010 15:56 On 5/19/2010 3:42 PM, alex65111 wrote: >> On 5/19/2010 2:39 PM, alex65111 wrote: >>> Let's assume at us is available 1024 discrete samples. Further it is >>> carried out FFT. Whether probably from received 1024 spectral samples > to >>> receive 256 spectral samples which are equivalent as if we have > executed >>> FFT only on 256 input discrete samples? >> >> I'm sorry. I can decode the first two sentences, but not the last one. I >> simply can't imagine what you are trying to ask. >> >> Jerry >> -- >> "I view the progress of science as ... the slow erosion of the tendency >> to dichotomize." --Barbara Smuts, U. Mich. >> ??????????????????????????????????????????????????????????????????????? >> > > > Let's assume there are 1024 samples X = [X1...X1024]. > Y=FFT(X), Y =[Y1...Y1024]. > It is required from Y to receive Z, where Z=FFT(X1...X256) > or > Z=FFT((X1...X256 + X257...X512 + X513...X768 + X769...X1024)/4). Reconstitute the original samples with IFFT(Y) and go from there. Jerry -- "I view the progress of science as ... the slow erosion of the tendency to dichotomize." --Barbara Smuts, U. Mich. �����������������������������������������������������������������������
From: alex65111 on 19 May 2010 16:05
>Reconstitute the original samples with IFFT(Y) and go from there. > >Jerry >-- >"I view the progress of science as ... the slow erosion of the tendency > to dichotomize." --Barbara Smuts, U. Mich. >??????????????????????????????????????????????????????????????????????? > The problem to receive result without reconstruction, operating only with spectral samples. |