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| Low frequencies Vector Network Analyzer, arduino based. |
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| Kleinstein:
The FFT is just an numerical efficient algrorithm calculating the DFT for all the bins. The result is essentially the same for the fourier-transformation for single bins by the basic formula. If at all there might be a minor difference due to rounding effects - here the FFT might be slightly worse. However with a 12 Bit ADC and thus likely 16 bit math, this should not be significant. I think the hardware analog to the DFT is rather confusing, and might be wrong. Fact is that it does not help all those extra bins by FFT if you don't need them. No SNR gain from calculating all all bins and ignoring it later. |
| MasterT:
Link to doc: http://www.analog.com/media/en/training-seminars/design-handbooks/Data-Conversion-Handbook/Chapter5.pdf page 57. |
| Kleinstein:
The same SNR gain as with the FFT also applies to calculating the Fourier components in an other way. So there is the gain from the reduced bandwidth, but this is not exclusive to an FFT. |
| MasterT:
--- Quote from: Kleinstein on September 22, 2018, 05:49:15 pm ---The same SNR gain as with the FFT also applies to calculating the Fourier components in an other way. So there is the gain from the reduced bandwidth, but this is not exclusive to an FFT. --- End quote --- No, it's not. Reducing bandwidth is usually done by RF preselectors. To do it in software, there is no alternative to FFT in efficiency. Difference is enormous, compare for example with BP FIR, I 'd estimate for fft-2048 fft is x10^6 times more efficient. |
| Bud:
This device is limited to series passive DUTs, correct? It can only work with 2 wire circuits that can be inserted between the source and receiver terminals, so no ground referenced and/or active circuits can be measured - is my understanding correct? |
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