I have both PCSU1000 and PCGU1000 and I like Circuit Analizer feature of this setup.
But as I see on Bode Plotter, I can measure Vrms (and Phase) correctly in narrow 0…-25dB range. Of course, I can turn on ‘Automatic Voltage Scale’, but it doesn’t help if I measure milivolts, or have a noisy circuit.
But if we assume that circuit has linear response, we can filter out all frequencies except desired, and calculate it’s amplitude and phase much better.
To measure V and phase of desired frequency, I propose to use a part of ‘simple’ Fourier transform:
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apply one of ‘FFT window’ to input data, for exapmle, Hamming window-
for(i=0, i<4096,++i) data[i] = (1.0-cos(i/2048.0pi)); -
integrate data with sin(ik) and cos(ik) (where k is calculated from frequency and time/sample rate). As a result you get ‘x’ and ‘y’ amplitude values.
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Calculate phaseCH1 = atan2(x,y); VrmsCH1 = sqrt(xx + yy);
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If you need to show phase on plot, do the same calculations with second channel and get final Phase = phaseCH1 - phaseCH2 (rounded to 0…360 region)
I think this approach can give us extra 20…30dB of signal/noise resolution (0…-50dB range).
This approach is not valid for nonlinear circuits (such as frequency multipliers), so I think it can be an option in menu.