by VirtinsTech » Thu Aug 29, 2019 9:51 pm
There are a number of ways to do frquency response measurement using Multi-Instrument, even with a Lite or Standard version, such as:
1. Single-Channel Methods
1) FFT analysis + white noise excitation
very easy to setup, no synchronization between the signal generator and oscilloscope is required, average required and thus a bit slow. Rectangle window should be used in the Spectrum Analyzer.
2) FFT analysis + linear frequency sweep
oscilloscope frame width must be equal to or a little longer than signal generator frequency sweep duration. The oscilloscope trigger parameters need to be set properly to ensure that the entire sweep is right captured inside one oscilloscope frame, and the FFT Size must be equal to or greater than the Record Length of the oscilloscope. No average required. Rectangle window should be used in the Spectrum Analyzer.
3) FFT analysis + MLS
MLS length must be greater than FFT Size, the rest is the same as 1). Rectangle window should be used in the Spectrum Analyzer.
4) FFT analysis + Impulse
Oscilloscope trigger parameters needs to be set properly to capture the single impulse. Low measurement SNR. Rectangle window should be used in the Spectrum Analyzer.
5) FFT analysis + Multitones that aligns to FFT bands
easy to setup, no synchronization between the signal generator and oscilloscope is required, no average is required. Please refer to Section 4.3.1.8.2 of the software manual. Rectangle window should be used in the Spectrum Analyzer.
6) FFT analysis with peak hold + linear frequency sweep
Signal generator frequency sweep duration must be much greater than oscilloscope frame width to ensure no notch in the frequency response plot during the frequency sweep and peak holding process. Rectangle window should be used in the Spectrum Analyzer.
7) Octave analysis + pink noise
very easy to setup, no synchronization between the signal generator and oscilloscope is required, average required and thus a bit slow. Rectangle window should be used in the Spectrum Analyzer.
8) Octave analysis + logarithmic frequency sweep
oscilloscope frame width must be equal to or a little longer than signal generator frequency sweep duration, the oscilloscope trigger parameters need to be set properly to ensure that the entire sweep is right captured inside one oscilloscope frame, and the FFT Size must be equal to or greater than the Record Length of the oscilloscope. No average required. Rectangle window should be used in the Spectrum Analyzer.
9) Octave analysis + Multitones that aligns to octave bands
easy to setup, no synchronization between the signal generator and oscilloscope is required, no average is required. Please refer to Section 4.3.1.8.2 of the software manual. Rectangle window should be used in the Spectrum Analyzer.
10) FFT analysis + frequency stepped sinewave (Device Test Plan required)
highest accuracy, need to configure a device test plan, very slow. A low spectral leakge window such as Kaiser 6 is recommended in the Spectrum Analyzer.
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2. Two-Channel Methods (Multi-Instrument Pro required)
Bode Plot with any wide-band stimulus shown in 1.
Multi-Instrument comes with some pre-configured frequency response measurement Panel Setting Files. Some of them can be found in the third toolbar from the top (called Hot Panel Setting Toolbar): FRwhite, Frswph, Frswlog, Bode Plot. You may need to change the setting to suit your specific need (e.g. frequency range of interest, input & output voltage range, etc.)
As for impedance measurement, it is possible to do it without LCR meter add-on. For signal-channel method, please refer to Section 3.2.1.10 Impedance Measurement Mode. For two-channel method, please refer to Section 3.6.1.10 Impedance Analyzer Mode.