Computes the single-sided Coherence Function, the averaged single-sided Cross Power Spectrum, the averaged single-sided Frequency Response, or transfer function, and the Impulse Response. Details
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Stimulus Signal is a 2D array containing a time-domain signal, usually the network stimulus. Each row in the Stimulus Signal array represents one frame of the network stimulus and is associated with one row of the Response Signal array which represents one frame of the network response. | ||||
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Response Signal is a 2D array containing a time-domain signal, usually the network response. | ||||
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dt is the sample period of the time-domain signal, usually in seconds.
dt is also ![]() ![]() |
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Cross Power Spectrum is the averaged, single-sided cross power spectrum between Stimulus Signal and Response Signal.
The output is a cluster of the Magnitude array and the Phase array.
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Frequency Response is the averaged, single-sided transfer function between Stimulus Signal and Response Signal.
The output is a cluster of the Magnitude array and the Phase array.
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Coherence Function is the single-sided coherence function spectrum.
Coherence Function is unitless and ranges from 0, no coherence, to 1, complete coherence. Coherence Function shows the frequency content of Response Signal due to Stimulus Signal and measures the validity of the network frequency response measurement. The Network Functions (avg) VI computes this value as
The Network Functions (avg) VI requires more than one set of data for both Stimulus Signal and Response Signal to calculate Coherence Function properly. If your input arrays contain only one reading, that is, one row of data each, the Coherence Function will register unity at all frequencies. |
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Impulse Response is the inverse real FFT of the averaged, single-sided transfer function between Stimulus Signal and Response Signal. This parameter is unitless. | ||||
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df is the line frequency interval of the power spectrum in Hertz, if dt is in seconds. |
The Network Functions (avg) VI computes coherence, averaged cross power spectrum magnitude and phase, averaged transfer function, or frequency response, and averaged impulse response.
You usually compute these functions on the stimulus and response signals from a network under test.
The network functions are computed as
avg Cross Power Spectrum = avg of
avg Frequency Response = avg /avg
avg Impulse Response = Inverse Real FFT(avg Frequency Response),
where
x is Stimulus Signal y is Response SignalCoherence Function shows the frequency content of Response Signal, y, due to Stimulus Signal, x, and measures the validity of the network frequency response measurement.
You can use the Network Functions (avg) VI to measure the coherence between any two signals. The Network Functions (avg) VI averages multiple stimulus and response signals to get valid coherence measurements.