Network Functions (avg) (Not in Base Package)

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  

	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.
	Response Signal is a 2D array containing a time-domain signal, usually the network response.
	dt is the sample period of the time-domain signal, usually in seconds. dt is also where fs is the sampling frequency of the time-domain signal.
	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. Magnitude is the single-sided, cross power spectrum between Stimulus Signal and Response Signal in volts rms squared if the input signals are in volts. If the input signals are not in volts, the results are in input signal units rms squared. Phase is the phase spectrum in radians showing the difference between the phases of Stimulus Signal and Response Signal.
	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. Magnitude is the single-sided, frequency response specimen of the network. This is the averaged amplitude gain of the network. Phase is the phase spectrum in radians showing the difference between the phases of Stimulus Signal and Response Signal.
	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.
	Impulse Response is the inverse real FFT of the averaged, single-sided transfer function between Stimulus Signal and Response Signal. This parameter is unitless.
	df is the frequency interval of the power spectrum in hertz, if dt is in seconds.

Network Functions (avg) Details

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 S_xy(f)

avg Frequency Response = avg S_xy(f)/avg S_xx(f)

avg Impulse Response = Inverse Real FFT(avg Frequency Response),

where

x is Stimulus Signal,

y is Response Signal,

S_xy(f) is the two-sided cross power spectrum of x and y,

S_xx(f) is the two-sided auto power spectrum of x,

S_yy(f) is the two-sided auto power spectrum of y,

Coherence 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.