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tfe

(/tools/hpmatlab/toolbox/signal/tfe.m)

Function Synopsis

[Txy, f] = tfe(P1,P2,P3,P4,P5,P6,P7)

Help text

 TFE	Transfer Function Estimate 
	Txy = TFE(X,Y,NFFT,Fs,WINDOW) estimates the transfer function of the 
	system with input X and output Y using Welch's averaged periodogram 
	method.  X and Y are divided into overlapping sections, each of which 
	is detrended, then windowed by the WINDOW parameter, then zero-padded 
	to length NFFT.  The magnitude squared of the length NFFT DFTs of the 
	sections of X are averaged to form Pxx, the Power Spectral Density of X.
	The products of the length NFFT DFTs of the sections of X and Y are 
	averaged to form Pxy, the Cross Spectral Density of X and Y.  Txy
	is the quotient of Pxy and Pxx; it has length NFFT/2+1 for NFFT even, 
	(NFFT+1)/2 for NFFT odd, or NFFT if X or Y is complex. If you specify 
	a scalar for WINDOW, a Hanning window of that length is used.  Fs is 
	the sampling frequency which does not effect the transfer function 
	estimate but is used for scaling of plots.

	[Txy,F] = TFE(X,Y,NFFT,Fs,WINDOW,NOVERLAP) returns a vector of freq-
	uencies the same size as Txy at which the transfer function is 
	estimated, and overlaps the sections of X and Y by NOVERLAP samples.

	TFE(X,Y,...,DFLAG), where DFLAG can be 'linear', 'mean' or 'none', 
	specifies a detrending mode for the prewindowed sections of X and Y.
	DFLAG can take the place of any parameter in the parameter list
	(besides X and Y) as long as it is last, e.g. TFE(X,Y,'none');
	
	TFE with no output arguments plots the transfer function estimate in 
	the current figure window.

	The default values for the parameters are NFFT = 256 (or LENGTH(X),
	whichever is smaller), NOVERLAP = 0, WINDOW = HANNING(NFFT), Fs = 2, 
	P = .95, and DFLAG = 'linear'.  You can obtain a default parameter by 
	leaving it off or inserting an empty matrix [], e.g. TFE(X,Y,[],10000).

	See also PSD, CSD, COHERE
	ETFE, SPA, and ARX in the Identification Toolbox.

Cross-Reference Information

This function calls
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