function WNNOISE, x,QMF, TT
;+
;NAME:
;	WNNOISE
;
;PURPOSE:
;	This function normalizes the signal to noise level 1. 
;
;CATEGORY:
;	Wavelets.
;
;CALLING SEQUENCE:
;	y = WNNOISE(x,QMF)
;
;INPUTS:
;   x =  1-d/2-d signal 
;   QMF = quadrature mirror filter 
;
;OUTPUTS:
;   y = 1-d signal, scaled so wavelet coefficients 
;         at finest level have median absolute deviation 1 
;	TT = 'I' if image and 'S' if signal
;
;EXAMPLE: 
;	IDL> ;Truncate sig array appropriately and get QMF
;	IDL> WINTWAVE, sig, WaveType, ParVal, QMF, LD
;	IDL> tt = 'S' if 1D dataset or tt = 'I' if 2D dataset
;	IDL> sig = WNNOISE(sig,QMF, tt)
;	IDL> If tt EQ 'S' then WPLOTIT, st, 1, sig ELSE WPLOTIT, st, 10, sig
;
;NOTES:
;   This is required pre-processing to use any of the DeNoising 
;   tools on naturally-occurring data 
;
;SEE ALSO:
;   wpdnoise 
;
;MODIFICATION HISTORY:
; 	Written by:	Amara Graps		September, 1995
;Translated from MatLab Wavelab routine: normnoise.m
;-


TT = WSIGTYPE(x, len, error)

CASE error OF
	1: BEGIN
		;Valid array or matrix
	
		CASE TT OF
			'I': BEGIN
				;byte image.. normalize row by row
				y = BYTARR(len, len)		;initialize y
				FOR ix = 0, len-1 DO BEGIN
					row = x(*, ix)
					u = WDNDYDHI(row,QMF) 
					s = MEDIAN(ABS(u))/ .6745	;make byte?
					y(0,ix) = row /s 	
					END	;end				
				END
			'S': BEGIN
				;signal
				u = WDNDYDHI(x,QMF) 
				s = MEDIAN(ABS(u))/ .6745 
				y = x /s 
				END				
		ENDCASE	;TT	
		END	;valid array or matrix
		
	ELSE: PRINT, 'Not valid data/signal array or matrix!'

ENDCASE		;error
     
;    
; Algorithm Source:  WaveLab Version 0.600
; WaveLab WWW site: http://playfair.stanford.edu/ 
; WaveLab Questions? e-mail wavelab@playfair.stanford.edu
;    
     
 
RETURN, y  
END  
;***************************************************