LAB ASSIGNMENT 11 (due 04/23/14)
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(20 pts.)

	
The signal in the file DIALTONES11.WAV is a sequence of eight DTMF 
tones obtained using a nonstandard set of frequencies (in Hz):

       Frow = [622 715 823 946]

       Fcol = [1183 1360 1565]

The signal vector x was generated using the function DTMFDIAL introduced
in Lab 11, with Frow and Fcol modified as above. Thus

	x = dtmfdial(key_string,Fs,T,Tpause)

The objective is to recover key_string from x.

i)	Use WAVREAD to import the vector x. What is its length N 
	and sampling rate Fs? Listen to x using SOUNDSC.

ii)	Plot x (in the time domain).  Use your plot to estimate the values
	of T and Tpause.

iii)	By examining the magnitude spectra of eight segments selected from
	x, determine key_string.

iv)	Using your results for Fs, T, Tpause and key_string, re-synthesize
	x (as, e.g., x_est) using the function DTMFDIAL with Frow and 
	Fcol modified as above.  Play it back using SOUNDSC to verify
	that it sounds like x.

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Submit (use exact file names as shown):

lastname_labhw_11.m

	State the values of N and Fs, obtained in part (i).  Give your
	estimates of T and Tpause from part (ii).  Give your answer
	for key_string, together with the MATLAB code used to obtain
	the first key in key_string.  Useful comments should be given.


lastname_labhw_11.pdf

	Graph of the magnitude spectrum used for obtaining the first
	key in key_string.

The zip or rar package should be named as lastname_labhw_11.zip / .rar, and 
should be uploaded from the upload link on the course lab web page 
<http://terpconnect.umd.edu/~jzsimon/enee222/lab.html>, or if not possible, 
emailed to enee222S2013@gmail.com.