project3

# project3 - ECE 301 Project 3 Telephone Dialing Due July 8...

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ECE 301 Project 3: Telephone Dialing Due July 8, 2011 Introduction This project is intended to familiarize you with the concepts of frequency response and ﬁltering. You will use the knowledge and material covered in class to synthesize and detect the tones made by touch-tone telephones. All touch-tone telephones use a combination of two tones to encode the buttons pressed. See Table 1 below to get the combinations. For example, any time button “1” is pressed, the phone transmits a combination of 697 Hz and 1209 Hz on the phone line. The switching equipment then detects these frequencies and decodes the button pressed. These combinations of frequencies were chosen to be signiﬁcantly unnatural and therefore unlikely to be picked up by the receiver by mistake. Part 1: Synthesizing Tones Write Matlab code to generate the corresponding tones in response to a button press. It should be a function of the form: y = tone gen(t, button) where t is a time vector during which the tones should be active and button is a character corresponding to a button. A sample call of the function would be something like y = tone gen(0:(1/4000):1, ‘5’) , and would produce a vector, y , containing frequencies 770 Hz and 1336 Hz. If you would like to listen to the output of your function, use the

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## This note was uploaded on 02/14/2012 for the course ECE 301 taught by Professor V."ragu"balakrishnan during the Fall '06 term at Purdue.

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project3 - ECE 301 Project 3 Telephone Dialing Due July 8...

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