Infinite Impulse Response Filter Design - Digital Signal Processing: Fundamentals and Applications - page 403

1209 Hz 133 6 Hz 147 7 Hz 163 3 Hz

697 Hz

3 A

1 2

770 Hz

4 5 6

B

7 8 9 C

852 Hz

941 Hz

0 # D

*

FIGURE 8.61

DTMF key frequencies.

8.53. DTMF tone generation and detection:
Implement the DTMF tone generation and detection according to Section 8.11 with the
following specifications:
a. Input keys: 1, 2, 3, 4, 5, 6, 7, 8, 9, *, 0, #, A, B, C, D (key frequencies are given in
Figure 8.61 ) .
b. Sampling frequency is 8,000 Hz.
c. Program will respond to each input key with its DTMF tone and display the detected key.