Page 200 - Asterisk™: The Future of Telephony

0110
0101
0100
0011
0010
0001
Amplitude 0000
1000
1001
1010
1011
1100
1101
Samples

Figure 7-2. A simple sinusoidal (sine) wave

0110
0101
0100
0011
0010
0001
Amplitude 0000

1000
1001
1010
1011
1100
1101
Samples

Figure 7-3. Sampling our sine wave using four bits
Figure 7-3 shows the information that will be captured when we sample our sine wave
at four-bit resolution.

At each time interval, we measure the amplitude of the wave and record the corre-
sponding intensity—in other words, we sample it. You will notice that the four-bit
resolution limits our accuracy. The first sample has to be rounded to 0011, and the next
quantization yields a sample of 0101. Then comes 0100, followed by 1001, 1011, and so
forth. In total, we have 14 samples (in reality, several thousand samples must be taken
per second).

172 | Chapter 7: Understanding Telephony