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4 Cards in this Set
- Front
- Back
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Pulse Code Modulation(PCM) |
-Common technique to convert analog sinal to digital signal. 1.analog signal is sampled 2.sampled signal is quantized 3.quantized value are encoded as a stream of bits. |
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Sampling |
-First step in pcm. -analog signal is samples every T(s) sec where T(s) is sample interval of period. Inverse of sample interval is Sample rate or Sample frequency,denoted as f(s)=1/T(s). -sampling process is referred as Pulse Amplitude Modulation(PAM). |
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Quantization |
-Second step in PCM. -result of sampling is a series of pulses with ampli between max ampli & min ampli. -involve following steps. 1.assume original analog signal has ampli betn Vmax & V min. 2.divide the range into L zones, each of height delta=(Vmax-Vmin)/L. 3.assign quantized value of 0 t L-1 to the midpoint of each zone. 4.approax value of sample ampli to quantized values. |
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Encoding |
-Thrid step in PCM. -after each sample is quantized and no. of bits per sample is decided and each sample is changed to an n(b)-bit code word. -no. of bits on each sample is determined by from the no. of quantization level(L). - n(b)=log(2) L |
