Draw a block diagram of PCM clearly explaining how a basic frame
structure is achieved in each block.
|Total number of bits in the
||8 * 32
|Data rate of the frame
|Time taken for one slot
|Data rate of a slot
This gives a PCM frame of 32 time slots (each
with 64Kbit/s rate) at a data rate of
2.048Mbit/s where time slot 0 is used for synchronizing while time
slot 16 is used for
A PCM system will comprise of sampling, quantizing and encoding.
Explain each block. clearly.
Sampling a band limited analog signal at a frequency higher than
maximum frequency of the analog signal
Non-linear quantizing of sampled values
Sampling Quantizing Encoding
Assigning ‘0’s and ‘1’s for the quantized
Sign: + or – (1-bit)
Segment No.: 3-bits
Level No.: 4-bits
Three consecutive voice samples in a 30 channel PCM system are identified
+50V, 0V, -68V
Draw the wave forms that you can observe in the transmission media,
assuming HDB3 transcoding.
(Assuming A-Law compression for non-linear quantizing)