How is overhead and signalling data calculated for T-hierarchy?
While calculating data rate/speed of T-carrier system/T-multiplexer output, we add some overhead and signalling data rate. How are they calculated?
1) T1-multiplexer ouptut-:
24 channels of 8-bit PCMed voice signal sampled at 8000 samples/sec are multiplexed into one T1 carrier system.
24*8+1=193 bits in 1 frame.
=1.544 Mbps (OK)
2) T2-multiplexer output-:
4 T1 carrier signals are multiplexed. i.e-:
1.544*46.176 (should be this, according to my calculation) BUT the speed is 6.3120 Mbps(0.136 Mbps extra for overhead and signalling data extra).
3) T3-multiplexer ouptut- -:
7 T2 carrier signals are multiplexed into one T3-carrier signal. i,.e
7*6.312=44.184(should be this, according to my calculation) BUT the speed is 44.736 Mbps(0.552 Mbps extra for overhead and signalling).
4) T4-multiplexer ouptut--:
6 T3-signals are multiplexed into one T4 carrier signals.
6*44.736=268.426 Mbps (should be this, according to my calculation)
BUT the speed is 274.176(5.76 Mbps extra)
How are they calculated? How are these overhead and signalling data rates calculated?
Why are they calculated? While calculating 1.544 Mbps as a T1 multiplexer output,we have already added a synchronization bit. Isn't it?
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