Tuesday 24 September 2013

Bandwidth , Modulation and Data Rate.

Bandwidth is the range of frequency or band of frequency i.e the difference between the highest and the lowest frequency over which the data is to be transmitted.

Data rate is the rate at which data is transmitted from one point to another.


Modulation is the alteration in the characteristic of carrier frequency as per the baseband frequency , In digital communicationthe data rate depends on the selected modulation level.

The data rate will be lowest at BPSK and it will increase as we move towards the higher modulation level QAM64 , QAM 128 ...but the coverage range at same transmit power will decrease.

Larger channel bandwidth , higher modulation level and greater transmit power yields higher data rate.

BPSK   --- 1 bit / symbol
QPSK ---- 2 bit/ symbol
QAM 16  -- 4bit/symbol
QAM64 ---  6 bit/symbol.
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