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 t - VTU e-Learning Centre

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d<br />

(i) Find D t <br />

dP<br />

d d <br />

1 <br />

i.e., D t <br />

2P<br />

log 2 P (<br />

1<br />

2P)<br />

log<br />

P<br />

2P<br />

dP dP<br />

<br />

<br />

2 <br />

<br />

1 <br />

<br />

<br />

2<br />

P<br />

log2<br />

e<br />

2 . P log<br />

<br />

2 e<br />

<br />

2 <br />

1 <br />

<br />

( 2)<br />

log <br />

2 log P<br />

2<br />

<br />

2 P<br />

P<br />

1 <br />

2 <br />

<br />

P<br />

<br />

2 <br />

<br />

<br />

Simplifying we get,<br />

d<br />

dP<br />

D log P log Q <br />

t<br />

Setting this to zero, you get<br />

log2 P = log2 Q + <br />

OR<br />

P = Q . 2 = Q . ,<br />

Where, = 2 <br />

How to get the optimum values of P & Q?<br />

2<br />

Substitute, P = Q in 2P + 2Q = 1<br />

i.e., 2Q + 2Q = 1<br />

OR<br />

1<br />

Q =<br />

2(<br />

1 )<br />

1<br />

Hence, P = Q . = . =<br />

2(<br />

1 )<br />

Step – 6: Channel capacity is,<br />

2<br />

<br />

2( 1 )<br />

2P<br />

log P 2Q<br />

log Q 2 <br />

C Max<br />

Q<br />

P(<br />

x)<br />

Q(<br />

X)<br />

Substituting for P & Q we get,<br />

-----(9)<br />

-----(10)<br />

-----(11)<br />

-----(12)

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