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Q1:
Consider a baseband binary PAM receiver shown below. The additive channel noise n(t) is whit with power spectral density SN(f) = N0/2 = 10-20 W/Hz. The low-pass filter is ideal with unity gain and cutoff frequency 1 MHz. Let Yk represent the random variable y(tk).
Yk = nNk if transmitted bit bk = 0
Yk = a + Nk if transmitted bit bk = 1
Where Nk represents the noise sample value. The noise sample has a probability density function, PNk(n) = 0.5ae-a|n| (This has mean zero and variance 2/a2). Assume transmitted bits to be equiprobable and threshold z is set to a/2 = 10-6 V.

The value of the parameter a (in V-1) is

A 1010

B 107

C 1.414 x 10-10

D 2 x 10-20

ANS:B - 107

→ exist in fourier transform Variance = which is equal to power since mean is zero ⇒ a = 107.



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