The raised cosine pulse p(t) is used for zero ISI in digital communications. The expression for p(t) with unity roll-off factor is given by $$p\left( t \right) = \frac{{\sin 4\pi Wt}}{{4\pi Wt\left( {1 - 16{W^2}{t^2}} \right)}}.$$      The value of p(t) at $$t = \frac{1}{{4W}}$$  is

A 1.0 kHz signal is flat top sampled at the rate of 1800 samples/sec and the samples are applied to an ideal rectangular LPF with cut-off frequency of 1100 Hz, then the output of the filter contains

A. Only 800 Hz component

B. 800 Hz and 900 Hz components

C. 800 Hz and 1000 Hz components

D. 800 Hz, 900 Hz and 100 Hz components

A 4 GHz carrier is DSB-SC modulated by a low pass message signal with maximum frequency of 2 MHz. The resultant signal is to be ideally sampled. The minimum frequency of the sampling impulse train should be

A. 4 MHz

B. 8 MHz

C. 8 GHz

D. 8.004 GHz

Increased pulse width in the flat top sampling, leads to

A. Attenuation of high frequencies in reproduction

B. Attenuation of low frequencies in reproduction

C. Greater aliasing errors in reproduction.

D. No harmful effects in reproduction

A video transmission system transmits 625 picture frames per second. Each frame consists of a 400 × 400 pixel grid with 64 intensity levels per pixel. The data rate of the system is

A. 16 Mbps

B. 100 Mbps

C. 600 Mbps

D. 6.4 Gbps