Communication Systems Questions

• If C is capacity of noisy channel, (bits/s), δf is bandwidth Hz and S/N is signal to noise ratio, then
• Which of the following cannot be the Fourier series expansion of a periodic signal?
• In colour TV receiver, varactor diode is used for
• Frequency shift keying is used mostly in
• Which of the following has the highest input impedance?
• Degaussing in a picture tube means
• Space wave may be a direct wave or wave reflected from earth.
• If the bandwidth is increased by 2, the γFM γAM (where γ is the ratio of SNR of output to SNR at input, FM is frequency modulation and AM is amplitude modulation) is increased by a factor of
• When the channel is noisy, producing a conditional probability of error p = 0.5; the channel capacity and entropy function would be, respectively,
• c(t) and m(t) are used to generate an FM signal. If the peak frequency deviation of the generated FM signal is three times the transmission bandwidth of the AM signal, then the coefficient of the term cos [2p(1008 x 103t)] in the FM signal (in terms of the Bessel Coefficients) is
• A carrier is simultaneously modulated by two sine waves having modulation indices of 0.4 and 0.3. The total modulation index will be
• In radar systems PRF stands for
• In a fascimile reproduction time to scan one line is 2 ms. If it has 4% blanking, the visible trace time is
• The rate at which information can be carried through a communication channel depends on
• A telephone exchange has 9000 subscribers. If the number of calls originating at peak time is 10, 000 in one hour, the calling rate is
• In the figure , the output y(t) will be
• It is desired that transmission line and load should match for a range of frequencies. The best method is
• In FM signal with a modulation index mf is passed through a frequency tripler. The wave in the output of the tripler will have a modulation index of
• Direct and reflected sound waves may interfere with each other.
• In standing wave pattern on a transmission line