69802. If f is frequency and d is distance, path attenuation a between isotropic antennas is given by
69803. In a FM signal, the modulation index increases, then the power
69804. Higher order TDM levels are obtained by
69805. Assertion (A): In AM, use of SSB reduces the power and bandwidth requirementReason (R): A balanced modulator produces AM with carrier suppressed
69806. Limiter is not essential in the following detector
69807. An FM signal is modulated by an 8 kHz sine wave and has maximum and minimum frequencies of 100.05 MHz and 99.95 MHz respectively. Its deviation frequency is
69808. Assertion (A): RF tuner is called front end of TV receiverReason (R): RF tuner receives the TV signal and selects the required channel.
69809. In TV broadcast, UHF range is
69810. The most commonly used microphone for public address systems is
69811. Pre-emphasis and De-emphasis is done by using R-C circuit.
69812. Which of the following is Doppler effect not used?
69813. If the AF voltage is raised to 10 V, while the AM is dropped to 200 Hz, what is the deviation?
69814. In pulse code modulation when the maximum frequency in the signal is fmax the bandwidth required will be
69815. The oscillator frequency is set for
69816. The main advantage of DM over PCM is
69817. Chrome signals in PAL colour television system consist of
69818. In TV system in India, each frame is divided into
69819. In PAL system
69820. Among the various modulation systems, the most favoured from the point of linearity of modulation and efficiency is
69821. The phase of colour subcarrier burst in PAL is along the axis at
69822. Which of the following is correct (fm is maximum usable frequency, S is speed and G is width of air gap)?
69823. In a hi-fi system the frequency response over the audio frequency range should be within
69824. Multiplex techniques are used for
69825. In delta modulation, the output signal to quantization noise ratio S0/Nq is (N is the number of bits)
69826. In an AM system, doubling of modulation index doubles the antenna current. The system is
69827. A frequency multiplier stage should operate as
69828. All are true about ‘Wartenberg syndrom’EXCEPT
69829. A carrier signal at frequency 100 MHz is frequency modulated with modulation index 2 by a signal at 2 kHz. At what frequencies are the sidebands produced?
69830. Which is not purpose of modulation?
69831. An FM transmitter has maximum frequency deviation of 75 kHz and reproduces audio signals up to 15 kHz. Minimum channel width required is __________ kHz.
69832. A 360 W carrier is simultaneously modulated by two audio wave with modulation percentage of 55 and 65 respectively. Total sideband power radiated will be
69833. In a radio detector
69834. ISDN stands for
69835. Under identical conditions, for a single modulating frequency, FM and PM are indistinguishable. Now if the modulating frequency is reduced, then
69836. The main advantage of superheterodyne receiver is
69837. PAL system was proposed first in
69838. MCVF telegraphy causes
69839. Consider the following statements as regards noise If Gaussian noise is applied at input of a rectifier, the output is not gaussianThe noise encountered on a telephone line consists of short, pulse type disturbances whose amplitude distribution is not GaussianShot noise results from random emission of electrons from a cathodeShot noise results from phenomenon associated with the flow of current across semi conductor junctions Which of the above are correct?
69840. Noise can be reduced by increasing sampling rate
69841. In tape recorder erase head is active during recording.
69842. Which of the following microphones has maximum distortion?
69843. The relation between bandwidth B, modulating frequency fm and frequency deviation Δf for a sinusoidally modulated FM signal is
69844. FM broadcast is used in
69845. The power requirement of a RADAR used in military operations is
69846. The percentage saving in power when the carrier and one of the sidebands are suppressed in an AM wave modulated to a depth of 100% will be nearly
69847. The difference between phase and frequency modulation
69848. A signal m(t) amplitude modulates a carrier Ac cos ωct. The final signal will be
69849. An oscillator at 4.2 MHz is followed by two frequency doublers and two triplers. The output frequency will be
69850. Over which frequency range the effect of atmospheric noise is significant?
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