55751. Which of the following has the highest input impedance?
55752. In a fascimile reproduction time to scan one line is 2 ms. If it has 4% blanking, the visible trace time is
55753. Consider the following statements The amplitude of an FM wave is constantFM is more immune to noise than AMFM broadcasts operate in upper VHF and UHF frequency rangesFM transmitting and receiving equipments are simpler as compared to AM transmitting and receiving equipments Which of the above are correct?
55754. Signal to noise ratio of microphone is defined as the ratio of output when the sound pressure is __________ to the output in the absence of any sound signal.
55755. A generator is feeding power to a transmission line of characteristic impedance Z0. The line is terminated in impedance ZL. Standing waves will be set up if
55756. In sound recording the degree of pre-emphasis is about 6 dB/ octave.
55757. Space wave may be a direct wave or wave reflected from earth.
55758. Radio broadcasts are generally
55759. If the frequency of a wave 20 Hz, the time period is
55760. Which of the following is taken as reference antenna for directive gain?
55761. Push pull amplifier is
55762. When the channel is noisy, producing a conditional probability of error p = 0.5; the channel capacity and entropy function would be, respectively,
55763. In CCIR-B system, the time between start of one H syn. pulse and next is
55764. Counterpoise is used in coils having
55765. For an ideal 3000 Hz channel, S/N ratio is
55766. Which of the following types of noise assumes greater importance at high frequencies?
55767. In transistor radio receivers the number of IF amplifier stages are
55768. To relay outdoor remotely located live programs, TV transmitter use
55769. If each short element of signal occupies 20 ms, the speed is
55770. It is found that in a telephone system 60 subscribers initiate calls during a 30 minute interval and the total duration of all the calls is 100 minutes. The load is
55771. E and H fields are perpendicular to each other.
55772. Consider the following: A TV receiver antenna should pick up the TV signal and develop maximum voltage from the available strength of signalIt should reject unwanted signalsIt should not suffer from co-channel interferenceIt should have a very narrowband The correct statements are
55773. If transmission bandwidth is doubled in FM, SNR is
55774. Directivity means
55775. If the oscillator output is modulated by audio frequencies upto 10 kHz, the frequency range occupied by the side bands will be
55776. The power to the portable unit of a cordless telephone is provided by
55777. In a AM wave the carrier and one of the side bands is suppressed. If m = 0.5, the percentage saving in power is
55778. Computer communication networks have
55779. Assertion (A): A balun is an RF impedance matching transformer. Reason (R): Sometimes a booster amplifier is used with a TV set.
55780. In an FM system, when the AF is 500 Hz and the AF voltage is 2.4 V, the deviation is 4.8 kHz. If the AF voltage is now increased to 7.2 V, the new deviation will be
55781. Modulation is also called detection.
55782. The maximum range of a transmitter depends on
55783. Consider the following statements about Yagi Uda antenna It is unidirectionalIts gain is about 7 dBIt is used at VLFThe optimum separation is 0.11 Which of the above are correct?
55784. In a two stage cascade amplifier, each stage has a gain of 10 dB and noise figure of 10 dB. The overall noise factor is
55785. Fields are said to be circularly polarised if their magnitudes are
55786. Three analog signals, having bandwidths 1200 Hz, 600 Hz, 600 Hz are sampled at their Nyquist rates, encoded with 12 bit words, and time division multiplexed. The bit rate for the multiplexed signal is
55787. In a CD player the speed of CD is
55788. In the output of a DM speech encoder, the consecutive pulses are of opposite polarity during time interval t1 < t < t2. This indicates that during this interval
55789. A fascimile reproduction has a specification of 200 lines per frame, progressive scanning and 5 frames per second. The time to scan one line is
55790. Consider the following features of monochrome TV Number of lines per picture 625Interlace ratio 2 : 1Aspect ratio 4 : 3Channel bandwidth 8 MHz As regards CCIR system B, which of the above are correct?
55791. In the absence of noise, if C is channel capacity in bits/s, δf is channel bandwidth in Hz and N is number of coding levels. Then
55792. The open loop gain of an amplifier is 50 but is likely to change by 20%. If negative feedback with β = 0.1 is used, the change in gain will be about
55793. Audio amplifiers need
55794. Meig’s syndrom is associated with
55795. In a TV, studio the function of vision switcher is to
55796. In the equation of M-ary PSK signal (where Ey is symbol energy), M becomes large. Then d will approach
55797. The trapezoidal pattern of figure is obtained when examining an AM wave by an oscilloscope. Modulation factor of the wave is
55798. Y signal has maximum percentage of
55799. To ensure good transient response in audio systems the natural frequencies should be
55800. If k is dielectric constant of a medium, the velocity factor in that medium is