70051. Frequency frogging is used in a carrier system to
70052. TDM
70053. Which of the following oscillator is not in FM?
70054. The number of spectral component of impulse wave is
70055. Assertion (A): If a carrier is modulated by three sine waves and m1, m2, m3 are the modulation indices, the total modulation index mt is mt = (m12 + m22 + m32)0.5Reason (R): An AM, higher the level of modulation, lower is the audio power required to produce modulation.
70056. If M (jω) = £[m(t)] where £ denotes Fourier transform, then £[m(t) cos ωct] =
70057. When a wave reaches the open circuited end of a line
70058. A signal having uniformly distributed amplitude in the interval (- V to + V) is to be encoded using PCM with uniform quantization. The signal to quantization noise ratio is determined by
70059. Bipolar signalling uses the following bits
70060. The first geostationary satellite was named
70061. Typical value of power consumption of TV transmitter is
70062. In a colour TV receiver, which of the following incorporates colour saturation control?
70063. Consider the following types of distortions in diode detectors Distortion is caused due to the reason that dc and ac load impedances are unequalDistortion is caused because ac load impedance has a reactive component at high audio frequenciesAudio frequency diode current is less than dc current Which of the above are true?
70064. Satellites used for international communication are called
70065. In a phase discriminator fc, is the IF to which primary circuit is tuned. Consider the following statements: The primary and secondary voltages are exactly 90° out of phase when input frequency is fcmore than 90° out of phase when input frequency is higher than fcless than 90° out of phase when input frequency is lower than fc Which of the above statements is correct?
70066. Electronic tubes used for transmitter differ from their counterparts in the receivers in respect that
70067. A plot of modulation index vs carrier amplitude yields a
70068. In a certain '12 channel TDM' system it is found that channel no. 3 and channel no. 8 are connected to the same input signal. This technique
70069. Which wave is also called surface wave?
70070. ADM stands for
70071. The atmospheric absorption of radio waves depends on
70072. On modulating a carrier of frequency fc by an audio signal fs, the following components has resulted: fc, fc + fs and fc - fs What is this type of modulation likely to be?
70073. Strength of space wave is not dependent on distance.
70074. Which of the following is not necessarily the advantage of SSB over double sideband, full carrier AM?
70075. A signal m(t) = 5 cos 2p 100 t frequency modulates a carrier. The resulting FM signal is 10 cos {(2p 105 t) + 15 sin (2p 100 t)} The approximate bandwidth of the FM would be
70076. Some possible functions of AGC in a TV receiver are To increase gain for weak signalsTo decrease gain for strong signalsTo change the contrast when we switch from one channel to otherTo reduce flutter Which of the above are correct?
70077. A monostable multivibrator is used to generate PWM because it can
70078. Consider the following statements in amplitude modulation The harmonic and intermodulation distortion may occur in audio and RF amplifiersThe sum and difference frequencies are present in the output of mixerThe diode detector has audio frequencies in its outputA balanced modulator cannot produce an AM with suppressed carrier Which of the above are true?
70079. A resistor R is in parallel with capacitance C. The rms noise voltage of resistor in the equivalent circuit can be written as
70080. Assertion (A): In angle modulation the transmitted amplitude is constant.Reason (R): Angle modulation has good immunity to noise and interference.
70081. A 1000 kHz carrier is simultaneously modulated with 300 Hz, 800 Hz and 2 kHz audio sine waves. The frequencies present in the output will be
70082. Each of the following equation expressing decibel gain is correct except
70083. The satellites used for intercontinental communication are called
70084. Armoured submarine cable is used
70085. The frequency deviation of a FM signal produced from PM is
70086. Good frequency stability can be available
70087. In a colour TV receiver, PAL Dematrix consists of
70088. The type of radiation emitted from Cobalt 60 radioactive isotope is
70089. For a resistance of about 15 kΩ operating in a frequency range of a few MHz, the noise voltage is in the range of
70090. In a 50 cm TV tube, a path difference of 2 km between direct wave and interfering wave would mean a displacement between main image and ghost image equal to
70091. In a colour TV receiver, the sound intercarrier IF is generated in
70092. Assertion (A): In AM carrier component remains constant in amplitude and frequency.Reason (R): In AM the two side bands are images of each other.
70093. In tape recorders the hissing noise is due to irregularities in magnetic coating on tape.
70094. The main advantage of TDM over FDM is
70095. In FM reception, amplitude disturbances due to static change
70096. The power consumption of a present day colour TV receiver is about
70097. Consider the following differences between QPSK and MSK The side lobes in MSK are relatively much smaller in comparison to the main lobeThe spectrum of MSK has a main centre lobe which is 1.5 times as wide as the main lobe of QPSKThe waveforms of both MSK and QPSK exhibit phase continuity Which of the above statements are correct?
70098. As per Hartley law
70099. The speeds used in recording audio programs in house hold recorders are
70100. During transmission over a communication channel, bit errors occur independently with probability P. If a block of n bits is transmitted, the probability of at most one bit error is equal to
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