Q. The constellation diagram of a modem has four states as shown in the figure given below. What is the bit rate of this modem?

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Q. What is the RF amplifier plate voltage when the audio-modulating voltage is +600 V?

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Q. If carrier power is P and amplitude modulation index is m, the total power after modulation is

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Q. In figure the output v(t) is

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Q. Efficiency of general AM signal with em = E₁ cos ω₁t + E₂ cos ω₂ tj ec = Ec cos ωct; E₁ cos ω₁t with modulation index m₂ is __________ .

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Q. Each of the following equation expressing decibel gain is correct except

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Q. Waves travel on each of the line configurations in figure. In which case would the radiation be maximum

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Q. The figure shows a simple detector circuit for amplitude modulated wave v(t) = (1 + m cos ωmt) cost ωct. If the detector is to follow the envelope of modulated wave at all times the extent of modulation m must be less than or equal to m0 where m0 is given by equation

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Q. In figure the output v(t) is

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Q. If Pk be the probability of the message to be received or transmitted, then the amount of information (Ik) associated, in bits, will be

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Q. The ratio given by below equation for 100% amplitude modulation with identical total transmitted power (mf is modulation index of FM) is

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Q. The power density spectrum of noise voltage at the input of a network is Sni and that at the output of the network is Sno. If transfer function of network is H(ω), the corresponding noise figure is

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Q. The modulation index of an AM wave is measured using a CRO. The waveform is as shown in figure, the modulation index is nearly

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Q. On a smooth surface, the line of sight distance between transmitting antenna (height ht metres) and receiving antenna (height hr metres) is about

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Q. Which stage generates RF carrier?

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Q. If F(ω) is Fourier transform of f(t), then Fourier transform of f(t) cos² ωct is

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Q. The circuit of figure give an output which is

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Q. A carrier A cos ωct is modulated by a signal mt A cos ω₁t + m₂ A cos ω₂t + m₃ A cos ω₃t. The total modulated power is

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Q. If an isotropic source is radiating power P in all directions, the electric field at a distance d from the source is proportional to

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Q. Waveform shown in figure is that for

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