(i) R = 1 kΩ, C = 0.01µF (ii) R = 10 kΩ, C = 0.01µF (iii) R = 10 kΩ, C = 0.1µF Answer: Carrier wave frequency, fc – 20 MHz = 20 × 106 Hz Bandwidth = 2fm = 3 × 103 Hz fm = 1.5 × 103 Hz 1/fc = 0.5 ×...

(ii) Is the plot symmetrical about ωc? Comment especially about plot in region ω < ωc (iii) Extrapolate and predict the problems one can expect if more waves are to be modulated (iv) Suggest...

(i) the percentage modulation (ii) peak carrier voltage and (iii) peak value of information voltage Answer; Maximum voltage is given by $ {{V}_{\max }}=\frac{100}{2}=50V $ Minimum voltage is given...

Answer: According to the question, the velocity of waves = 3 × 108 m/s The time to reach a receiver = 4.04 × 10-3 s we know that the height of satellite is: h = 600 km And the radius of earth = 6400...

 channel decreases exponentially with distance x according to the relation I = Ioe–αx, where I o is the intensity at x = 0 and α is the attenuation constant. Show that the intensity reduces by 75...

Answer: The total radiated power is due to ωc, (ωc – ωm) and (ωc + ωm) carrying energy. The carrier frequency is usually close to the sideband frequencies. In an amplitude modulated transmission,...

Answer: Expression fpor the maximum frequency is: fmax = 9(Nmax)1/2 According to the question, for Layer F1, fmax = 5 MHz $ {{N}_{\max }}=\frac{F_{\max }^{2}}{9\times 9}=\frac{5\times...

Answer: We know that the distance or range of transmission tower is given by the expression: $dT=\sqrt{2{{h}_{T}}R}$ R represents the radius of the earth (approximately 6400 km). hT​ denotes the...

 (i) at ground level, (ii) at a height of 25 m? Calculate the percentage increase in area covered in case (ii) relative to case (i). Answer: We know that: $ {{R}_{e}}=6.4\times {{10}^{6}}m $ The...

Answer: It is given that there is a loss of signal 2dB per km. So total loss suffered in 5km = -2 x 5 = -10 dB. In both input and output amplifiers, the total gain of the signal is given by: =...

Answer: In an amplitude modulated wave, the carrier wave's instantaneous voltage varies. As a result, assuming noise as a part of the modulated signal, a noise signal can be added and received...

Answer: $ v=1MHz={{10}^{6}}Hz $ $ v=\frac{1}{2\pi \sqrt{LC}} $ $ Or,\sqrt{LC}=\frac{1}{2\pi v} $ $ LC=\frac{1}{{{(2\pi v)}^{2}}}=\frac{1}{4\times 3.14\times 3.14\times {{10}^{12}}} $ $...

Answer: The modulation index is the ratio of the change in carrier wave amplitude to the original carrier wave amplitude. according to the question, the maximum amplitude of AM wave is  Amax = Ac +...

Answer: The refractive index rises as the frequency rises, implying that the angle of refraction is smaller for higher frequency waves. In other words, bending is less. As a result, after covering a...

Answer; Skywaves will not be suitable for transmitting TV signals with a frequency of 60 MHz since the TV signals are higher than 60 MHz. It is necessary to use space wave transmission.

(i) A vibrating tuning fork (ii) Musical sound due to a vibrating sitar string (iii) Light pulse (iv) Output of NAND gate Answer: i) A vibrating tuning fork will produce an analog signal ii) musical...

 (a) m > 1, will result in interference between the carrier frequency and message frequency, resulting in distortion (b) m > 1 will result in overlapping of both sidebands resulting into loss...

(a) (i) followed by(ii) (b) (ii) followed by (i) (c) (iii) (d) (iv) Answer: The correct options are: (a) (i) followed by(ii) (b) (ii) followed by (i) (c) (iii) Explanation: The band pass filter...

(a) 100 km (b) 24 km (c) 55 km (d) 50 km Answer: The correct options are (b) 24 km (c) 55 km and (d) 50 km Explanation: $ {{h}_{T}}=240m $ $ R=6.4\times {{10}^{6}}m $ For, LOS communication we have:...

(a) The sideband frequencies are 1506 kHz and 1494 kHz (b) The bandwidth required for amplitude modulation is 6kHz (c) The bandwidth required for amplitude modulation is 3 MHz (d) The sideband...

(a) the size of the required antenna would be at least 5 km which is not convenient (b) the audio signal can not be transmitted through sky waves (c) the size of the required antenna would be at...

a) Ac sin [{ωc + k1vm(t)}t + φ ] (b) Ac sin {ωc t + φ + k2 vm(t)} (c) {Ac + k2 vm(t)} sin (ωc t + φ ) (d) Ac vm(t) sin (ωc t + φ ) Answer: The correct option is (c) {Ac + k2 vm(t)} sin (ωc t + φ )...

(A) transmitter (B) information source (C) user of information (D) channel (E) receiver Choose the correct sequence in which these are arranged in a basic communication system: (a) ABCDE (b) BADEC...

 a) poor selection of modulation index (selected 0 < m < 1) (b) poor bandwidth selection of amplifiers (c) poor selection of carrier frequency (d) loss of energy in transmission Answer: The...

Identify devices that can be used for modulation: (a) ‘i’ and ‘iii’ (b) only ‘iii’ (c) ‘ii’ and some regions of ‘iv’ (d) All the devices can be used. Answer: The correct option is (c) ‘ii’ and some...

(a) ωm (b) ωc (c) ωc + ωm/2 (d) ωc – ωm/2 Answer: The correct option is (b) ωc Explanation: Frequency of carrier wave = ωc​ Frequency of modulated wave = ωc​

(a) 1.003 MHz and 0.997 MHz (b) 3001 kHz and 2997 kHz (c) 1003 kHz and 1000 kHz (d) 1 MHz and 0.997 MHz Answer: The correct option is (a) 1.003 MHz and 0.997 MHz Explanation: $ {{\omega...

(a) 900 W (b) 100 W (c) 990 W (d) 1010 W Answer: The correct option is (b) 100 W Explanation: According to the question, Pi​ =1 kW = 1000W The rate of attenuation of the signal = -2dB/km Length of...

(a) ~ 400 m (b) ~ 25 m (c) ~ 150 m (d) ~ 2400 m Answer: The correct option is (a) ~ 400 m Explanation: According to the question, the length of building ois l = 500m and Length of antenna is 100m...

(a) A is transmitted via space wave while B and C are transmitted via skywave (b) A is transmitted via ground wave, B via skywave and C via space wave (c) B and C are transmitted via ground wave...