Description : Compare narrow band FM with wide-band FM w.r.t. following points. (i) Modulation index (ii) Maximum deviation (iii)Range of modulating frequency (iv)Application
Answer : Sr. No Parameters Narrow band FM Wide band FM 1 Modulation index Less than or slightly greater than 1 Greater than 1 2 Maximum deviation ... like police wireless, ambulance etc. Entertainment broadcasting can be used for high quality music transmission
Description : Differentiate between AM and FM on the basis of: (i) Definition (ii) Bandwidth (iii) Modulation Index (iv) Application
Answer : Compare AM and FM on the basis of i)Definition ii)Bandwidth iii) Wave propogation iv)Number of sidebands
Description : For AM, fc =500kHz , fm = 5 kHz Determine: (i) Upper and lower sideband frequencies (ii) Bandwidth
Answer : Given data fc = 500KHz , fm = 5KHz USB =fc+fm USB = 500+5 =505 KHz. LSB =fc – fm LSB = 500 – 5 =495 KHz Bandwidth = 2fm . = 2* 5 =10 KHz
Description : Show that AM wave consist of two side bands and carrier. Also prove the bandwidth of AM is double of the modulating frequency.
Description : Define modulation index in FM. What is maximum value of deviation ratio.
Answer : Modulation Index of FM: It is defined as the ratio of Frequency Deviation (δ) to the modulating signal frequency (fm). (OR)
Description : Compare PAM, PWM, and PPM on the basis of i. Variable characteristics ii. Bandwidth iii. Information contained in iv. Transmitted power
Answer : Compare PAM, PWM, and PPM on the basis of i. Variable characteristics ii. Bandwidth iii. Information contained in iv. Transmitted power
Description : State the IF frequency and bandwidth of FM receiver.
Answer : IF for FM receiver: 10.7 MHz. Bandwidth of FM receiver:88MHz to 108 MHz
Description : The modulation index of a FM Signal having modulating frequency 2 KHz and Max deviation is 10 KHz, is: - a) 2 b) 5 c) 3 d) 4
Answer : The modulation index of a FM Signal having modulating frequency 2 KHz and Max deviation is 10 KHz, is: - 5
Description : a) For a transmission line, Find SWR and reflection coefficient R if, i. There is no reflected voltage. ii. Reflected voltage and incident voltage is equal. iii. If reflected voltage=20V and incident voltage=10V. iv. If reflected voltage=10V and incident voltage =20V.
Answer : reflection coefficient R=Vr/Vi i. There is no reflected voltage. i.e,Vr=0 R=0 SWR= 1+R/1-R=1 ii. Reflected voltage and incident voltage is equal. Vr=Vi; R=1 SWR= 1+R/1-R=1+1/1-1=infinity iii. If reflected ... and incident voltage =20V. Vr=10 and Vi=20 R=10/20=0.5 SWR= 1+R/1-R=1+.5/1-.5=3
Description : Draw radiation pattern for following antenna i) Yagi-Uda antenna ii) Loop antenna iii) Dish antenna iv) Horn antenna
Answer : Type of antenna Radiation Patteren Yagi-Uda antenna Loop antenna Dish antenna Horn antenna
Description : A superheterodyne radio receiver with an IF of 455KHZ is turned to 1000KHZ. Find: (i) Image frequency (ii) Local oscillator frequency
Answer : Given Intermediate Frequency fi=455KHz Signal frequency =fs=1000KHz Local oscillator frequency fo=fs+fi Fo=1000KHz+455KHz =1455KHz Image frequency is the input frequency which produces the same intermediate frequency fsi=fs+2fi =1000KHz+2*455KHz =1910KHz
Description : Consider the following statements and select the correct answer from the code given below: i. Rajasthan receives the highest solar radiation in the country. ii. India has the fifth largest installed wind power in the world. iii. The ... (A) i and ii (B) i, ii and iii (C) ii and iii (D) i and iv
Answer : Answer: D
Description : In commercial FM broadcasting, the maximum frequency deviation is normally (A) 5 KHz (B) 15 KHz (C) 75 KHz (D) 200 KHz
Answer : In commercial FM broadcasting, the maximum frequency deviation is normally 75 KHz
Description : Draw the radiation pattern for Dipole antenna: (i) Half wave dipole (ii) Folded dipole.
Answer : The radiation pattern for Half wave dipole antenna The radiation pattern for Folded dipole antenna.
Description : Define the following terms related to antennas; (i) Antenna resistance (ii) Directivity (iii) Antenna gain (iv) Power density
Answer : Antenna Resistance - The resistance of an antenna has two components: 1. Its radiation resistance due to conversion of power into electromagnetic waves 2. The resistance due to actual losses in the ... the transmitter power divided by the surface area of a sphere (4πR2) at that distance.
Description : Write one application of following antenna i. Rectangular antenna ii. Dish antenna iii. Yagi-Uda antenna iv. Horn antenna
Answer : i. Rectangular antenna is used in direction finding in portable recievers. ii. Dish antenna is used to transmit and receive signal from satellite. iii. Yagi-Uda antenna is used in HF and VHF range as a TV receiving antenna. iv. Horn antenna is used in satellite tracking.
Description : Describe with respect to antenna (i) radiation pattern (ii) directive gain (iii) power gam (iv) polarization
Answer : (i) Radiation pattern:-A graph or diagram which tells us about the manner in which an antenna radiates more power in different directions is known as the radiation patteren of antenna. ( ... as the direction of the electric vector in the electromagnetic wave radiated by the transmitting antenna.
Description : Define the following terms: (i) Polarization (ii) Antenna gain (iii)Antenna resistance (iv)Directivity
Answer : i) Polarization:- It is defined as the direction of electric field vector in the EM wave radiated by the transmitting antenna. ii) Antenna Gain:- Antenna gain is defined as the ratio of ... in only one direction in which the radiation is maximum. That is directivity = Max. directive gain
Description : Define: 1)Frequency 2)Bandwidth 3)Wavelength 4)Time period
Answer : Frequency: Frequency is the number of cycles per second. Bandwidth: A range of frequencies within a given band, in particular that used for transmitting a signal. Wavelength: Wavelength can be defined as ... for one complete cycle of vibration to pass a given point. OR Time period=1/frequency
Description : A smart classroom is a teaching space which has (i) Smart portion with a touch panel control system. (ii) PC/Laptop connection and DVD/VCR player. (iii) Document camera and specialized software (iv) Projector and screen Select the ... (C) (i), (ii) and (iii) only (D) (i), (ii), (iii) and (iv)
Answer : Answer: B
Description : A telephone cable has following primary constants per loop kilometer ,R=30Ω, L=20mH,C=0.06µF,G=0.If the applied signal has an angular frequency of 5000 rad/sec.., Determine (i) Characteristics impedence (ii) Attenuation constant
Answer : A telephone cable has following primary constants per loop kilometer ,R=30Ω, L=20mH,C=0.06µF,G=0.If the applied signal has an angular frequency of 5000 rad/sec.., Determine (i) Characteristics impedence (ii) Attenuation constant
Description : Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.
Answer : Compare ground wave and space wave propagation on the basis of: (i) Frequency range (ii) Method of propagation.
Description : Define: (i) Image frequency and (ii) Double spotting
Answer : i)Image frequency:- Image Frequency is defined as the signal frequency plus twice the intermediate frequency. It is denoted as fsi = fs+2fi Where, fs = Signal Frequency fi =intermediate frequency ... It is due to the poor front end selectivity i.e., inadequate image frequency rejection.
Description : Draw block diagram of FM receiver and explain the use of limiter circuit.
Answer : Diagram Explanation Amplitude limiter: The function of amplitude limiter is to remove all amplitude variation of FM carrier voltage that may occur due to atmospheric disturbances. Use of amplitude limiter makes the system less noisy.
Description : Draw and explain PLL as an FM demodulator.
Answer : Explanation:- FM signal which is to be demodulated is applied to input of PLL.VCO output must be identical to input signal if PLL is to remain locked. As PLL is locked, VCO ... error voltage represents the modulating signal. Thus at the error amplifier output we get demodulated FM output.
Description : Draw the block diagram of FM super heterodyne radio receiver with waveforms.
Answer : block diagram of FM super heterodyne radio receiver
Description : Draw the circuit diagram of varactor diode FM modulator and explain its working.
Answer : Varactor diode modulator is the direct method of FM generation wherein the carrier frequency is directly varied by the modulating signal. A varactor diode is a semiconductor diode whose ... the magnitude of frequency change is proportional to the amplitude of the modulating signal voltage.
Description : Draw the structure and state applications of: i) Ferrite loop (rod) antenna ii) Horn antenna
Answer : Horn antenna: Application:- i) Used at microwave frequency. ii) Used in satellite tracking. Ferrite loop antenna: Application:- In Am radio receiver to receive MW and SW band signals. In FM radio receiver
Description : Encryption is required to (i) protect business information from eavesdropping when it is transmitted on internet (ii)efficiently use the bandwidth available in PSTN (iii) to protect information stored in companies' databases from ... a. i and ii b. ii and iii c. iii and iv d. i and iv
Answer : d. i and iv
Description : Digital Empowerment means (i) Universal digit literacy (ii) Universal access to all digital resources (iii) Collaborative digital platform for participative governance. (iv) Probability of all entitlements for individuals through cloud. ... (ii) and (iii) only (D) (i), (ii), (iii) and (iv)
Description : For FM signal, the frequency deviation
Answer : For FM signal, the frequency deviation Independent of the modulation frequency
Description : Given below are two premises and four conclusions drawn from those premises. Select the code that expresses conclusion drawn validly from the premises (separately or jointly). Premises: (a) All dogs are mammals. (b) No cats are ... ) (i) and (ii) (C) (iii) and (iv) (D) (ii) and (iii)
Answer : Answer: C
Description : An a.c series circuit has resistance of 10ohm, inductance of 0.1H and capacitance of 10µf, voltage applied to circuit is 200V. find (i) Resonant frequency (ii) Current at resonance (iii) Power at resonance
Answer : Solution: For RLC series circuit
Description : A super heterodyne AM receiver is tuned to a station operating at 1200 KHz .Find local oscillator frequency and image frequency.
Answer : A super heterodyne AM receiver is tuned to a station operating at 1200 KHz Intermediate frequency is 455KHz. IF frequency=f0-fs Local oscillator frequency is f0=IF +fs=455K+1200K=1655kHz The image frequency which gives the same IF is f0+2*IF=2110KHz
Description : Define the terms: 1) Maximum usable frequency 2) Fading
Answer : 1)Maximum usable frequency:- Maximum usable frequency is defined as the limiting frequency ,when the angle of incidence is other than the normal . OR The highest frequency that can be used for sky ... which left the same source but arrived at the destination by different paths is known as fading.
Description : Explain reactance modulator for FM generation.
Answer : Explanation :- Audio modulating signal is applied to Q1 which varies the base voltage and current of Q1 according to the input information to be transmitted. The collector current ... lower the frequency & decrease capacitance increase the frequency and thus produce direct FM at output.
Description : Give the expression for modulation index for AM and FM.
Answer : 1.Modulation index for AM ma=Vm / Vc Where Vm is modulating voltage Vc is the carrier voltage 2.Modulation index for FM mf=δ /fm where δ is the deviation fm is the modulating frequency
Description : Which of the following statement/s are ALWAYS FALSE ? (i) The sun will not rise in the East some day. (ii) A wooden table is not a table. (iii) Delhi city will be drowned under water. (iv) Cars run on water as fuel. ... i), (iii) and (iv) (B) Only (iii) (C) (i), (ii) and (iii) (D) (ii) alone
Answer : (D) (ii) alone
Description : Which of the codes given below contains only the correct statements? Statements: (i) Venn diagram is a clear method of notation (ii) Venn diagram is the most direct method of testing the validity of categorical syllogisms (iii) ... ) (C) (ii) (iii) & (iv) (D) (i) (iii) & (iv)
Description : Who were made the members of the Committee of Publicity ? Choose the answer from codes given below : (i) Representatives from different political parties. (ii) Representatives from the leftist parties. (iii) Representatives from the women's ... (iii) (B) (i), (ii) (C) (i), (ii), (iii) (D) (iv)
Answer : Answer: A
Description : Which of the following are correct ways of arguing ? (i) There can be no second husband without a second wife. (ii) Anil is a friend of Bob, Bob is a friend of Raj, hence Anil is a friend of Raj. (iii) A is equal to B, B ... , (iii) and (iv) (C) (ii), (iii) and (iv) (D) (i), (ii), (iii) and (iv)
Answer : (A) (iii) and (iv)
Description : Which of the following statements say the same thing ? (i) I am a teacher (said by Arvind) (ii) I am a teacher (said by Binod) (iii) My son is a teacher (said by Binod's father) (iv) My brother is a teacher (said ... (ii) (B) (ii), (iii), (iv) and (v) (C) (ii) and (vi) (D) (v) and (vi)
Answer : (B) (ii), (iii), (iv) and (v)
Description : Which of the following statements are mutually contradictory ? (i) All flowers are not fragrant. (ii) Most flowers are not fragrant. (iii) None of the flowers is fragrant. (iv) Most flowers are fragrant. Choose the correct answer ... ii) (B) (i) and (iii) (C) (ii) and (iii) (D) (iii) and (iv)
Answer : (D) (iii) and (iv)
Description : Draw amplitude modulated waveform in time domain and frequency domain with proper labeling.
Answer : AM in Time domain AM in frequency domain
Description : For a transmission line, the incident voltage. Ei = 6V and Er =2V ,Calculate: (i) Reflection Coefficient (ii) SWR
Answer : Reflection Coefficient(K) = Er / Ei = 2V / 6V K = 0.333 SWR = 1+K / 1- K = 1+0.333 / 1-0.333 = 1.333 / 0.667 SWR= 1.998
Description : Explain the working of amplitude limiter in FM receiver with circuit diagram.
Answer : Amplitude limiter: The function of amplitude limiter is to remove all amplitude variation of FM carrier voltage that may occur due to atmospheric disturbances. Use of amplitude limiter makes the system less noisy Circuit Diagram:
Description : Explain pre-emphasis and de-emphasis concept in FM.
Answer : Pre-emphasis:- In an FM system the higher frequencies contribute more to the noise than the lower frequencies. Because of this all FM systems adopt a system of pre-emphasis where the higher frequencies are ... at receiver to improve the noise immunity Pre-emphasis/ De-emphasis graph:
Description : Theoretical bandwidth requirement for FM system is: (1) Same as that of the modulating signal bandwidth (2) Twice of modulating signal Bandwidth (3) Thrice as of modulating signal Bandwidth (4) Infinite
Answer : Theoretical bandwidth requirement for FM system is: Infinite
Description : State the process FM detection? State it‟s any two types.
Answer : FM detection: In any radio that is designed to receive frequency modulated signals there is some form of FM demodulator or detector. This circuit takes in frequency modulated RF signals and takes the ... 3. Ratio Detector 4. Phase Discriminator 5. FM Detector using Phase Locked Loop (PLL)
Description : Describe the block diagram of FM superhetrodyne receiver
Answer : RF amplifier:- There are two important functions of RF amplifier: 1) To increase the strength of weak RF signal. 2) To reject image frequency signal. In FM broadcast the ... FM broadcast, the maximum modulating frequency is 15 kHz. Hence the audio amplifier must have large bandwidth.