Electronic Engineering: Radio Transmission Test

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Electronic Engineering: Radio Transmission Test

Radio transmission in simple words is a travel of some kind of information using radio waves. Just like infrared, microwaves, ultraviolet, gamma rays, and x-rays, radio waves are too electromagnetic wave. This quiz primarily focuses on the all the technical terms of a radio transmission and has more than fifty important questions. So, I suggest you to keep a notepad with you in case you need to take some notes.


Questions and Answers
  • 1. 
    An AM broadcast receiver has two identical tuned circuits with a Q prior to the IF stage. The IF frequency is 460 kHz and the receiver is tuned to a station on 550 kHz. The image frequency rejection is?
    • A. 

      41 dB

    • B. 

      82 dB

    • C. 

      36.2 dB

    • D. 

      72.4 dB

  • 2. 
    The acronym CDMA stand for?
    • A. 

      Code division multiple access system

    • B. 

      Carrier division multiple access system

    • C. 

      Capture division multiple access system

    • D. 

      Channel division multiple access system

  • 3. 
    The tuned circuit prior to the mixer in a superheterodyne receiver are called the:
    • A. 

      Front end

    • B. 

      Tuner

    • C. 

      Preselector

    • D. 

      All of the above

  • 4. 
    A certain FM reciever provides a voltage gain of 113 dB prior to its limiter. The limiter's quieting voltage is 400mV, its sensitivity is approximateley:
    • A. 

      2uV

    • B. 

      0.9uV

    • C. 

      1uV

    • D. 

      0.7uV

  • 5. 
    An FM transmitter has an output power of 1000 W when it is not modulated. When intelligence is added, its modulation index is 2.0. What is its output with a modulation index of 2.0?
    • A. 

      500 W

    • B. 

      250 W

    • C. 

      1000 W

    • D. 

      2000 W

  • 6. 
    The simplest Am detector is the:
    • A. 

      Diode detector

    • B. 

      Product detector

    • C. 

      Synchronous detector

    • D. 

      Heterodyne detector

  • 7. 
    Which of the following is the best value for the image frequency rejection ratio (IFRR)?
    • A. 

      70 dB

    • B. 

      50 dB

    • C. 

      40 dB

    • D. 

      60 dB

  • 8. 
    A device that takes the information to be communicated and converts it into an electronic signal compatible with the communication medium is called a:
    • A. 

      Radio transmitter

    • B. 

      Transmission channel

    • C. 

      Radio reciever

    • D. 

      Dynamic range

  • 9. 
    The ability of a receiver to identify and pick the desired signal from other signals present in the frequency spectrum:
    • A. 

      Selectivity

    • B. 

      Dynamic range

    • C. 

      Sensitivity

    • D. 

      Image frequency rejection

  • 10. 
    FM broadcasting uses what type of multiplexing scheme?
    • A. 

      FDM

    • B. 

      Synchronous TDM

    • C. 

      Statistical TDM

    • D. 

      TDM

  • 11. 
    What percent of thee VHF band does the FM broadcast band occupy?
    • A. 

      7.4%

    • B. 

      9.2%

    • C. 

      8.8%

    • D. 

      6.1%

  • 12. 
    A Colpits oscillator uses:
    • A. 

      Tapped capacitor

    • B. 

      Varactor

    • C. 

      Tapped inductor

    • D. 

      Piezoelectric crystal

  • 13. 
    A spectrum analyzer is:
    • A. 

      An instrument that displays amplitude versus frequency on CRT

    • B. 

      Used to determine if a transmitter's output signal is free from any spurious signal

    • C. 

      A radio receiver with broad frequency range

    • D. 

      None of the above

  • 14. 
    The noise figure for an amplifier with noise is:
    • A. 

      0 dB

    • B. 

      Less than 1

    • C. 

      Infinite

    • D. 

      Greater than 1

  • 15. 
    What is the purpose of a buffer amplifier stage in a transmitter ?
    • A. 

      It amplifies audio frequencies before modulation occurs

    • B. 

      It prevents transmitters from producing spurious frequency on CRT

    • C. 

      It provides power amplification with high effieciency

    • D. 

      Its high input impedance prevents oscillators from drifting off frequency

  • 16. 
    The sensitivity of a reciever has to do with its ability to:
    • A. 

      Receive weak stations

    • B. 

      Withstand shock

    • C. 

      Receive one station over another

    • D. 

      All of the above

  • 17. 
    The input signal into a PLL is the:
    • A. 

      Phase detector

    • B. 

      Low pass filter

    • C. 

      VCO

    • D. 

      Comparator

  • 18. 
    Suppose a certain FM signal uses frequency deviation of 100 kHz and a modulating index of 5. Calculate the bandwidth using Carsons rule.
    • A. 

      240 kHz

    • B. 

      230 kHz

    • C. 

      200 kHz

    • D. 

      260 kHz

  • 19. 
    If the frequency fed to the pre - amplifier of a basic transmitter with multipliers is composed of a pair of triplers and a doubler is 198 Mhz, what frequency should the oscillator operate? 
    • A. 

      11 MHz

    • B. 

      16.5 MHz

    • C. 

      30 MHz

    • D. 

      5.5 MHz

  • 20. 
    What is Piezoelectric effect?
    • A. 

      Mechanical vibration of a crystal by the application of voltage

    • B. 

      Mechanical deformation of a crystal by the application of a magnetic field

    • C. 

      The generation of electrical energy by the application of voltage

    • D. 

      Reversed conduction states when pn-junction is exposed to a biased potential

  • 21. 
    A circuit that isolates the carrier oscillator from load changes is called a:
    • A. 

      Linear amplifier

    • B. 

      Final power amplifier

    • C. 

      Buffer amplifier

    • D. 

      Driver amplifier

  • 22. 
    How is a positive feedback coupled to the input in a Hartley oscillator?
    • A. 

      Through a neutralizing capacitor

    • B. 

      Through a capacitive divider

    • C. 

      Through a link coupling

    • D. 

      Through a tapped coil

  • 23. 
    What is the shape factor of a receiver whose 60 dB bandwidth is 12 kHz and a 6 dB bandwidth of 3 kHz?
    • A. 

      4

    • B. 

      2

    • C. 

      0.25

    • D. 

      0.5

  • 24. 
    An AM receiver is tuned to broadcast station 600 kHz. Calculate the image rejection in dB, assuming that the input filter consists of one tuned circuit with a Q of 40:
    • A. 

      29.57 dB

    • B. 

      38.57 dB

    • C. 

      43.57 dB

    • D. 

      34.57 dB

  • 25. 
    An AM superheterodyne receiver is experiencing image channel interference on a frequency of 1570 kHz. What frequency is the receiver tuned to?
    • A. 

      720 kHz

    • B. 

      455 kHz

    • C. 

      600 kHz

    • D. 

      650 kHz

  • 26. 
    What is the source of sidebands in frequency modulation?
    • A. 

      Baseband frequency

    • B. 

      Mixer/converter section

    • C. 

      Oscillator frequency

    • D. 

      Bandpass filter

  • 27. 
    A phase modulator has K=2 rad/V. What RMS value of a sine would cause a peak phase deviation of 30 degrees?
    • A. 

      0.16 V

    • B. 

      0.19 V

    • C. 

      0.52 V

    • D. 

      0.82 V

  • 28. 
    Which is a disadvantage of direct FM generation:
    • A. 

      The need for AFC circuit

    • B. 

      The use of class A amplifiers

    • C. 

      The need for an AGC circuit

    • D. 

      Two balanced modulators are required

  • 29. 
    Which frequency band is the standard AM radio broadcast band:
    • A. 

      MF

    • B. 

      VHF

    • C. 

      HF

    • D. 

      UHF

  • 30. 
    How can an SSB phone signal be generated:
    • A. 

      By dividing product detector with a DSB signal

    • B. 

      By using a reactance modulator followed by a mixer

    • C. 

      By using a loop modulator followed by a mixer

    • D. 

      By using balanced modulator followed by a mixer

  • 31. 
    What is a reactance modulator?
    • A. 

      A circuit that acts as a variable inductance or capacitance to produce FM signals

    • B. 

      A circuit that acts as a variable resistance or capacitance to produce FM signals

    • C. 

      A circuit that acts as a variable resistance or capacitance to produce AM signals

    • D. 

      A circuit that acts as a variable inductance or capacitance to produce AM signals

  • 32. 
    Time-division multiplexing is used for:
    • A. 

      Digital transmission

    • B. 

      Analog transmission

    • C. 

      Both analog and digital transmition

  • 33. 
    Two resistors in series (R1=50 ohms; T1=350K)and (R2=100 ohms; T2=450K). Determine the total noise voltage over a bandwidth of 120 kHz.
    • A. 

      543.4 nV

    • B. 

      534.4 nV

    • C. 

      643.4 nV

    • D. 

      634.4 nV

  • 34. 
    What would be the noise voltage generated of a 0.73 ohms resistance at room temperature over the bandwidth of an FM channel?
    • A. 

      492 nV

    • B. 

      16 nV

    • C. 

      110 nV

    • D. 

      4.91 uV

  • 35. 
    Four telephone circuits are connected in tandem. What is the overall S/N ratio of each circuit has S/N of 30 dB.
    • A. 

      24 dB

    • B. 

      12 dB

    • C. 

      36 dB

    • D. 

      48 dB

  • 36. 
    If the voltage is equal to twice its original value, what is its corresponding change in dB?
    • A. 

      6 dB

    • B. 

      3 dB

    • C. 

      4 dB

    • D. 

      2 dB

  • 37. 
    What is the effect on the SNR of a system (in dB) if the bandwidth is doubled considering all other parameters to remain unchanged except the normal thermal noise only. The S/N will be:
    • A. 

      Decreased to 1/2 its value

    • B. 

      Increased by a factor of 2

    • C. 

      Decreased to 1/4 its value

    • D. 

      Increased by a factor of 4

  • 38. 
    A satellite has a noise figure of 1.6 dB. Find its equivalent noise temperature: 
    • A. 

      129 K

    • B. 

      198 K

    • C. 

      271 K

    • D. 

      381 K

  • 39. 
    A third symbol emission which represents data transmission including telemetry, and telecommand:
    • A. 

      D

    • B. 

      C

    • C. 

      B

    • D. 

      F

  • 40. 
    The process by which the intelligence signals normally at lower frequency are removed from the transmission frequency after it is received in the receiver station:
    • A. 

      Demodulation

    • B. 

      Detection

    • C. 

      Conversion

    • D. 

      Heterodyning

  • 41. 
    A transmission has a power dissipation rating of 30 W. assuming that the transistor is the only element that dissipated power in the circuit, calculate the power an amplifier, using the transistor, could deliver the load if it operates as class A with an efficiency of 30%. (n = Po/Pin)
    • A. 

      12.86 W

    • B. 

      9.21 W

    • C. 

      15.19 W

    • D. 

      18.33 W

  • 42. 
    Determine the power saving in percent when the carrier is supressed in an AM signal modulated to 80%?
    • A. 

      75.76%

    • B. 

      66.67%

    • C. 

      91.28%

    • D. 

      83.33%

  • 43. 
    What is a balanced modulator:
    • A. 

      A modulator that produces a DSBFC signal

    • B. 

      A modulator that produces a full carrier signal

    • C. 

      A modulator that produces SSBSC signal

    • D. 

      A modulator that produces balance deviation

  • 44. 
    Find the modulation index of an AM signal if 5 V signal carrier is modulated by 3 different frequencies with amplitude 1 V, 2 V and 3V:
    • A. 

      0.75

    • B. 

      0.56

    • C. 

      0.22

    • D. 

      0.47

  • 45. 
    What kind of emission would your FM transmitter produce if its microphone failed to work?
    • A. 

      An unmodulated carier

    • B. 

      A phase modulated carrier

    • C. 

      An amplitude modulated carrier

    • D. 

      A frequency modulated carrier

  • 46. 
    The main function of the RF amplifier in Superheterodyne receiver is to:
    • A. 

      Permits better adjacent channel rejection

    • B. 

      Improve the rejection of the image frequency

    • C. 

      Provide improves tuning

    • D. 

      All of these

  • 47. 
    What signal to noise ratio is required for satisfactory telephone service?
    • A. 

      50 dB

    • B. 

      30 dB

    • C. 

      40 dB

    • D. 

      60 dB

  • 48. 
    The approximate wavelength of the violet light:
    • A. 

      7000 angstroms

    • B. 

      5000 angstroms

    • C. 

      1000 micrometer

    • D. 

      3500 angstroms

  • 49. 
    An AM transmitter antenna current is measures with no modulation found to be 2.6 amperes. With no modulation, the current rises to 2.9 amperes. The percentage modulation is:
    • A. 

      70 %

    • B. 

      35 %

    • C. 

      42 %

    • D. 

      89 %

  • 50. 
    Type of power amplifier that is used primarily in push-pull amplifiers:
    • A. 

      Class B

    • B. 

      Class D

    • C. 

      Class A

    • D. 

      Class C

  • 51. 
    This circuit provides an output signal that is an identical, enlarges replica of the input since the output is directly proportional to input:
    • A. 

      Linear amplifiers

    • B. 

      Switching amplifiers

    • C. 

      Tuning amplifiers

    • D. 

      Operational amplifiers

  • 52. 
    Communication systems are most often categorized by what characteristic:
    • A. 

      Information transmitted

    • B. 

      Carrier frequency

    • C. 

      Modulation frequency

    • D. 

      Transmission distance

  • 53. 
    An AM waveform at maximum is 100 V peak to peak and at minimum 40 V peak to peak. The modulation percentage is:
    • A. 

      40%

    • B. 

      67%

    • C. 

      25%

    • D. 

      37%

  • 54. 
    An SSB receiver recreates the original intelligence signal by:
    • A. 

      Amplifying the dc term produces by mixing action

    • B. 

      Filtering out the difference between either sideband and the internally generated carrier signal

    • C. 

      Mixing the USB with LSB signals and filtering out hte resulting different frequencies

    • D. 

      Filtering out the harmonics of the received sideband signal frequencies

  • 55. 
    Double conversion is used to overcome the problem of:
    • A. 

      Image frequency

    • B. 

      Tracking

    • C. 

      Diagonal clipping

    • D. 

      Poor sensitivity