Q. A PCM system uses a uniform Quantizer which has a range- V to +V and is followed by a 7 bit binary encoder. A zero mean signal applied to the quantizer extends over its entire range and has uniform probability density. The ratio of the signal power of the quantization noise power at the output of the quantizer is (Take log102 = 0.3 ) ?
  • (A) 14dB
  • (B) 28dB
  • (C) 42dB
  • (D) 56dB
💬 Discuss
✅ Correct Answer: (C) 42dB
Q. Two resistors R1 and R2 and (in ohms) at temperatures T1K and T2K respectively, are connected in series. Their equivalent noise temperature is ?
  • (A) T1+T2
  • (B) R1T2+R2T2
  • (C) (R1T1+R2T2)/(R1R2)
  • (D) (R1T1+R2T2)/(R1+R2)
💬 Discuss
✅ Correct Answer: (D) (R1T1+R2T2)/(R1+R2)
Q. De-emphasis circuit is used ?
  • (A) After modulation
  • (B) After detection
  • (C) Before modulation
  • (D) Before detection
💬 Discuss
✅ Correct Answer: (B) After detection
Q. Identify the modulation schemes for the shown signal constellation diagrams ?
  • (A) A-QPSK B-BPSK C-QAM
  • (B) A-OPSK B-OQPSK C-MSK
  • (C) A-OQPSK B-QAM C-QPSK
  • (D) A-OQPSK B-QPSK C-MSK
💬 Discuss
✅ Correct Answer: (B) A-OPSK B-OQPSK C-MSK
Q. In communication systems, noise is most likely to effect the signal ?
  • (A) In the transmitter
  • (B) In the information source
  • (C) In the channel
  • (D) At the destinations
💬 Discuss
✅ Correct Answer: (C) In the channel
Q. Time gap between two byte in a synchronous transmission is ?
  • (A) Fixed
  • (B) Zero
  • (C) Differentiation of data rate
  • (D) variable
💬 Discuss
✅ Correct Answer: (D) variable
Q. When signal frequency is 2000 KHz and IF is 455 KHz, the image frequency could be ?
  • (A) 2910 KHz
  • (B) 1645 KHz
  • (C) 2455 KHz
  • (D) 2090 KHz
💬 Discuss
✅ Correct Answer: (A) 2910 KHz
Q. One important application for diodes is recovering information from transmitted signals. This is referred to as ?
  • (A) Regeneration
  • (B) Ionization
  • (C) Biasing
  • (D) demodulation
💬 Discuss
✅ Correct Answer: (D) demodulation
Q. The ring modulator is generally used for generating ?
  • (A) SSB/SC signal
  • (B) DSB/SC
  • (C) ISI signal
  • (D) Wideband signal
💬 Discuss
✅ Correct Answer: (B) DSB/SC
Q. De-emphasis circuit is used ?
  • (A) To attenuate low frequencies
  • (B) To attenuate misbrand frequencies
  • (C) To attenuate high frequencies
  • (D) None of the above
💬 Discuss
✅ Correct Answer: (C) To attenuate high frequencies

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