183. PAM signals can be demodulaed by using a
A. low pass filter (LPF) alone
B. a Schmitt trigger followed by a LPF
C. a differentiator followed by a LPF
D. a clipper circuit followed by a LPF

---

184. For 10-bit PCM system, the signal to quantisation noise ratio is 62 dB. If the number of bits is increased by 2, then the signal to quantisation noise will
A. increase by 6 dB
B. increase by 12 dB
C. decrease by 6 dB
D. decrease by 12 dB

---

185. A communication channel with additive white Gaussian noise, has a bandwidth of 4 kHz and an SNR of 15. Its channel copacity is
A. 1.6 kbps
B. 16 kbps
C. 32 kbps
D. 256 kbps

---

186. In a PCM system, the number of quantization levels are 16 and the maximum signal frequency is 4 kHz, the bit transmission rate is
A. 64 K bits/sec
B.
C.(b) 16 K bits/sec
D.(c) 32 K bits/sec

---

187. MODEM stands for
A. modulator ar transmitting side and detector at thereceiving side
B. which deals with analog signals and shows digital information
C. analog at digital at transmitting side and digital to analog at a receiving side
D. a device which deals with digital signals only

---

188. Which of the following requires a transmitted in a 7 unit code. The synchronizing signal?sampling is done at the rate of 10 Hz. The bandwidth should be
A. single channel PPM system
B. PAM
C. PDM
D. all of these

---

189. The signal to quantisation noise in a PCM system depends upon
A. Sampling rate
B. Number of quantisation levels
C. Message signal bandwidth
D. None of these

---