Q2. the Information Capacity of a Channel Is Given By

Modulation Quiz

Q1. The baseband bandwidth of music for a broadcast FM signal is 15kHz, the deviation ratio is 5. The RF bandwidth is:

(a)75kHz

(b)150kHz

(d)180kHz

Q2. The information capacity of a channel is given by:

(a) bits/sec

(b) bits/sec

(d) dB

Q3. The theoretical maximum spectral efficiency of a simple binary transmission is:

(a)1 bit/sec/Hz

(b)1 bit/Hz

(d)1 bit/sec/Hz

Q4. A PAM scheme employs 8 amplitude levels, the spectral efficiency is:

(a)3 bits/sec

(b)6 bits/sec/Hz

(d)3 bits/sec/Hz

Q5. A PCM scheme for hi fidelity audio with baseband bandwidth 20kHz employs a 16 bit code for each transmitted sample, the spectral efficiency of the scheme is

(a)2 bits/sec/Hz

(b)20k bits/sec/Hz

(d)640 kbits/sec/Hz

Q6. A PCM scheme for hi fidelity audio with baseband bandwidth 20kHz employs a 16 bit code for each transmitted sample, the minimum transmission bandwidth required is:

(a)20kHz

(b)40kHz

(d)640kHz

Q7. The data rate for the PCM scheme of Q 6 is:

(a)640kbits/sec

(b)320kbits/sec

(d)40kbits/sec

Q8. A modulation system has Eb/No = 10dB with a signal to noise ratio of 13dB. The spectral efficiency is:

(a)2 bits/sec

(b)2 bits/sec/Hz

(d)0.5 bits/sec/Hz

Q9. Pulse shaping is employed in digital transmission to:

(a)Minimise ISI

(b)Maximise signal speed

(c)Prevent inter-modulation

(d)Remove sharp edges

Q10. The peak frequency deviation for an FM system with a 1 MHz sinusoidal modulation is 100kHz. The peak phase deviation is:

(a)0.1 radian

(b)0.1o

(d)10o

Q11. An analogue telephone speech signal is to be used to modulate a carrier for transmission over a channel. The required channel bandwidth for:

(a)AM is 3.4kHz

(b)FM with peak frequency deviation 8.5 kHz is 20.4kHz

(d)Conversion to 32kbit/sec ADPCM and then MSK is 32kHz.

Q12. A broadcast FM high fidelity audio signal is transmitted at 88.1MHz with a deviation ratio of 5. The required transmission bandwidth is:

(a)200kHz

(b)150kHz

(d)180kHz

Q13. GMSK gives a practical spectral efficiency of:

(a)1bps/Hz

(b)2bps

(d)1.9bps

Q14. MSK is:

(a)equivalent to QPSK

(b)binary FSK with the minimum distance between the two transmission frequencies

(c)FSK with Gaussian pulse shaping

(d)PSK with Gaussian pulse shaping

Q15. AM is

(a)An efficient modulation scheme in power terms.

(b)Very wasteful in power terms but easy to demodulate

(c)Inefficient and difficult to demodulate

(d)Spectrally inefficient but easy to demodulate

Q16. The signal spectrum for a 2Mbits/sec QPSK signal is:

(a)(b)

(c)(d)

Q17. The spectral efficiency of n-level PAM is:

(a)n bits/sec

(b)2n bits/sec/Hz

(c)n bits/sec/Hz

(d)2n bits/Hz

Q18. A 2kbits/sec digital signal is transmitted using PRK, the spectrum is:

(a)(b)

(b)(d)

Q19. A 2Mbits/sec binary FSK signal with peak deviation = 10MHz has a spectrum:

(a)(b)

(b)(d)

Q20. A channel has a bandwidth of 1MHz. The signal to noise ratio required to allow error free communication at an information rate of 2 MBits/sec is:

(a)2

(b)3dB

(d)2dB

Q21. FM is:

(a)a linear modulation scheme

(b)a non-linear modulation scheme

(c)wasteful of signal power

(d)spectrally efficient

Q22. AM is:

(a)a linear modulation scheme

(b)a non-linear modulation scheme

(c)spectrally inefficient

(d)power efficient

Q23. The peak frequency deviation for an MSK system with data rate 56kbits/sec is:

(a)56kHz

(b)28kHz

(d)14kHz

Q24. The Signal to noise ratio for a certain system is 10dB. The maximum information rate over the channel for error free communications is found to be 1Mbit/sec. the transmission bandwidth is:

(a)289kHz

(b)1MHz

(d)2MHz

Q25. OOK is:

(a)More power efficient than AM

(b)Less power efficient than AM

(c)The same as AM

(d)More spectrally efficient than AM