Final Exam - EE 513, Spring 2003
Name: ____________________
Student No. ___________________
1. According to the Shannon limit, a 2.7-kHz bandwidth phone modem with a signal
to noise ratio of 33 dB should provide an uplink at: (a) 56 k (b) 28.8 k (c) 14.4 k
(d) 9.6 k.
2. The 7-bit ASCII code of letter “E” is 1000101. To transmit in 8-bit, even parity,
one should send (a)11000101 (b) 01000101 (c) 10001010 (d) 10001011
3. What is SWR for a 50- transmission line terminated with 40 ? (a) 1.25 (b) 0.8
(c) none of the above.
4. The direct benefit of encoding schemes, e.g., 4B5B, B8ZS, or B3ZS, is to (a)
increase the information capacity (b) facilitate clock recovery (c) increase S/N.
5. Two signals are fed to a balanced modulator, sin mt and sin ct. The output is (a)
sin mt + sin ct (b) sin mt  sin ct (c) sin (m+ c)t.
6. For a 0.4 V input, what is the output using the -law companding? Assume the
full voltage is 4 V and  equals 255. (a) 0.4 V (b) 4 V (c) 2.36 V (d) none of the
above.
7. A prescaler circuit used in a frequency synthesizer is shown as follows. P=16,
m=4, n=64, fi=1 MHz. The frequency of the output signal is (a) 1028 MHz (b) 16
MHz (c) 1 MHz (d) none of the above.
8. For AM DSBFC with a modulation index of 0.9, what is the percentage power of
the carrier, i.e., power of carrier / total power? (a) 66.7 (b) 50.0 (c) 71.2 (d) none
of the above.
9. A Hertz, half-wave dipole antenna is aligned along the x-axis. The radiation
pattern peaks (a) along x-axis, (b) uniformly in space, (c) on the yz-plane.
10. Two amplifiers with a gain of 10.0 dB and a noise figure of 3.0 dB each are
placed in series. The cascaded amplifier has a noise figure of (a) 3.0 dB, (b) 6.0
dB, (c) 3.2 dB (d) none of the above.
11. In North America, the phone companies use TDM to multiplex digital phone lines.
The so-called T1 line has a data rate of 1.544 Mbps. How many calls can be
carried? (a) 1 (b) 24 (c) 256 (d) none of the above.
12. In stereo FM broadcasting, the total bandwidth approaches 75 kH. Below 15 kHz,
the information carried corresponds to (a) L channel (b) R channel (c) L-R (d)
L+R.
13. The specification on the output power of a signal generator is 25 dBm. In other
words, the signal generator is capable of producing (a) 25 mW (b) 250 mW (c)
316 mW (d) > 1 W.
14. The voltage of logic level 1 in the RS-232 serial port of a pc should be (a) 0 V
(b) –5 to –15 V (c) 5 V (d) –5 V.
15. Four waveforms are shown in the following figures. The first waveform is the
source. Which waveform is the single-side band suppressed carrier AM
modulation?
Source signal
16. Determine the oscillating frequency of the following oscillator?
100 pF
100 H
100 pF
17. Draw the Manchester code of the bit sequence 011000101.
18. Which is the output phase sequence of a differential phase shift keying (DPSK)
modulator for the following input bit sequence, 010100111? Assume the first
reference bit is 0.
19. For data 110101011 and CRC-generating polynomial 101011, which is the block
check sequence?
20. Based on the Smith chart, what is the input impedance for a transmission line
which is 1.25 long with a characteristic impedance of 50  and a complex load
impedance of 25+j25 ?