1. Dr. Hugh Blanton ENTC 4307/ENTC 5307
TELECOMMUNICATIONS
Dr. Hugh Blanton
ENTC 4307/ENTC 5307

2. Solutions to Test 1

3. 1. Definitions
RF—Implies the frequencies where the wavelength, l, becomes equal or smaller than the physical components in the circuits.
Continuous—A signal which can take an infinite number of different values between a minimum and a maximum.
Dr. Blanton - ENTC Solution_Test_

4. Discrete—A signal which can take only a finite number of different value.
Wireless—A term used to describe telecommunications in which electromagnetic waves (rather than some form of wire) carry the signal over part or all of the communication path.
Dr. Blanton - ENTC Solution_Test_

5. Random—A rule that assigns one and only one numerical value to each sample point in a random experiment.
Deterministic—A model where a set inputs always produce the same outputs.
Dr. Blanton - ENTC Solution_Test_

6. 2. Complex Numbers a. Express z1 and z2 in polar form.
b. Find | z1 | and | z2 | and calculate the product z1  z2 and the ratio z1 / z2 in polar form.
Dr. Blanton - ENTC Solution_Test_

7. 3. RF The presence of the transmission line can be ignored when:
a. l = 0.1 m, f = 1 GHz transmission line cannot be ignored!
b. l = 1 m, f = 1.8 GHz transmission line cannot be ignored!
Dr. Blanton - ENTC Solution_Test_

8. 3. RF c. l = 0.01 m, f = 0.9 GHz transmission line cannot be ignored!
d. l = 5 cm, f = 5.4 GHz transmission line cannot be ignored!
Dr. Blanton - ENTC Solution_Test_

9. 4. Smith Chart a. Reflection coefficient (G):
b. Standing wave ratio (SWR):
c. Input impedance (ZIN):
Dr. Blanton - ENTC Solution_Test_

10. 4. Smith Chart d. Input admittance (YIN): e. Shortest line length
Dr. Blanton - ENTC Solution_Test_

11. 4. Smith Chart
0.144l
0.494l
Dr. Blanton - ENTC Solution_Test_

12. 5. Stub Tuning
Dr. Blanton - ENTC Solution_Test_

13. 6. Uniform Distribution
Dr. Blanton - ENTC Solution_Test_

14. 7. PDF Dr. Blanton - ENTC 4307 - Solution_Test_1 14 pX(x) x ½ ⅜ ⅛ 1 2

15. 8. Signal r(t) = s(t) + n(t)
s(t) = 5 cos(2p x 1000t )+ 10cos (2p x 1100t)
noise n(t) is white noise with power No = 0.05 watt/Hz
passband between 990 Hz and 1100 Hz
Dr. Blanton - ENTC Solution_Test_

16. 9. RC
The output power spectral density is the input density multiplied by the square of the magnitude of the transfer function:
Note the Fourier transform pair:
x(t) R C
Dr. Blanton - ENTC Solution_Test_

17. Dr. Blanton - ENTC 4307 - Solution_Test_1 17

18. Dr. Blanton - ENTC 4307 - Solution_Test_1 18

19. 10. Ideal Filter Dr. Blanton - ENTC 4307 - Solution_Test_1 19 H(f) ffm
-fm 1
Dr. Blanton - ENTC Solution_Test_