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Homework answers / question archive / Mapa Institute of Technology - ECE 103L 1)A interconnects LAN having identical protocols at the physical and data link layers
Mapa Institute of Technology - ECE 103L
1)A interconnects LAN having identical protocols at the physical and data link layers.
B. 3.94
C. 394
D. 0.394
A. 11.59 dB
B. 11.23 dB
D. 10.5 dB
7. Waveguide becomes compulsory above what frequencies?
B. 14.77dB
C. 30 dB
D. 40 dB
B. 14.77dB
C. 30 dB
D. 40 dB
10. Quarter-wavelength line is used as .
B. 41.1
C. 31.4
D. 1.25
13. The modulated peak value of a signal is 125 V and the unmodulated carrier value is 85 V. What is the modulation index?
A. 0.47
B. 0.68
C. 0.32
D. 1.47
14. What is the wavelength of a signal at 500 MHz?
A. 0.062 cm
15. Not more than digits make up an international telephone number as recommended by CCITT REC. E. 161.
.
A. 250 and 500 Hz
C. 500 and 1000 Hz
D. 3000 and 5000 Hz
19. A transmitter operating at 30 MHz with 4 W output is connected via 10 m of RG-8A/u cable to an antenna that has an input resistance of 300 ohms. Find the reflection coefficient.
b. 0.77
c. 0.97
d. 0.76
20. Cellular CDMA system uses what modulation method?
21. One of the following is not a bounded media.
22. A microwave-transmitting antenna is 550ft high. The receiving antenna is 200ft high. The minimum transmission distance is
24. 1 Angstrom (A) is equal to .
a. 10-3 micron
b. 10-10 m
c. 10-6 micron
d. 10-6 m
25. A wide-bandwidth communications systems in which the RF carrier varies according to some predetermined sequence.
26. If N = 250, what is the earth radius K- factor?
b. 1.29
c. 1.33
d. 1.32
27. An 891 kHz carrier having an amplitude of 80 V is modulated by a 4.5 kHz audio signal having an amplitude of 45 V. The modulation factor is
B. 0.65
C. 1.78
D. 1.25
B. 2000 W
C. 126 W
D. 260 W
36. A quarter wave transformer is connected to a parallel wire line in order to match the line to a load of 1000 ohms. The transformer has a characteristic impedance of 316.23 ohms. The distance between centers is 4 inches. What is the percentage reduction in the diameter of the line?
a. 85%
c. 86%
d. 90%
39. Light leaves a slab of transparent material whose index of refraction is 2 at an angle of refraction of 0 degrees. The angle of incidence is
42. Block calls held condition specified the held probability at a time period equal to an average holding time.
43. A unit of noisiness related to the perceived noise level
44. The shortest distance measured along the earth’s surface that a skywave is returned to earth.
SHORT QUESTIONS AND ANSWERS
1.) most commonly used microwave antenna -
2.) When the value of k increases, the effective result is of the equivalent curvature –
3.) Unit of pitch –
4.) Not more than digits make up an international telephone number as recommended by CCITT REC. E. 161. –
5.) Impedance inversion can be obtained by
6.) Which of the following is not a common microwave application? –
7.) A waveguide is also a –
8.) Calculated the noise figure of the amplifier whose Req equals 2518Ω (Rt=600Ω) if its driven by a generator whose output impedance is 50Ω. –
9.) Sixteen different levels (symbols) are used to encode binary data. The channel bandwidth is 36 MHz. The maximum channel capacity is –
10.) Which of the following refers to the video signal amplitude that determines the quality of the picture? –
11.) Which of the following is not a low impedance microphone? –
12.) Which one of the following emission transmits the lower sideband and half of the upper sideband? –
13.) The modulated peak value of a signal is 125 V and the unmodulated carrier value is 85 V. What is the modulation index? –
14.) The noise figure of the first circuit in tandem connection is 10.5 dB while its
power gain is 15, what is the over all noise figure if the second circuit has a noise figure of 11 dB? –
15.) An 891 kHz carrier having an amplitude of 80 V is modulated by a 4.5 kHz audio signal having an amplitude of 45 V. The modulation factor is –
16.) Indicate which one of the following terms applies to troposcatter propagation: -
17.) Three identical circuits having 10 dB signal noise-to-noise ratio each are connected in tandem with each other, what is the overall S/N? –
18.) Space diversity transmission means transmitting and receiving on two or more. -
19.) A microwave system requires the use of repeaters when -
20.) The process of impressing intelligence on the carrier is called –
21.) What is the method of diversity reception where the signal is transmitted on 2 different frequencies over the same path? –
22.) A broadcast TV channel has a bandwidth of 6 MHz. Ignoring noise, calculate the maximum data rate that could be carried in a TV channel using a 16-level code –
23.) The minimum sound pressure of a s pecified signal that is capable of evoking an auditory sensation -
24.) Wave motion consisting of series of refraction & condensation produced in air or other medium by vibrating body. –
25.) Access method of Ethernet technology -
26.) Radio communication in the Philippines is regulated by –
27.) Maximum usable frequency fir critical frequency = 12 MHz angle = 70 –