EST PREBOARD EXAM PART 1

1. 1. The Philippine Electronics Code or the Code of Technical Standards of Practice for

Professional Electronics Engineer, Electronics Engineers and Electronics Technicians

defines distribution architecture s in Cable TV system. Which type of Cable TV

distribution arrangement fiber-fed termination units are shared by several dwellings?

• A. FTTH - Fiber to the Home

• B. FTTF - Fiber to the Feeder

• C. FTTC - Fiber to the Curb

• D. FTTP - Fiber to the Premises

2. 2. A digital radio system, using 2.5 GHz is to be established between Ortigas Center and Calamba which is 52 km away. You want to know if the link is feasible using the available data below by determining the signal level at each stage of the link. Assuming no obstruction along the path, what is the RSL of the link in dBm?

Transmitter power = 30 dBm

Total cable losses = 1.2 dB

Total connector losses = 1 dB

Antenna Tx and Rx Gain = 20 dB each

Miscellaneous losses = 10 dB

• A. -40.80

• B. -134.70

• C. -64.70

• D. -76.90

3. 3. Which of the following statements is FALSE?

• A. Sunspot increase and decrease in 11-year cycle and higher sunspot numbers cause

  less ionization, lower sunspot numbers increase ionization.

• B. The density of the ionospheric layers varies with the intensity of solar radiations, which

  changes according to the time of the day, season, and sunspot cycle.

• C. There are layers of varying electrons density in the ionosphere that absorb, pass or

  reflect radio waves.

• D. Ionization is caused by solar radiation, strips electrons from atoms, producing electrically

  neutral particles in the ionosphere.

4. 4. Which layer in the OSI model handles the management and synchronization of the data

transmission?

• A. Physical

• B. Transport

• C. Network

• D. Data link

5. The figure shows a simple block diagram of a digital communication system. Which block recreates incoming binary sequence?

• A. Source encoder

• B. Channel encoder

• C. Channel decoder

• D. Source decoder

6. 6. Which describes the value of the inductance, capacitance, and resistance in a

   transmission line spread along the entire length of the line that cannot be distinguished

   separately?

• A. Distributed constants

• B. Impedance constants

• C. Characteristic impedance

• D. Lumped constants

Answer explanation

Ang nakalagay sa answer key ay D. pero pag sinearch ay A.

7. 7. Which one most appropriate dynamic system?

• A. y(n) = x(n – 1) + x(n + 1)

• B. y(n) = x(n) + 2x(n)

• C. y(n) = x (n) + u(n)

• D. y(n) = 2x(n) + x (n)

8. 8. Determine the ERP of a transmitter system with the following data:Antenna Gain = 30

dB, Input power = 100 W, and Efficiency = 80%.

• A. 49 dB

• B. 48 dB

• C. 47 dB

• D. 46 dB

Answer explanation

Given:

• Antenna Gain = 30 dB

• Input Power = 100 W

• Efficiency = 80%

1. Calculate the output power: Output Power = Input Power Efficiency = 100 W 0.80 = 80 W

2. Convert the input power to dB: Input Power (dB) = 10 log10(Output Power) = 10 log10(80) ≈ 19 dB

3. Calculate the ERP in dB: ERP (dB) = Input Power (dB) + Antenna Gain = 19 dB + 30 dB = 49 dB

So, the Effective Radiated Power (ERP) of the transmitter system is approximately 49 dB. -GPT-

9. 9. Shannon's theorem describes the parameters affecting communication channel

   capacity. In the Shannon's formula a low value of SNR indicates that:

• A. transmission is most likely error free.

• B. more capacity can be accommodated

• C. there is a need to install repeater

• D. data is 100% error free

Radio horizon is very much influenced by diffraction and refraction of radio waves.

Refraction is dependent of _______.

• A. wave velocity

• B. antenna height

• C. signal frequency

• D. atmospheric condition