# Surveying Questions and Answers – EDM – Modulation

This set of Surveying Multiple Choice Questions & Answers (MCQs) focuses on “EDM – Modulation”.

1. In amplitude modulation, which among the following is constant?
a) Amplitude
b) Frequency
c) Wave length
d) Time period

Explanation: In amplitude modulation, the carrier wave has constant frequency and the modulating wave information is conveyed by the amplitude of the carrier waves.

2. Modern phase techniques are capable of __________
a) Resolving modulation
b) Resolving amplitude
c) Resolving frequency
d) Resolving wave length

Explanation: Modern phase comparison techniques are able to possess a better resolving capacity than the remaining techniques. They can resolve better than 1/1000 part of a wavelength.

3. Lower frequency is not suitable in_________
a) Direct transmission
b) Distance calculation
c) Determination of wavelength
d) Determination of frequency

Explanation: The range of lower frequency is not suitable in case of direct transmission through the atmosphere because it may involve in atmospheric conditions like interference, reflection, fading and scattering. This may decrease the impact of frequency which may reduce the information being transmitted.

4. Which of the following represents the correct set of modulation classification?
a) Frequency, time period
b) Frequency, amplitude
c) Amplitude, wavelength
d) Wavelength, frequency

Explanation: The interference technique can be eradicated by modulation, which involves two classifications. They are amplitude and frequency modulations, which can be super imposed during phase comparison.

5. Which of the following indicates the correct set of frequency employed in measuring process?
a) 7*106 to 5*108 Hz
b) 7.5*106 to 4.5*108 Hz
c) 7.5*106 to 5.9*108 Hz
d) 7.5*106 to 5*108 Hz

Explanation: In general, the present situation needs a frequency range of approximately 7.5*106 to 5*108 Hz. This can be used in order to determine the distance between the points and also employed in EDM instruments.
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6. Which of the following is constant in the case of frequency modulation?
a) Modulation
b) Wavelength
c) Amplitude
d) Frequency

Explanation: In frequency modulation, the carrier wave has constant amplitude and the modulating wave information is conveyed by the amplitude of the carrier waves.

7. Which can’t be done in high frequency zones?
a) Phase comparison
b) Super imposition of waves
c) Distance measurement
d) Wavelength measurement

Explanation: In high frequency zones, the phase comparison techniques cannot be applied. The high frequency may be determined as 5*108 Hz which may correspond to a wave length of 0.6 m.

8. Modulating wave can also be known as ______
a) Total wave
b) Measuring wave
c) Super wave
d) Incubation wave

Explanation: Modulation involves the overcoming of the problems raised due to the interference, scattering, etc. In this, the measuring wave is super imposed on a carrier wave of high frequency, so it is also known as measuring wave.

9. If 10mm is the accuracy considered, what will be the maximum value of λ for 1/1000 part?
a) 10000 m
b) 10 cm
c) 10 m
d) 10000 cm

Explanation: The maximum value of the wave length can be determined by multiplying assumed wave length with the accuracy considered, which means, λ = 10*1000 = 10 m.

10. Frequency modulation is equipped in all EDM instruments.
a) True
b) False

Explanation: In frequency modulation, the carrier wave has constant amplitude and frequency varies in proportion to the amplitude of the modulating wave. Frequency modulation is used in all EDM instruments, while amplitude modulation is done in visible light instruments and infrared instruments.

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