What type of waveform must be transmitted to reduce Doppler shit errors?

A)
Sine
B)
Cosine
C)
Triangular
D)
Square

Correct Answer :   Triangular

Explanation : To reduce the errors due to the Doppler shift of the return, a triangular waveform is usually used to modulate the transmitter. Thus a positive Doppler shift will produce a negative frequency error on the rising modulation slope. By averaging the frequency count the error can be minimized.

Recently Updated in Avionics Questions
Anti reflection coated optics reduce ________
A)
Refraction
B)
Reflection angle
C)
Intensity of star image
D)
Optical transmission losses

Correct Answer : Option (D) :   Optical transmission losses

Explanation : For anti-reflection coated optics, the optical transmission losses may be 1% or 2% at each air to glass or glass to air optical control surface within the telescope, including windows or sensor covers or surfaces. For uncoated optics, the loss per surface is about 4% to 5%.

The ratio of the focal length to aperture is called the ________
A)
Focal number
B)
f/ number
C)
Critical aperture
D)
Effective aperture

Correct Answer : Option (B) :   f/ number

Explanation : The ratio of focal length to aperture is called the f/ number. For example, an f/10 telescope may have a 30 in. focal length and a 3 in. aperture.

The physical size of the star depends upon _____
A)
Shape of image
B)
Colour of image
C)
Angular size of image
D)
Intensity of image

Correct Answer : Option (C) :   Angular size of image

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