Signal Processing & Antenna Theory Flashcards

What is the primary advantage of pulse compression in marine radar?

Answer: Achieves fine range resolution without requiring a very short transmitted pulse

Pulse compression transmits a long modulated pulse and compresses it on receive, achieving the range resolution of a short pulse with the energy of a long pulse.

Which of the following best describes the polarization of a typical marine radar antenna?

Answer: Horizontal polarization

Marine radar antennas use horizontal polarization because it provides better sea clutter rejection compared to vertical polarization.

When a radar receiver is described as having a noise figure of 6 dB, this means the receiver adds noise equivalent to:

Answer: Quadrupling the input thermal noise power

A 6 dB noise figure means the SNR degrades by a factor of 4 (quadrupling noise power) through the receiver.

In FMCW radar used in some marine systems, the target range is determined by:

Answer: Measuring the frequency difference between transmitted and received signals

In FMCW radar, the frequency difference (beat frequency) between the linearly swept transmit and receive signals is proportional to target range.

What effect does increasing radar antenna height have on maximum detection range?

Answer: Extends the radar horizon and increases maximum range

Greater antenna height extends the radar horizon because range to the horizon is proportional to the square root of antenna height.

A CFAR (Constant False Alarm Rate) processor in marine radar is designed to:

Answer: Keep the false alarm rate constant regardless of sea state

CFAR processors adaptively adjust the detection threshold so that the probability of false alarms remains constant across varying clutter conditions.

The effective aperture of an antenna is related to its gain by which relationship?

Answer: Ae = G × λ² / (4π)

Effective aperture Ae = Gλ²/(4π), linking an antenna's ability to capture power to its gain and operating wavelength.