FMCW Radar Fundamentals

What they ask

For the engineering side of the Egypt office (automotive and sensing work), the technical interview is one session with two engineers after an HR screening call. The questions focus on FMCW and mmWave radar signal processing fundamentals and then on your past projects.

Questions in this area, for example:

• In an FMCW radar, how is range measured? Explain the beat frequency and why an FFT over one chirp gives you range bins.
• How is velocity measured? Explain the phase change across consecutive chirps and the second FFT (the range-Doppler map).
• How is angle of arrival estimated with multiple receive antennas, and what limits the angular resolution?
• What sets range resolution, maximum unambiguous range and maximum unambiguous velocity? Relate each to bandwidth, sampling rate and chirp timing.
• What is CFAR detection and why not use a fixed threshold?
• Two targets at the same range and speed but different angles: where do they separate in your processing chain?

Example

Given a chirp bandwidth of 1 GHz, they may ask you to state the range resolution (about 15 cm, from c divided by 2B) and then ask what happens to it when regulations cut your bandwidth in half.

What they look for

• Solid theory expressed simply, with the right formulas but without hiding behind them.
• Honest mapping from your projects to the role: which parts of the chain you actually implemented, on what hardware, and what you would do differently.
• Practical awareness: computational cost of the 2D FFT on an embedded target, fixed-point versus floating point, windowing choices.