== Overview of the FMCW Radar System ==
In an FMCW radar system, a chirp signal is launched into the free space using a transmit antenna. A chirp signal is an FM-modulated signal of a known stable frequency whose instantaneous frequency varies linearly over a fixed period of time (sweep time) by a modulating signal. The transmitted signal hits at the target and reflect reflects back to a receive antenna. The frequency difference between the receive received signal and the transmit transmitted signal increases with delay, and the delay is linear linearly proportional to the range, that is the distance between the radar and of the targetfrom the radar. Echoes The echo from the target are is then mixed with the transmitted signal and down-converted to produce a beat signal which will give the distance of is linearly proportional to the target range after demodulation.The figure below shows the transmitted and received ramp signals:
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The delay &tua; is equal to the round-trip wave travel time and given by:
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<math> \tau = \frac{2R}{c} </math>
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where R is the target range and c is the free-space speed of light. The beat frequency at the output of the receiver is given by:
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<math> f_b = \frac{B}{T_s}\tau </math>
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where B is the total frequency deviation of the chirp signal and T<sub>s</sub> is the sweep time (chirp period).
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