FMCW Radar System
This tutorial section on radar basics covers following sub topics:
Main Page Terminology Measurements Doppler Radar FMCW RADAR BANDs RADAR SCOPE Weather Radar Ground radar RANGE and RESOLUTION Range calculator
This page covers FMCW radar system with equation.This radar system is based on FM CW signal.
FMCW radar basically is a frequency modulated continuous wave radar.
Here carrier signal frequency f0 is frequency modulated by frequency fm(t) such that transmitted frequency fi
can be as follows.
fi = f0 + fm(t).
Doppler radar is not used for distance or range measurement. This is due to lack of marking the transmit and receive time stamp in the doppler radar. This time stamp difference is used to determine range information. To overcome this, change in frequency with time is exploited to determine the range. The same is depicted in the fmcw radar waveform below.
As shown in the waveform, received signal fir = f0 + fm (t-Te)
Here Te is the time of the echo after the transmission.
The frequency difference is, fd = fm(t) - fm(t-Te)
Range of the FMCW radar system can be given by following equation:
Range = c * fd/2*a;
where a= fd/Te
The fmcw radar operates at comparatively lower power than pulse radar. It is used for targets at very short ranges.