Howtosignalprocessing
FMCW works on the principle that the frequency variations of the emitted radar signals permit the distance measurement to the subject over time. The respiration activity of the subject changes the reflected waveform' amplitude resulting in sensing the respiratory illness [34] .
- How does an FMCW radar work?
- What's the difference between FMCW and CW radars?
- What is the range of FMCW radar?
- How is FM used in radar?
How does an FMCW radar work?
How Does FMCW Radar System Work? In an FMCW system, the transmitter antenna emits frequency modulated continuous radio waves, and the reflected signal from the target is received by the receiving antenna. The output of the receiving antenna is given to the mixer stage of the receiver via a pre-amplifier.
What's the difference between FMCW and CW radars?
The CW radar can measure the Doppler frequency of the target, but it cannot measure the target range. The frequency-modulated CW radar (FM–CW) can measure both the range and Doppler frequency of the target.
What is the range of FMCW radar?
Frequency Modulation is used in FMCW radar. FMCW radars use mm wave electromagnetic spectrum which has very short wavelengths upto 4 mm [9], [10]. The frequency used is in range of 76–81 GHz. Higher frequencies are used so that even smaller objects can be detected effectively.
How is FM used in radar?
FM radar using passive transponders
In the classic FM technique, the microwave source sweeps in frequency over time, usually with a linear ramp. By mixing the received signal with the outgoing signal, the difference frequency is proportional to the range at which the reflection occurred.
