How is the range resolution of a FMCW radar determined?

How is the range resolution of a FMCW radar determined?

For the range resolution of an FMCW radar, the bandwidth BW of the transmitted signal is decisive (as in so-called chirp radar ). However, the technical possibilities of Fast Fourier Transformation are limited in time (i.e. by the duration of the sawtooth Τ ).

When does the radar operate at the second frequency?

During the pulse top of the rectangular pulse, the radar operates at the first frequency, and during the interpulse period the radar operates at the second frequency. During these times in the millisecond range, the radar will work as for CW radar method.

Why are continuous wave radars cannot determine target range?

Simple continuous wave radar devices without frequency modulation have the disadvantage that it cannot determine target range because it lacks the timing mark necessary to allow the system to time accurately the transmit and receive cycle and to convert this into range.

How does a Doppler effect affect a radar signal?

An occurring Doppler frequency would now move the frequency of the entire echo signal either up (moving towards the radar) or down (moving away from the radar). In this form of modulation, the receiver has no way to separate the two frequencies.

How is the range of a FMCW pulse determined?

A very important type of FMCW radar pulse is the linear FM sweep. In this case, the range to the target is found by detecting the frequency difference between the received and emitted radar signals. The range to the target is proportional to this frequency difference, which is also referred to as the beat frequency.

How is the FMCW signal split into two parts?

In FMCW radar, the signal generated by the radar is split into two parts. A small portion is allowed to pass into the upper port of the radar mixer where it is used as a reference signal for detection of the echo signal.

How does a W-band FMCW radar work?

This Demonstration investigates the performance of a W-band (94 GHz) FMCW radar emitting an FM sweep with a 5 kHz pulse repetition frequency. You can select the range to the target , the target radar cross section , the transmit power of the radar , and the gain of the radar transmit-receive antenna.

How is the difference in radar frequency measured?

The measured difference frequency Δf is by the Doppler frequency fD higher than according to the real run time should be.

How to calculate the Doppler frequency of a moving target?

The Doppler frequency-adjusted frequency for the distance determination and the Doppler frequency of a moving target is calculated by: The frequency f  (R) can then be used in the formula (1) to calculate the exact distance.

How is the maximum unambiguous range of a radar determined?

The maximum frequency shift and steepness of the edge can be varied depending on the capabilities of the technology implemented circuit. The maximum unambiguous range is determined by the necessary temporal overlap of the (delayed) received signal with the transmitted signal.