# How should you decide on the number of sweeps to be used in FMCW radar?

I am designing an FMCW radar in MATLAB and I would like to know on how should I decide on the number of linear sweeps in FMCW .Does the number of sweeps affect the performance?

The basic performance requirement of FMCW radar is to measure the radial distance and velocity.

The number of sweeps or linear sweeps relates with the velocity measurement, thus if for a constant integration (processing) period you have more number of chirps (which can be achieved by decreasing the sweep duration) the max measurable velocity is increased.

For the case when the number of sweeps are increased by increasing the processing (integration) time the velocity resolution is enhanced.

In order to read more detail about the basic of the FMCW parameters, I would recommend to go through this paper FMCW Signal Processing

Of course it does!!

Note that you should distinguisg between number of sweeps and sweep time (beat). For the question answer, they are fortunately the same.

The more/longer beats:

• The more resolution you obtain.

As trade-off, the more/longer sweeps:

• The more energy consumed by the antenna and the RF source by its extended operation, per effective sample. Note that the transmitted signal must still be the narrowest possible for the radar physical effect in the sweep to be accurate.

• The longer effective sampling time $dT$, this is, the time between target estimates.

The $dT$ could be the biggest design parameter by far. You dont want to locate the rocket when it is 10m from you!. So, you increment $dE$ for maximize your resolution in the minimum possible $dT$.

This is similar to any application involving Fourier Transform. The longest is the time measuring, the better resolution you have in frequency.