AWR1843BOOST: Parameters for max. speed.

Hi,

In general, the velocity can get limited if multiple antennas are being used in TDM configuration. Maximum velocity is inversely proportional to the chirp period. If the chirps are alternated among multiple antennas however, the effective chirp period for max velocity calculation becomes NTx times the chirp period, which decreases the maximum velocity by a factor of NTx. This is because every NTx'th chirp can be used to get doppler information (successive chirps in multiple antenna case also have a phase component associated with the antenna position, and hence can't be used to get doppler information). When you set NTx=1, this concern is eliminated.

Another limiting factor will be the size of memory available. A higher maximum velocity can mean more doppler bins in the radarcube. So, beyond a point, the bottleneck will be the size of the memory (L3 typically) in which the radarcube is stored.

Another concern is that a certain minimum value for TX start time, ADC valid time and chirp idle time is needed for ensuring that the quality of the acquired data is high, and that there is enough processing time for 1D FFT, which happens per chirp in the chirp period itself. Also, the BSS itself also needs a small chirp idle time to reconfigure for the next chirp (though this is not large).

Another natural tradeoff to get a high Vmax (i.e. lower the chirp period) is that there could be an impact on the bandwidth that can be sweeped, and the number of ADC samples that can be acquired.

These were a few concerns I could think of that would indirectly impose additional limits to the maximum velocity.

Apart from having a high maximum native velocity, there are ways with which the native maximum velocity can be extended. The MRR lab uses a method based on using fast and slow period chirps and the Chinese Remained Theorem to extend the velocity. The gtrack tracker also has the ability to extend the maximum velocity output of the targets.

Regards,

Aayush