4.4 Radial Velocity Extension Support

Low level processing delivers radial velocity information for every detected point. Regardless of the true radial velocity of the object, Tthe value of this measurement is limited to the range

where V_{r, max} is maximum radial velocity of the sensor, and V_{r, min} is radial velocity resolution. Both V_{r, max} and V_{r, min} are derived from RF chirp configuration. Therefore in the absence of extra processing, there will be ambiguity because the velocity measurement will wrap around.

High level processing uses radial velocity measurements to estimate target position and velocities in Cartesian space.

Therefore, theoretically, the radar-based traffic monitoring solution should be able to resolve any ambiguity on the target radial velocity. However, for the algorithm to work properly, additional work is required both at low and high level processing.

In the case of TDM-MIMO, Doppler effect for the detected point needs to be compensated for the second Tx antenna for angle estimation. Velocity ambiguity will further cause angle ambiguity when applying the Doppler compensation. It’s the job of low level processing to correct the angle ambiguity. And it’s the high level processing’s job to unroll the velocity of the target based on target position and velocity estimation.