AWR6843AOP: Range Switching of AWR6843AOP

HI, Karthik:

Please see my answers inline:

1) In most of the examples maximum range is specified around 400m. What limits the same ? Is it possible to increase the maximum range to 800m-1Km, may be with reduced resolution ?

You can change your chirp design to change your maximum range.  But you also need to understand the max range is not the maximum detectable range for a certain target.  The maximum detectable range is related to chirp design as well as output power, antenna gain, propagation loss, noise figure and RCS of the target.   These concept and equation is given in section 2.1.1 at app notes https://www.ti.com/lit/an/swra553a/swra553a.pdf.   

2) We believe the Maximum range and resolution are dependent so that if we increase the range, the resolution will become poor and the chirp configuration ALONE determines high range/low resolution or low range/high resolution. Please correct if wrong.

Yes, you can reduce the chirp RF bandwidth to get a coarse range resolution and increase the max range.  But again, your chirp allow a big max range, does not mean you will be able to detect any object at that range. 

3) In our application scenario (UAV landing), can we have a range switching ? Means at high altitude, we use chirp corresponding to high range/low resolution and at lower altitudes we use low range/high resolution chrips. If its possible, what will be the time taken for range switching (loading the new chirp and getting new values)

We support sub-frame structure in SDK Out-of-box demo, which means you can define more than one chirp type to address different need.  At the same time, you can also change the frame by stopping the sensor and reconfigure all the chirps.  If time is critical to you, you can consider the first method.

4) What is the maximum relative velocity limit to get a true estimate of range, means if the UAV is landing at a very high velocity (free fall due to any failure condition), whether it can sense the range correctly.

Each designed chirp has a maximum un-ambitious velocity.  You can find the equation in section 2.2.1, at https://www.ti.com/lit/an/swra553a/swra553a.pdf/  For the target moving at very high speed that beyond this max non-ambiguous velocity, it can still be detected, but the speed estimation can be tricky (the speed will alias back).   So, I do not see the range estimation will be affected.   It is more like whether you can track the velocity right. 

Best.

Zigang