Hi Support team ,
I am using AWR1642BOOST (ES2.0) + DCA1000 EVM (FPGA version 2.8) +mmwave studio 2.1.1.0 with complex 2x ADC data format.
I am currently using advanced frame config with 2 subframes but for sake of simplicity, I will just share data for one subframe.
I have searched e2e database, but could not find my exact answer, therefore I am approaching you for guidance and help.
I request some basic but concise guidance on zero-doppler and then may be an advanced question. Please refer the following figure which shows 2d fft from mmwave studio GUI and no target (especially no moving target) in radar field of view (FoV)
Figure 1
1) I understand that zero-doppler bin shows the target with zero radial velocity. However, I am not much clear about it though it is a very basic question. Can you please advise that what does it mean physically ?
2) After that, can you please explain that what does zero-doppler mean mathematically ? I understand that above plot is produced by magnitude plotting of dB values of 2d fft (with fft shift anf prior flipus function to bring +ve range inupper half of plot) from the radar cube data with velocity at x-axis. But what causes those relatively high energy cells to appear in zero-doppler column ? And more specially what and why is there a very high energy (may be single) cell at the 0 intersection of range and velocity axes ?
3) Then a moving target passed the radar FoV. As the target speed was more than the maximum unambiguous speed (as dictated by relevant chirp configuration), therefore there was velocity ambiguity and also there was energy smear / leakage as can be see in the following figure 2.
Figure 2
4) I am learning to use Chinese Remainder Theorem (CRT) for resolving velocity ambiguity. I understand that CRT is prone to noise and even one cell error in 2d fft Range-doppler map will produce big error but I am trying to study and implement any way. I am familiar that CRT is applied in TI mmwave SRR lab but I am not familiar with CCS and I am preferring to work on raw adc data from DCA1000 and I am working on my own MATLAB coding so I am working for a very basic and generic understanding. I cant understand CRT implementation in SRR therefore I request help here.
Any way, for using CRT, I need to identify, one particular cell in this 2d fft range-doppler magnitude map. I know and I repeat that we can already see the energy spread in figure and the reading will be probably not right, but that is another topic.
My question to you is that how can I obtain a single cell ( and its row (Velocity) and column (range) indices from this 2d fft range-doppler map data ? Should I use some " maximum find " type of function to get information about cell with highest magnitude of 2d fft ?
5) You can see in figure 2, that it appears that, most probably, the single cell at 0 place, at intersection of range and velocity axes, has the highest energy value. So most probably, a function trying to find maximum magnitude will select this cell, but it will be wrong as I am looking for a cell with a velocity, not a cell with zero-velocity. So what could be a solution in that case ?
6) Can a solution to para 5 above could be that I just replace the center column (zero-doppler column) with zeros in the relevant data ? But as the heatmap is working on relative magnitudes, then it will result in more energy smearing in other cells.
Another option could be that I find minimum value in the 2d fft range-doppler magnitude map and then I use that minimum value to fill the full column of zero-doppler column. Can you please comment ?
Or may be you can advise something else, more better ?
Thanks in advance and regards
