IWR6843: mmWave Sensing Estimator Discrepancies

Hello Curtis,

Your calculations are correct for range and velocity resolution respectively (based on the physics). However the two values you are comparing to can be thought of as the effective resolutions (subsequent to sampling/FFT processing).

So for velocity resolution if we take the resolution you calculated and multiply by (Nchirp_loops/#doppler fft bins) we arrive at the value indicated in the estimator.

The same should apply for range: where deltaRbin = detaR * (#samples per chirp/#range fft bins).

I would recommend that if you want to see how any of the other calculations are performed you can view the source code of the visualizer. The relevant calculations are in the input.js file:

	var range_inter_bin_resolution = function(range_resolution, number_of_samples_per_chirp, num_range_fft_bins) {
	    return range_resolution*number_of_samples_per_chirp/num_range_fft_bins;
	};
	
	var velocity_inter_bin_resolution = function(velocity_resolution, min_num_of_chirp_loops, num_doppler_fft_bins) {
	    return velocity_resolution*min_num_of_chirp_loops/num_doppler_fft_bins;
	};

These steps apply to the sensing estimator:

https://e2e.ti.com/support/sensors/f/1023/t/797254?-FAQ-AWR1843-Where-can-I-find-the-source-code-for-the-mmWave-Demo-Visualizer

Amanda