IWR6843ISK: Question about carrier frequency in sensing estimator tool

HI, Moon:

The carrier frequency is the center frequency of your RF chirp.

For example: if the start_frequency = 60G, and ramp_slope = 40MHz/us, total ramp time = 50us. 

Then the chirp ramp actually starts from 60G and ends at 60G + 40M*50 = 62GHz. The middle RF frequency of this chirp is roughly at 61GHz. 

But to get more accurate number, you can take a look at the chirp structure at figure 1 of following document www.ti.com/.../swra553a.pdf

The first part of ramp: ADC start time is not really used for ADC sampling, that is why the actually starting frequency of the chirp is moved to: 

 starting_frequency*1000+ramp_slope*adc_valid_start_time 

Then the second half should be really (half_of_the_ADC_sample_time * ramp_slope).   

Best,

Zigang 

Is it possible for you to check different version of the sensing estimator and see whether this is a bug introduced at the last version?

Best,

Zigang

Thank you for your reply

your last version was fixed thanks

and

I have one more question about sensing estimator variable "chirp time"

var chirp_time = function(aux_comp_coeff_b, aux_comp_coeff_a) {
  return -1000000*aux_comp_coeff_b/aux_comp_coeff_a;
 };

and

var aux_comp_coeff_a = function(starting_frequency, valid_sweep_bandwidth) {
  return (starting_frequency*1000+valid_sweep_bandwidth/2)*1000000;
 };
 
 var aux_comp_coeff_b = function(valid_sweep_bandwidth, adc_valid_start_time, starting_frequency, inter_chirp_time, lightSpeed, maximum_velocity, num_tx) {
  return (valid_sweep_bandwidth*adc_valid_start_time +
             starting_frequency*1000*inter_chirp_time +
    inter_chirp_time*valid_sweep_bandwidth/2 -
    lightSpeed/(4*maximum_velocity*num_tx));
 };
 

what is the physical meaning of "aux_comp_coeff_a" and "aux_comp_coeff_b"?

I think "aux_comp_coeff_a" means center frequency of chirp but I don't know

what aux_comp_coeff_b is and why does chrip_time calculate by "-1000000*aux_comp_coeff_b/aux_comp_coeff_a"

thanks