IWR1443BOOST: chirp parameters

HI, Filippo:

1) The range resolution is only related to the RF bandwidth.  If you did not change the chirp slope, and the number of ADC samples, but only increase the ADC sample rate.  Then the actual ramp time, which is numAdcSample / ADC sample rate, becomes smaller.  Then the RF bandwidth, which is chirp slope * actual ramp time, becomes smaller.  When the RF bandwidth get smaller, the range resolution increases.   For example, your ADC sample rate is 10MHz, and the number of ADC samples per chirp is 256 sample, then the actual used ramp time is numAdcSample / ADC sample rate  = 256/10e6 = 25.6us. 

2) The range profile in radar studio is calculated from the Doppler FFT output (it is the zero doppler bin output).   Although you do not care about the Doppler resolution.  But you will get more post process gain with higher number of loops, which means your SNR will be better with higher number of chirps in the frame.    In the SDK users guide, it is mentioned that this value has to be 4 or above.   (search for frameCfg in SDK users guide)

3) Regarding your question on the maximum unambitious range, where did you get this information.  We just can not see range beyond the maximum range.  There is no ambiguity about range estimation like velocity.   Since IF bandwidth is little smaller than the ADC sampling rate (due to the filters), the signal beyond IF bandwidth is distorted and can not be used for good estimation. 

Best,

Zigang

Very clear. Regarding 3). I send a configuration to the IWR1443 from which mmWave_Demo_Visualizer estimates a maximum unambiguous range of 59 m, but the maximum value on the x axis of the range plot is ca. 63, see image below, where both values are highlighted. I think that maximum unambiguous range is computed as Maximum IF bandwidth x speed_of_light / (Slope*2). While the max value on the x axis is the number of bins multiplied by the range resolution (ca. 1024*0.0662=ca. 63).

Is it deeply not suggested to measure range beyond the maximum unambiguous range because of what you refer to as distortion? Because typically we measure in the range interval 50-60 m. 

HI, Filippo:

What is the IF bandwidth and ADC sampling rate in your configuration?  50 vs 63, the difference is little bit larger than I expected. I thought it will be 90~95%.    

Can you provide your complete profile/chirp configuration?

Best,

Zigang

Sweep bandwidth is 2.41 GHz and ADC sampling rate is 6.25 Msps

Below is the configuration

% ***************************************************************
% Created for SDK ver:02.01
% Created using Visualizer ver:2.1.0.3
% Frequency:77
% Platform:xWR14xx
% Scene Classifier:best_range
% Azimuth Resolution(deg):60
% Range Resolution(m):0.062
% Maximum unambiguous Range(m):50
% Maximum Radial Velocity(m/s):1
% Radial velocity resolution(m/s):0.13
% Frame Duration(msec):100
% Range Detection Threshold (dB):15
% Range Peak Grouping:enabled
% Doppler Peak Grouping:enabled
% Static clutter removal:disabled
% ***************************************************************
sensorStop
flushCfg
dfeDataOutputMode 1
channelCfg 3 1 0
adcCfg 2 1
adcbufCfg 0 1 0 1
profileCfg 0 77 804 7 169.29 0 0 15 1 1008 6250 0 0 30
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 0
frameCfg 0 0 16 0 100 1 0
lowPower 0 1
guiMonitor 1 1 0 0 0 1
cfarCfg 0 2 8 4 3 0 1280
peakGrouping 1 1 1 1 920
multiObjBeamForming 1 0.5
clutterRemoval 0
calibDcRangeSig 0 -5 8 256
compRangeBiasAndRxChanPhase 0.0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0
measureRangeBiasAndRxChanPhase 0 1.5 0.2
CQRxSatMonitor 0 3 16 125 0
CQSigImgMonitor 0 125 16
analogMonitor 1 1
sensorStart

HI, 

Sorry for the delay.  Do you have these two lines in your configuration?

cfarFovCfg -1 0 0 49.99

cfarFovCfg -1 1 -1 1.00

Best,

Zigang

Hello.

I do  not have those lines and I have never seen them in the SDK documentation.

All the best

Which SDK version you are using?

Best,

Zigang

Hi,

as specified in the configuration file:  SDK ver:02.01. From what I know, it is the most recent version compatible with AWR1443boost.

All the best

HI, 

It seems that in the document here http://www.ti.com/lit/an/swra553a/swra553a.pdf, 90% of the ADC sampling rate is used for maximum IF bandwidth.   But in the visualizer 80% is used for maximum IF bandwidth.  

I am still discuss with the team to figure out which one is recommended. 

Best,

Zigang

HI,

We have an internal discussion, and 80% is the right value.  The datasheet always lists the IF bandwidth as 80% of the ADC sampling rate.   

Best,

Zigang