IWR6843AOPEVM: IWR6843AOP – Ramp-like bias in raw ADC data with custom config

Tool/software:

IWR6843AOP – Ramp-like bias in raw ADC data with custom config

Hello TI Team,

I am working with an IWR6843AOP and recording raw ADC data (via DCA1000). With our custom configuration, I consistently observe a ramp-like bias in the time-domain ADC samples. However, when I use the default Demo Visualizer configuration, this issue is not present.

To illustrate:

• Config 1 (our custom setup) → shows the ramp/bias in ADC time domain.

• Config 2 (TI Demo Visualizer setup) → no such ramp, the ADC baseline is stable.

I have attached the two configuration files below, as well as an ADC time-domain plot showing the bias when using our config.

Our Config (shows ramp):

sensorStop
flushCfg
dfeDataOutputMode 1
channelCfg 15 7 0
adcCfg 2 1
adcbufCfg -1 0 1 1 1
profileCfg 0 60 100 9.83 76.26 0 0 39.107 1 128 2000 0 0 36
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 2
chirpCfg 2 2 0 0 0 0 0 4
frameCfg 0 2 103 0 100 1 0
lowPower 0 0
guiMonitor -1 1 0 0 0 0 1
cfarCfg -1 0 1 8 4 3 0 15 1
cfarCfg -1 1 0 4 2 3 1 5 1
multiObjBeamForming -1 1 0.5
clutterRemoval -1 1
calibDcRangeSig -1 0 -5 8 256
extendedMaxVelocity -1 0
lvdsStreamCfg -1 0 1 0
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 4 19 0
CQSigImgMonitor 0 31 4
analogMonitor 0 0
aoaFovCfg -1 -90 90 -90 90
cfarFovCfg -1 0 0 6.137
cfarFovCfg -1 1 -5.02 5.02
calibData 0 0 0
sensorStart

Default config of Demo visualizer (no ramp):

% ***************************************************************

% Created for SDK ver:03.06

% Created using Visualizer ver:3.6.0.0

% Frequency:60

% Platform:xWR68xx_AOP

% Scene Classifier:best_range_res

% Azimuth Resolution(deg):30 + 30

% Range Resolution(m):0.044

% Maximum unambiguous Range(m):9.02

% Maximum Radial Velocity(m/s):1

% Radial velocity resolution(m/s):0.13

% Frame Duration(msec):100

% RF calibration data:None

% Range Detection Threshold (dB):15

% Doppler Detection Threshold (dB):15

% Range Peak Grouping:enabled

% Doppler Peak Grouping:enabled

% Static clutter removal:disabled

% Angle of Arrival FoV: Full FoV

% Range FoV: Full FoV

% Doppler FoV: Full FoV

% ***************************************************************

sensorStop

flushCfg

dfeDataOutputMode 1

channelCfg 15 7 0

adcCfg 2 1

adcbufCfg -1 0 1 1 1

profileCfg 0 60 359 7 57.14 0 0 70 1 256 5209 0 0 158

chirpCfg 0 0 0 0 0 0 0 1

chirpCfg 1 1 0 0 0 0 0 2

chirpCfg 2 2 0 0 0 0 0 4

frameCfg 0 2 16 0 100 1 0

lowPower 0 0

guiMonitor -1 1 1 0 0 0 1

cfarCfg -1 0 2 8 4 3 0 15 1

cfarCfg -1 1 0 4 2 3 1 15 1

multiObjBeamForming -1 1 0.5

clutterRemoval -1 0

calibDcRangeSig -1 0 -5 8 256

extendedMaxVelocity -1 0

lvdsStreamCfg -1 0 1 0

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 5 121 0

CQSigImgMonitor 0 127 4

analogMonitor 0 0

aoaFovCfg -1 -90 90 -90 90

cfarFovCfg -1 0 0 8.92

cfarFovCfg -1 1 -1 1.00

calibData 0 0 0

sensorStart

My Questions:

1. What is the root cause of this ramp/bias in the ADC data (in time domain) for our custom profile?

2. Why is it visible in our configuration but not in the Demo Visualizer configuration?

3. Which parameters (profileCfg / adcCfg / chirpCfg / frameCfg, etc.) are most likely responsible?

4. What is the recommended way to eliminate or reduce this issue?

Thank you very much for your support!