IWR6843ISK-ODS: Calibration program and config

Hi Denis,

Before I address the questions, please note that you have the TX and RX annotations in your picture are incorrect (swapped). The 4 patches to the left are the RX channels and the 3 patches to the right are the TX channels (the device has 3TX and 4RX).

1. It says on ti/demo/xwr68xx/mmw/docs/doxygen/html/index.html page that we must use profile_calibration.cfg from ti\demo\xwr68xx\mmw\profiles folder. Is this profile and calibration results that we will get are universal? Is it right to apply calibration results (compRangeBiasAndRxChanPhase string) to any other profile config-file?

Ans: The calibration coefficients apply to all demos which have the compRangeBiasAndRxChanPhase command in their configuration, for the same EVM. Each ISK board needs to calibrated individually and the calibration results updated in the corresponding demo configuration for that EVM, because the calibration results are specific to that EVM.

2.  For example, in our own config-file we use all antennas and freqSlopeConst = 166, in profile_calibration.cfg   freqSlopeConst = 156. To calibrarte our sensor to work with 166, do we have to change freqSlopeConst in profile_calibration.cfg from 156 to 166?

Ans: No, the calibration coefficients are calculated once using the profile_calibration.cfg configuration file, and apply to any chirp configuration for that specific board. They do not change with chirp parameters.

3.  It says that we have to set a strong target at the distance of X meter at boresight. Were should we choose the center of our antenna system?

Ans: The strong target is typically a corner reflector which you can keep in facing the center of the RX channels.

Thanks

-Nitin 

Hi Denis,

Sorry, I missed that:

2. Which program should be loaded to IWR6843ISK-ODS during calibration? Do we have to use .xe674, .xer4f images from ti\demo\xwr68xx\mmw ? Or we can load our program? Is it matter that we use 2D Rx antenna pattern?

Ans: You need to use the SDK Out of Box demo program in ti\demo\xwr68xx\mmw. You can use .xe674, .xer4f if you want to run in CCS debug mode, oryou can flash the flashable binary xwr68xx_mmw_demo.bin if you want to run in deployment mode. Both these are explained in the mmWave SDK user guide. The idea behind the calibration procedure is to estimate the differences in antenna gains and phases across all TX-RX pairs so that they could be corrected using the runtime compensation in the code, so you need to use 3D antenna pattern for the calibration procedure.

-Nitin

Hi Denis,

The antenna geometry for the IWR6843AOP antenna is defined in the AoA2DProc DPU HTML documentation available at the following path:

file:///C:/ti/mmwave_sdk_03_04_00_03/packages/ti/datapath/dpc/dpu/aoa2dproc/docs/doxygen/html/index.html

The ODS antenna is similar just inverted so you can assume the boresight location as shown below

Please refer to the following thread for the same discussion.

IWR6843ISK: Combined Antenna boresight for ISK

As noted in the thread referenced in this post, the exact location of origin is not defined and relevant for far field (far field is the assumption made in angle/range calculations) which is considered to be anything beyond 10cm in the demo code. So for calibration purpose, where the corner reflector target will be kept at 1m or far, you can imagine the origin as the entire rectangle on the sensor board which spans the physical tx-rx azimuth and elevation antennas.

Regards

-Nitin