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TIDEP-01012: Matlab problems of TX beamforming mode in the Cascaded mmWave Sensor Reference Design

SHENGXIANG ZHU88409
Prodigy 220 points
Part Number: TIDEP-01012
Other Parts Discussed in Thread: MMWCAS-DSP-EVM, MMWCAS-RF-EVM

Hello，everyone.
 I am using the MMWCAS-DSP-EVM and MMWCAS-RF-EVM with matlab in TX Beamforming mode.
Now I have some questions.
1)  In D:\program\ti\mmstudio\mmwave_studio_02_01_00_00\mmWaveStudio\MatlabExamples\4chip_cascade_TxBF_example\Calibrations,
there are phaseMismatchCalibration.mat and phaseShifterCalibration.mat.
As the mmwave user's guide said, "phaseShiftCalibfile -> Phase shifter calibration file, the same calibration file is used by default for all boards
o phaseMismatchCalibfile -> Phase Mismatch calibration file, the same calibration matrix generated in the MIMO mode will apply"
However, in MIMO mode， I can only obtain the file----calibrateResults_high.mat. What should I do ?
2) I calibrated the EVM with a metal target at around 5 meters (Not in an anechoic chamber, just in lab ).
 I captured the ADC data in TX beamforming mode then ran the cascade_TxBF_signalProcessing.m.
I got the range profile peak at about 6.587 meters .
Then I moved the target to about 2 meters and do it again.
I got almost the same range profile peak.
It seems that the target range does not change at all.
Even though the calibration result is not precise, the ranges of two experiments should be different.

3) What's the difference among the chirpProfile_TxBF_LRR.m, chirpProfile_TxBF_SMRR.m,chirpProfile_TxBF_USRR.m.
As the comments in Matlab ,they are for different ranges.
However, what I want to know is the details.
In other words, which parameters should be changed for my applications?
Please help me.
Thanks.
  • 0
    TI__Guru*** 148514 points

    Hi,


    We will be able to get back to you before end of the week.

    thank you

    Cesar

  • 0 in reply to Cesar
    Prodigy 220 points

    Hi, Cesar.

    I really need your help.

    Thank you.

  • 0 in reply to SHENGXIANG ZHU88409
    TI__Mastermind 18500 points

    Hi Shengxiang, 

    Q1. At the moment, we have not published TX phase shifter calibration flow for the cascade EVM. We have not provided a way to generate the example phaseShifterCalibration.mat. 

    Q2. In higher clutter environments it is sometimes difficult to separate out intentional calibration targets from clutter that may resolve to the same or similar range bins. If you cannot get access to an anechoic chamber, I recommend calibrating in as large of an open indoor or outdoor space as possible. 

    Q3. Between these three example TX-BF setups the chirps have been modified for different automotive range scenarios. That is the only change. Other setup and processing are identical. 

    I hope that helps. 

    Thank you,

    -Randy

  • 0 in reply to Randy Rosales
    Prodigy 220 points

    Hi, Randy.

    Thank you for your reply.

    I still have some questions.

    As you said,  TX phase shifter calibration flow is NOT supported,

    that means if I just use the default phaseShifterCalibration.mat file, it would not affect the results ,right ?

    Then how can I get the phaseMismatchCalibration.mat file for my own EVM?

    I doubt that there is something wrong with my calibration flow which resulted in faliure.

    Please help me.

  • 0 in reply to SHENGXIANG ZHU88409
    TI__Mastermind 18500 points

    Hi Shengxiang, 

    You can use the phaseMismatchCalibration.mat. This is included as an example taken on one MMWCAS-RF-EVM. However, TX phase-shifter calibration should be done each EVM for best results since this allows you to compensate PCB-specific phase offsets.

    You would need to develop your own TX phase-shifter calibration flow for now. The basic flow is: 

    1. Take data from each TX channel and phase-shifter offset relative to a single RX in the system in a single, bore-sight reflector scene
    2. Subtract the measured absolute phase from this target from each TX relative to a reference TX to generate a relative phase graph for each TX/phase-shifter combination
    3. Use these relative phase graphs to construct a look-up table mapping the desired phase differences to the programmed phase-shifter offset

    Thank you,

    -Randy