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AWR2944: TX output Power

Yuto Kitamura
Expert 6705 points
Part Number: AWR2944


Dear team,

We are evaluating AWR2944 and want to change Tx output power by changing profileCfg. We are referring the apps note (here) and change as red-highlighted to decrease the power from maximum.
We have tried it but could not confirm changing the power.(Now we are changing profileCfg and checking azimPeakSamples to confirm it)

e.g.,
profileCfg 0 79.00 10 7 20.81 0 0 24 0 512 37500 0 0 36
to
profileCfg 0 79.00 10 7 20.81 10 0 24 0 512 37500 0 0 36


<txOutPower>

1. Is this process correct to change Tx output power?
2. If no, how can we change the power?
3. If yes, how can we verify it is changed correctly? I am a little concerning about the comment, "only values "0" has been tested...".

Best regards,
Yuto

  • 0
    TI__Expert 6705 points

    Hi team,

    I hope I could get response as early as possible.
    We get new information.

    Please refer to the attached file. We had an evaluation with AWR2944 and the visualizer. According to the result, The relative power of TDM and DDM is different, and the amount of change in DDM looks to be less. Then we got a new question.

    Is this setting slope is correct? How can we reduce power more?

    What is "relative power" definition on source code as we can see in SDK? (why txOutPower ratio is not same as rxGain?)

    231114_TxOutPower_調査.pdf

    Best regards,
    Yuto

  • 0
    TI__Guru 70050 points

    Hi Yuto,

    To measure the TX output power, I suggest you to try it with mmWave Studio and check the ADC data (process it using mmWAve Studio post-process tool).

    Other way to probe on the external Tx output RF signal and measure the TX output power.

    DDMA and TDM process the ADC data in different way so peak value may differ with given TX_BackOff option.

    .

    Regards,

    Jitendra

  • 0 in reply to Jitendra Gupta
    TI__Expert 6705 points

    Hi Jitendra,

    Thanks for feedback but the point is slight different.

    Our questions are about the specification and design of TI chip.

    Q1: How much power dB can be back-off by DDMA mode in AWR2944?
    Q2: Would you tell me the setting to obtain >5dB back-off about Tx power?

    If you need to discuss internal forum, please contact me directly via email.

    Best regards,
    Yuto

  • 0 in reply to Yuto Kitamura
    TI__Expert 6705 points

    Hi Jitendra,

    Sorry for rushing, but please update for this topic as early as possible.

    Yuto Kitamura

  • 0 in reply to Yuto Kitamura
    TI__Expert 6705 points

    Hello, 

    Hope we can get response soon. But let me follow up with additional information. 

    As you mentioned, using mmwave studio is one of the measuring method, but we want to know the method to set >5dB back-off. And we are using cfg file to set the parameters, so we want to know where to change on the source code to achieve it.

    Warm regards,
    Yuto

  • +1 in reply to Yuto Kitamura
    TI__Guru 70050 points

    Hi Yuto,

    That CLI configuration is being handled by the cli_mmwave.c : CLI_MMWaveProfileCfg function.

    and further same parameter is being passed to BSS via mmwavelink (rlSetProfileConfig API and rlProfileCfg_t struct)

    So with the CLI parameter change TX-power backoff should be applied to rf-front end.

    -> Valid Range for xWR294x devices: 0 to 20 in 1dB steps
    Best way to measure this change is to measure the Rf-Signal on TX antenna edge.

    with mmw demo, only 0 value had been tested, with that reason only I suggest to refer above statement to measure it on TX signal for confirmation.

    .

    Regards,

    Jitendra

  • 0 in reply to Jitendra Gupta
    TI__Expert 6705 points

    Hi Jitendra,

    Thank you for your support. We could resolve the issue and success to make back-off by changing cfg file because of your example code.

    We understand that  txOutPower in cgf file indicates only Tx1 value. Therefore is we want to decrease the total tx power with DDM, we must set the all channel of Tx1~Tx4 by setting 4* 8bit (interger) for each 4ch as shown below.
    Incorrect setting:  profileCfg 0 79.00 10 7 20.81 5 0 24 0 512 37500 0 0 36
    => 
    Correct setting:    profileCfg 0 79.00 10 7 20.81 84215045 0 24 0 512 37500 0 0 36

    ex: 5dB back-off
    5(10) = 101(2)
    00000101000001010000010100000101(2) => 84215045(10) 

    Best regards,
    Yuto