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AWR2944EVM: Tx power adjustment with the mmWave Demo Visualizer

Sean Ho
Prodigy 80 points
Part Number: AWR2944EVM
Other Parts Discussed in Thread: AWR2944

Hi TI experts,

I am measuring the radiated Tx power from a single Tx antenna array "AWR2944EVM + mmWave Demo Visualizer". Since only TDM is available for Demo Visualizer, I could ensure any instant power that I measure is from a single antenna. According to the datasheet of AWR2944 and the user guide of the AWR2944 Evaluation Module, I've learned the typical Tx power is 13.5dBm on AWR2944, and the peak gain of an antenna is 13dBi.

Question 1: I would like to know if the radiated Tx power is 13.5dBm + 13dBi = 26.5dBm when my configurations on the Demo Visualizer are like the two pictures below,

Config1:

Config2:

Question 2: According to the "MMWAVE SDK User Guide", one command in profileCFG is as below picture. I would like to know if I am not allowed to change another value to change TX power when I am running over the mmWave Demo Visualizer. Per my experiments, the radiated Tx power didn't have any change when modifying this value.

  

Question 3: Is there any way to enable the parameter to change Tx power?

Thanks,

Sean

  • 0
    TI__Mastermind 20605 points

    Hi Sean,

    Please find my responses below:

    1. Yes, this would be the overall Tx out power of the AWR2944EVM. I would suggest you use the Tx Power out monitoring API available in the mmwave ICD for more details when the device is chirping. Please find the same here.
      mmwave_mcuplus_sdk_04_04_01_02/mmwave_dfp_02_04_09_01/docs/mmWave-Radar-Interface-Control.pdf
    2. This is the Tx out power back off config which is used to maintain amplifier's output linearity. More details are there in the image below. May I know how you are measuring the out power?
    3. If you are talking about the <txOutPower>, it is already enabled in the demo when you configure the profile.

    Regards,

    Kaushik

  • 0 in reply to Kaushik Gowda
    Prodigy 80 points

    Hi Kaushik,

    The attached CFG file below was dumped from my EVM, but I cannot find the parameters as your image.

    Fullscreen Best range resolution mode 54m, resolution 0.75m, velocity 2.29ms (2).cfg.txt Download 
    % ***************************************************************
% Created for SDK ver:04.04
% Created using Visualizer ver:4.4.0.0
% Frequency:76
% Platform:AWR294X
% Scene Classifier:best_range_res
% Azimuth Resolution(deg):3Azim
% Range Resolution(m):0.75
% Maximum unambiguous Range(m):54
% Maximum Radial Velocity(m/s):18.27
% Radial velocity resolution(m/s):2.29
% Frame Duration(msec):100
% RF calibration data:None
% ***************************************************************
sensorStop
flushCfg
dfeDataOutputMode 1
channelCfg 15 13 0
adcCfg 2 0
adcbufCfg -1 1 1 1 1
lowPower 0 0
profileCfg 0 76 8 7 10 0 0 100 1 80 39999 0 0 30
chirpCfg 0 0 0 0 0 0 0 1
chirpCfg 1 1 0 0 0 0 0 4
chirpCfg 2 2 0 0 0 0 0 8
frameCfg 0 2 16 0 80 100 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
calibDcRangeSig -1 0 -5 8 256
clutterRemoval -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 1 0 1 0 1 0 1 0
measureRangeBiasAndRxChanPhase 0 1.5 0.2
aoaFovCfg -1 -90 90 -90 90
cfarFovCfg -1 0 0 47.99
cfarFovCfg -1 1 -18.27 18.27
extendedMaxVelocity -1 0
calibData 0 0 0
sensorStart

    In my profileCfg, the 6th bit marked in red is <txOutPower>, and the measured power was kept the same when the bit was set to 0, 10, or 20. 

    profileCfg 0 76 8 7 10 0 0 100 1 80 39999 0 0 30

    Here is my setup to measure TX output power. 

    Regards,

    Sean

  • 0 in reply to Sean Ho
    TI__Mastermind 20605 points

    Hi Sean,

    I will reassign this thread to the right expert to comment further. Please expect a response within a day or two.

    Regards,

    Kaushik

  • 0 in reply to Kaushik Gowda
    TI__Genius 16120 points

    Hello Sean,

    Are you saying that you are observing the same o/p power irrespective of what the <txOutPower> is set to?

    What is the value of the Output power you are measuring?

    Thanks,

    E. Shareef

  • 0 in reply to E. Shareef
    Prodigy 80 points

    Hi Ehtesham,

    I have retested and found the tx power could back off while increasing the value of <txOutPower>. Here is my test setup and test result. I could have 10dB power back off with txOutPower set to 30. Do you think my measurement is correct?

    Thanks,

    Sean

  • 0 in reply to Sean Ho
    TI__Genius 16120 points

    Hello Sean,

    Allow me to get back to you in a day on this. 

    -E. Shareef

  • 0 in reply to E. Shareef
    TI__Genius 16120 points

    I will need to understand the power loss for the distance, but on a higher level, your measurement set up looks correct

  • 0 in reply to E. Shareef
    Prodigy 80 points

    Hi E. Shareef,

    Thank you for the confirmation of my measurement setup. Based on my measurement setup, I am afraid that the power loss for the distance could not be measured. 

    Regarding the plot of the "range profile for zero Doppler", what is the "relative power" on Y-axle? What is it relative to? How do I know the absolutive power (dBm) then?

    Thanks,

    Sean

  • 0 in reply to Sean Ho
    TI__Genius 16120 points

    The freespace path loss would account to 79.72dB at 77GHz for the signal to transmit and come back from the corner reflector. You should try and enable only one TX and one RX if you are trying to calculate the Output power. 

    Now for the relative power, I would need to understand where you are getting this plot from?

  • 0 in reply to E. Shareef
    Prodigy 80 points

    Hi E. Shareef,

    Can I consider that only one Tx antenna is enabled as I did experiments since the "mmWave Demo Visualizer" only supports TDM? As for single Rx, I don't know how to make it with the mmWave Demo Visualizer. Could you show me the way? 

    The relative power I mentioned is as I circled in the below picture. 

     

    Thanks,

    Sean

  • 0 in reply to Sean Ho
    TI__Genius 16120 points

    I am requesting my software colleague to respond here. He would have a better undertsanding of the visualizer. 

    -E. Shareef

  • 0 in reply to E. Shareef
    TI__Guru*** 148334 points

    Hi,

    Sean Ho said:
    what is the "relative power" on Y-axle?

    This power is computed based on the value of the ADC samples. I think the terminology "relative power" is used because this is not the "absolute power"

    Sean Ho said:
    As for single Rx, I don't know how to make it with the mmWave Demo Visualizer. Could you show me the way? 

    The demo that is being used may not support 1 Rx configuration.

    Please note that the mmWave demo was designed to show the performance of the sensor and provides limited configuration for power measurement.

    Usually, for power measurement,  the mmWave studio tool + the DCA1000 EVM is used. With the mmWave Studio tool one can perform full configuration of the device.

    Please see some older threads related power estimation

    https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/914685/awr1642-awr-series-received-power-estimation

    Please also use google site search as follows to find more threads related to this topic:

    site e2e.ti.com awr power estimation

    Thank you

    Cesar

  • 0 in reply to Cesar
    Prodigy 80 points

    Hi Cesar,

    Thank you for your elaboration. 

    For example, the Relative Power is read as 120 in the picture. Does "120" here stand for 0x078 with a 12-bit ADC mode?

    If I am using 12bit ADC mode, a value of 0x7FF corresponds to a positive peak value at the ADC input, which corresponds to 1V peak voltage at the ADC input. Thus, 0x078 of ADC means a 0.058V at ADC input which is around -15dBm power based on a 50ohm system. Then, -45dBm is the power at the LNA input if the gain of LNA is set to 30dB.  Are there any mistakes with my inference?

     

    Thanks,

    Sean

  • 0 in reply to Sean Ho
    TI__Guru*** 148334 points

    Hi,

    Please give us some time to review this with extended team.

    Will get back to you next week

    thank you

    Cesar

  • +1 in reply to Cesar
    TI__Guru*** 148334 points

    Hi,

    I was able to get an answer earlier than expected.

    Your computation is correct if the scaling of the ADC data is 1.

    The processing of the data may perform scaling.

    What processing chain is being used for this experiment?

    Thank you

    Cesar