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Original question:

MMWCAS-DSP-EVM: Why does the device drop some frames while capturing frames?

MMWCAS-DSP-EVM: Data loss, frame loss , mmwcas-rf-evm

Lubo Zegov
Prodigy 50 points
Part Number: MMWCAS-DSP-EVM
Other Parts Discussed in Thread: MMWCAS-RF-EVM

I am using a modified Lua script to record 7500 frames where each frame consists of one loop of 12 chirps, same as in the example (all Transmitters are sequentiall turned on during one frame) with the mmwav-dsp-evm and mmwcas-rf-evm.

Then using a frame time of 2ms, but also different, e.g, 10, 20, 30... I never get 7500 frames recorded in the data files. Always the number of recorded frames is about 7200 -7300. I tried changing the DDR data rate, etc. but does not seem to fix the problem... 

I checked that my MMWAVEstudio is up to date - version 3 and the DFP too is up to date. 

Any ideas what could I try and how I can fix this? Why is the device dropping frames? 

I see that other people have the same issues but no answer/ solution seems to be have been provided??! 

  • 0
    TI__Guru*** 148294 points

    Hi,

    As you have probably seen in the other similar threads, dropped frames are related to limitation of the system bandwidth. Basically there is too much data to be transferred.

    This is a limitation of the system. Some chirp configurations generate too much data and frames will be dropped.

    There is no solution to solve this limitation

    thank you

    Cesar

  • 0 in reply to Cesar
    Prodigy 50 points

    Hello Cesar, 

    Thank you for your reply... Can you please elaborate more on this limitation.

    Is there a hard number related to it and how can I calculate my radar parameters in order to be sure that  frames will not be dropped?  

    Is the frame drop related to the inter-frame time? 

    Is the frame drop related to something else, which parameter I shall change. 

  • 0 in reply to Lubo Zegov
    TI__Guru*** 148294 points

    Hi, the amount of data is usually related to the number of ADC samples.

    If you decrease this number you should be able to see that no more frames are dropped

    Thank you

    Cesar

  • 0 in reply to Cesar
    Prodigy 50 points

    Hello Cesar, 

    Indeed I have tried that but still same...dropping frames and files are always with different size if I redo a few measurements with same parameters. 

    Furthermore, I tried to do the following. I used the default settings provided with the MIMO_configure.lua and capture.lua.. -> No data drop. 

    Then I increased the number of recorded frames nframes_master and nframes_slave from 20 to 100 and again data begin to be missing. 

    The other thing that I tried is to use the same default settings in MIMO_configure.lua but use only one chirp loop per frame instead of 64, which should in general reduce the data stream 64 times, but again always data drop...

    TO be honest at his moment I could not find any correlation between data dropping and frame rate, or ADC samples... It seems to be always, unless I do use the default settings for a measurement of 2sec?! 

    In that case I cannot be sure if the RF board or/and the DSP board  are functioning correctly or anything else in my setup is faulty... Do you have any recommendations of how to proceed or can you suggest some settings which would allow me to make measurements without data drops for lets say 20sec, s.t. I can test if there is some error with my system. 

  • 0 in reply to Lubo Zegov
    TI__Guru*** 148294 points

    Hi,

    If I understand correctly

    • the same MIMO configuration is used
    • ONLY nframes_master and nframes_slave are increased from 20 to 100
    • Frames are dropped.

    Would it be possible to

    • increase the frame duration. I think by default it is 20 fps. Could you try 10fps?

    Thank you

    Cesar

  • 0 in reply to Cesar
    Prodigy 50 points

    Hi, yes that is correct. What I actually would like to do with my application is use only one chirp loop with 12 chirps (all transmitters) per frame with frame duration of up to 3us and low sampling rate, e.g. 128 samples per sweep. Measurement time of about 10-15 seconds. Until now I could not record a measurement without frame drops. 

    I will increase the frame duration and let you know about the results. 

    Thanks. 

  • 0 in reply to Lubo Zegov
    TI__Guru*** 148294 points

    thank you

    Cesar