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OPT3101EVM: Long distance measurements with Latte

Tejas Vasekar
Prodigy 90 points
Part Number: OPT3101EVM

Hi,

So when I use EVM board with Latte  software, I get a lot of noise in GUI. Even if I use it in superHDR mode with 8 frames for average. 

I got proper output upto 2-2.5m after that output became to noisy. 

I saw this video : https://www.youtube.com/watch?v=GJodu6OgzNg

and in that video, in first demo operators got pretty accurate distances for entire duration.

Can someone please tell me what kind of settings you used to get those results?

I referred http://www.ti.com/lit/an/sbaa303/sbaa303.pdf and enabled de-aliasing in Latte. Though output became steady, it was wrong.

So do I have to do some other adjustments as well? 

Thanks,

Tejas 

  • 0
    TI__Mastermind 25895 points

    Hi Tejas,

    What is the amplitude you are reading when you start getting noisy data? You can also try increasing the averaging from 8 to something like 32 and see if that helps at all.

    Best,

    Alex

  • 0 in reply to Alex Bhandari-Young
    Prodigy 90 points

    Hi Alex,

    Amplitude and distance readings keep varying even if I use 32 samples for average.

    Amplitude range : 

    At 3.5 m : 130-135 codes

    At 4.0 m : 25-45 codes

    Thanks,

    Tejas

  • 0 in reply to Tejas Vasekar
    TI__Mastermind 25895 points

    Hi Tejas,

    At 4m with the amplitude that low I am not surprised that the readings are noisy. In the videos you referenced the amplitude reading was higher so this is I believe the reason for the lower noise. Is your target low reflectivity? Amplitude is effected by distance, reflectivity, and percent of the field of view covered by the target.

    Best,

    Alex

  • 0 in reply to Alex Bhandari-Young
    Prodigy 90 points

    Hey Alex,

    We have a white wall as target.

    I tried with enabling de-aliasing from register view and there was significant drop in noise.

    But with de-aliasing, distance values that I got are wrong.

    Do you know any other registers that I need to change with de-aliasing to reduce the error in distance values?

    Thanks,

    Tejas

  • 0 in reply to Tejas Vasekar
    TI__Mastermind 25895 points

    Hi Tejas,

    Enabling de-aliasing would require running a full calibration at the second frequency used for de-aliasing before you could get meaningful data. The fact that noise decreased if you just enabled in registers but didn't recalibrate likely is just from measuring crosstalk rather than signal. I would not expect de-aliasing mode to give better performance - it is used for extending range above 15m and has to do with the phase shift of light exceeding one period of the 10MHz pulse at >15m so it would not improve signal strength. Please let me know if you still need info on de-aliasing, but I do not think this would help <15m.

    What is the size of your white target?

    Best,

    Alex