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Compiler/OPT3101: OPT3101

Kevin_wang
Prodigy 230 points
Part Number: OPT3101

Tool/software: TI C/C++ Compiler

Hi Alex:

I have several problems now and I need your help!

1. A brief description of the light source: we use the light source USES a laser to transmit and receive Angle are 5 °, when working under the condition of the maximum current (173.6 mA), the optical power of about 100 mw, the measurement is 10 ~ 15 meters AMP_OUT is about 300, PHASE_OUT is about 44000, is this because of our impact on the circuit design?The front-end AFE is designed to work at 100mW what should the theoretical AMP_OUT value be close to?

2. Regarding the problem of mass production, since all four currents need to be calibrated in super-hdr mode, can the four currents be calibrated at a fixed distance?If possible, I would like to know the value of IPHASE and QPHASE after xtalk calibration.If not, can you give us a better mass production plan?

Thanks,

Best,

Kevin

  • 0
    TI__Mastermind 25895 points

    Hi Kevin,

    1.

    - For "The front-end AFE is designed to work at 100mW what should the theoretical AMP_OUT value be close to?" - have you used our system estimator tool? You will be able to use this to simulate the expected amp_out.

    - I also wanted to note eye safety if you are using max current with a laser. Have you checked this?

    - I do not follow this question "the measurement is 10 ~ 15 meters AMP_OUT is about 300, PHASE_OUT is about 44000, is this because of our impact on the circuit design", could you please clarify what the problem here is and what you are asking?

    2.

    - By calibrated at a fixed distance do you mean using the same distance for all 4 currents? This is possible, but not recommended as error will increase for the lower currents if the amplitude is too low. You can calculate the error in mm as error = atan(residue crosstalk/amplitude)/(2pi)*15000. Given your residue crosstalk after illumination crosstalk calibration this will be the error to expect due to calibrating phase offset at a given amplitude.

    - When you say "If possible, I would like to know the value of IPHASE and QPHASE after xtalk calibration" is this to determine the residue crosstalk? If you keep the photodiode covered after applying xtalk calibration the remaining amplitude and phase is the residue in polar coordinates. Is this what you are looking for?

    Best,

    Alex

  • 0 in reply to Alex Bhandari-Young
    Prodigy 230 points
    Hi Alex,
    I used the system estimator tool, but amp_out is greatly different from the actual output;What I want to know now is how your EVM is calibrated. As mentioned before, it is calibrated at two distances. So how much should be set for these two distances?We now it is under the same distance as 50 cm, by switching reflectivity (white and black) two kinds, for correction, four groups of super - HDR current TX0HDR0 used with TX0HDR1 reflectivity high white object correction, TX1HDR0 used with TX1HDR1 reflectivity low black objects correction, correction of 50 cm place again after the completion of the test two different reflectivity of the object distance is about 50 cm, but the degree of linearity is not enough, measuring 100 cm location object when low reflectivity of the deviation of about 15 cm,What causes this?Is it due to a lack of linearity, a problem with calibration, or is opt3101 particularly sensitive to objects with different reflectance?Can you give us a correction plan?Or tell us what the simple correction process of EVM is, the offset correction part is the key?
    Thanks!

    Best，
    Kevin
  • 0 in reply to Kevin_wang
    TI__Mastermind 25895 points
    Hi Kevin,

    Could you provide the boardID of the EVM you are using? Could you also provide the error you see with the EVM vs. the error you see with the calibration on your board? If you can include all data read from the device (amplitude, phase or distance, temperature, channel selected by super HDR, etc) that will be most helpful. If easier you can also email it to me at bhandari at ti.com

    Have you done the temperature calibration coefficients for phase offset and crosstalk already? I am wondering if the board temperature that you are testing at is different from the temperature you are calibrating at. We don't expect to see this type of linearity error. However, if the temperature and ambient coefficients are not there I would expect drift over change in temperature and change in ambient light (outdoors vs indoors). You can check for this by looking at the temperature reported by the IC when you did the calibration vs the temperature during testing.

    Best,

    Alex
  • 0 in reply to Alex Bhandari-Young
    TI__Mastermind 25895 points
    Kevin,

    Do you still need help here?

    Best,

    Alex
  • 0 in reply to Alex Bhandari-Young
    Prodigy 230 points
    Hi Alex：
    Yes, I need!But I don't know what the problem is,Correction with the temperature at which the measurement is not the same, AMB_OUT values are the same, and AMB_OUT value is almost stable at about 66, non-linear reason may be due to we didn't have to join the lighting circuit, which is caused by the temperature sensor of temperature compensation just using the chip internal temperature sensor to compensate, now we are through the high and low temperature experiment got the temperature curve is very linear, so we decided to use this article to compensate temperature curve, we think this is reasonable;At present, the most important problem is the correction. If the four current correction in super-hdr mode is to correct the corresponding current set by four different distances, the current will be switched when the reflectance of the object is changed, but the measured distance after switching is not accurate.It was mentioned before that EVM is calibrated at two distances, so what are the conditions that these distances need to meet, and in which groups of current do they work?

    Best,

    Kevin
  • 0 in reply to Kevin_wang
    TI__Mastermind 25895 points

    Hi Kevin,

    I saw your email. Are you planning to provide some more details over email? If you can provide some data that you are seeing that will help me a lot in debugging. If so let's move the debugging to email.

    Best,

    Alex