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DS90UB927QEVM: DS90UB927QEVM interfere with GPS signal

Eric Chen4
Expert 2370 points
Part Number: DS90UB927QEVM


Hi,

I need your suggestion about  DS90UB927QEVM interfere GPS signal issue.

I use DS90UB927QEVM closed to GPS receiver device then find the DS90UB927QEVM to interfere GPS signal as below.

May I have your suggestion how to solve this?

Thanks.

Plug in USB Cable.

Remove USB Cable

Regards,

Eric

  • 0
    TI__Mastermind 30515 points
    Eric,
    what is the impact? which bandwidth has this issue?
    basically, grounding / filtering / shielding are basic skills to remove EMC issue.

    best regards,
    Steven
  • 0 in reply to Steven(Shenzhen) Shi
    Expert 2370 points
    Hi Steven,
    I just testing when using DS90UB927QEVM and put it close to GPS receive effect.
    I find only plug USB power with EVM board then GPS signal will disappear even away from 30cm and also got same situation.
    So DS90UB927QEVM doesn't do any certification, such FCC/ CE, right?
    And I can't use the EVM to do any simulation verify?
    Thanks.

    Regards,
    Eric
  • 0 in reply to Eric Chen4
    TI__Expert 5435 points
    Hi Steven,

    This issue means TI EVM board DS90UB927 has strong EMI interference that causes GPS band (around 1.5GHz) communication worse. TI clams DS90UB927 is low EMI in datasheet and that would confuses engineer with this test result. The impact is: when design DS90UB927 in a system that GPS is also equipped, it should need some way to prevent such EMI issue.

    Please provide a guidance on how to improve the EMI on DS90UB9267EVB. That would be more helpful. Thank.

    Cheers,
    Alex
  • 0 in reply to Alex Yeh
    TI__Mastermind 30515 points
    Alex,
    EMI is one design issue, system-level issue. In your application, you should try to remove the impact of EMI/EMC.
    regarding UB927EVM board, this is designed for performance evaluation. also based on standard EMI/EMC test guideline, TI's EVM board also passed the EMI/EMC test in the 3rd party, but the test condition follows the automotive grade such as the power supply is from the 12V battery NOT from USB. as you know, the power supply should have large conduct emission.
    for TI's claimed low EMI, please note the I/f is based on LVDS which is designed for low EMI, this is different with your case. in your case, you should have good grounding, filtering and shielding performance if the EMI/EMC can't catch your need. the EMI source could be from conduct or radiation emission.


    best regards,
    Steven