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DS90UB934-Q1: FPD LInk III WiFi intereference

Goran Fiolic
Intellectual 410 points
Part Number: DS90UB934-Q1

We have a camera utilizing DS90UB933Q and two deserializer boards - one utilizing DS90UB934-Q1, and the other utilizing DS90UB914-Q1. PCBs are identical, only deserializers are different. When Camera is connected to DS90UB914-Q1 based board everything works fine. If camera is connected to DS90UB934-Q1,based board, image becomes unstable when WiFi router is brought to a close proximity of a coaxial cable connecting camera and deserializer board. What would be the reason for this difference in performance between two deserializers, and is there any way to make DS90UB934-Q1 less susceptible to WIFI interference.

  • 0
    TI__Expert 4555 points

    Hi Goran,

    There should be no difference in performance between the two deserializers in regards to the susceptibility towards WiFi. Do you have other 934/914 boards that you can test so that you can confirm that this is happening across all of the 934 devices?

    In the meantime, you can also use this application note as a resource. It highlights the main features and differences between the 914 and 934, and also details how to migrate from the 914 to the 934 -->  http://www.ti.com/lit/an/snla286a/snla286a.pdf

    Regards,

    Jonny

    Training on FPD-Link Serializer Deserializer devices and system: https://training.ti.com/fpd-link-learning-center

    More information on IVI or ADAS FPD-Link products: http://www.ti.com/interface/fpd-link-serdes/overview.html

  • 0 in reply to Jonathan Nguyen
    Intellectual 410 points

    Hi Jonathan,

    We have two additional, completely different hardware platforms - one with 914, and the other with 934. Same thing happens - no problem with 914, unstable picture with 934. I was hoping that, perhaps, there is some "reserved" 934 register where I could try to manually adjust signal equalization parameters because I doesn’t look like adding some sort of filtering is possible.

    Regards

    Goran

  • 0 in reply to Goran Fiolic
    TI__Guru* 87750 points
    Hi Goran,

    did I understood it correct that you are using two deserializers on an identical PCB? The 914 and 934 are not 100% compatible!! please refer to the document mentioned by Jonathan to see where and what are the differences. You need to do those changes to make the 934 stable.
  • 0 in reply to Hamzeh Jaradat
    Intellectual 410 points

    Hi Hamzeh,

    We have two almost identical boards. The board was first designed for 914 deserializer and modified afterwards so that it may accept 934 deserializers. 934 board works perfectly stable unless there is a WiFi router or a mobile phone in a close proximity to the coaxial cable connecting imager and the 934 board. Same thing happens with 954 deserializers on a completely different board and with different imagers (cameras). Since 913 deserializer supports lower bit rates I assumed that might be the reason why it is less susceptible to the external electro-magnetic interference. I was, therefore, wondering if you already had experience with similar issues and what can be done to overcome it.

    Regards

    Goran  

  • 0 in reply to Goran Fiolic
    TI__Intellectual 2930 points

    Hello Goran

         Usually the Immunity is dependent on the shield effectiveness of the cable. As you mentioned, it is likely that because 934/954 uses higher data rate and the interference from Wifi is causing an issue at the higher data rates. We had not experienced or seen these type of specific issues, possibly because of the cables we may use

    Regards

    Vijay

  • 0 in reply to Vijaya Ceekala
    Intellectual 410 points

    Hi Vijaya,

    Thank you for your support. We have, in the meantime, discovered that the issue was related to the way how coaxial cable was attached to the board at one side of the link. Cable was soldered directly and that created a small pigtail which decreased shield effectives.

    Regards

    Goran