9 Replies Latest reply on Apr 2, 2017 2:01 AM by fnoop

    Massive USB3 EMI

    fnoop

      So, I'm trying to use the joule and realsense camera to learn how to do funky things on a drone.  I've already got the joule interfaced and connected to the flight controller (pixhawk) and written some vision code using the realsense camera.  That's all good, and the joule and realsense is a fantastic platform for this stuff, which is why Intel is pushing it so hard for drones.

      However, as soon as I turn the realsense camera on, the entire drone gets swamped with EMI from the USB bus which knocks out any nearby GPS, wireless radios etc.

      This isn't particularly specific to Intel or the joule/realsense platform, but the joule and realsense are being touted for drones.  Does Intel, or any other community members here, have any experience or recommendations for minimising or mitigating USB EMI from this platform?

        • 1. Re: Massive USB3 EMI
          Intel Corporation
          This message was posted on behalf of Intel Corporation

          Hello fnoop,

          Thank you for interest in the Intel® Joule Products.

          I once had a similar problem in a drone-related project, and I could minimize the electromagnetic interference changing the cables for shorter ones.

          We will always recommend using the cables that come with the product because those are the ones officially tested. But I think it’s worth it to try out the previous suggestion.

          Other method to reduce EMI is using a ferrite bead (also known as ferrite choke), I haven’t tested it myself, but it seems to have worked for another developers.

          If you are willing to share a picture of your setup, I may be able to provide better assistance. 

          Please let me know if you find the previous information useful.

          If you need further assistance, don’t hesitate to contact us.

          Regards,
          Andres V.

          • 2. Re: Massive USB3 EMI
            Intel Corporation
            This message was posted on behalf of Intel Corporation

            Hello fnoop,

            I was wondering if you had the chance to check the suggestions provided.

            If you have any other question or update, don’t hesitate to contact us.

            Regards,
            Andres V.

            • 3. Re: Massive USB3 EMI
              fnoop

              Hi Andres, the USB cable that comes with the r200 is about as short as they come but I've tested a couple of other similar short cables with the same results.   There are some good articles and research from intel on this subject:

              http://www.ti.com/sc/docs/apps/msp/intrface/usb/emitest.pdf

              USB 3.0* Radio Frequency Interference on 2.4 GHz Devices

              http://www.usb.org/developers/docs/hs_usb_pdg_r1_0.pdf

               

              It does not look like cables or ferrites on the cables will make much difference - the cables should already be sufficiently shielded and it looks like the ferrites need to be between the connector and the controller, not on the cable.  I've tried externally shielding the cables further with no difference.  The problem is perhaps EMI leaking at the connectors, and from the peripheral/dev kit themselves.  The above docs indicate that shielding the kits and peripherals will make a big difference, but the dev kit and 3d-printable cases don't lend themselves well to shielding (the ports would need to be inset from the edge of the case).

              • 4. Re: Massive USB3 EMI
                fnoop

                BTW here Intel sells pretty much the same setup for robotics, so it should be useable:

                RealSense - Intel® RealSense™ Robotic Development Kit | Intel® Software

                • 5. Re: Massive USB3 EMI
                  Intel Corporation
                  This message was posted on behalf of Intel Corporation

                  Hello fnoop, 

                  Thank you for the information provided.

                  If you consider that the EMI leaking may be due to the connectors (which seem to be the case) then the issue is more shielding-related than Joule or RealSense camera related, which will make the case out of the scope of our technical support team. 

                  I understand that even if the board and the camera should be fully functional in various scenarios, it is impossible to guarantee a perfect cohesion with every system.

                  I’m sorry for the inconvenience this may cause.

                  Have a nice day.

                  Regards,
                  Andres V.

                  • 6. Re: Massive USB3 EMI
                    fnoop

                    I realise the dev kit is more of a reference platform than an end user product, but it would still be useful to know if the usb3 ports have been engineered with the (intel) recommended engineering guidelines to minimise EMI.  I do agree the wider conversation is probably better suited to RealSense so I'll ask the same question there.

                    • 7. Re: Massive USB3 EMI
                      Intel Corporation
                      This message was posted on behalf of Intel Corporation

                      Hello fnoop, 

                      I’ll be needing more time to investigate if there has been an official statement regarding electromagnetic interference and the manufacturing process of the USB 3.0 ports in the Joule platform. 

                      If I find information that you may find useful, I’ll post it here.

                      Thank you for your patience.

                      Regards,
                      Andres V.

                      • 8. Re: Massive USB3 EMI
                        Intel Corporation
                        This message was posted on behalf of Intel Corporation

                        Hello fnoop,

                        The Intel Joule was designed to meet FCC regulations and all validations show USB 3.0 signal integrity satisfies Intel’s eye diagram mask.

                        Since you keep experiencing issues related to electromagnetic interference, I’ll suggest you to check the Intel® RealSense™ Camera R200 – Product Datasheet http://www.intel.com/content/dam/support/us/en/documents/emerging-technologies/intel-realsense-technology/realsense-camera-r200-datasheet.pdf.  In Section 7.7 (page 28), there is an explanation of best practices for shielding with the R200 camera that you may want to try. 

                        I hope you find the previous information useful.

                        Regards,
                        Andres V.

                        • 9. Re: Massive USB3 EMI
                          fnoop

                          Hi Andres

                           

                          That document is really for the embedded (non-peripheral) version of the r200, I was asking specifically about the expansion board and if the engineering of the usb ports are to the intel guidelines with respect to ferrites, grounded shields etc.

                           

                          But I do accept this is probably out of bounds of joule discussion and more on the realsense side of things!  Thanks for your help.