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Experienced terrible headaches trying to fix issues with GPS and USB3 at work. I was also surprised by how sparse information online was. Almost all mentions ca

by voqv 6y ago

Experienced terrible headaches trying to fix issues with GPS and USB3 at work. I was also surprised by how sparse information online was. Almost all mentions came from random drone hobbyist's forums when I was searching some time ago.

anamexis 6y ago
Are you suggesting that you got headaches from radio interference?
- neon_electro 6y ago
  I think they're suggesting that they do professional work on/with GPS and USB3.0.
- jandrese 6y ago
  I think he was speaking metaphorically about having to fix equipment that was interfering with neighboring equipment.
  - anamexis 6y ago
    Ahh, this makes more sense.
- voqv 6y ago
  As others have said. I edited the post for clarity.
ilogik 6y ago
your GPS device doesn't actually transmit anything
- LeoPanthera 6y ago
  I believe he meant that USB 3 devices were effectively jamming GPS receivers.
- voqv 6y ago
  Yeah, it receives things.
- fortran77 6y ago
  You can fix that! Get a BladeRF, HackRF, LimeSDR, and you can transmit your own GPS signals: https://github.com/osqzss/gps-sdr-sim https://github.com/osqzss/gps-sdr-sim (Seriously: Don't do this unless you're taking extreme care not to radiate outside your lab.)
Badfood 6y ago
I make gps enabled cameras and am battling with RFI from USB3. Juat ordered a bunch of chokes to try on cables to mitigate. Im surprised this level of RFI is allowed. Either that or these devices aren't being tested properly. Like they are powered up for testing but aren't used with actual data being sent to and from them
- bradfa 6y ago
  In my experience, USB connected products are EMI tested only with the cable shipped with the product in the box and used per the product instructions or in a "typical" use. Quite a decent amount of effort and cost is spent for some products to ensure that the cable which ships with the product will properly comply with all regulations regarding interference in the countries in which the product is sold. There's no way a manufacturer could be expected to EMI test a product in every conceivable way a customer might wish to use it. For many products there's simply too many combinations of use-cases or features. So the rules generally require to test in a typical customer use or by following the instructions for use which come with the product. As soon as you start using cables which didn't come with the product, it's on you to ensure that the emissions of the new cable and the product don't combine to cause problems. Some cables (not just USB cables) are utter crap for interference.
  - Johnythree 6y ago
    A well designed product will have good shielding and PCB design, and effective low-pass-filters, all of which keep the stray interference within the enclosure. It should not rely on the cable to meet EMC testing, and the test protocol should define a suitable generic cable. If it does require a particular cable, then the cable should not be removable.
    - bradfa 6y ago
      In an ideal world, I agree with you. But if you ever try to make a mass market USB device you will quickly learn that the computers which your customers will connect your device to and the cables which your customers will use will greatly vary in terms of quality and compliance to the specs.
sebastos 6y ago
Yup, this is well known in the small UAS industry at this point, and I was part of a lab that lived through that "wtf, how does nobody talk about this" experience. It seems like many folks in the space have learned this the hard way.
pgorczak 6y ago
Same here while working on a UAV even though the GPS module was mounted about 20 cm away from the single board computer. We looked at it with a spectrum analyzer back in the lab and the USB 3.0 ports really sent out some wide band interference that covered the GPS bands. Using USB 2 cables fixed it (apart from USB being really not great mechanically for a combustion engine powered UAV).

by voqv 6y ago

anamexis 6y ago

Are you suggesting that you got headaches from radio interference?

neon_electro 6y ago
I think they're suggesting that they do professional work on/with GPS and USB3.0.
jandrese 6y ago
I think he was speaking metaphorically about having to fix equipment that was interfering with neighboring equipment.
- anamexis 6y ago
  Ahh, this makes more sense.
voqv 6y ago
As others have said. I edited the post for clarity.

ilogik 6y ago

your GPS device doesn't actually transmit anything

LeoPanthera 6y ago
I believe he meant that USB 3 devices were effectively jamming GPS receivers.
voqv 6y ago
Yeah, it receives things.
fortran77 6y ago
You can fix that! Get a BladeRF, HackRF, LimeSDR, and you can transmit your own GPS signals: https://github.com/osqzss/gps-sdr-sim https://github.com/osqzss/gps-sdr-sim (Seriously: Don't do this unless you're taking extreme care not to radiate outside your lab.)

Badfood 6y ago

I make gps enabled cameras and am battling with RFI from USB3. Juat ordered a bunch of chokes to try on cables to mitigate. Im surprised this level of RFI is allowed. Either that or these devices aren't being tested properly. Like they are powered up for testing but aren't used with actual data being sent to and from them

bradfa 6y ago
In my experience, USB connected products are EMI tested only with the cable shipped with the product in the box and used per the product instructions or in a "typical" use. Quite a decent amount of effort and cost is spent for some products to ensure that the cable which ships with the product will properly comply with all regulations regarding interference in the countries in which the product is sold. There's no way a manufacturer could be expected to EMI test a product in every conceivable way a customer might wish to use it. For many products there's simply too many combinations of use-cases or features. So the rules generally require to test in a typical customer use or by following the instructions for use which come with the product. As soon as you start using cables which didn't come with the product, it's on you to ensure that the emissions of the new cable and the product don't combine to cause problems. Some cables (not just USB cables) are utter crap for interference.
- Johnythree 6y ago
  A well designed product will have good shielding and PCB design, and effective low-pass-filters, all of which keep the stray interference within the enclosure. It should not rely on the cable to meet EMC testing, and the test protocol should define a suitable generic cable. If it does require a particular cable, then the cable should not be removable.
  - bradfa 6y ago
    In an ideal world, I agree with you. But if you ever try to make a mass market USB device you will quickly learn that the computers which your customers will connect your device to and the cables which your customers will use will greatly vary in terms of quality and compliance to the specs.

sebastos 6y ago

Yup, this is well known in the small UAS industry at this point, and I was part of a lab that lived through that "wtf, how does nobody talk about this" experience. It seems like many folks in the space have learned this the hard way.

pgorczak 6y ago

Same here while working on a UAV even though the GPS module was mounted about 20 cm away from the single board computer. We looked at it with a spectrum analyzer back in the lab and the USB 3.0 ports really sent out some wide band interference that covered the GPS bands. Using USB 2 cables fixed it (apart from USB being really not great mechanically for a combustion engine powered UAV).