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.
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).
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.
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
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.
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.
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.
I’ve been wondering whether the clock spreading in the USB standard could be manipulated to notch out certain frequencies, like in noise shaping for ADCs.
It also interferes with GPS and Iridium. USB3 is a broadband jammer.
Previous thread on the subject: https://news.ycombinator.com/item?id=24707479