FlightAware Discussions

USB 3.0 Broadband Interference!

So here’s a fun tidbit for you all:

Shielding the hell out of your USB 3 peripherals - if they’re anywhere near your antenna, will substantially improve your reception.

Backstory: I’m in an apartment so the quest to get an antenna on the roof is dicey at best - but, I’m on the top floor on top of a small hill and from my window have an unobstructed view of most of the Manhattan skyline. I’m about a mile from LGA so even with the crappy stock antenna, reception wasn’t bad.

Made a crappy little dipole, experimented with the FA antenna - but ABCD’s cantenna was the clear winner. With this setup I get pretty decent range.


Anyway, I was troubleshooting my laptop the other day and when I took it out of the room, I happened to notice the number of tracked aircraft jumped pretty dramatically. (from about 50 to about 70)

After walking around my apartment like a crazy person, with a scanner squelched at 0 and set to 1000mhz AM, on a very strange hunt for EMI - I set it down on top of the USB 3 cable from the computer to a hub and some external hard drives and it started chirping like a 1990’s modem. .

Turns out, this is pretty much a known issue of USB3. Intel has a whole whitepaper on the subject.
http://www.usb.org/developers/whitepapers/327216.pdf

Here’s the part that jumped out at me:

Intel’s paper focuses on 2400mhz, but look at how much bandwidth it’s using in the 1000mhz band! Any RF leak has Gotta be causing some interference, right?

Now, The USB 3 hub I was using was quite old. and likely, was not sheilded anywhere near properly. Threw a ferrite on the cable, but it didn’t help much. With my external drives plugged in and the unsquelched scanner 12 feet away by my ADS-B antenna, I could hear the noise floor raise when I plugged in the drives, and drop when I ejected them.

My crazy solution was to wrap the entire USB cable, and hub, in aluminum tape, and then ground said tape with some jumpers to… to ground. That did help. I have a new (and all metal) usb3 hub coming that I hope will let me take off my computer’s tinfoil hat.

Hopefully this helps a few of you eek out some extra range and better message rate!

Probably more related to cheap cables and equipment rather than usb 3.
Use a well made and shielded usb cable with maybe ferrite cores on the end and it should help.
A metal case for the RPI and dongle couldn’t hurt.
I do all of the above.

Yes. The primary source of RF leak was the cheap hub - but this underscores the point of USB 3.0 being a potential source of interference.

I added ferrites, changed cables - it didn’t help. The only thing that helped was shielding the hub.

My dongle is already in a metal case and The metal case on the pi wouldn’t help because i’m not talking about the USB on the PI: The interference was comping from a computer 12-15 feet away.

If you read that intel white paper it identifies the two sources of RF leak from USB3 as the peripherals and the USB ports on the host device as well.

Shielding both reduces RF leak in their tests.

There absolutely IS an RF leak concern with USB3 - one significant enough that the USB consortium*** published a whitepaper on it


It’s short and illustrated, check it out:
http://www.usb.org/developers/whitepapers/327216.pdf

Some homemade shielding helps a bunch. Very much improved reception.
(81 aircraft tracked right now ! )

Hey @JonHanford,

thank you so much for this solution!
just to add some input on the discussion: I’m running a FlightAware Pro Stick Plus on a RPI 3B+ and I was (let’s say) “underwhelmed” with its performance, so I tried to look for possible interferences. I noticed a strange correlation: whenever I turned on my tower PC close to the RPi and the dongle (~2ft from them), the number of tracked aircraft dropped dramatically (by factor of around 10), however the mainboard of said PC doesn’t have any wireless components (no BT, no Wifi etc).

I also have a rather cheap USB 3.0 Hub connected to this very computer. After unplugging it, the number of AC increased significantly (not on the same level as when the computer is not running but good enough). I could replicate the behaviour by plugging in the hub and removing it, always changing the number of tracked AC. As I need the hub, I will also try the “tinfoil hat” version.

Thanks again!