USB 3 interference


I was just reading a bit on USB 3 interference with 2.4 GHz spectrum (WLAN, Bluetooth, …).


  • This can affect 2.4 GHz spectrum. WLAN (802.11b/g/n/ax; outdoor WLAN is legally forced to be in 2.4 GHz), every Bluetooth version (802.15.1), and a plethora (?) of proprietary technologies on 2.4 GHz.

  • NFC is unaffected; it sits on a completely different frequency (13.56 MHz).

  • FP3 has USB-C and USB 2 according to the specs, not USB 3.


  • Has anyone ever confirmed that this interfered with their smartphone (FP or non-FP)?

  • Is a laptop with USB-C the most likely culprit? If not, what else?

  • What is the likelihood that this was the cause of bad WLAN and/or Bluetooth performance for reviews?

  • What is the likelihood that this was the cause of bad WLAN and/or Bluetooth performance for user reports on the forum?

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Interesting, I hadn’t heard about this. I remember having quite some trouble with a wireless keyboard at a previous job, but I don’t believe I used any USB 3.0 devices there.

I am using a USB-C dock with my laptop. Checking the connected devices on my computer, it becomes apparent that the dock uses USB 3.0 for the network adapter, besides there is a video stream (DP alternate mode) being passed over the same wires as the USB 3.0 signal. All other devices are wired to USB 2.0.

The dock’s manual states that you should connect 2.4 GHz wireless keyboards/mouses to the front of the device, not to the back (where the USB-C cable to the computer is plugged in), and that you should not plug in a USB 3.0 device into the (USB-C) port next to the front USB port. I have no wireless input device at hand to test it, though.

Just to try, I have disabled 5GHz in my router and laid my phone on top of the dock. The phone gets 47.7 down / 12.8 up in the Speedtest app. I did the same with the phone on top of the desk, a metre away from the dock, and I got 50.9 down / 12.8 up. I would say it is not significant in my case, with the router being just metres away in the same room.

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Unfortunately, I am not able to test this on anything I own yet. However, my understanding of this article is that USB 3.0 interference can only happen when the USB port is actually connected to a USB 3.0 peripheral device. There is no mention of interference when the port is not in use. As you mention, the Fairphone 3 uses USB 2.0 anyway. This article makes no mention of USB 2.0 interference. I assume that USB 3.1 and higher can cause the same problem as USB 3.0.

Until I read this article, I did not understand why smartphone manufacturers stopped putting the USB port at the top of the phone, where the wire pointed away from me and was much more comfortable. They used to be soldered directly onto the motherboard at the top, no? I had assumed that it would save battery space if a separate Input/Output board were sandwiched over the top of the motherboard at the top of the phone. Perhaps it was placed at the bottom to avoid interference with the antenna at the top, and this became standard practice regardless of the type of USB used. This would not explain how metal back covers can be used though. I can only assume that if a metal back cover is used on a phone, it either not used on a device with USB 3.0 or else it is heavily insulated from the USB board.

I find your effort here to try to troubleshoot potential wireless issues on the Fairphone 3 at this early stage to be commendable.

That was definitely the case on the FP1.

From the thread on USB Power Delivery:
This page shows the Google certification requirements for USB ports, and states that the device should have a possibility to rotate the screen such that the port is on the bottom. As the FP2 (since Android 7, I believe) is able to turn the screen upside-down, it seems to me that you can be creative with this, though.

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I am glad to see that Google is enforcing interoperability of charging ports on all future Android phones. I’m also glad to see that they recommend that USB ports ‘should’ support alternate modes such as display out.

Actually, I already have a smartphone - a BQ Aquaris X2 with a severely cracked but functional screen. It uses stock Google Android 9.0, updated from 8.1. Unfortunately, if I put the phone in landscape mode and turned the phone so that the wire was directly away from me, the screen would not rotate. Google must have got rid of this feature. Oh well, it’s just a minor nuisance.

I also have a device that uses USB 3.1 (a BossTouch PM156T external monitor). Unfortunately, I can not use this to test USB interference because the USB 3.1 port doesn’t function (I’ve tried another compatible device with it and the buttons don’t work on this monitor either). HDMI works. The reseller refunded me, so I’m more than happy. I might have a NexDock 2 sometime before Christmas though if there are no further problems with shipping and I’ll test it then.

Actually, I might just get the right wire for the job before then.

Correction to a previous post of mine – actually, I do already have all I need to test for USB 3 interference without getting any more cables and gadgets. I thought I needed something with USB Type C but I realise now that I don’t.

Therefore, I’ve tested for interference. Just like AlbertJP, I’ve tested 2.4GHz wireless internet. I do not have any Bluetooth device for testing Bluetooth and I don’t plan on getting one anytime soon. I’ve looked into testing Bluetooth itself though. Here’s what I found on testing latency: I’ve also found that one can look for potential causes of Bluetooth problems by USB debugging ( I also found an interesting article on the role of the operating system in Bluetooth latency: Apparently, Google Android is better than Apple iOS but I can’t find the article now (2015 I think). Anyway, here’s a comparison by an ‘app’ selling it’s wares: I do actually have a point to make with all these unnecessary links – the Guardian review of the latest Fairphone could have given some hard facts on Bluetooth performance, but it didn’t. Sure, subjective experience is important too, but you can’t beat hard facts. The comparison to the Moto G7 in this review is somewhat inaccurate too. Look at its wireless internet hardware: (this was already mentioned in a different thread, but there is no harm in reiterating it).

Anyway, to get back to JeroenH’s question – yes I can confirm that USB 3 causes interference with the 2.4GHz band. That is to say, internet speed was slower, but its almost negligible. Here are the details in case they are of use:

I used an external hard drive with with USB micro-B 3.0 to the USB Type A 3.1 port on my proper computer. A smartphone (BQ Aquaris X2) was placed on its back on top (screen facing up). The smartphone had no protective case on it.

No interference (hard drive completely disconnected) average of 3 tests
ping (ms) 12.7 jitter (ms) 3.3 download (Mb/s) 39.2 upload (Mb/s) 36.7
Speedometer 2.0: 26.5 (only one test run)

No interference (hard drive connected to USB 2.0 port, 720p mp4 film playing)
ping (ms) 11,3 jitter (ms) 4,7 download (Mb/s) 38.8 upload (Mb/s) 36.7
Speedometer 2.0 26,5

Interference (hard drive connected to USB 3.1 port, same 720p mp4 film playing)
ping (ms) 12.0 jitter (ms) 3.7 download (Mb/s) 37.7 upload (Mb/s) 36.8
Speedometer 2.0: 25.4

On an anecdotal final note, the move to USB Type C will be painful for me. I was perfectly happy with Type A and micro USB.

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