Specific questions about USB/WiFi interference

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Billiam29 Senior Member • Posts: 1,763
Specific questions about USB/WiFi interference

Main Question:
As best I can recall this became an issue with USB 3.0 and 2.4 GHz WiFi. What if a device attached to your computer’s USB 3 port is just a USB 2.0 device? Does that negate the potential for interference or is there something about the frequencies involved with the USB 3 controller and port themselves that might cause issues?

Related Questions:
Did anything change with what is now USB 3.1 Gen2 (10 Gbps)? Does the type of port actually factor in now for interference potential: Type-A vs. Type-C?

Reason:
I’m thinking about running an Intel NUC in a headless configuration with WiFi connectivity for access. The NUC would be a music file host attached to an external DAC via USB. I’m just wondering whether I need to get a 5 GHz WiFi dongle in order to avoid interference from the NUC/DAC USB connection. I’m reasonably certain that a majority of DACs with USB attachments are only USB 2 devices. Hence that piece of the puzzle.

Aristide Rutilant Forum Member • Posts: 84
Re: Specific questions about USB/WiFi interference

You look to be very confused on how these things works.

USB is a physical interface used to easily plug and use devices into your computer, including wifi dongles. USB is backward compatible, so if you plug an USB 2 device in an USB 3 connector, provided that the plug and connector are the same type, and that your computer has the right driver, it will work. The reverse should also be possible although it may depend on the device. USB 3 features, which include much faster transfer speeds won't be used. It can be an issue with an USB 2 dongle if the said dongle proudly pretends it's able to provide more than maximum 480 Mbits/s transfer speed offered by USB 2. In practice, it shouldn't be a problem as advertised Wifi speeds are about 10 to 20 times higher than actual, real life ones and that modern, fast Wifi dongles should be using modern, fast USB 3 interfaces.

Wifi is a standard to do networking on a particular physical support that's known as air, instead of a copper cable or a fiber. There's now about 6 major revisions, and it almost always provided a choice between two frequency ranges, the 2.4 GHz and the 5 Ghz. 2,4 GHz is the most used one, features a better range at the expense of much much less available spectrum and slower speeds. 5 GHz is the reverse, it's still rarely used, provides better speeds and has more spectrum available to it but the range is shorter. In practice, the range you'll use will depend on what's provided by your access point / router and then it'll be negociated between this and your computer in an attempt to give you the best possible stability.

I mentionned interfaces for a good reason, in computing, interfaces are also here to provide some kind of abstraction for whatever is using them. So when you use wifi, you have in effect at least two physical interfaces. One between the air and you network card, that's the antenna, and one between the network card and the rest of your computer, that can be USB. Usually, USB ports are then routed to a controller chipset that interfaces itself with PCI express before speaking to the other parts of your computer. A lot of network cards are also directly interfaced through PCIe to computers.

Unless the Wifi card is physically broken or damaged, there will be no interference between your USB ports and your wifi network.

However, there can be interferences between wifi networks, especially in the 2,4 GHz range. Not only it's the most used one, but the limited amount of spectrum make it so that there can be at most 3 wifi networks in the same space before you'll encounter interferences and those networks need to be on 'opposite' channels (that is 1, 6 and 12). Also a lot of other devices also use this range, such as bluetooth or various cordless / wireless appliances.

There can also be interferences between USB devices, sort of. If the manufacturer hasn't built the controller and ports to spec, if an USB 2 device is plugged in an USB 3 port or vice-versa, or if too many USB devices are plugged in a computer and try to draw too much power from it, then malfunction can happen too.

In your case: the NUC should already have a Wifi network card integrated. Plug whatever you want in its USB ports. If your wifi turns out to be crappy try the following by order of effectiveness:

  • Use a wired network
  • Better place your AP, it should be in a high, central position in your house
  • Try to force the use of a given frequency (but be warned that 5 GHz won't help you if the devices are 50 m appart with thick walls).
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ken_in_nh Contributing Member • Posts: 976
Re: Specific questions about USB/WiFi interference

Some microwave ovens, those with defective shielding, will interfere with 2.4 G wifi.  The defect can be as simple as a dirty or defective gasket around the door.  There are other home appliances that use the same band, too, which is why some of us far prefer the 5 g band.

OP Billiam29 Senior Member • Posts: 1,763
Re: Specific questions about USB/WiFi interference
2

I’m not confused at all. Active USB 3.0 connections were well known to potentially cause interference with devices using 2.4 GHz spectrum. To the best of my recollection this was most likely to be encountered when both the USB and 2.4 GHz device were running from the same physical system which is exactly the scenario I was asking about with my Intel NUC. This may be a nearly extinct issue for devices form the last several years but as a reminder the NUC I’m dealing with is fairly old. It also does not have integrated WiFi, only hardwired Ethernet.

Tom_N Forum Pro • Posts: 18,152
Re: Specific questions about USB/WiFi interference
1
PHXAZCRAIG
PHXAZCRAIG Forum Pro • Posts: 16,845
Re: Specific questions about USB/WiFi interference

Any way to test for a problem?

I'm sitting here typing on a laptop that has three options:

-wifi6

-10/100 ethernet

-10/100/1000 ethernet via USB 3.  (3.1?)

The laptop is about 12 inches from my Wifi router, a Zenwifi X-8 mech system that does 2.4 and 5 Ghz.

How would I notice interference?  I get 100mbps on my ethernet, 1000mbps on my USB ethernet and I've seen 1.2Gps on the Wifi.   The ethernet cable is plugged into the Zenwifi as well.   My connections are 5ghz, but there are a number of streaming devices (Amazon echo and dot) and a few oddballs (thermostat, light control) that might connect on 2.4.

I have up to 70 wired and wireless devices running here, but only 4 are showing at 2.4Ghz.

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Aristide Rutilant Forum Member • Posts: 84
Re: Specific questions about USB/WiFi interference

Billiam29 wrote:

I’m not confused at all. Active USB 3.0 connections were well known to potentially cause interference with devices using 2.4 GHz spectrum. To the best of my recollection this was most likely to be encountered when both the USB and 2.4 GHz device were running from the same physical system which is exactly the scenario I was asking about with my Intel NUC. This may be a nearly extinct issue for devices form the last several years but as a reminder the NUC I’m dealing with is fairly old. It also does not have integrated WiFi, only hardwired Ethernet.

Well my bad then. I made searches for the subject and quickly found Intel's whitepaper. It might not be that well known however: I didn't knew about it  until today despite reading very regularly a bunch of tech websites.

In this case, the answers seem rather obvious:

  • Check if your USB devices are properly shielded
  • Try to use Wifi 5 Ghz if possible
  • Try to use wired Ethernet if possible

Also, try to see if you NUC has some kind of mini PCI port or M.2 connector. You should then be able to plug a Wifi card in it. You can check at least some of your NUC specifications on ark.intel.com

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Eric Carlson
Eric Carlson Veteran Member • Posts: 6,836
Re: Specific questions about USB/WiFi interference

ken_in_nh wrote:

Some microwave ovens, those with defective shielding, will interfere with 2.4 G wifi. The defect can be as simple as a dirty or defective gasket around the door. There are other home appliances that use the same band, too, which is why some of us far prefer the 5 g band.

My 5.8 GHz Uniden cordless phone system uses the same frequencies as the upper 5.8Ghz WiFi channels, so they had interference between the each other, both ways, until I set my WiFi router to use the lower WiFi channels.

I still have the 5.8GHz phone system connected, for now, but we mainly use a new Panasonic DECT phone system, which uses entirely different frequencies (1.9Ghz) from WiFi, so no interference.

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a_c_skinner Forum Pro • Posts: 10,095
Re: Specific questions about USB/WiFi interference

Isn't that interesting?

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calson Forum Pro • Posts: 10,433
Re: Specific questions about USB/WiFi interference

Wifi interference is not uncommon but you need both a dirty device and a long unshielded cable (funtions as an antenna). The FCC stopped testing and regulating RF emissions and has never done a good job in its history, allowing manufactures to cherry pick devices attached to computers.

Most RF comes from computer keyboards as they use a high frequency chip and being plastic there is zero RF suppression.

RF decreases by the square of the distance so at 12 feet it is 25% of the signal at 3 feet. Runninng USB cables of lengths of 3 meters or more could cause problems. The easiest way to block RF from a cable is to attach a ferrite bead where it connects to a device. I bought 10 of them for $9 on Amazon to use with a dirty magnetic transformer used to power outdoor LED lights. The RF from the cables out of the transformer interferred with our garage door openers. Adding a bead to each of the cables from the transformer fixed the problem.

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a_c_skinner Forum Pro • Posts: 10,095
Re: Specific questions about USB/WiFi interference

Oh, is that what they are for?  Again fascinating.

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Eric Carlson
Eric Carlson Veteran Member • Posts: 6,836
Re: Specific questions about USB/WiFi interference

As a ham radio operator, I use those snap on ferrites to keep RF out of devices that it shouldn't get into, and to keep RF from getting out of devices that it should stay inside of.

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Philip Eihuyar
Philip Eihuyar Regular Member • Posts: 372
Re: Specific questions about USB/WiFi interference
1

Billiam29 wrote:

Main Question:
As best I can recall this became an issue with USB 3.0 and 2.4 GHz WiFi. What if a device attached to your computer’s USB 3 port is just a USB 2.0 device? Does that negate the potential for interference or is there something about the frequencies involved with the USB 3 controller and port themselves that might cause issues?

Related Questions:
Did anything change with what is now USB 3.1 Gen2 (10 Gbps)? Does the type of port actually factor in now for interference potential: Type-A vs. Type-C?

Reason:
I’m thinking about running an Intel NUC in a headless configuration with WiFi connectivity for access. The NUC would be a music file host attached to an external DAC via USB. I’m just wondering whether I need to get a 5 GHz WiFi dongle in order to avoid interference from the NUC/DAC USB connection. I’m reasonably certain that a majority of DACs with USB attachments are only USB 2 devices. Hence that piece of the puzzle.

I recall that I posted this on the Mac forum a couple or so years ago. I had a new USB connected monitor that would not read a signal -blank screen. The answer was to move the USB monitor connection away by a port or two from the USB WIFi extender. It worked.

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