Wireless NICs, External USB Hubs, and Noise

As a WiFi engineer I find reaching out to the WiFi community helps when you have questions, need advice, or real world first hand experience. You can favor Aruba, Cisco, Ruckus or any other vendor product. At the end of the day. We're all WiFi engineers. Our community as small as it is, has experts and peers a tweet away.

My issue was no different. I'm pondering the purchase of a Surface Pro 3. The Surface Pro 3 would exclusively be used for wireless tools. AirMagnet Survey, AirMagnet WiFi Analyzer, AirMagnet XT, OmniPeek, Wi-Spy and the list goes on.

All these tools have something in common a USB form factor. The Surface Pro 3 has a single USB 3.0 port. This is very restricting, since many of these application allow for multi adapter support. USB connectivity has always been a crapshoot for me. I've found that certain laptops / tablets while allowing USB hubs complain of issues when 1 more more USB devices are used. Of course we can deep dive this subject of power, USB 2.0 vs USB 3.0, USB drivers, etc. But I want to focus on something that is almost never talked about. USB hub induced noise.

When using devices like USB nics you run the chance of issues involving bad drivers, bad NICs, faulty ports, etc. One thing that most people might not consider is how well an external HUB communicates with the laptop and applications.

Kevin Franzen fellow WiFi engineer and WiFi bad ass provided me the following captures.

What you're seeing is a spectrum capture with AirMagnet XT and MeetaGeek Wi-Spy. What you should pay attention to is the noise floor elevation when the Cable Master USB hub is used. Both Spectrum products are reporting very similar noise floor elevations. When comparing direct connect and both USB hubs. Its clear the Cable Master USB hub is inducing noise.

NO USB HUB - Direct Connection

HOOTTOO USB HUB

CABLE MASTER HUB

Surface Pro 3 - No USB HUB; Direct Connect; AirMagnet Spectrum XT

surface3.AirMagnet.XT.no.hub.png