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Wireless NICs, External USB Hubs, and Noise

By gstefanick posted Sep 17, 2014 01:00 PM

  

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

 

 

Surface Pro 3 - USB HUB; HooToo; AirMagnet Spectrum XT

 surface3.AirMagnet.Xt.hootoo.hub.png

 

 

Surface Pro 3 - USB HUB; Cable Master; AirMagnet Spectrum XT 

 

surface3.AirMagnet.XT.cablemaster.hub.png

 

 

Surface Pro 3 - No USB HUB; Direct Connect; Wi-Spy

 

surface3.wispy.no.hub.png

 

 

Surface Pro 3 - USB HUB; HooToo; Wi-Spy 

 

surface3.wispy.hoot.too.png

 

 

Surface Pro 3 - USB HUB; Cable Master; Wi-Spy 

 

surface3.wispy.cable.master.png

 

 

 

Test your USB hubs my friends.

6 comments
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Comments

cdurgin
Jan 26, 2016 02:56 PM

Hi, I have been looking for a better USB hub for supporting my devices for site surveys (2-3 proxim cards, spectrum kits etc). The hub provided in my ekahau kit is just faulty and craps out when 3-4 devices are connected. I noticed the hootoo that is referenced in this write up has been disconnected. Do you have a recommendation on an updated tool?

 

Thanks!

gstefanick
Nov 06, 2014 01:17 PM

Im SP3 is used only for wifi tools, nothing else. I went on the cheap side, one model up from the lowest. The lowest model is the 128 gig drive. Problem was after the OS install and assuming the tools I was going to install it left 60 gig free. So I stepped up one model. 

dpi
Oct 30, 2014 12:08 PM

We are also evaluating Surface 3 for use with Ekahau. What min. specs for the Surface 3 Pro are recomended based on your experience?

 

 

WiFivomFranMan
Sep 22, 2014 02:07 PM

Great write up

Christoffer
Sep 17, 2014 03:43 PM

Thank you for a nice post. I´m running Ekahau site survey on my Surface Pro 3 with a USB hub that connects three Ekahau NICs. I´ll test my hub as soon as I get the chance =)

 

Anyone else running Ekahau on the SP3?

Srynearson
Sep 17, 2014 01:33 PM

Great writeup. My Surface Pro 3 came in the other day. I plan to write a few blogs on the WLAN design and troubleshooting uses over the next month or so. Overall I love it.