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Archive for October 2014

Not Sniffing, But… Oscium WiPry-Pro

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It’s been over two-and-a-half years since yours truly last wrote about Oscium WiPry, but there is reason to today: they fixed it!  Now the only 2.4 GHz spectrum analyzer for Apple iOS reads signal level correctly.  And using the new, corrected version reminded the author why WiPry is a nice product at a reasonable price.

The concept of a spectrum analyzer hasn’t changed in decades, and for good reason.  It’s simple.  A device listens for activity at a given frequency and displays a readout of said activity, usually in a fancy, colorful way.

In the last two years, however, many things have changed about spectrum analysis for WiFi.  PC card slots have become increasingly rare, thus leaving the Cisco Spectrum Expert in the margins.  Sensor-based spectrum analysis has increased in popularity.  Metageek, makers of my favored spectrum analyzer, stopped offering free software with their signature WiSpy series of spectrum analyzers.

What hadn’t changed in the last couple of years was the signal readings for Oscium WiPry.  They remained about 63 dB higher than they should have been.  The incorrect display wasn’t a dealbreaker, because WiFi spectrum analysis isn’t (or, at least, shouldn’t be) about precise decibel levels.  It’s about locating interference sources.  WiPry did a fine job showing lots of activity when an interference source was near.

The new WiPry is an improvement.  The signal readings are finally accurate!

Check that above screenshot out.  The horizontal line reads around -70 dBm.  The SNR comparison with the dotted noise floor line below is about 25 dB.  Excellent!  Those were the real numbers in the office where I ran my test.
Oscium made an adjustment to the WiPry’s form factor in giving it a Lightning connector instead of the old 30-pin connector.  That was a nice update, especially since I have been using my iPod Touch a lot for troubleshooting and surveying.  I’ve learned that spectrum analysis is really only useful to WiFi folks when looking for an interference source, so I don’t really need a device the size of an iPad.      I prefer the lighter, smaller iPod Touch.  And if you do like the screen size of the iPad, then Lightning will work for any iPad that was released after the iPad 3.
(At this point I should offer a link to my previous blog post on why I find spectrum analysis to be an inadequate form of WiFi troubleshooting.  That post was written months ago, but if anything my view on protocol analyzers’ superiority to spectrum analyzers has only hardened.  Maybe someone will let me debate the topic at the next WLAN Professionals Conference.)
The Oscium WiPry Pro is $200 and the software is a free download from the App Store.  If you’re just using a spectrum analyzer to locate interference sources, then it’s a nice piece of equipment to have.
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ben at sniffwifi dot com

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October 27, 2014 at 11:24 pm

Not Sniffing, but… Fluke Networks LinkSprinter

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It’s time to switch things up a bit.  WiFi sniffing is a fascinating topic and all, but good ol’ Yours Truly wants to try something new.  

This will be the first in the “Not Sniffing, but…” series on the Sniff WiFi blog.  I come across interesting topics outside of sniffing all the time, so I want to add short blog posts on some of these topics.

Several months ago WLAN bon vivant Keith Parsons posted a blurb on his WLANPros.com blog about the Fluke Networks LinkSprinter.  I contacted someone from Fluke Networks to ask about the LinkSprinter, and they were gracious enough to send me one to test.

LinkSprinter is a wired testing tool.  It’s more for people who install APs than for people who, like me, primarily do frame captures.  Still, we both do troubleshooting.  The LinkSprinter is definitely for troubleshooting.

The tool is pretty simple.  You plug in an Ethernet cable, and you press the lone button to start the test.  You’ll immediately get an indication of whether PoE is present.  The tool then proceeds on an up-the-OSI-layers network connection test.  First it’s physical connectivity to a switch.  Then it’s a DHCP check.  Then it pings the default gateway.  Finally it tries to reach the Internet.  Every step is confirmed (or not confirmed) by a simple green light.

When yours truly used LinkSprinter, the network was working.  That’s great, but it also meant that I didn’t really test the tool out.  The value in a troubleshooting tool isn’t to tell me that’s it’s working.  It’s to help me find out what’s going on when things aren’t working.

According to my contacts from Fluke Networks, the LinkSprinter records information that can help identify why a cable isn’t working.  PoE voltage levels, VLAN and default gateway information are all recorded by LinkSprinter.  the information can be accessed in one of two ways.  Both models of LinkSprinter — the “100” w/o WiFi and the “200” w/ WiFi — have their information automatically uploaded to a cloud service.  (I have yet to try the cloud service, but I know that it is accessed via LinkSprinter.com and I know that my Fluke contact told me that it will be free for life.)  The WiFi model also turns into an access point to allow nearby devices to access the connection information via a web browser.  The WiFi model costs an extra hundred bucks ($300 instead of $200), but I would think that having a local GUI would be worth it.

Would the author buy a LinkSprinter?  My initial reaction was, “No”.  My thinking was, “I don’t install APs for a living, so I don’t need to test cables when installing APs”.  Then I thought about it some more.  I do sometimes deal with downed APs.  In the past that has always been Someone Else’s Job, but it would be nice to be able to stick a LinkSprinter on the end of that cable and see it there’s PoE.  Or if there’s an IP address.  And if I have a Link Sprinter 200 w/ WiFi, which IP address in which VLAN.  Because even when something is Someone Else’s Job, it’s still good to help them out.

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If you like my blog, you can support it by shopping through my Amazon link or donating Bitcoin to 1N8m1o9phSkFXpa9VUrMVHx4LJWfratseU

ben at sniffwifi dot com

Twitter: @Ben_SniffWiFi

Written by sniffwifi

October 14, 2014 at 12:56 am