Wi-Spy ... good inexpensive wifi scanning tool

A couple folks on the www.ITdiscuss.org email list were mentioning and recommending this inexpensive wifi scanner called Wi-Spy from www.MetaGeek.net ... for the ridiculously low price of $99 ... I had to check it out.

So I googled 'wi-spy review' and found several good articles on the Wi-Spy product ... this review on www.smallnetbuilder..com was particularly helpful as it compared the $99 Wi-Spy to a beefy $4000 wifi scanner product.  All the reviews I read gave the Wi-Spy 2 thumbs up ... kewl ... so over to MetaGeek for a quick purchase :-)

At GCC we have 6 Proxim AP4000 access points (AP's) running 802.11a/b/g that cover the entire building with private and public wifi access ... then 1 AP is used strictly for our F1 checkin kiosks (we're adding another soon for redundancy).  Then we have 4 2.4GHz Panasonic cordless phone "access points" that our phone dudes swear don't interfere with 802.11b/g wireless ... which I find very hard to believe.  Of course there's an abundance of wireless mics all over the building ... all of which are running at 900MHz I believe (Adam?).  Then to make matters worse, we have 2 apartment complexes on either side of the church ... they are close enough that we see many interesting SSID's showing up inside the church.  So all that to say the wireless signals inside GCC are many so a tool like Wi-Spy could be quite handy to help identify and correct interference issues for maximum wifi throughput and enjoyment.

I got the Wi-Spy on Saturday and have just now started playing with it.  Initial reaction ... this thing is sweet.  Here's some screenshots I took at home tonight.  Although it's not said to be compatible with Vista, I'm running Vista on my Thinkpad T60p and it installed just fine.

Here's a view (click to enlarge) from my laptop sitting about 3 feet from my AP.  Can you tell what channel my AP is running? :-) 

The lower graph is signal strength per frequency value ... I have the X or horizontal axis set to display wifi channel rather than frequency values.  The upper graph is signal strength per time ... with time being on the Y (vertical) axis.
It's very apparent my access point is broadcasting on channel 6.  The other thing I really like is that I can now actually see the channel bleed over that I've always read about. 

What's this bleed over?  Well, let's just say that .11b/g is very sloppy and thus it doesn't actually broadcast at exactly one channel ... it bleeds a good 1.5-2 channels on either side of what it's set to.  Look at the graph again.  You'll see that my AP, although set to use channel 6, is broadcasting significantly to either side.  And since I'm so close to the AP it's actually bleeding 3 channels over from 6.  This is why if you read tech docs on setting up a wireless infrastructure it's recommended to have your AP's only running on channels 1, 6, and 11 ... so that there's no bleed over from one access point to another.  Put 2 AP's near each other on channels too close together and you'll have major problems.  Here's a helpful article on this channel overlap issue that I posted about way back in 2005!

Here's another shot this time upstairs and quite far from my AP and thus less signal strength.  Again, notice the clear indication while channel 6 has the peak signal strength there's still a lot of bleed over down to almost to channel 4 and up almost to channel 8.

I should also note that the above graph can't differentiate between multiple AP's running on the same channel.  For instance, in my bedroom (above graph) I can see not only my AP, but 3 others from my neighbors ... and of course they too are running on channel 6 as show below.

Ok, so now for some fun.  Microwaves are notorious from causing major problems with wifi ... so let's test it.  Down to the kitchen for an experiment :-)

Here's a graph with the laptop sitting about 5 feet from the microwave which is off. 

And now I fire up the microwave for 30s ...

WOW, that's some ridiculous signal spew-age!   It's a miracle Ashlee was able to be conceived after looking at that graph! :-)  If you lay the before and after graphs on top each other the microwave completely buries the wifi signal ... I mean just look at how the graph is pegged from channel 4/5 up to 10 ... and there's just lots of signal noise across all the channels!

Now drawn your attention to the upper time-signal graph above ... notice in the middle there a small gap?  That's a 10 second time period where I shut the microwave off then back on.  So for those 10s the upper graph looks mostly empty ... just some signals showing up around channel 6.  That's a pretty amazing contrast.  From the graph it looks like my best bet is to move my AP over to channel 1 where the microwave is spewing the least to minimize intereference between my wifi and the kids making popcorn. 

I ran out of time tonight, but this weekend I'll fire up our prior 2.4GHz phone ... it would always knock me off wireless anytime the phone rang/was used so I'm sure it will have an interesting graph as well.

So I'm already finding the Wi-Spy useful just for my simple home setup and I'm very curious to see what it will reveal at GCC.  If you have to deal with wireless setups you should probably go get yourself a Wi-Spy ... now excuse me, I've got to go decontaminate from operating our microwave.

(note: MetaGeek raised the price on the Wi-Spy as of Feb 1 ... it's now $199 ... which is still a steal!)

(note #2:  apparently www.thinkgeek.com still has the Wi-Spy for $99 ... get one now!)

Comments

[Gene]

Hey Jason (and the rest of Church IT geekdom),

www.thinkgeek.com still has the Wi-Spy for $99. Get it here: http://www.thinkgeek.com/gadgets/electronic/80ce/

Great review of the Wi-Spy, btw

[Nathan]

Jason,

Great review man! I'm impressed...with this site and with the wi-spy. Is it Mac compatible?

Nathan

[Matt Singley]

Whoa!!! I think I'll order one today. That's seriously interesting. Well, to geeks anyway. If my wife read this she would yawn about one paragraph into it....but I was fascinated! Thanks for taking the time to put up all of the screen shots.

Gotta go...I'm heading over to thinkgeek.com to pick one up...

[Jason Powell]

Nathan - It appears there is a beta version of the software available for OSX :-)

Thanks for the update guys on the $99 pricing at thinkgeek.

[Joshua Wells]

I used the Wi-Spy at home to determine why my Motorola 2.4ghz cordless phone *didn't* interfere with my 802.11g. I determined that the Motorola phone constantly (and quickly) jumps frequencies, starting at channel 1, going up through channel 11, and then back to channel 1. The time it spends at a particular frequency is so short, in the fractions of a second, that it seems to not affect my wifi. It seems to me that this varies by phone manufacturer.

Another thing to be careful with... Most 5.8ghz phones use 5.8ghz for base-handset communications, and 2.4ghz for handset-base communications... Saves battery life. Sneaky!

[Tom Templin]

Jason: a fine report! I ordered mine today at www.saveateagle.com for $94.01. If you use the coupon code "PG" you get free shipping on orders over $100, so I added the USB-to-Serial Adapter Cable for $6.95 (cheaper than shipping) for a total $100.96 shipped.

[Trace Pupke]

There's also wireless mapping software that you can use with the Wi-Spy.

VisiWave Site Survey
http://www.visiwave.com/

It's kinda pricy but if you email their support and let them know you're a church/school they'll send you a discount code for 20% off.