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Wireless Spectrum Analyzer on the Cheap
PennyManDeux writes "There's an article over at TheTechLounge looking at the Wi-Spy wireless spectrum analyzer. Here's a quote: 'Although most wireless boxes are able to push through the lower amounts of interference, some people, such as those living in apartments or otherwise deluged with many wireless signals may have problems. It is with this dilemma in mind that the people at MetaGeek created the Wi-Spy spectrum analyzer.' Cool thing is, it's only $100..."
Yes, it's under $100. That's news. But many other comparisons to the higher-priced analyzers aren't there.
1. Does it do channel characterizations? Apparently not.
2. Does it have channel reticules? Apparently not.
3. Does it do 802.11a? Apparently not.
4. Does it have enough resolution to find Bluetooth and other spread-spectrum devices? Apparenly not.
5. Can it identify specific kinds of interfering devices, like 2.4Ghz phones, microwaves, door openers, etc? Apparently not.
I say apparently not because none of this functionality, commonly found in other spectrum analyzers of this type, is even mentioned. It's nice to have a cool A-to-D converter in the 2.4Ghz region, but comparing this to Cognio or Air Magnet is like comparing a bicycle to a Porche. I can buy a bicycle for under $100. I can barely touch the ugliest old 914 Porche for $3K.
Don't be fooled by price, or comparisions that hardly scratch the surface of what diagnostic tools are all about. For under $100, it's pretty damn cute. But it's just the basics.... and minimalist basics at best.
---- Teach Peace. It's Cheaper Than War.
A link to the actual product page?
http://www.metageek.net/
You feel sleepy. Close your eyes. The opinions stated above are yours. You cannot imagine why you ever felt otherwise.
Netstumbler will do most of what you need done and it's free. Here's a link to a tutorial.3 589131
http://www.wi-fiplanet.com/tutorials/article.php/
I'm not trying to justify the price of more expensive SAs. Instead, the article misses a lot of points and comparisons with the higher priced stuff, then baits the article with price so as to justify it. A good RF engineer could do his/her own fairly easily. The software that does the rest takes a helluva lot more. Basic FFTs are cute and a freaking high schooler ought to be able to do them.
This 'review', however, tries to make the comparison with higher priced equipment, then doesn't cite the features that makes that higher costing equipment compare to the under $100 variety-- only cost is used. Nice bait.... not very sharp hook.
---- Teach Peace. It's Cheaper Than War.
does it run with Linux?
Yes.
Yes, there are Linux and OSX applications available.
The linux app pretty much looks and works just like the Windows app, but it does have a raw output util that you can do some interesting things with.
I haven't used the OSX app, but the screenshots on their site look very good.
I'm against picketing, but I don't know how to show it.
Tom's Hardware (Networking) had a pretty good review on this awhile back.
i spy/
http://www.tomsnetworking.com/2006/02/12/review_w
www.wifigear.co.uk
.NET 2.0 to run
And from the review if you can't load it:
Conclusion
The 2.4 GHz spectrum is unlicensed. This means anyone can throw any type of signal they want into it. Anything from wireless AP's, to home automation products, to everyday appliances will throw out signals in this radio frequency. What all this means to the average person is this... interference. Either interference from other AP's, or a microwave, or a cordless phone. Either way, multiple devices vying for the same spectrum can never be good; it will affect your signal and degrade your throughput. The way to deal with this type of interference is to either ignore it, or try to go around it. Ignoring it might be acceptable for some, but finding ways around it is really a hit or miss proposition. It is hard to work around something you can't see. Sure, changing the channel on the router or physically moving the device might work, but in the end, you are just guessing. Now you no longer have to guess. With the introduction of the Wi-Spy, you can "see" the interference you are trying so hard to avoid. Before, you might have gotten the channel or the position right and enjoyed a cleaner signal, but I doubt that happened quickly. With the Wi-Spy, you should be able to figure out quickly and definitively just what your monkeying around might have eventually revealed. If anything, being able to rule out what won't work, you have won half the battle. With all the time you save, you can finally get out and do more important things like mow the lawn or clean the kitchen. (Ed: Oh goody!)
You just can't beat being able to "see" the spectrum you are using. Not having to take out a personal loan to buy the equipment is another plus. The software may have its quirks here and there, but no matter what, it still provides a good view of the spectrum you will be attempting to navigate. Software can be upgraded and fixed, and I believe that as time goes by, it will only get better. Considering its competition, the Wi-Spy is a steal at $100. If you do any type of wireless network setups, or you get drafted to set up everyone else's, the Wi-Spy should most definitely be in your laptop bag.
If you'd like to purchase the MetaGeek Wi-Spy, you can get it for about $100 directly through MetaGeek.net or you can buy it at ThinkGeek.com.
Pros
A spectrum Analyzer on the cheap
Portable
Easy to use
Did I mention it wasn't $3000+
Cons
Software could use some tweaking
Requires
Only works on 802.11b and g, not 802.11a
I bought one of these...neat toy. The hardware is nothing special, it appears to be a Cypress WUSB reference design manufactured by Unigen. The firmware may have been modded a bit...if for no other reason than to change the USB strings (or not, I can't remember how it enumerates.) At any rate, I'm going to bet that they just look at RSSI across the band and report it back in a meaningful way. Clever use of the technology.
As many other readers point out, a spectrum analyzer it's not. I really don't think that's the intended purpose. It gives you an indication of band occupancy over time, and that's about it. For many uses that's just fine. If I'm trying to get some ISM-band device to form a link and it won't, the WiSpy gives a good first-order indication of band conditions. If WiSpy comes back clean, I move on to other diagnostic steps, generally involving test gear that costs (easily) 100 times what the WiSpy did. If it saves you some time, great. In my opinion, it's cheap insurance.
It's not a spectrum analyzer, but it is a nice panaramic receiver.
The difference between the two is resolution. A panaramic receiver is just
a band scanner. It will tell you what channels are occupied and the relative
signal strength. A spectrum analyzer will do the same and more, such as
giving you a good idea of the kind of signal you are looking at, and it's
purity. Many years ago Hams used panaramic receivers (scope display) to
see where the dx and band openings were without having to tune from one
end of the band to the other. If you are looking for a clear (or occupied)
channel the panaramic receiver is good enough. If you want to know why the
FCC cited you for a dirty signal, then you want a spectrum analyzer.
How about a USB extension lead and mount the whole device in the can?
I've done exactly this to yagi antennas to eliminate transmission line loss. The result is a thin USB wifi wand:
http://www.dattaway.org/antenna2.jpg
I'm a small office / home office IT consultant, and I bought one of these a few weeks ago after stumbling across it on ThinkGeek. It's fabulous for my needs, which are simple: figure out if interference is the reason someone's wireless network is flaky.
Wi-Spy does a great job of doing this. I fired it up at a downtown client and saw there was a strip of intense interference down in channel 1. Moved them up to 11- problem solved. I've also done some tests at home... it's very easy to tell the difference between a microwave, spread spectrum phone system, video sender, and other wifi networks... they have rather distinctive appearences in the graphs Wi-Spy produces. Now that I know what they look like, I can take an educated guess, where before, I was grasping at straws.
For those of you getting your panties in a wad about it not matching a $5000 spectrum analyzer: Duh? Of course it doesn't. But that doesn't mean it's useless... there are a lot of folks (like me) for whom the cost of a "real" spectrum analyzer is completely unjustifiable. But I can spend $100 easily, and *for what I do*, which is occasionally troubleshoot SOHO wireless networks, it provides most of the functionality I need.
The really interesting fact is that this thing defines an entirely new product category: inexpensive spectrum analyzers. I would really like to see what could be done for $500... that's still an order of magnitude cheaper than the existing solutions, but I bet you could add a bunch of features.
-R
Netstumbler only shows you other *wireless networks*. Wi-Spy shows you *all* RF interference in the 2.4 GHz spectrum, such as that caused by cordless phones, microwave ovens, etc...
-R
A better review is available from Tom's Networking, including comparison to one of the $4000 Cognio devices:
i spy/
i spy/page2.html
http://www.tomsnetworking.com/2006/02/12/review_w
Comparison table on page 2:
http://www.tomsnetworking.com/2006/02/12/review_w
There is already a separate Linux app that has most of the functionality of the Windows app. I suggest using that versio (available from http://www.kismetwireless.net/wispy.shtml) instead of trying to get the Windows app running under Mono. The reason for this is that the USB library used by the Windows app, probably will not work under Mono.
Circuit Cellar published an article on how to build one of these a few months back, I wouldn't be surprised if it was exactly the same hardware. The circuit cellar version costs a fraction of the cost to build yourself
r mitage-189/index.htm
http://www.circuitcellar.com/library/print/0406/A
Like the other poster pointed out, $5000 gets you some pretty decent SA hardware nowadays. Not state-of-the-art, but then, the actual RF hardware hasn't changed much since the 1980s. Most of the R&D progress has gone into making them cheaper and faster (e.g., replacing crystal filters with FFTs), rather than "better." And obviously, instrument firmware is way more capable now.
Host-based utility programs can go a long way toward covering the "firmware gap" between older and newer instruments, though. I have an open-source surveillance package that works well with most of the late-80s and newer-vintage Tektronix and HP analyzers (see website in comment header), and there are others. A $2000-$3000 (US) Tektronix portable took this screenshot with my freeware Win32 app.
But yeah, for simple WiFi diagnostics, this USB dongle sounds like a much better fit. High-resolution, high-precision spectrum analyzers don't add much value when dealing with wideband modes like WiFi. Cheap ones are fine. I don't know that I would advocate that the average Slashdotter drop $5K on an HP 8566B.
Dahlmann tightly grips the knife, which he may have no idea how to use, and steps out into the plain.
...fiddling with my HP8590 spectrum analyzer bought via the internet....
/Me *hugs* his REAL spectrum analyzer ;)
You can keep your 100 Dollar wifi-thingy
My baby can do so much stuff the owners of a 100 Dollar wifi-spy can dream about
It can scan everything realtime (I do mean REAL-TIME) oh...and did I mention it can scan
the WHOLE darn spectrum...not just the Wi-Fi spectrum? And yes...it's still realtime
and it's from the 80's and didn't cost an arm and a leg.
I'd say it's better with a 1000 Dollars worth of real results rather than 100 dollars of promises!
What this world is coming to - is for you and me to decide.