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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.
Wires: the new wireless!
You can analyze spectrums all day long, meanwhile me and my Cat 6 are enjoying gigabit speeds! Thats some fast, fast porn baby!
I don't need no instructions to know how to rock!!!!
This is surely not a replacement for a spectrum analyzer, but it will give you a general idea of interference in your house.
I have conducted many site surveys for businesses wanting wireless networks. The purpose of a spectrum analyzer is to pin-point sources of RF interference that may limit wireless connectivity, so that measures may be put in place to reduce RF emissions. You'd be surprised at amount of RF interference generated by industrial equipment, which poses a problem for RF engineers.
This product merely shows you that you have interference, and lacks the ability to pin-point the source. This product would be better if you could have an external parabolic antenna, but it looks like someone will need to figure out how to jimmy rig a Pringles can antenna to this unit. What can you expect for $100?
/whisper/ Thanks for the candy!
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.
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.
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.
>you didn't need a spectrum analyzer to get you to buy the higher frequency phones. You would have done that anyway.
to find the biggest offender, radios do go bad.
I got a SpreadSpectrum 2.4Ghz phone, 2*2.4Ghz access point, and a 5Ghz wireless video link, and 3*2.4Ghz devices accesing the access points, and a Microwave. It all works no problem together (except the microwave kills the video link when in use.)
My brother has a cordless phone, and 1 AP, and 1 Laptop. His phone knocks his laptop off the network everytime. whats the difference? could be his A.P. isn't switching frequencies when he tried to force it. Could be any other device in his house (or unshielded cable TV) is tieing up all but one frequeny in the AP's range, or it could be a really bad phone. It is cheap to replace the phone, since the problem is obviously tied to it's use, but if it is the A.P. he will likely be fighting the same issue in the future. If a neighbors device steps into the now open frequency at next power outage/etc.
with this we could look at what the phone, PC, TV, Sat, Laptop, etc each contribute to that spectrum (and walk around the house to find the strongest area to locate.) not just which device pushed us over the edge, and is easiest to power off for a long period. IE maybe he just needs to replace a $2 coax cable, but what a pain to cut the feed for hours while he tests every other scenariao.
...I prefer to roll my own... Granted, it's only 250KHz of resolution (although you can change the filter, not sure how narrow you can get), but it's enough to get you started. I'm also seeing references to SA front-ends made from old TV IF strips. With lots of people upgrading their TVs, I expect to see a lot of these IF strips available.
Just junk food for thought...
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
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