Anyone have experience with handheld "sniffers"

I've been looking at handheld wireless connection "sniffers" as a way to locate open wireless connections and strengths. Anyone tried one of these? I see them on EBay for as little as 8 bucks but know nothing about them. I plan to set up a wireless network at our new building and want to be able to see what I got and where.

TIA

JohnF

Wouldn't it just be easier to use something like NetStumbler and your laptop?

let you "positively" know that there is a network AND you can connect to it.

It's just a PITA stumbling around with my laptop trying to detect a conection. A little hand held thingie would be great, just pull it out of my pocket and see what is around. I know there are some dead spots here at work but I don't want to drag the damned laptop around especially when half the time I'll have to set it down in the crap in the shop to fix somebodys machine. Those sniffers would be perfect and for only about $8.00 you can't go wrong..............IF they're worth a damned.

JohnF

seems to tickle more avail info & eye candy too.

I recall someone talking about a real low buck wifi detector, said it might be good for finding leaks in your microwave door if you held it real close.

I have several microwave oven leakage detectors. The most sensitive will respond to 1mw/cm^2. 5mw/cm^2 is considered a leaky microwave oven. It will barely respond when place next to my access point antenna. I also have some Proxim 7400 frequency hopping cards that are setup with tweaked firmware to act like a spectrum analyzer. They're not terribly sensitive (lack of processing gain and synchronous detection), but do show the classic direct sequence spectra and microwave oven leakage. I borrowed a Kensington WiFinder and found that it would not detect 802.11g access points, was basically comatose, and falsely responded to spread spectrum cordless phones (Panasonic Gigarange).

Great idea. I just tried it with several cordless phones I have around the house. All of them, including the 900Mhz flavor, responded inside the microwave oven. I could probably calculate the attenuation provided by the oven, but my guess(tm) based upon screen room characteristics is that it's about 60dB. 60dB down from about 600 watts CW power is conveniently 600 milliwatts of leakage, which is not enough to do any human damage, but is certainly more than what an

802.11 radio belches. For the cordless phone test, the average base unit belches about +10dBm. 60dB below that is -50dBm. Path loss to the handset drops perhaps another 40dB (at 6ft) for a -90dBm receive signal. That should be sufficient for the cordless phone to respond.

Actually, if you look carefully, many 5.6Ghz cordless phones are crossband type that use 2.4Ghz in one direction and 5.6GHz in the other. It's much easier and cheaper to build a full duplex system (diplexer) with radically different frequencies. I don't have a list of which ones do this. Lookup the FCCID on your cordless phone and dig through the test results.

Ugh. I had to look that one up and found this physics class notes: |

molecule resonates at about 22Ghz. Apparently, the selection of

2.45Ghz was quite arbitrary.

That sounds like pure marketing. If anything, such a detector'(detecting raw continuous wave RF) would be less desirable than a detector that specifically detects 802.11 frame formating since it would be prone to false readings.

Microwave's have a CF at 2.45 Ghz, which is attenuated well by the microwave, but you'd be surprised how much 2.4 Ghz is escaping. At work, we looked at a microwave operating in another room on a spec annie. You can do the opposite at home by simply placing a 2.4 Ghz cordless phone handset inside a microwave, shutting the door, and hitting the "page button" (or calling from another phone) on the base unit. The handset will beep/ring with no problem. Or simply look at the noise floor, using Netstumbler, while relatively near a microwave. Microwaves play major havoc with

802.11g/b. (One of the main reasons I'm using 802.11a for my WLAN traffic, as have many cordless phones and microwaves in the house.)

Off-topic but interesting tidbit on microwaves. Common misunderstanding on how microwaves work is that the resonance frequency of water is at 2.4 Ghz. Been a while since I've taken physics, but I do recall that the resonance frequency of water is in the 20-something Ghz range. Water, a dipole molecule, can vibrate by the E/H fields caused by a wide range of frequencies. 2.45 Ghz was chosen for the kitchen nuker out of government mandate (at least in the US) since its in the "junk band". 2.45 Ghz also allows the cavity size of the magnetron to be managable for the manufacturers. Finally, if the microwave used 20-something Ghz to cook food it would scour the outside of that frozen burrito while leaving the inside completetly frozen as higher frequencies attenuate much easier.

Cheers!

-Eric

Try a Microalert detector.

Sensitive from under 500 kHz to 3 GHz. Mine goes off if I'm within a couple of meters of an oven, when the oven turns on.

Li Battery lasts over a year; about $85.