cooper Posted March 19, 2014 Share Posted March 19, 2014 I'm thinking about the best way to scan and map APs without drawing attention from the general populace. Specifically, I'm thinking about creating one of those metallic (look) briefcases by making a mold, paper mache-ing it and then spray-painting it to look the part. Inside the case you could mount on a motorized rotating platform with a digital compass and GPS and a small system capable of receiving and storing the data. GPS and compass modules which connect to the I2C bus can be had fairly cheaply and are quite small.The scenario would then be that on a nice day you walk somewhere carrying your briefcase. You sit down anywhere (grassy field, some bench at a park, whatever) and place your briefcase flat either on your lap or by your side as you grab a magazine/book/paper. By laying the briefcase flat on its side you activate the internals (gravitational switch) and the system acquires its barings from the digital compass. Then, as the platform inside rotates slowly it records the AP's discovered and any other interesting bits you may already want to quickly scan for along with the signal strength for each at all the degrees reported by the digital compass. At the end the system extracts the current position from the GPS module which should've found out where it's at by now and the machine gives off a not too audible beep (optional - you could just time a run and assume that + 2 minutes or whatever) and shuts down. At this point you pick up your gear and move on to the next spot. When you get home you open the case and extract the information which you can then overlay onto Google Maps by finding compass bearing with the most powerful signal for a given AP and triangulating with the same information from a second (3rd, 4th, Nth) scan performed at a different location. This way you could covertly create a fairly accurate map of AP locations in that area. I'm not sure if the paper mache would be the best way to go as far as not blocking the reception goes, so comments and/or ideas here are welcomed. Overall thoughts? Quote Link to comment Share on other sites More sharing options...
madhak Posted March 19, 2014 Share Posted March 19, 2014 (edited) Most "Aluminium" looking brief case are actually made of plastic and wood that are painted. Thin wood and plastic wont affect your signal to much but any material will attenuate your signal to some extent. Check my Control Ground Station (CGS): http://www.basement-rc.com/forums/index.php?topic=3376.0 It has built in antenna and external antenna option. Look at your hardware store, they have tool case, or at your office supply store, brief case, almost none of them are actually made of real metal, except the corners. Very cool project by the way, what are you planning to use to control the antenna orientation, what kind of antenna are you looking for, I had good experience with patch and parabolic antenne for WiFi but nothing that can fit in a brief case, I used an old 36" tv parabolic dish to pickup wifi signal 2 mile away hehe, but smaller dish or patch are not as strong but I was able to get WiFi from the store across the street. Edited March 19, 2014 by madhak Quote Link to comment Share on other sites More sharing options...
madhak Posted March 19, 2014 Share Posted March 19, 2014 (edited) Oops, I reread your post and found you want to use this antenna: https://www.youtube.com/watch?v=TanbyHBKrvU That look sick, I have a bi-quad, not a yagi one but I'm impress by the gain it has, gotta try a bi-quad yagi now :) Edited March 19, 2014 by madhak Quote Link to comment Share on other sites More sharing options...
i8igmac Posted March 19, 2014 Share Posted March 19, 2014 Watch "Long range biquad. Home build" on YouTube Long range biquad. Home build: I have a few videos on some ddwrt with antenna builds. I used only things around the house. The video above is a biquad in a can and a parabolic dish HUGE gain from about 1000 feet away no lag during online gameplay its all about the perfect parabolic dish... Quote Link to comment Share on other sites More sharing options...
cooper Posted March 19, 2014 Author Share Posted March 19, 2014 Cool antenna but light on instructions (on mobile so I just watched the video. It might say more in the notes). It's probably also too large to fit inconspicuously in a briefcase. Quote Link to comment Share on other sites More sharing options...
cooper Posted March 20, 2014 Author Share Posted March 20, 2014 I'm now thinking about something like this instead of the regular briefcase. I mean, what's more inconspicuous these days than someone walking around with a laptop bag? Everything on the bag is made of plastic, so there's no combination lock or handle with metal fixings and probably also because of that the thing is very, very cheap. Because of the shoulder strap I can keep it at some distance from myself and still hold on to it aswell, as an anti-theft measure. And finally there's the inside measurement (not listed on that page) that claim it to have an internal height of 9cm. You'd have to gut the bag a bit of course since they separated it out into compartments, but that's no biggie. With the height of the biquad yagi being just under 5 cm it should leave sufficient room for the rotating platform. Yes, I'm liking this idea more and more. Quote Link to comment Share on other sites More sharing options...
i8igmac Posted March 22, 2014 Share Posted March 22, 2014 I have not attempted the yagi biquad. I have made the yagi 19 element and was unsatisfied. Each element must be positioned perfectly, if one is out of place then the rest will be useless... So my idea of a perfect biquad yagi build would consist of each element could be sprayed with a metallic paint that is a conductor... stencil's could be made for precisely positioned elements on a plexy glass... I still have better success with a parabolic dish and a single biquad for the driven element... I'm sure I could build one to fit in a bag you have picked... Quote Link to comment Share on other sites More sharing options...
barry99705 Posted March 25, 2014 Share Posted March 25, 2014 Why not just put a panel antenna on the side of the bag? Quote Link to comment Share on other sites More sharing options...
cooper Posted March 25, 2014 Author Share Posted March 25, 2014 The bag would need to be upright and I'd have to manually rotate it slowly. The current way seems less suspicious. Quote Link to comment Share on other sites More sharing options...
barry99705 Posted March 25, 2014 Share Posted March 25, 2014 (edited) Not really. Have the bag over your shoulder while "talking" on the phone. Just stand there chatting away while changing body direction. Or sitting on a park bench with the bag sitting/leaning against your leg, like everybody does. Might need to reposition it a few times, but no one will give it a second thought. Besides, if you're looking at these directionals, you don't need to be that close in the first place. Edited March 25, 2014 by barry99705 Quote Link to comment Share on other sites More sharing options...
i8igmac Posted March 26, 2014 Share Posted March 26, 2014 I'm in the process of rebuilding repeater with a wrt54g v8... this version does not have detachable antennas... so I'm do for a mod... Can I use a biquad directional to establish a source connection and then use a 9dbi omni directional for broadcasting in my home a open wifi? This was my old setup and I just read that you want identical antennas installed... ill share clean instructions when im done... Quote Link to comment Share on other sites More sharing options...
cooper Posted March 26, 2014 Author Share Posted March 26, 2014 Not sure if you posted this to the appropriate topic, but sure you can combine those 2 antennas like that. Best make them use different and preferably non-overlapping channels. This little project will use a single antenna. Quote Link to comment Share on other sites More sharing options...
barry99705 Posted March 26, 2014 Share Posted March 26, 2014 I'm in the process of rebuilding repeater with a wrt54g v8... this version does not have detachable antennas... so I'm do for a mod... Can I use a biquad directional to establish a source connection and then use a 9dbi omni directional for broadcasting in my home a open wifi? This was my old setup and I just read that you want identical antennas installed... ill share clean instructions when im done... No, it doesn't work that way with the wrt's. They have only one radio, one antenna is for transmit and the other is for receive. If you use a device with two radios, what you're thinking would work great. Quote Link to comment Share on other sites More sharing options...
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