Instructables
Picture of WiFi Pinger
A Pyxis Design Project.

This instructable describes an RF beacon using WiFi - we call it a 'Pinger'. It is intended to be used as an alternative to, or to complement, GPS in location based applications. The 'WiFi Pinger' has been specifically designed to operate with the mediascape software described here (nb still under development April 2008). An early application using similar non-WiFi technology is described in this press release.

The Pinger uses a WLAN Compact Serial Module to transmit a pre-configured beacon signal as part of the WiFi standard. It can thus be recognised by any WiFi equipped device. It is compact and low powered and has an (approximately) omnidirectional radiation characteristic. We use it to identify (or tag) places, people or objects enabling recognition by mobile receivers such as WiFi equipped PDAs or cellphones.

The range of the Pinger is around 100m outdoors - and it's intended that the mscaper software will be able to be set for short, medium or long range. It can be powered and/or charged from a USB source - its battery life is over 12 hours.

 
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Step 1: Parts List

Picture of Parts List
To build a WiFi Pinger you'll need the following (mostly from RS ):-

1 x 0.22 ohm resistor (RS 135-500)
1 x 47uF 6.5v capacitor (RS 547-9732)
2 x 10uF 10v capacitors (RS 547-9776)
3 x MBRA140 Schottky diodes (RS 625-5650)
1 x flashing red LED (RS 228-6032)
1 x FMMT717 pnp transistor (RS 215-6515)
1 x LM3622 LiPoly charger IC ( DigiKey )

1 x USB socket (RS 515-2011)
1 x 4 way Molex 1.25mm socket (RS 279-9285)
1 x 12 way Molex plug case plus leads (RS 319-1042 & 279-9544)
1 x on/off switch (RS 334-268)

S103 WLAN Compact Serial Module ( RF Solutions (UK) or Datahunter (US) )
pcb from expressPCB (or pyxisdesign) (pcb shown below and file attached)
1 x dual PLF423566-S Varta LiPoly battery (RS 457-8282)
Hammond case (RS 613-8319)

... and tools for surface mounting soldering.

Step 2: Schematic

Picture of Schematic
Here's the circuit diagram :-

Step 3: Build

Here's a sequence of photos showing how to assemble the Pinger - this is where you build-it-yourself!
mobimation1 year ago
Friends, I have been thinking of making a beacon chip for quite some time, see my blog on the topic: http://mobimation.blogspot.se/2011/10/wifi-beacon-chips.html?showComment=1372549170668
The point is to manufacture very inexpensive chips with small power requirements that do nothing else than transmit a Wifi beacon.
That way the environment could be blessed with having such beacons placed at locations where it is otherwise impossible to get a location indication, such as underground, subways or some shopping malls for example. Complete Wifi chips are in many cases too expensive for the purpose.
If any of you want to collaborate with me to drive a project on what a beacon design would take you are welcomed. One question to clear up is if there are frequency band restrictions that forbid anything else than certified full Wifi standard chips to operate in that band.
pyxis (author)  mobimation1 year ago
Thanks for your mail - your chips would have been great when I was designing this! Sadly at this time I don't think they would work with an iPhone (Apple block access to the data needed to recognise the WiFi signature) but they should be ok with an Android phone.
It looks as if WiFi fingerprinting may become a common way of finding indoor location (google "WiFiSLAM"). IF Apple do include this feature in a future version of iOS then low power WiFi beacons will be really useful (and in great demand).
I can't help with the certification question - but the 2.4GHz band is used for a whole bunch of different applications (though the 5GHz WiFi band would be better for location purposes).

dmonday3 years ago
This could also be used to verify an open wifi connection, Unlike the wifi detectors, that scan for a signal on wifi, You can use this to be sure you can get on wifi, Rather then find it locked.
static4 years ago
Appears that you should have called the device a beacon and left it that. :) naming it a pinger confuses A ping is generally sent to a target, with a response from the taget expected. Beacons are generally broadcasts that can be received by multiple stations, even if only 1 or more can make use of the data broadcast,  response from a receiving station may not be expected.  Then again it may be HP fault for first calling something that's not a ping a ping
Davedwin5 years ago
Hi, I'm looking to make a similar project (very similar). All I need to do is broadcast a pre-configured SSID. No traffic, just the SSID as a kind of 'hey I'm on' deal. I'm trying to find a retailer for your S103 WLAN module used, but can't find it on the recommended sites. Does ANYONE (not just pyxis) know of any other brands that might help me out? --Davedwin
agent Davedwin5 years ago
.;dHmm... It'd be pretty cool to make an SSID 'spammer'. ;P
Masowai agent5 years ago
Already exists, at least a software version. Its called MDK3. Its only available for a Linux-based OS, though. The SSID "spammer" you're looking for is more commonly referred to as "beacon flooding". Check out MDK3, it has sooo many cool modes. I think you'll like it.
agent Masowai4 years ago
I actually found this feature in Metasploit. Problem is that the wireless card needs a certain chipset (that I don't have) or to get an expensive external card.
pyxis (author)  Davedwin5 years ago
RF Solutions in Lewes UK have stock ...
http://www.rfsolutions.co.uk/acatalog/WLAN_to_RS232_Module.html

Cliff
Davedwin pyxis5 years ago
Thanks Cliff. Not sure if I'm ready to pay for shipping from the UK just yet ;-) Plus I started testing the XBee + Arduino for now. Hopefully I will be able to lose the PC and get this LCD working soon. It's always something when your inventing. LOL
2 things can i use a mini usb cable and use on a bus
pyxis (author)  tater killer5 years ago
Hi - my design uses the USB mini AB socket, so a mini USB cable should be ok (note - this only provides power and can't be used for configuring the modules). Not sure which type of 'bus' you're asking about - if it's a USB bus, then yes, no problem; if it's a transport bus it should also be ok (though I don't know anyone who's tried this).
pierow6 years ago
I guess I'm still unclear on what this is used for? I read through the Mediascapes page briefly but I don't understand what role the WiFi pinger plays?
it obviously pings your WiFi connection..
Yes? And the practical side of that is .. what?
You can "ping" a WiFi router, like a WiFi hot spot detector tells you when your in range of a WiFi point. The practical side would be that you can test for your router has its wifi "on" so that you do not spend hours trying to trouble shoot your issues with connecting to the internet... Turning off WiFi in the router when not using it is best all round security as is setting WPA and using a non-broadcast SSID.
that you can see how fast your WiFi connection is.
It sounds more like a location based wireless appliance. Meaning that your access point( at cisco it would require an access point with lightweight software, and a Wireless Lan Controller licenses for Location. Then, using the WLC you can determine where the pinger is - or any other client on the network. That, anyway, is how it sounds to me, coming from Cisco :)
covcreo6 years ago
BUT WHAT DOES IT DO????????
-Aj- covcreo6 years ago
it transmits a "pre-configured beacon signal" ... or so ive heard. O.o
-Aj-6 years ago
Swaeet bro! use these puppies for ground based GPS. so what i have to print my own boards then? coolies, need an excuse to use up the old supplies. lol
nilmahj6 years ago
so...... you strap one to your kids when they're playing in the woods and you find 'em with your GPS? sounds like a hide'n'seek hack to me. looks cool though.
pyxis (author) 6 years ago
Thanks for your comments and suggestions. Obviously my intro didn't do its job! I've added some more background which I hope will clear things up.
NETSYS6 years ago
lol...you guys are so funny.....cant stop laughing.... lol
I am with you on that one, I am lost
Same here...can't it be used to check if a device is connected to wifi?
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