I’ve bought (paradigit sells them for 1/2 the price atm) a Sitecom Wireless PC Lock today. Just for playing around.
Looking around a bit I found a program that can access it ( http://www.schau.com/gz/linux/wsl/) It worked nice, but the code wasn’t suitable for using in a gui program.
What it does is very simple, it queries the reciever for data, if it recieves data it knows the transmitter is in range, if it doesn’t it’s out of range. The timeout on the usb_interrupt_read was at least 5 seconds.. This is completely useless in a (single thread) gui program.
So I’ve been experimenting with polling every 500 ms for data (with a 50 ms timeout), logging the time it took to receive the next data package (with the transmitter in range).
With 1000 sample, I got the following graph:
As you can see, the time doesn’t exceed 10 seconds, and averages around 6.5. (With a std of 2.1).
So I can detect in around 10 seconds if the transmitter is in range. I am going to write a little (notification tray) applet that allows you to bind actions to entering/leaving the 2 meter range of your computer.