WiFi propagation model

Posted by Benoit Papillault on Jun 11, 2011 in WiFi

For those interested, here are the results of my research in order to properly compute WiFi propagation (at 5 GHz) over ground without any trees, obstacles or whatever. Fading has been observed and I’d like to find out a formula that allows to compute it :

  1. Few base concepts regarding radio propagation : http://www.csdptt.org/article410.html (in French)
  2. Rice model propagation (mentioned in the previous document) : http://flattop.its.bldrdoc.gov/itm.html

Stay tuned!



Convert your Android into a GPS for Linux

Posted by Benoit Papillault on Jun 8, 2011 in Android

Problem description:

I want to use my Android phone as a GPS for my Linux laptop. Here is a way to do it :

  1. First, install BlueNMEA on your Android. Once launched, it listens on TCP port 4352 and sends NMEA strings to clients
  2. Next, make sure your laptop and Android phone are connected via TCP/IP (for instance, they might be connected to the same WiFi AP or the Android phone is acting as a WiFi AP itself). You can check this by doing : telnet 4352 (Note : is the default IP of the Android phone when acting as a WiFi AP)
  3. Install gpsd on your laptop : aptitude install gpsd gpsd-clients. Since we are using gpsd 2.95, it can directly use the TCP/IP port. Otherwise, you need to use socat to relay data read from a TCP port to a special serial device : aptitude install socat ; socat TCP: PTY,link=/tmp/gps
  4. Start gpsd manually : gpsd -N /tmp/gps or gpsd -N tcp:// (add -D 2 for debug to see NMEA sentences)
  5. Start xgps to show your position

Futher work :

  1. Display your position on google maps using HTML5 geolocation API
  2. Record your position with ms resolution and generate a KML file for Google Maps

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