APRS 102 : Beyond Line of Sight and some terminology

Someone is bound to say “Wait ! Cars ? People ? Weather Stations ?  These things are small potatoes.  How do they ‘get out’ ?”

Go listen to the short bursts on 144.390 MHz for a few minutes.
Messages (aka “packets”) transmitted from these transmitters (the soft bursts) are stored then repeated (the LOUD bursts) shortly there after by digipeaters (digital + repeater, get it?).  The “digis” are also called store-and-forward repeaters, and long story short, each one makes an adjustment in the “header” of the packets (think address and return address of a letter) and passes along a perfect copy of the packet’s “payload” (consider the payload like the body of a letter.)

The local Digi is called ETULSA.  Check it out.
http://aprs.fi/?call=a%2FETULSA

RF to Internet

So what gets the packets flying around Tulsa into the Internet ?  That is a special type of repeater composed of an Internet connection and a radio (instead of two radios) called an IGate.

The regional IGATE  is W5BGM.  It hears ETULSA and passes those packets over the Internet to a server in Texas.

See ?  http://aprs.fi/?call=a%2FW5BGM

Click around and have fun.
73

Scott / KD5NJR