An APRS iGate is an Internet gateway that sends packets from the radio/RF side to the APRS-IS on the Internet (and vice-versa).
The APRS-IS is an Internet based network that connects APRS networks from all around the world and facilitates APRS applications (Realtime Postion reporting of objects overlaid over Google maps.
1. Handheld 2-metreband Transceiver (any 2m transceiver will do).
2. A 2m antenna.
3. The piGate in an enclosure
(a) A Raspberry-Pi
(b) A MicroNEXT MN-WD152B WiF USB Adapter with external antenna
(b) Sony Singstar usb adapter (used as the sound card)
(c) A dual-color LED connected to the GPIO header (to indicate status).
There are various versions of IAPRS software available on the internet to do this task, here are a few links.