Telemetry from all receivers is sent to a central server that then drives a live map which can be viewed by anyone with an internet connection.
The system works extremely well and has been used to track payloads at distances of 800km and more even though the transmitter is limited by UK law to 10m W ERP.
I settled on 432 x 240 pixels with 50% compression as a good compromise between quality and download speed.
I measured the webcam current and it went from 50m A at idle to 250m A peak when taking a picture, hence the need to short out the USB fuse (140m A max).
I looked at the Pi and saw none of these desirable features!