An amateur radio satellite is an artificial satellite built and used by amateur radio operators for use in the Amateur-satellite service. The designation is assigned by AMSAT , an organization which promotes the development and launch of amateur radio satellites. Because of the prevalence of this designation, amateur radio satellites are often referred to as OSCARs. Currently, over 18 fully operational amateur radio satellites in orbit  act as repeaters , linear transponders , or store and forward digital relays.
Networks of autonomous satellites that can communicate with each other: this is how the future of space travel should look and how it can be used in key areas such as communication, Earth observation, and the exploration of distant planets. In addition, the possible failure of a single satellite within an autonomous network can be better compensated. It is also possible to transmit data and signals much faster to the receiving stations on earth: In the previously customary satellite communication in low Earth orbit, resulting raw data are sent to a ground flight over ground stations with a delay of several hours to Earth, processed, archived and distributed. The delivery of data products usually takes one to several days.
APRS is digital communications information channel for Ham radio. As a single national channel see map at right , it gives the mobile ham a place to monitor for 10 to 30 minutes in any area, at any time to capture what is happening in ham radio in the surrounding area. Announcements, Bulletins, Messages, Alerts, Weather, and of course a map of all this activity including objects, frequencies, satellites, nets, meetings, Hamfests, etc.
Packet radio is a digital radio communications mode used to send packets of data. Packet radio uses packet switching to transmit datagrams. This is very similar to how packets of data are transferred between nodes on the Internet. Packet radio can be used to transmit data long distances.