A Wireless Communications System that works When Cell Phones and the Internet are Down.

[adirondacker]

8. There is AMateur Packet Radio Network for the HAM enthusiasts.

from wiki...
"The AMPRNet (AMateur Packet Radio Network) is a name used by amateur radio operators for computer networks connected over amateur radio. Other names for the network include IPv4 Network 44/8 and Network 44. Much of the information here is historical, as packet radio had an exponential decline within the amateur radio hobby over twenty years, and remaining users have switched to the private address space (10/8, 172.16/12, 192.168/16, etc.).

The use of TCP/IP on amateur radio, using packet radio networks, preceded the appearance of the public Internet. The class A 44 netblock of 16.7 Million IP addresses was set aside for amateur radio users worldwide, having been secured in the 1970s by Hank Magnuski, when computer networking was in its infancy. Packet radio was used as a low level protocol for many competing higher level protocols, and TCP/IP users were essentially a minority due to the complexity of the configuration. The low baud rates also inflamed packet node site owners, as they saw the IP protocol as having too high of a protocol overhead. Very few systems operated over HF for this reason. The best solution on 1200 baud VHF networks emerged as TCP/IP over the ROSE protocol, just before the public Internet made them obsolete. The ROSE system today is maintained by the Open Source FPAC linux project.

The AMPRNet is connected by wireless links and Internet tunnels. Due to the bandwidth limitations of the radio spectrum, VHF and UHF links are commonly 1200 baud, and usually restricted to a maximum of 9600 baud. 300 baud is normally used on HF. Microwave links generally do not use packet radio, and instead use the commercial Wi-Fi access points (HSMM). The AMPRNet fully supports TCP/IP allowing for support of all network protocols.

The AMPRNet is composed of a series of subnets throughout the world. Portions of the network have point to point radio links to adjacent nodes, while others are completely isolated.

Geographically dispersed radio subnets can be connected using an IP tunnel between sites with Internet connectivity. Many of these sites also have a tunnel to a central router, which routes between the 44/8 network and the rest of the Internet using static tables updated by volunteers.

Recent experimentation has moved beyond these centrally controlled static solutions, to dynamic configurations provided by Peer to Peer VPN."

http://www.ampr.org/

The first program I wrote in Basic was to convert the alphabetical letters on the keyboard into Morse code and vise versa. The timing of the space bar (dit) and the enter (da) proved to be beyond my high school level expertise at the time (Pet Commodore).