At many times, my interests in computers and amateur (ham) radio seem to coincide.
For a while, I have desired connectivity whenever I am near home as, being a volunteer EMT, I am often in my truck or at our building. While I can SSH in from the building, I've been looking for a mobile solution. A data plan for my Treo is $50/month, which is cost-prohibitive, and a Verizon PCMCIA broadband card is around $200, with service running between $70-90/month.
As a result, I have been, for a while, considering some sort of radio-based connectivity. It was brought to my attention that the frequencies which 802.11 WiFi operates on are also shared with amateur radio. Standard WiFi networking components are limited to 1/2 Watt of output power, whereas the Amateur Radio regulations allow up to 25 Watts on this band. However, there are a number of issues with such a plan:
- Amateur Radio regulations prohibit "harmful" interference to other devices, and while transceivers are made that will do up to 25W on such frequencies, with a limited set of 12 channels, such a setup would surely interfere with other peoples' networks
- Amateur Radio regulations prohibit encrypted transmissions, therefore the only security would have to be the obscurity of assuming that nobody in the area could figure out what's going on
- The other possibility that I considered was implementing the server-side radio link in a dedicated gateway, which would allow the client to add some sort of password/hash to the transmission, which would then be checked before allowing the communication through. However, this would pretty much limit it to a text-only interface, where all transmissions would be in clear text.
At the moment, I am investigating two alternatives: 1) Some sort of carrier-based connectivity which is cheaper than Verizon but still reliable. (Problem: this would be a WAN connection, and would still require a VPN to connect to my servers.) 2) Licensing a commercial radio frequency and obtaining radio modems.