NFA Ham Radio Club
Introduction
For our first project, we will be developing a packet radio BBS. What is a BBS, let alone "packet radio"? Bulletin Board Systems (BBS) are a way of using computers to allow people to communicate with each other, using only text. Back in the day (1980s, early 1990s) my friends and I called up BBSes with our computers and telephone modems to e-mail each other, post messages to forums, and trade files. Usually, only one person could use a BBS at a time because the BBS was using someone's home telephone line! (Sometimes without their parents' knowledge! There are plenty of stories about parents' headaches, answering a phone call at home only to hear the eeeee-aaaaaah of a modem on the other end.) Back then the Internet wasn't accessible at home yet, so BBSes allowed us to communicate with each other. Since low data rates (investigate what "1200 baud" means) found in amateur radio are ideal for moving textual data, BBSes are a good match for hams.
Modems
The 70cm (~440MHz) and 2m (~143MHz) VHF amateur radio bands can handle data traffic providing a modem is used. (Other bands can handle data traffic but that's outside the scope of this project. Transmitting on VHF is allowed with a Technician license and transmissions can travel farther than on the other upper bands like 2.4GHz [e.g. WiFi].) With your cable modem and the Internet, transferring images and videos seem to happen at light speed. This is not necessarily the case with amateur radio as data transfers are limited to the relatively slow audio signals. (To give a comparison, if a DSL modem is 1.2Mb/s, then an amateur radio modem could move data at 0.0012Mb/s. That's 1000 times less the speed of a DSL modem!) So, transferring high-def images and video over amateur radio would take a VERY long time compared to a DSL modem. That's why BBSes are a good fit for amateur radio. As I mentioned before, BBSes are text-only and transferring text requires a fraction of the transfer speeds needed for high-def images and video. Amateur radio is a perfect medium for using BBSes like back in the day with telephone modems. To allow computers to connect to a BBS using amateur radio, packet modems are needed.
Packet Radio
What is a modem or a "packet modem"? The modem converts computer data into sounds (modulate) and can convert the sounds back into computer data (demodulate). "Modem" is a contraction of words: modulate + demodulate = "modem". Computers can control the modems so they send data in small chunks called "packets". If the receiving computer doesn't receive a packet when it's expecting one, it can ask the sending computer to resend the packet. This is good for using modems where there is a lot of interference and packets can be missed or "dropped", as is the case with amateur radio. Transferring data between computers (e.g. a computer to a BBS with packet modems) is called "packet radio".
Our Project
So, what could we do to give BBSes a modern twist with amateur radio? Please go to Packet BBS Project Ideas so you can add comments with your ideas. Here are some of mine to get us started:
Comments
kurttetrault
Nov 12, 2009
I don't quite understand how our BBS system would connect to the internet and allow dual connectivity (Radio and internet logging in)
Anthony Girasoli
Nov 17, 2009
Hi Kurt,
To answer your question, the BBS would need a "traffic cop" of sorts. Basically, a program that would either allow calls to come from the Internet (via telnet) or from the packet modem. Kind of like the way Leif Bloomquist's (see http://home.ica.net/~leifb/bbs/ ) Commodore 64 connects to the Internet. To begin, we should probably just start out with a DOS-based BBS (or maybe a Linux MUSH) set up with a packet modem on 2 meters and see if we can connect to it with another computer and a packet modem.