On Nov 5, 2007, at 3:26 PM, Bob Stewart wrote:
Bob can you or anyone tell me if there are software TNCs for soundcards out there? I know almost nothing about APRS or even where to turn to get useful information. Unfortunately, buying a TNC is simply not going to happen at this time. I am a Linux user.
Bob,
In the "early" days of packet radio, TNC's or "Terminal Node Controllers" were often used because the PC's themselves had little or no soundcard support, and most folks were comfortable with external modems for calling BBS's, and later dialing into the early Internet.
TNC's are still available for specialized functions like acting as standalone digipeaters (a TNC and a radio on a mountain, no computer required), etc... and some people still like them for other reasons... but they're FAR more expensive than software on a PC, a sound card, and a simple audio and keying interface to the rig, nowadays.
Too bad most of the "official" books from ARRL and others on the subject still have 1980's black and white photos of TNC's to guide the new hams doing this stuff off into oblivion.
But most "modern" digital setups include at least one connection from the sound card of a modern PC to a radio directly or via one of the many interface "boxes", which are just a nicer way to package up all the connectors and possibly some isolation electronics to isolate the PC (an excellent RF noise generator) from the rig, and also to provide simpler "plug and play" connections for things like keying logic from the PC to the rig.
The TigerTronics website has a good listing of a whole bunch of software that will work with soundcards, for example, since they sell one of these interfaces. (A pretty good one too. They also sell the TigerTronics Signalink USB which contains a USB-based sound chipset that "looks" like a secondary sound card to the PC, which has a VOX circuit for keying).
http://www.tigertronics.com/sl_soft.htm
There's a LOT of ways and a LOT of software out there for the various digital modes that will work with a sound card, a simple audio interface and some way for the PC to key the rig. Almost too many to describe all the options.
What kind of rig do you have Bob? Perhaps the group can tell you the easiest and cheapest way to get it going for APRS. Some software is free, other software costs a few bucks, but it's far cheaper than anything using a real TNC will be.
-- Nate Duehr, WY0X nate@natetech.com