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by Ralph
Milnes, KC2RLM |
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Introduction |
Advantages and
Limitations OverviewThe key to sound card packet is a free program called AGWPE. AGWPE was written by George Rossopoulos, SV2AGW, and is an acronym for " SV2AGW's Packet Engine". It was originally created as a TNC management utility and has many super features of value to TNC users, however, this web site deals primarily with AGWPE's ability to encode and decode packet tones using your computer's sound card. AGWPE is the only program that can do this, other than MixW , Flexnet32 and MultiPSK. AGWPE is particularly valuable since it can act as a "host" program for several good packet "client" programs that do not have sound card packet capabilities of their own but have been written to take advantage of AGWPE. Advantages of AGWPE: Why use a sound card instead of a real TNC? First of all, it can be much cheaper. You only need a sound card interface, which is a set of cables to connect your sound card to your radio. Interfaces can be made for a few dollars or purchased for as little as $30-40 US, while the cheapest external TNC costs at least 100 US. And if you use the stereo qualities of the sound card to simulate two TNCs, you could be saving the cost of two TNCs! Other good reasons are that an interface is lighter and less bulky than a TNC and an interface usually requires no external power; a TNC will need some power source. Another reason is that according to the program author, George SV2AGW, the AGWPE soundcard modem gives better results than a TNC . George says the 300 baud HF modem is so sensitive that it decodes packets you cannot hear; the 1200 baud modem can decode packets even with S3 or less signal strength; and the 9600 baud modem is better than the original G3RUH. Limitations: To be fair, other users claim they get better results with a TNC; that TNCs are easier to setup; and that TNCs usually have built-in watch-dog timers to prevent continuous transmitting in the event of an error. Note that most packet programs will not work with AGWPE. Only compatible programs that have been specifically written to take advantage of AGWPE's host services will work, but there are several good ones. Hardware Requirements: AGWPE will run in Windows 95, 98, ME, XP, 2000 and Vista. It will not run in plain old DOS or Windows 3.1. Some users have been able to run it on NT 4.0. The sound card features of AGWPE should work with most 16 or 32-bit sound cards (and integrated main board sound chips), although it will not run on all cards (see compatible sound cards). You should also have the most up-to-date drivers for your sound card. Generally any Pentium II or newer processor will work with AGWPE. Some users have even used it on a 486, but other users have found it will not run satisfactorily on a Pentium I without MMX. See More About AGWPE for more information about processor requirements. Feature Highlights: The sound card option in AGWPE will allow you to:
Setup Steps: Getting AGWPE to work correctly can be tricky, since you will need the radio-to-computer interface with 3 wires and some circuitry, plus you'll need to configure three different programs correctly -- Windows, AGWPE, and your packet application. Hence, this web site. (Note that the AGWPE Help file included with the program is becoming out of date; in some cases it is wrong.) There are 6 basic steps in getting AGWPE and your sound card to handle packet. These steps are discussed in 6 different sections on this site: 1. Build or buy a radio-to-soundcard interface --
one wire each for RX, TX, and PTT. If you get hung up, you can e-mail me, KC2RLM. I'll try to answer your questions, but I won't pretend to be the complete AGWPE sound card expert. I am more of a technical writer than a technician. In fact, if you find any errors or omissions on these pages, please let me know. For the best troubleshooting help, I suggest you subscribe to a special AGWPE Yahoo Group email list to ask for help from other AGWPE users and even the author, George, SV2AGW.
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