Sound Card Packet  with AGWPE

Translations and PDF of this site
Most recent AGWPE version is:  2013.415  15 Apr 2013

Computer requirements
Packet Engine Pro

Configure AGWPE
Download and Install
Basic AGWPE Setup
2 Radio Setup
2 Card Setup

Sound Device Setup
Basic Device Settings
Rename Sound Device
Additional Settings
Using the Tuning Aid

Program Behavior

AGWPE Features
AGWPE on a Network
Baud Rates & Modes
Remote Control
TCP/IP Over Radio
Tips and Tricks
Traffic Parameters

Compatible Programs:
Setup Help

Radio Interface
Getting Started
Kits and Pre-assembled
USB SignaLink
Receive Audio Cable
Transmit Audio Cable
PTT (TX Control) Cable
2 Radio Modification

About Packet
Packet Overview
Exchange Modes
What To Do with Packet
Common Frequencies
Frame Headers
Further Reading

AGWPE Overview

What AGWPE Does
Advantages and Limitations
Important Features
Basic Setup Steps

What it does

The AGWPE program has many features, but its sound card features allow it to simulate a TNC. AGWPE was written so that other packet programs (clients) can link to AGWPE and use AGWPE as a host that will send and received packets for them. Call them AGWPE-compatible programs.  In fact, most popular packet programs -- APRS, BBS, terminal and WinLink programs  -- now have a way to link to AGWPE.

To run packet by sound card, you need:

  •  AGWPE
  • an AGWPE-compatible program(s)
  • an "interface" to connect your computer sound card to a radio
       (in its simplest form an interface is three wire cables, two with simple circuitry)

This website provides information about obtaining and configuring those three components.

History of AGWPE:

AGWPE was written by George Rossopoulos SV2AGW in the 1990s. AGWPE is an acronym for "SV2AGW's Packet Engine". It did not have sound card packet features at first. It was originally designed as TNC management utility and still has many super features of value to TNC users. For example, AGWPE makes it possible  for TNCs to connect to more than one packet program at a time (TNCs can't do that without AGWPE) or have programs connect to more than one TNC at a time (programs typically couldn't do that without AGWPE).

AGWPE performs its magic with a TNC by placing the TNC in KISS mode and then taking over responsibility for handling most of the logic functions built into the TNC. The TNC is left to handle just packet tone modulation/demodulation, or modem, functions. AGWPE handles the AX.25 protocol for connections and automatic repeat request for lost/damage packets. In addition, AGWPE provides dynamic re-setting of packet timing settings based on frequency traffic load, something TNCs do not do.

AGWPE was also designed to work with radio modems, such as the YAM and BayCom. Radio modems can do the tone modulation/demodulation, but do not have any of the logic functions built into TNCs. Instead, AGWPE provides the TNC logic functions for those devices, as well.

In time, the program author, George SV2AGW, realized that a computer sound card could emulate all the functions of a radio modem. So with the TNC logic already in AGWPE and new code to use sound cards as a radio modem, AGWPE was then able to simulate a TNC -- and Sound Card Packet was born in the late 1990s!

Remember, for AGWPE to act as a host for other packet programs, or clients, those programs must be written to link to AGWPE. Not all packet programs can do this, but many can. Client program authors have gladly added this option to their programs because AGWPE relieves them of the need to write all the programming code that would be needed to control different TNCs, radio modems, and Multi-mode Controllers. It's much easier to let AGWPE do it!  (Multi-mode controllers can run packet plus some other digital modes, typically RTTY, AMTOR and PACTOR I.)

Client programs can link to AGWPE in one of two ways. The best way is using the Windows TCP/IP Socket interface. (If you are a program author, see open development information). The other was is using an older, less capable protocol, the Windows DDE (Dynamic Data Exchange) Manager, which only a few older programs use.

Note that when a client program is using AGWPE as a host, any settings in the client to control a TNC are no longer functional. Instead, AGWPE controls the TNC.

Advantages and Limitations 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. The cheapest TNCs 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 does not require a 12 V power source as a TNC does.

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 with S3 or less signal strength; and the 9600 baud modem is better than the original G3RUH modem.

Limitations: To be fair, some users claim they still get better results with a TNC and that TNCs are easier to setup and much less likely to get mis-configured. TNCs also have:

  •  a built-in digipeater function (although you can run a separate digipeater program with AGWPE)
  • a mailbox system (although there are separate BBS programs that can link to AGWPE)
  •  a built-in "watch dog" timers  to prevent continuous transmitting in the event of an error (although you can add a watch-dog timer circuit to your AGWPE interface)
  • the ability to run without a computer (for digipeating, beaconing)

Please note that many 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 directly with AGWPE, but there are several good ones. In addition, Tim Pearson KB9VQF has written a AGWPE Serial Loopback utility (cost $25) that creates virtual serial ports that will let you link AGWPE to ANY packet program that can link to a KISS-enabled TNC.

Important Features

The sound card option in AGWPE will allow you to:

  • Use "on air" baud rates of 300 (HF), 1200, 2400, and 9600. (See the Baud Rates and Modes page for additional info about 300 baud SSB operations and 9600 FSK operations.)
  • Use the stereo ( 2 channel ) feature of your sound card to connect to two radios on different frequencies at the same time using just one sound card.
  • Install additional sound cards that can be used exclusively for sound card packet. Your first sound card can then be used by Windows and other sound-producing programs and devices, such as your CD player.
  • Use a Sound Card Tuning Aid feature for accurately tuning signals, particularly on HF, and for setting the correct RX (receive) audio volume.
  • Access AGWPE on a remote computer over a home network or even the internet!

Basic Setup Steps

Getting AGWPE to work correctly can be tricky, since you will need the radio-to-computer interface, 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 out of date and in some cases it is wrong.)

There are 4 basic steps in getting AGWPE and your sound card to handle packet. These steps are discussed in different sections on this site (see the top left margin of this page):

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