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Introduction
Overview
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
Problems?
Program Behavior
Receiving
Transmitting
Connections
Firewalls
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
TNCs and AGWPE
What
To Do with Packet
Common Frequencies
Frame Headers
Further Reading
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Interface (Computer-to-Radio Cables)
Getting Started
To connect your radio to the sound card in your
computer, you'll need
an interface. The simplest interface consists of three (3) cables, one
each to handle :
- RX
(receiver audio)
- TX (transmit audio)
- and PTT (transmit) functions.
On two of those
cables (TX and PTT), there will be some simple circuitry built from a few easy-to find
components.
Back when sound card packet started in 2000, most
hams built their own
interface. Soon, vendors began to offer kits
or
pre-assembled interfaces. Recently, many vendors have been offering
an interface that includes an auxiliary sound card. Although these
USB interfaces are a bit more
expensive, they have become very popular because they provide a second
"sound card" that can be dedicated to ham radio purposes. They are also
easy to hook up -- just plug one cable into your radio and plug another
one into a USB port on your computer.
A radio-to-computer interface for packet is
probably the same as
one as would be used for other
sound card digital programs such as PSK31
or Slow Scan TV. So, if you already have such an interface, you may be
able to
use it for sound card packet. (Warning: This may not
always be true. Some radios have jacks that use certain pins for HF
operations and other pins for VHF/UHF operations.)
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Note for 9600 baud
operations: Well designed kits, pre-assembled interfaces and USB
interfaces usually have isolation transformers
on the TX and
RX audio lines. Those transformers work fine for 1200 baud AFSK operations but do not have the correct frequency response range
for 9600 baud FSK operations.
Actually, I know of no isolation transformers that will
work for 9600 baud operations. You may be better
building a special 9600 baud interface
omitting
any isolation
transformers, but understand the risks involved in directly
coupling two devices -- computer and radio -- that may be at different voltage
potentials. Those risks include ground loop noise and conceivably
even damage to
your radio or computer.
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If you build your own:
- You will find pages on this site which give
advice on building the three cables which are needed for an
interface. ◄ Look in the menu in the
left margin of this page -- under Section 7 -- to find pages for the
Receive Audio, Transmit Audio and PTT cables.
- Make sure you build the interface long enough to
reach from your radio to your computer sound card jacks, especially
for fixed position radios and computers. BUT keep them as short as possible
to reduce the chance of picking up stray RF (radio frequencies) or
EMI ( Electro Magnetic Interference ).
- Be sure to use cables with a shield in
them to help prevent stray RF from entering the
cables.
- Use isolation transformers in the Receive
(RX) and Transmit (TX) Audio cables (except for 9600 baud
packet ) and an opto-coupler/photo-transistor
in the PTT cable to break the ground path between the radio and computer.
- At least two of the cables will need small circuits. You'll find other variations at WM2U's PSK31
site. Circuit components should
be readily available at local electronics store or on-line.
Going beyond simple circuits, you'll find
instructions for home-brewing the "Cadillac of sound card interfaces" in
the March 2002 QST, p 31. Bob Lewis describes how to build an
interface for ICOM HF rigs with many deluxe features.
Also, take a look at Skip KH6YT's TX
audio-triggered (VOX) PTT interface which was featured in a QST article
in June 2009 (p.30):
https://sites.google.com/site/kh6tyinterface/ The beauty of Skip's
design is that you won't need a serial, parallel or USB port for
triggering the radio's PTT circuit; the TX audio will trigger it.
Stephen Smith WA8LMF has also
designed a VOX operated PTT interface. See his circuit on his
Tone
Keyer web page.
If you want to use your sound card
with
2 radios, you'll need a more complicated interface (see
cable2radio.htm).
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Special Tip:
If you want the flexibility of easily switching your
interface between different radios, you might be interested in this
cable construction trick.
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