Sound Card Digital Mode
Ingredients
Portions of this page were
excerpted from the Digi-Tales Article in the February 2005 Spark Gaps
Ingredients:
What things do you need for sound
card digital modes?
·
A radio
– most sound card modes are intended for use on the HF frequencies,
however, the NPARC digital net takes
place on a VHF frequency where Technician-class hams can participate.
For this local net, you’ll need a “two meter” radio capable of tuning to
145.75 mHz. (Even a hand-held 2 meter radio
will work, but its signal strength could be problem. A good antenna for
it will help, particularly for transmitting.) And of course an HF radio
can be used for “real” communicating on these modes with hams around the
globe.
·
A Windows computer with a sound card
– Most of the sound card digital programs run on a “basic” Windows
desktop or laptop, although some programs may require a
higher-level processor and more RAM. It is hard to
be more precise because many components affect the computer’s overall
ability to handle the digital signal processing that takes place with
sound card modes. “Try it and see” is the best advice I can give.
Any recent-vintage (within 5-6 years) sound card should work, but
occasionally you may encounter cards that
won’t work with some programs; again, “Try it and see”.
"On-board" cards (integrated into the motherboard) are more apt to cause
problems, but generally only with 1200 baud packet.
·
Software –
Nearly every sound card digital mode can be run with
a free Windows program which you can
download from the internet. The NPARC
'Digital Net’ web
page lists many digital
modes and includes
download and information links for each mode. (You can do your own web
search for even more info about a mode.) Unfortunately, there is little
software for Apple/Mac users and only slightly more for LINUX users.
For some less common digital modes, only Windows software exists.
·
Sound Card to Radio Interface
– You’ll need some way to feed audio signals to and from your radio and
your sound card. Generally this is handled with 3 wires (audio in, audio
out, PTT control) that together are called an interface. The basics of
obtaining or making an interface are discussed
on the Sound Card
Interface page.
Note that you may need a different interface for each radio you use. The
interface connections to the sound card are
generally fairly standardized, but the connections to the radio vary by
radio manufacturer and model.
You can also experiment with WA2DKJ’s patented
“poor man’s wireless interface”: To receive, put your computer microphone
next to your radio’s speaker. To transmit, put your radio microphone
next to your computer speaker and simply push the PTT right before you
push the “transmit” button in the computer program.
But even if this works for you, it's likely you'll opt for the
stability and convenience of a wired interface.
< back to the Sound Card Digital Modes page
