INTO DIGITAL COMMUNICATIONS
A primer from K8BE -
"Whitey", and Carolyn - N8ST
eBook is meant to be a starting point for the ever increasing number of
people wanting to get into amateur radio digital modes of
communication. I hope
this makes getting started in Digital a glad and easy experience. Even
if interfacing using other manufacturers interface devices other than
from Donner's Digital, most setup procedures are similar, so this
material should still be useful.
other than SSTV, it is
recommended to use a PC that runs at a minimal
speed of 100 Mhz. Some success has been attained as slow as 75 Mhz, but
that gives little or no margin of resource. Memory
is 32 megs or more. Your best bet is a 300 Mhz (or faster)
machine, with 64 megs (or more) of ram. The PC needs at very least, a
bit Sound card, ie: SoundBlaster Pro. Please note that some
softwares for digital communications use a direct access to the
sound card hardware, and in some instances, Soundblaster "compatible"
cards may not work. It is always best to use a Creative Labs
(Pro, 16, 32 AWE, 64 AWE) when possible. A "compatible" card will work
usually; but it depends on the software being used. Some programs will
work with most cards, but keep in mind that if you
have problems, you may need a genuine Creative Labs card.
install the latest driver available, since older drivers might contain
bugs. Some programs which run under 32 bit
operating systems may require a 32 bit sound card
driver. Some drivers for Windows 95/98 may actually
be a 16 bit driver instead of the 32 bit driver that you need.
Having tried several
types/brands of sound cards here, we have had best results using an
inexpensive Crystal Fusion card, which is also stable enough for
SSTV. Video is not too demanding
unless one wants to operate SSTV, and then all resources need to be
faster and stronger. The PC should have at least 1
free serial port, preferably a DB-9 style connector.
We have learned from personal
experience, as well as from several of
our thousands of customers, that not all computers lend
themselves for digital communications requirements. An example of this
is a Dell Inspiron Laptop. A good machine, but the worst choice for
digital use. This machine is notorious for the serial port coming up
high on startup, and along with that, a serial voltage much lower than
standard. There is a software fix to cure the high start, but none for
the low port voltage. There have been reports of a few Compaq laptops
also having low serial port voltage, but from experience I have only
incurred the trouble with the Dell. When we go mobile/portable,
we use an IBM Thinkpad, or a HP laptop. Nearly all desktop computers
seem to do the job very well.