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Info on radio fax
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MONITORING EQUIPMENT REVIEW
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R.P. MEGGS
PRESIDENT
INTERCEPT INC.
6014 OAK HILL DRIVE
FLOWERY BRANCH, GA. 30542
(404)967-9757
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Welcome Back!
JUST THE FAX, MA'AM.
This month we're going to take a look at three types of MULTI-MODE DECODERS,
how they work and what they're capable of doing.
WHAT IS A DECODER?
Though there are different types of decoders on the market today, they all
share a common function. To put it simply, a multi (or single) mode decoder
takes digital non-voice traffic from your shortwave or VHF/UHF receiver and
converts it into plain text, pictures, maps or charts.
THE UNIVERSAL M-900
Is a stand-alone decoder, that is it does not require a computer to do it's
thing, hence it's one big advantage-less noise to your receiver, more signal
from your receiver, thus a better copy on the signals you'll be decoding.
Did you know that on the shortwave bands, the vast majority of signals are
non-voice? Morse Code, Moore Code, AMTOR (Amateur Radio Over Telex), RTTY
(Radiotelephone/Telegraph), SITOR, FDM, FAX and ASCII are a few of the signal
types you'll encounter, and decode.
HOW DOES IT WORK?
Plug the M-900 into an AC outlet, run a cable from the earphone or line out
jack of your receiver, hook up a printer or monitor (or both) and you're ready
to rock and roll!
The best way to start out in decoding is by tuning a CW or Morse Code signal
on your on your shortwave rig. A BFO or beat frequency oscillator is the only
absolute necessity on your receiver. You won't need a full-blown Icom or Ken-
wood to do the job, we've been using a portable for our tests, a Grundig Satel-
lit 500.
Tuning across the bands, find a strong CW signal without too much interference
from neighboring stations, set the decoder for CW. All decoders have a certain
pitch of tone or frequency they are happy with, so you will have to adjust
somewhat to allow the decoder to process the signal. The status lights on the
M-900 will let you know when you're on target, and from there you're home free.
As the signals come in, you'll see the code in a plain text format, scrolling
line by line as decoding takes place. CW can vary in sending speed and the
900 is able to track and translate these automatically.
There is so much happening out there! High seas weather forecasts, ship to
shore traffic, embassy and news communications, satellite photos, WEFAX charts
and much more are available 24 hours a day. With a little patience and practice,
they are all yours.
SOFTWARE SYSTEMS CONSULTING-PC GOES/WEFAX, HFFAX, PC SWL
Are decoders that use your IBM PC to bring in the goodies. The package includes
a compact demodulator that plugs into a serial port, software and all of the
documentation you'll need to get started.
Before we tested the decoder packages, we were a bit skeptical as to how well
they would work. Computers generate a lot of RF and can play havoc with a short
wave (or VHF) receiver. That can make for an unhappy situation when the signal
you're trying to decode can't punch through your computer's own noise.
Much to the surprise of everyone, the Software System's Consulting PC decoders
worked wonderfully. Easy to understand and set up, they feature such niceties
as on screen digital, threshold and tuning scopes, automatic signal analysis
and automatic unattended capture. Even a novice can use these packages, the
software and users manuals are easy to understand and are definitely "user
friendly.
At $99, the PC SWL/HFFAX package represents one of the best values in all of
radio. If you have got a PC and a shortwave receiver and you DON'T have the
package, WAKE UP! You're missing it. Get in on the deal before they realize
that you're getting a lot more than your money's worth and decide to raise
the price!
ONE DECODER TO GO, PLEASE!
The last unit we tested was the new MICRODEC portable decoder from Somerset
Electronics. This palm-sized unit can decode Morse, RTTY, ASCII and Baudot
via a brightness-adjustable display on the front panel. It's simple and fun
to use, just hook it up, turn it on and tune it in!
One nice feature on the unit is a built-in speaker with volume control, so
if your receiver doesn't have a line out jack, you can plug into the earphone
jack and monitor what you're decoding. Another is the built in printer port
on the back of the unit to deliver hard copy.
Our test unit used an AC adaptor, but we understand a nicad battery option
is available as well, making the MICRODEC unit the only one suited for total
portablility. It's so small, you can stuff it in your suitcase or radio bag,
leaving plenty of room for your other gear.
We had no problems setting up and using the MICRODEC, it performs well, is
reasonably ($199) priced and can get the job done. If your demands require
a portable, lightweight unit, it's the only way to go.
OVERVIEW
Each of the decoders outlined occupy a unique niche in the market:
The Universal M-900 (stand-alone)
PC SWL, HFFAX, GOES/WEFAX: (computer-based)
Microdec: (portable)
So all that's left is to decide your own personal preference and pick the unit
that will best serve your needs. They all work great, and are fun to use.
TILLNEXTWEMEET.........R.P.
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