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