need help

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aatsma

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Oct 30, 2003
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Hanford, CA
I am using MixW to decode cw and it works like it is supposed to.
On the shortwave bands how do you know if you are listening to fsk, pfsk, mt31
or any of the other ones. What is mostly on shortwave and what are the steps
to figure it out.
Please help
 

ka3jjz

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Jul 22, 2002
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Bowie, Md.
While MixW is very good software, the vast majority of sigs outside of hams (and some maritime/aero stations) are in modes that it simply isn't designed to decode. SkySweeper is a much more comprehensive package for such modes, and it is upgradeable.

Now as to how to identify what you are hearing - the first way is listen. Some modes, such as Pactor and SITOR, have a repeating, rythmic sound to them, and you can identify things like that easily. ALE has a scratchy sound all its own (and is easily decodeable with Freeware- PC ALE is what you need there), and 75 baud RTTY also has its own sound.

The other way is to view a waveform, something MixW will allow you to do (at least, in the old version I have....). Each signal has a characteristic waveform which is likely to be even more accurate than your ear. For example, MT63 has a very wide (almost 1khz) bandwidth, as does PACTOR 3 (which is very controversial to find in the ham bands...). Baudot RTTY has a 2 tone system, which are seperated by a fixed amount.

The utility monitoring wiki (link below) has 3 or 4 links where you can check out audio samples of common - and not so common- signals found on HF and beyond...

http://wiki.radioreference.com/index.php/Utility_Monitoring

The other ways involve a little legwork. Checking references like the Klingenfuss guides are a good start, but a much more up to date way to find these things out is to join a Yahoo group which specializes in utilities - the UDXF. The link should be at the bottom of that article above. Keep in mind that such groups are worldwide; consider propagation characteristics before jumping to conclusions.

73 Mike
 
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