RTTY Question

[DeKP]

I recently purchased a ICOM 7300 to decode RTTY. It works fine for Ham. I pick up RTTY signals all over but when I attempt to decode them the twin peaks on my display are to far apart to decode. I can't get them to line up. I have used all the filters that I know about but no joy. Are these signals RTTY or something else? I've been out of the hobby for 30 years and it certainly has changed. Any help would be appreciated. Thanks, Keith

 

[nd5y]

Hams normally use 170 Hz shift 60 wpm Baudot RTTY.
A lot of the non-amateur RTTY is 850 Hz shift 75 wpm and a lot of it is either encrypted or other formats besides Baudot that can't easily be decoded.

 

[ka3jjz]

It is strictly illegal to encrypt transmissions in amateur radio (encoding it with a different protocol is quite another matter, and they are not the same thing). There are numerous other modes that can easily be decoded with the right software. The trick is to identify the mode and frequency. I've seen so many so-called bandplans for various modes that it boggles the imagination.

Take a look at this for a quick primer on the subject of digital amateur radio...

HF Digital Amateur Radio - The RadioReference Wiki

wiki.radioreference.com

The big modes these days seem to be FT4 and FT8. Why ham manufacturers continue to use modes that aren't as popular as they once were (Baudot RTTY, PSK31- altho they are certainly used) is beyond me.

Outside the ham bands is altogether different. There are several decodable modes, and many that are heavily encrypted and will likely never be broken. These include ALE, HFDL, SITOR-B, and weather FAX - all decodeable with the right software

Mike

 

[ka3jjz]

Get a fairly good sized jug of your favorite drink, and read through this. It will give you a reasonably good picture of the digital world outside the ham bands...

DXing Digital Utilities - The RadioReference Wiki

wiki.radioreference.com

THE place to be for such loggings is the UDXF - the Utility DXers Forum reflector on groups.io They have a HUGE website with lots of different non-ham (and non-broadcast) links. The digital modes page, along with the link for the above mentioned reflector, is in the last section of the article linked above

Mike

 

[jwt873]

You should have a way to change the RTTY settings in the IC-7300 menu. (My IC-7600 and IC-9700 can do this).

Open your manual and look for RTTY Mark, RTTY Shift, and RTTY Polarity. Changing these will let you decode different formats... So, for example RTTY shift will change the distance between the twin peak markers allowing you to line up the peaks on the display for different shifts.

This site has a lot of into (including sample tones) of various RTTY configurations. --> Radio Teletype (RTTY) - Signal Identification Wiki

Also. A some of what sounds like RTTY on the commercial bands isn't and you won't be able to decode it.. But it can be fun trying

 

[ka3jjz]

The single hottest mode - that is used by hams and non-hams alike - is ALE (also known as Mil-Std-188-141A/B). It sounds NOTHING like standard baudot RTTY. There are quite literally hundreds - sometimes thousands - of logs of this mode every month in the UDXF. While a few stations encrypt their ALE transmissions (protected mode), most everything else is in the clear. The SigID Wiki mentioned above has an entry for this mode

Mike

 

[ka3jjz]

If you try to tune what appears to be a 50 or 75 baud signal in the non-ham bands but always comes up with gibberish, chances are fair that it's a STANAG 4481 signal running NATO encryption. Here is a small list of frequencies....

Undecodeable NATO Digital Signals - The RadioReference Wiki

wiki.radioreference.com

Mike

 

[WB9YBM]

I recently purchased a ICOM 7300 to decode RTTY. It works fine for Ham. I pick up RTTY signals all over but when I attempt to decode them the twin peaks on my display are to far apart to decode. I can't get them to line up. I have used all the filters that I know about but no joy. Are these signals RTTY or something else? I've been out of the hobby for 30 years and it certainly has changed. Any help would be appreciated. Thanks, Keith

This might have more info than you need but--especially once past the intro portion--this has a lot of good info: Radioteletype - Wikipedia

 

[ka3jjz]

the ;primary users part of that article is mostly out of date (except for the occasional ham use)- but the reference to DWD is still correct. Also the Dutch Navy has been known to run standard Baudot RTTY. Outside of use by hams, that's about it.

Mike

 

[AK9R]

As others have said, most amateur radio RTTY uses 170 Hz shift between the Mark and Space tones. But, non-amateur radio users may be using other shifts.

If you haven't already, I suggest you go to the Icom website and download both the Basic and the Full manuals as PDF files. You can use your computer to search for things in the PDF manuals rather than flipping pages in a paper manual.

In the Set Menu of the radio in the Function category, you'll find the RTTY Mark Frequency (defaults to 2125 Hz) and the RTTY Shift Width (defaults to 170 Hz). The RTTY Shift Width can be changed to 200 or 425 Hz in addition to 170 Hz. But, there's a catch. The internal RTTY decoder in your radio only works when the RTTY Mark Frequency is 2125 Hz and the RTTY Shift Frequency is 170 Hz. This is a limitation in the Icom firmware that you can't get around. Your only option would be to use your computer to decode the signals using a RTTY decoder such as MMTTY or FLDigi.

Baudot RTTY using 45.45 baud is still very popular in amateur radio and there are several RTTY contests each year (most recent one was this past Saturday). But, outside of amateur radio, you may find other speeds and shifts being used as well as other modes that sound like RTTY, but aren't.

 

[WB9YBM]

the ;primary users part of that article is mostly out of date (except for the occasional ham use) Outside of use by hams, that's about it.

Actually, hams still use it enough to have a successful RTTY contest every year ("CQ" magazine's got a lot of information on that--and that magazine's also carried several good articles on the topic spanning several years). As for other services--as technology progresses and more and varied digital modes are invented, yeah the old modes are being left behind: the only service still using AM is the aeronautical industry, and in public safety it seems like most have given up even FM in favor of digital. So it's not just RTTY being left behind.

 

[AK9R]

There are many RTTY contests for amateur radio each year. See RTTY Records, Rules & Results – rttycontesting.com for a listing of (mostly) RTTY contests.

But, I don't think the OP is primarily interested in decoding amateur radio RTTY.