What's needed for SITOR?

[AA1PL]

I read the Utility Column in Popular Communications magazine regularly. I notice an increasing number of listeners are reporting maritime activity in the digital SITOR-A or SITOR-B modes. Can someone explain in simple terms what is needed to decode these transmissions at home? I would love to have that capability. What's the difference between SITOR A & B? I use an Icom IC-735 HF ham rig for my monitoring. I also have a Radio Shack DX400.

 

[ka3jjz]

Keep in mind that logs in pubs like PopComm have a 60 day or more lag between when they receive the log, and when they actually publish.

A basic definition of SITOR can be had here;

http://en.wikipedia.org/wiki/SITOR

There are a few variants of Sitor A reported on occasion - the Russians and Egyptian embassy have both used a variant in the past. Our wiki has
sites with audio samples of both Sitor A and B.
http://wiki.radioreference.com/index.php/Utility_Monitoring

Keep in mind that at first, PACTOR sounds to the ear much like SITOR-A, but PACTOR can and does change transmission speeds, and there is
a special variant of PACTOR that is used by Globe Wireless for email (supposedly secure).

As for software, there are numerous packages that can decode Sitor A/B - see this site;

http://www.chace-ortiz.org/umc/software.html

If the 735 has a general coverage receiver in it, that will do nicely. You need a good receiver with selectivity and the ability to hear SSB without drifting all over the place. Of course, with today's propagation conditions (cruddy) no matter what you use, a good antenna is an absolute must.

73s Mike