Monday, August 09, 2010

Digital Mode Programs That Work #3: SeaTTY

Recently, I read a rather impromptu test done by WZ7I. It seemed to indicate that a popular ham program called TrueTTY actually had better "sensitivity" than a tweaked version of the older MMTTY, which I'd always figured was the hot setup.

This got me interested, since I'd used TrueTTY in the past, and liked it. So I went to the DXSoft site where the clever Russian programmer Sergei Podstrigailo, UA9OSV, has his latest stuff.

What I noticed, though, is that his other NBDP program, called SeaTTY, was starting to look like a better deal for users who wanted to concentrate on receiving, especially in the maritime bands. Needless to say, I grabbed it, in version 2.30.

SeaTTY looks like TrueTTY, with the same sleek user interface showing the FFT amplitude plot at the top and the bit scope at the bottom. Its purpose, though, is not making ham QSOs. It's listed as a "weather messages decoder," and indeed it's set up to facilitate the unattended grabbing and filing of same.

Modes decoded are RTTY, Navtex/ Sitor-B, DSC (HF/VHF), HF FAX, and NWR-SAME. The latter is a VHF signaling mode used by weather broadcasts to target specific areas.

I put SeaTTY to work on the longwave RTTY weather broadcast from Hamburg/Pinneberg Meteo in Germany, as received by the WebSDR in the Netherlands. It started up, spat out a few garbage characters, then happily produced a steady 100% decode. I ran MMTTY and SkySweeper alongside, and MMTTY was also 100%. SkySweeper was good, but produced the inexplicable character errors I've come to expect from its RTTY mode.

This was too easy. I waited for propagation, and gave it the RTTY weather from CFH in Halifax, NS. This is never a good path to SoCal, and the geomagnetic storm had left some extra fading. Interestingly, SeaTTY and MMTTY produced about the same percentage of characters decoded, but messed up in different places. While the decode rate was about the same, SeaTTY actually produced somewhat more readable copy.

SeaTTY was about as good as DSCDecoder on Navtex and HF Sitor-B weather. It files successful Navtex decodes in a slick directory tree structure, with the copy showing in a window alongside. The save is automatic, as long as the Telex start code (ZCZC) and end code (NNNN) are detected.

DSC decode shows as a numeric dump of the raw symbols, but clicking the time stamp produces the message. The only missing feature compared to DSCDecoder is the instant lookup of MMSI numbers in the ITU database.

Where I really had fun, though, was the FAX. It's a very well thought out interface for this mode. Finally, there's a FAX decoder as intuitive and generally slick as the old JVComm, but which doesn't print "Demo" all over your faxes until you pony up. (SeaTTY, like DSCDecoder, waits a set number of days, then sulks until you pay. It's $35 and easy to register.)

I'd long since learned how to play SkySweeper's fax interface like a musical instrument, and turn out awesome copy, but right now I think I'll switch to SeaTTY. Once I get used to it, I suspect it'll be just as good, and with less general fuss to get working. Faxes, like Navtex messages, get time stamped and autosaved, accessible from the directory tree. Good stuff.

To sum up, SeaTTY is a keeper. I gladly paid up. Now I go forth into the Ether with some good tools.