Monday, July 26, 2010

Digital Mode Programs That Work #2: Multipsk

Multipsk is a multimode receive/transmit program that works with the PC sound card in Windows or Linux. It's rapidly becoming the big gun in freely available ham/SWL software for these platforms.

The program is by Patrick Lindecker, F6CTE. It can be downloaded from Patrick's F6CTE web site, which is in English. A Yahoo group (also in English) for users is reachable at Multipsk (at) I haven't looked at this group, but I keep meaning to.

Just about everyone I can think of who uses Windows or Linux for serious utility work has at least tried this program. Now that SkySweeper is no longer supported, Multipsk is the most viable PC multimode package for under $3000 US. WAY under, in fact, since a perfectly acceptable version is available free. As in $0000 US. This is not crippleware or nagware. When you pony up the $45 (last I looked), you get more features, and lose the time limits on some others.

New versions come out on a regular basis, and most add at least one new mode. The latest is 4.18. The major change from 4.17 is the addition of US weather radio SAME (Specific Area Message Encoding) decode. I've played with SAME on my scanner a bit. Its purpose is to alert local areas for bad weather.

The list of other modes is boggling:

110A (MIL-STD-188-110A/B), 1382 (1200 baud MSK), STANAG 4285, VHF ACARS, ALE, AMTOR/SITOR, ASCII, BPSK/QPSK 32/63/125/250, CHIP 64/128, Contestia, Coquelet, CW (OOK/Coherent/FSK), DGPS, Domino, DSC, DTMF, FAX, Hellschreiber (Feld/PSK/FM), JT65, MFSK8/16, MT63, Olivia, Packet/APRS, Pactor-I (used mostly for calling), PAX, PSK10/63F/220F, PSKAM, QRSS, RTTY, SELCAL, SSTV, and THROB.


Hams will be able to take advantage of many features for logging, radio control (with 3rd-party software), and display of things like maps. For utility, the later versions have steadily added "professional" modes, such as SITOR-A, non-amateur RTTY speeds and shifts, and a SYNOP decoder (time limited w/o registration). Now, if I could only get good skip on Hamburg Meteo when the SYNOP codes are on.

The package includes another program called Clock, which decodes the data hidden in most time signals and GPS. After registration, it can set your computer clock. I've used this on several low-frequency European time signals via the WebSDR in Holland. This is close to a worst case for decode, given the Internet link's general instability. With considerable patience, though, I've managed decodes on nearly all stations at one time or another.

Anything this complicated is going to have a learning curve. Also, many people have been intimidated at first by the user interface. Now, I have come to like this. It's way faster than going through menus or trying to remember presets when you're in a hurry to grab onto some signal. The downside, though, is that there really are a lot of little buttons.

The colors have also turned some people off, though I don't mind them at all. They help group the aforementioned little buttons in a fairly logical manner.

How do the decodes stack up against other programs? Most of the time, just fine. I like SkySweeper better for FAX, but a lot of people hate it. DGPS might be better than SkySweeper, though DSCdecoder beats them both. SIGMIRA is somewhat better than either for STANAG 4285, though that mode really pushes the edge for any sound card decoder.

Where Multipsk has the general edge, for me anyway, is its use as a tool for attacking completely weird signals. This is especially true for the PSK variants.

I realize that the high-end government packages are often pretty good at this. But they aren't free/ $45. Case closed.