PSK31

PSK31 was originally developed by Pawel Jalocha (SP9VRC) and was called "SLOWBPSK".  Peter Martinez (G3PLX) developed this idea further and came up with a very narrow (160 Hz) phase shift mode which uses a 31 bit/second data rate (hence the name).

While PSK31 is not an ARQ mode such as Pactor, it can correct errors using a mathematical construct called a Viterbi decoder.   If your are interested in the mathematics behind this, Peter has published a paper which can be found (in PDF format) here.  Peters' original program needed a Motorola DSP56002EVM board (this product has been discontinued ), but in December of 1998, he released a new version which can run on any

computer with Windows95 or NT and a SoundBlaster 16 compatible sound card.  This mode has become extremely popular, as it works very well with weak signals and is great for keyboard "chatting".  The following screen shot shows the PSK31 program, and at the bottom you can see the two tuning indicators. (The spectral plot above and any others on this page were made using EVMSpec by G3PLX).

IZ8BLY has a very good program for the soundcard.  A new "front-end" program has been written by Al Williams (WD5GNR).  This nice free-ware package adds a type-ahead buffer, programmable function keys, and many other features.  It will only work with Windows 95, 98, and NT.  The download can be found here.

HELL

HELL ("Feld-Hell" or "Hellschreiber") was invented by Rudolph Hell in 1929. It was first used to send newspaper text over telephone lines, and was later adapted by the German army for use in W.W.II. Hell sounds like high speed CW, and each character is generated as a series of dots looking somewhat like the output of a dot matrix printer. In order to minimize errors in timing and/or phase the inventor came up with the idea of printing each character twice for each single transmitted character. The letters in Hell tend to be slanted due to the nature of the timing, so a specially designed font is used to maximize readability. There is no electronic or mathematical error correction, but humans are very good at decoding noisy visual input, so up to 20% of the signal can be corrupted before the text is unreadable.

 

G3PLX has a program for the 5600EVM, and there are several others for DOS/Windows with a soundcard. One of the newest is by Nino Porcino (IZ8BLY) and can be found here.

MT-Hell was originated in 1937, but was first implemented in 1998. This mode uses combinations of 7 to 16 tones sent at the same time. This allows for higher throughput, vertical characters, and the ability to use different fonts, underlining, bolding, and italics.

 

MT-63 is a wide band (1 kHz) mode invented by SP9VRC. It uses 64 tones which can give millions of possible symbol combinations. Of these, only 128 are used for the ASCII characters. This fact is used for the error correction in this mode; if you think of the 128 characters being embedded in a much larger matrix, an error will in most cases fall close to the correct symbol, and the software can choose it. Nino has also written a sound card program (Beta version) for this mode. At this time, MT-63 is not specifically approved for use by the FCC, however (in my opinion) it falls under the same category as PSK31 which IS approved (the specifications are in the public domain).

PSK31

1.83815, 3.58015, 7.07015, 7,03515, 14.07015, 21.08015, 28.07015, and 28.12015 with 10.13715, 18.10015, and 24.92500 suggested for the WARC bands.

Feld Hell

3575.00 (Region 1) 3559.00 (Region3)

7030.00 - 7040.00

10135.00 - 10145.00

14063.00 - 14070.00 (many operators monitor 14063.00)

18100.00 - 18105.00

21063.00 - 21070.00

28063.00 - 28070.00 and 28100.00 - 28110.00 (novice)

MT63

At present 14.109.5 has been active (USB)

MFSK16

3.580

14.072 -14.079

18.106

THROB

14.079