MFSK16 and MFSK8 are powerful modes MFSK (Multi Frequency Shift Keying) modes designed specifically for DX. They use a convolutional FEC (Forward Error Correction) coding and an interleaver, which disperse the symbols over a long period of time, in a way that counters the effects of noise and multi-path that affect reception. Bits are sent on a carrier chosen among 16 (MFSK16) or 32 (MFSK8). The minimum ratio Signal-to-Noise ratio is about - 13.5 dB for MFSK16 and -15.5 dB for MFSK8.

    This mode is included into the software MULTIPSK by Patrick F6CTE, there is the description of this mode and its variants as well as the specifications coming from his software :


Created by : Nino Porcino IZ8BLY and Murray Greenman ZL1BPU
Description :
Baud rate : 15.625 for MFSK16 et 7.8125 for MFSK8
Speed : 42 wpm (average) (62.5 bits/sec) for MFSK16 and 26 wpm (average) (39.06 bits/sec) for MFSK8
Modulation : FSK 16 tones (4 bits) for MFSK16 and 32 tones (5 bits) for MFSK8
Reception mode : only one side (USB or LSB), USB is recommended
Character set : ASCII characters + almost all ANSI extended characters + an error reset character (« Varicode » characters)
Shape of pulse : rectangular
Space between tones : 15.625 Hz for MFSK16 et 7.8125 Hz for MFSK8,
Bandwidth : 316 Hz,
Demodulation : non-coherent,
Synchronization : automatic using the signal
Convolution code : R(Rate)=1/2, K (Constraint length)=7  with Viterbi type decoder
Interleaving : yes (for example, spreading of 120 bits for MFSK16)
Drift tolerance : 10 à 20 Hz/mn for MFSK16 and 4 to 7 Hz/mn according to signal-to-noise ratio,
Pmean/Ppeak : 1
Lowest S/N : -13.5 dB for MFSK16 and -15.5 dB for MFSK8
Note: pieces of information about Hellschreiber modes can be found on the WEB site of ZL1BPU (Murray Greenman). Pascal F1ULT make a french translation of ZL1BPU's site on http://f1ult.free.fr.


Recommanded frequencies for MFSK16, MFSK8,(USB)
Valid also for  THROB, THROBX, DOMINO.
1838, 3580, 7037, 10147, 14080, 18105, 21080, 24929, 28080 Khz
Note: for SSTV in MFSK16, in general, it is not authorized to transmit a mix of text and pictures because the authorized frequencies, for these modes (MFSK16 / SSTV), are different.

The MFSK8, DominoF, DominoEX and THROBX modes are QRP transmissions. They are very little used. Patrick F6CTE proposes to focus calls in the same conditions as for  PSK10, PSKFEC31, PSK63F, PSKAM10/31/50, at the following frequencies and times :

*   10148 kHz USB (BF autour de 1000 Hz) at 22h00 UTC.

          * 144620 kHz USB (BF autour de 1000 Hz) at 20h00 UTC.