February 24th 2008

Mode to try: MFSK16

Description
===========

MFSK16 is a Multi-Frequency-Shift-Keyed mode. It uses 16 tones 
and can utilize the entire ASCII character set. The mode has an 
approximate bandwidth of 316Hz and can be easily recognised from 
it's almost "musical" sound.

It is a very sensitive mode and works very well into the noise. 
There is a strong FEC coding and this helps to keep the text 
flowing during minor QSB.

There is also an associated analog SSTV mode that a number of 
programs have implemented for use in MFSK16. It is not a digital 
picture mode and it doesn't even use MFSK modulation however.

The basic theory of the SSTV mode is that when your MFSK16
program copies a piece of text of the form:
"Pic:(X)x(Y)(Format)" - then the analog SSTV reception mode
is started and the picture can be received.

So for instance sending "Pic:256x128C" would mean
"prepare for a color SSTV picture, 256 pixels wide by 128 pixels
high". All of this is done automatically by your software so
it's not something you would need to manually type!

The only real thing to say is that large pictures take a lot of 
time to send so you probably want to make the picture no larger 
than say "320x256" pixels (246 seconds).

There is a similar mode called MFSK8, this actually uses 32 
tones but is a bit slower and more difficult to tune. 
Sensitivity is slightly better however.

Specifications
==============

MultiPSK's help pages say this about MFSK16....

Baud rate           : 15.625
Speed               : 42 wpm (average) (62.5 bits/sec)
Modulation          : FSK 16 tones (4 bits)
Sideband            : USB is recommended
Character set       : ASCII characters + almost all ANSI extended
                      characters + a backspace character
Bandwidth           : 316 Hz
Interleaving        : Yes
Drift tolerance     : 10 to 20 Hz/min.
Duty Cycle          : 100%
Lowest S/N          : -13.5 dB

Operating guide
===============

MFSK16 signals are wider than PSK31 so make sure you have room 
to operate without causing QRM. Think about your power level 
too. This is a full duty Cycle mode and you should throttle back 
on your power or you may risk damaging your finals. 20W - 30W is 
probably the limit you want to use for a standard 100W rig. At 
this power level you shouldn't have any trouble making contacts 
however.

Make sure you have your software's AFC control turned on.
This makes tuning MFSK16 a lot easier.

Recommended Frequencies
=======================

Just like PSK31 the primary area on 30m is around 10.140 MHz 
(VFO) in USB.

Because the signals are wider than PSK31 you may need to spread 
out a bit on the band to avoid QRM. Just watch out for the QRPp 
folks and the PropNet beacons.

Availability
============

Just about every multi-mode program out there has
the MFSK16 mode.

Some recommended Windows software to try:

MultiPSK    http://f6cte.free.fr/
DM780       http://hrd.ham-radio.ch/DM780/DM780.htm
MixW        http://www.mixw.net/
TrueTTY     http://www.dxsoft.com/mitrtty.htm
Stream      http://xoomer.alice.it/aporcino/Stream/index.htm

As far as I know only MultiPSK and MixW incorporate support for
the associated SSTV mode in MFSK16. I am aware that DM780 is
rapidly being updated so it might already have this facility.

And for Linux, you could try

FLDigi      http://www.w1hkj.com/Fldigi.html

FLDigi does include support for SSTV.

I am not aware of any MFSK16 software at this time for
the Apple Macintosh computers.

Spotting is encouraged and you can use the spot page at 
http://www.projectsandparts.com/30m/

Sound Sample
============

Click here to listen to an MFSK16 signal (mp3 format)
Click here to listen to the MFSK16 SSTV mode (mp3 format)

73 es GL!
Sholto, KE7HPV
Republic, WA.

Comments or errata to: KE7HPV