Experiments with MFSK Wide modes

On the shortwave broadcast transmissions of Shortwave Radiogram, we have at least 2000 Hz of bandwidth per sideband. For the past few years I have wondered if we could use that extra bandwidth to add redundancy to our usual MFSK32 and MFSK64 modes, thereby increasing performance in
challenging reception conditions, especially fades.

John Phelps KK4FYD of the Fldigi team has developed the experimental modes MFSK32WIDE and MFSK64WIDE to test this concept. We will try these modes this weekend (29 October-1 November) on Shortwave Radiogram.

If you want to decode these new modes, you must download and install Fldigi alpha version 4.1.15.05 or later from http://www.w1hkj.com/alpha/fldigi/

(If you have trouble running the Fldigi setup [installation] file, try
to add an exclusion in the Windows 10 security settings: Settings >
Update & Security > Windows Security > Virus & Threat
Protection > Virus & threat protection settings  (manage
settings) > Exclusions > Add or remove an exclusion > Add an
exclusion > File)

When you decode the MFSK Wide modes, there will be a delay of about
18-20 seconds from the time your hear the mode and the time the text
begins printing out in the Fldigi receive pane.

“Studio” audio of this weekend’s experiment is here, if you want to try it before the broadcasts:
https://swradiogram.net/post/633261475902947329/this-9-minute-25-second-mp3-file-includes-a-news

The MFSK Wide modes are designed primarily to increase redundancy, but they also add some speed …
MFSK-32WIDE gives ~ 180 WPM  (50% faster than MFSK32)
MFSK-64WIDE gives ~ 300 WPM  (25% faster than MFSK64)

Additional information about the MFSK Wide modes is here:
https://sites.google.com/site/kl4yfd/home/mfskwide

The MFSK Wide modes replace the “long” MFSK32L and MFSK64L modes, which
we have not used recently on VOA Radiogram or Shortwave Radiogram.

Our tests of the MFSK Wide modes will be most interesting in challenging
reception conditions. The results we experience will help Dave W1HKJ
and the Fldigi team determine if these new modes will be permanently
added to the Fldigi suite.

Tomorrow (Thursday) I will distribute the usual weekly email with the
preview of this weekend’s Shortwave Radiogram (program 176).

Kim

 

Fuente: Experiments with MFSK Wide modes



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