Hello friends,
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 seetings) > Exclusons > 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 you 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 determines 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
Shortwave Radiogram Transmission Schedule
UTC Day UTC Time Frequency Transmitter
Thursday 2330-2400 UTC 9265 kHz WINB Pennsylvania
Friday 1300-1330 UTC 15770 kHz WRMI Florida
Friday 1500-1530 UTC 13690 kHz DRM WINB Pennsylvania
Saturday 0230-0300 UTC 9265 kHz WINB Pennsylvania
Saturday 1330-1400 UTC 15770 kHz WRMI Florida
Sunday 0800-0830 UTC 5850 kHz /7730 kHz WRMI Florida
Sunday 2330-2400 UTC 7780 kHz WRMI Florida