Now that the 'mystery signal' of last week has been identified and
decoded by a number of people, I'll be transmitting Low Speed Sequential
Multi Tone Hellschreiber again this weekend on 137.6kHz, this time with
bandwidths of 20Hz and 2.5Hz. Time duration per pixel will be scaled in
line with the frequency deviation in proportion to the tests last
weekend, so around 0.3s / pixel for the 20 Hz version and 2.5s for the
2.5Hz version. These correspond to 19 seconds and 2.67 minutes per
character respectively. Power will be in the 50 - 100 Watt region to
the antenna, giving 5 - 10mW (or probably less) ERP.
If anyone would like these parameters varied let me know on the other
EMail account [email protected] or via the reflector and I hope to be able
to accomodate this. You can also try phoning on 01489 787424 but expect
to get an answering machine as I'll be in the garden most of the day
building a conservatory and getting irradiated by the RF fields from
overhead !
Unfortunately, Dave and Mike, LSB is not an currently an option, so for
now get a mirror / scroll vertically / practise reading back to front.
I could alter the software in the future for this mode though, or even
transmit USB and LSB simultaneously, one above the other. Presumably
that becomes ISB.
Three other fonts are available, a simple 5x7 font similar to the
original Hellschreiber one, though reported by G3LDO to be not as good
as the 8x8 I was using; and larger 8x14 and 8x16 fonts which probably
have nothing to offer - on local strong signal copy anyway.
Andy G4JNT
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