> On Feb 26, 2018, at 10:45 AM, Ed Muns <ed@w0yk.com> wrote:
>
> Most users are unaware and don't change
> the default. And, why should they change it? By leaving it wide, they keep
> their neighbors away from their operating frequency!
Psst.... don't tell them that a narrower transmitted signal is easier for the
other end to copy too, Ed. I.e., you will be asked for fewer repeats.
Practically all (well perhaps not MMTTY) RTTY demodulators today use very
narrow tone filters, of the order of 50 Hz FWHM. The extra keying sidebands
are just wasted power that is thrown away by the demodulator anyway. If you
transmit 1 kW, some of it is simply wasted because the receiver is not even
looking at the keying sidebands (unless the other end is using RITTY, which
uses FSK Matched Filters).
We are lucky today that many, if not the majority, of hams have a panadapter
whose resolution is better than 30 Hz. Virtually everyone can see the wide
signals for themselves. Back in the beginning of the century, it was almost
impossible to convince anyone that FSK is unnecessarily broad. The following
was written in 2005 a month before I retired (!):
http://www.w7ay.net/site/Technical/RTTY%20Sidebands/sidebands.html
73
Chen, W7AY
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