RadioBanter - View Single Post - Echos from the past, code a hinderence to a ticket

August 8th 05, 09:56 PM

wrote:
From: John Smith on Sun 7 Aug 2005 23:27

Len:
cut
"Sidebands" as a result of modulations go only so far as voice
transmissions in the ham "textbooks." [operators don't need
smarts on theory?] Publishers and editors don't shine
spotlights much on anything but AM voice sidebands...which may
be THEIR deficiency. Radio amateurs get their theory where
they can and that is mostly from the periodicals. If that
theory ain't in those issues it seldom gets to the ham ops'
heads. The publisher decides what goes in them magazines.

You may not have seen the ham magazines of the 50s when
single channel SSB voice was beginning to take off. There
was great antipathy towards PHASING methods of modulation-
demodulation of SSB. Hams weren't told about PHASE, didn't
have the tools to see phase, few could afford 'scopes that
had passbands beyond 5 MHz. It was EASIER to build filter
SSB mod-demod even though it CO$T a lot more for those crystal
filters. Less thinking involved. AM voice spectra was
easier to understand and "brute-force" filtering to eliminate
an unwanted sideband almost intuitive. Despite some good
attempts at showing PHASING methods in the 50's magazines,
readers and editors alike didn't like it. Even after Mike
Gingell (UK ham, now living in USA) did his Polyphase Network
PhD paper on a low-cost, easy-component-tolerance quadrature
phase circuit, the U.S. periodicals didn't care for it. The
RSGB did and showed How and showed what UK and Yurp hams
were doing with it in the pages of Radio Communication. That
was 30 years ago...but European hams are having fun with that
Gingell polyphase network in homebrew SSB building.
cut

Sorry to butt in, but a bit confused here from the only famialr with
AM voice sidebands ad the talk of phasing sidebands are you refering to
a compatable system (that is can the brute force filtered SSb uint talk
to the phasing unit or are you discuing to different and Incompatable
systems (obviosuly if they were incompatable inerta is decent reason to
keep one over the other, after it has ekpt morse in place a LOT longer)

I migt as well learn something, and I am not afraid to admit the limits
of my knowledge that is of course the first step in increasing it