Tom, all you have to do is open you filter up to say 1800 hz or maybe a
little more, then sit and watch how many signals you can decode on a busy
20 meter psk31 day. I regularly copy signals that are almost in the noise
while surrounded by louder signals only 20 or 30 hz away..... 20 or 30, NOT
200 or 300 hz away. I kid you not..... Well, if the signals were as lousy
as you seem to think most of them are, you wouldn't be able to do that with
any regularity..... I have it happen almost every weekend and even during
weekdays on 20 and 15 meters. In fact, given the number of hams who call 20
meter digi "home," it is the NORM, not the exception.>>>>
The problem is almost never decoding signals near other signals of
relatively similar levels, say within 20 dB or so of each other.
Problems almost always occur when a strong signal of what might appear to be
reasonable purity in other cases is parked near noise floor signals. It is
all about dB.
<<I understand what you saying about Collins and the entire concept. BUT,
the truth of the matter, experientially, is that we MUST be producing mostly
clean signals or you wouldn't be able to pack so many signals into a SSB BW
and be able to decode each and every one of them.>>
That is probably what Collins thought, too. After all, if a dozen S6 to
S9+10 32S1 transmitters were near each other and able to work, why would
the FCC be sending out pick tickets, and why would other people be
complaining about the same system? Because the other people were trying to
work S2 -S4 signals, and the birdies and carrier were falling on them.
The same is true for NDB's with a bit too much drive. If airplanes don't
notice a problem with an overdriven NDB at the next airport, they must be
pretty good. Why do they bother Hams 2000 miles away?
Most 30S1's actually were around -40 dB or so for spurious, and most NDB's
are better than that. That doesn't change the fact both systems are poor
ideas, and cause problems that could have been avoided.
.... Even if there is some disparity with regard to the strength of those
signals. In other words, I don't know whose signal you have been listening
to, but it can't be the majority....... I am not pinging on you here, just
stating fact, whether it is anecdotal or measured. The logic of your well
stated argument is good..... But experience says that the basic premise MUST
be wrong. Most of s are, indeed, producing clean signals..... The proximity
of our digi "neighbors" in the digi portions of ALL the bands says so.....
:) :) >>>>>
Most doesn't make something the best choice. You'll find very few people
who want to park in a neighborhood where **most** cars don't get broken
into, when there might be a better choice.
My basic premise is exactly correct. Modes generated at baseband audio and
transmitted through SSB transmitters are only as clean as the basic SSB
transmitter, and are subject to operator and external wiring error. SSB
transmitters are not especially clean, so it seems a little short-sighted to
park S9+ signals next to S3 signals unless there is no other choice.
Also, when that 5 kHz slot (or whatever it is today) fills up, where will it
expand? Will the digimodes push the SSB up above 1850kHz or will it push the
CW below 1830?
160 is not at all like 80 or higher.
Placing digimode local operation between 1835 and 40 really does not show
much foresight at all, if there is long term increased activity. Maybe
digital mode operation will never grow, and none of this will ever be more
of an issue than it is now.
73 Tom
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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