Topband: TB digital

[Jim Brown]

On 9/16/2012 7:16 PM, wa3mej at comcast.net wrote:
> Finally,  you cant mean to tell me that the little bit of space being used by digital at the top of the CW window causes a hardship on anyone.. heck half of the time the SSB stations are even down there and no one growls about that.. and wait until a SSB contest you wont find an empty spot in the CW band.. so what is the beef with 5 KHz or less being used, sometimes for a sound card digital mode when much of the CW band is empty 75 percent of the time.

Right. And for the record, JT65 uses ONLY 2 kHz between 1838.5 and 
1840.5, and it's not unusual for there to be 6-8 signals in that bandwidth.

Another point -- most digital operators I know LISTEN to their receiver, 
especially when running RTTY, JT65, FSK441, and ISCAT.  If you're 
listening, of course you're going to hear if another station is there -- 
assuming your noise level isn't too high.  AND, because you've got a 
spectrum display in front of you tuned to that 2 kHz bandwidth, and so 
does everyone else operating that mode in that space, any rig with hum, 
buzz, or audio harmonics is going to stand out like a you know what in 
the punchbowl.

AND, if all these signals were as full of hum and buzz as you imagine, 
the combined hum and buzz resulting from all those guys transmitting at 
once with their VFOs all set to 1838 USB would be very close to zero 
beat, and would more or less add by 3dB for every doubling of the number 
of dirty signals.  Reality is that it doesn't happen that way, because 
digital operators are NOT mostly lids, they DO work on making their 
signals as clean as they know how, and other digital operators will make 
sure that they do because they don't want the QRM.

And since which is 1835-1840 "reserved for weak signal work?"  I've been 
on Topband for a while, but this is news to me.  There used to be a "DX 
window between 1830 and 1835, but that's long gone.

But all of this begs the obvious question -- if I'm here in California 
having fun on my run frequency in a contest (CW, of course) and 2,500 
miles away in GA Tom want's to work an S1 station who just got spotted 
on my frequency, which I've busted my butt to find and hold..You think I 
should QSY?  Heck no. Now tell me how that is different from some guys 
mostly running 10-20 watts, mostly into a wet string, using about 200 Hz 
in a 2 kHz chunk of spectrum?

73, Jim K9YC