[amsat-bb] Re: Listening on USB when operating CW

tosca005 at umn.edu tosca005 at umn.edu
Sat Feb 8 09:33:30 PST 2014


I don't think that the OP was trying to complain about SSB operators being 
less capable or less polite or less facile in their Doppler tuning 
correction or whatever in comparison to CW operators. He was just making an 
observation that sometimes two pairs of communicating operators have their 
frequencies "collide" due to shifting Doppler and different ways of 
tracking the tuning to compensate.

The issue is that (at least on all of my radios), when you are set to 
receive in CW mode the radio does narrow its bandwidth considerably to get 
the maximum benefit of CW's narrower frequency bandwidth requirement, which 
is part of what makes it able to dig deeper into the noise level and pull 
out an intelligible signal. When I am set to receive in CW and tune in an 
SSB station (for example, during a terrestrial contest when there are lots 
of signals of both types present), I can't understand the SSB conversation, 
but if I am set to receive in SSB, the radio sets a wider bandwidth and I 
can hear a CW signal quite well, and understanding it is mainly dependent 
on how well or poorly I can copy CW at all. So the OP was pointing out that 
if the CW operator was set to receive in SSB instead of CW, he would lose 
the selectivity of the narrower bandwidth but probably would still be able 
to copy the CW signal, with the added benefit of being able to hear and 
understand a SSB QSO whose frequency happened to collide with his CW 
operating frequency. No judgment was meant to be implied on who intruded on 
whom, or why (strictly because of shifting Doppler vs. different techniques 
of Doppler tuning correction). Just that for whatever combination of 
reasons, the two QSO's happened to cross frequencies and intrude on one 
another. By listening in SSB mode the CW operator would become more aware 
of the intrusion and could better adjust his tuning to avoid it or move 
away from the colliding signal.

When I am operating in a terrestrial VHF/UHF/microwave contest, there are 
times when I can hear an operator well enough to copy him on SSB, but he is 
unable to hear me well enough to copy me on SSB. I will then switch to CW 
mode and send my information that way, counting on the superior legibility 
of CW (to an operator who understands CW) to get my information across. The 
problem that arises is that if the other operator copies my CW and realizes 
that I copied his SSB just fine, he may reply in SSB (because he doesn't 
have to change any settings on his radio, he just hits the transmit button 
and talks), and with my radio set to CW mode, I can no longer copy him 
legibly. So I have to quickly switch back to SSB mode as soon as I finish 
sending my CW to hear his SSB reply. I guess my point is simply that while 
I have not experienced the exact problem that the OP was talking about, 
since I don't normally operate CW on the satellites, I understand what he 
is talking about regarding the legibility of a CW signal in SSB receive 
mode vs. the illegibility of an SSB signal in CW receive mode.

Bottom line: if you can hear the CW coming down from the satellite well 
enough in SSB mode, it might very well be a good idea to listen in that 
fashion. It may or may not be easy to configure your radio(s) to transmit 
CW and listen to SSB, but if you can do it, and not lose the CW signal in 
the noise, it may be a good way to go.

73 de John Toscano, W0JT/5, AMSAT-NA LM#2292

On Feb 7 2014, Kevin M wrote:

>> Computer-control stations and manual-control stations are adjusting for
>> Doppler differently. I have done - and will continue to do - both. In my
>> opinion, neither is incorrect; they simply differ from each other.
 This was posted during the assemblage of my long winded reply. I think it 
gets at the same thing I was beating around the bush at. I'm glad to know 
when I am eventually able to get back on the linear birds (yagis, preamps, 
cables and rotor in the closet... conduit for burying piled up outside) I 
will be able to find someone to work without getting my rig hooked up to a 
PC. (It will be enough to get the rotor hooked up to one!) I just hope I 
can remember which dial to turn when... anyone hearing me screw the pooch, 
please send instructions promptly! X^D
>73 all,
>Kevin, N4UFO
>proud to be a full fledged Gridiot!
>Sent via AMSAT-BB at amsat.org. Opinions expressed are those of the author.
>Not an AMSAT-NA member? Join now to support the amateur satellite program!
>Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb

More information about the AMSAT-BB mailing list