When I experience the problem the signals are all quite close ... probably within a 30 Hz window, but not exactly the same. My hearing isn't as good as it was when I was younger (mostly high frequency loss above 10 KHz), but I can tell when signals are exactly the same and if that was the issue I'd obviously never be complaining about that. The RIT on the K3 varies in 10 Hz steps and that difference is very noticeable to me, so it would not normally be difficult for me to separate a few pileup signals within that 30 Hz window if frequency was the only factor.
As you mentioned, signals are often very close these days. People are using narrower and narrower receive filters and that puts them more precisely on frequency than in the past, and of course packet cluster spots put callers pretty close on frequency subject only to the accuracy of their rigs. As I mentioned in another post, I think these are the key conditions for the problem: a. the signals need to be close enough that the children (sum/difference mixer products) overlap in frequency with the parents b. the signals need to be keyed, which makes me suspect at least some gain non-linearity that varies with time. The addition of AFC-SOFT represented an significant improvement, but not enough. Possibly some insight into this aspect of the problem might be gained by varying the keying speeds and observing the effect. Even there is not a time non-linearity, though, having keyed signals is important. In real life, keyed signals help us mentally separate signals spaced closer in frequency than if they were not keyed. c. The signals need to be weak, which makes me convinced that there is a gain non-linearity at the low end. I can't really quantify just how weak, but I would estimate less than S-2 and it seems to get worse as the signals get weaker. I have a very low ambient noise level here and S-1 signals are typically quite readable. Strong signals do not cause the problem we are discussing here. Hope some of this helps. 73, Dave AB7E On 12/4/2011 1:31 PM, Eric Swartz WA6HHQ - Elecraft wrote: > We actually have a 'pile-up' generator we designed that sends multiple > cw signals. So far it has not reproduced the issue here. > > What is the signal spacing you are hearing this with? All -exactly- on > the same freq? Or spread out? > > 73, Eric > > _..._ > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
