I am a new 5000A owner, so thought I'd throw in my two cents on this thread.
Like Dave, as a CW operator I enjoy and prefer QSK CW keying and my experience with other rigs has been that their QSK operations work very well. I have read the threads below about QSK systems, and as I am not an engineer or software designer, I think I can follow somewhat what has been said. So my comments are only based on what I observe and hopefully these observations will contribute to the understanding of what is going on. First, I spent the first month of ownership pulling my hair out trying to get the rig to key CW properly at all. At any speed it drops code segments, sends segments at varying lengths, sometimes won't key dits or dahs at all, and has enough latency in the keying that I began to think I needed code sending practice in the worst way, since at first I thought I was making all the errors. Result of all that would be that at the other end the receiving ham would think I was a pretty poor CW op with all the errors. After much frustration I was ready to give up and return the radio for refund. Since I live in Austin, however, I was able to carry the radio and computer over to Flex Radio and have them work out what is going on and they are currently working out the problems. They were able to duplicate the problem in my radio and in others in their shop and find that the problem seems to be key contact bounce with some keys, not all, that causes the problem. The temporary fix at present is to use a MicroHam "paddle processor / keybounce" cable inline with the key, and set the buffers correctly to cause the radio to key properly. The definitive fix is that they are now in the process of re-writing a software fix to eliminate the problem in the radio itself. Incidently Gerald, Ken, Ed, Eric and others at Flex Radio were and are very helpful and responsive to the problem, and impressively so. Now that the radio is keying properly, I wanted to set it up for QSK. The only way I can figure out how to do that is to set the break-in delay to its minimum setting of 10 ms. At this setting, it still is not QSK. I do not hear any signal between code segments nor between characters or even words unles I pause my sending. I think I am hearing the TR relay follow the key at this 10 ms setting. However, whether I hear the other station's signal while sending is for all practical purposes just about the same whether I have it set at 10ms or 60 ms, since the receiver has to recover before I hear anything. My observation is that the receiver does not recover fast enough even at very slow CW of less than 10 wpm, much less at higher speeds. Another observation is that when the relays return to receive, whether at the 10ms setting or at even, say, 60 ms settings where the relays don't follow keying, there is a relatively quiet "pop" in the audio which may be causing the delay in receiver recovery perhaps by causing AGC response or some other issue. At any rate, I cannot get the 5000A to do QSK, which is disappointing. Anyway, that's my observations. Hope it helps. 73, Jay W5SL Austin ----- Original Message ----- From: "Jim Lux" <[EMAIL PROTECTED]> To: "Dave Blaschke" <[EMAIL PROTECTED]> Cc: <flexradio@flex-radio.biz> Sent: Thursday, April 24, 2008 12:13 AM Subject: Re: [Flexradio] CW QSK ability > Quoting Dave Blaschke <[EMAIL PROTECTED]>, on Wed 23 Apr 2008 09:33:37 PM PDT: > >> At 03:08 4/24/2008, you wrote: >> >> . .......I'm not a CW kind of guy, so I don't recall the details of >> the problem), because >>> that allows you to get a rhythm. (after all, absolute delay isn't a >>> huge deal, because there's already 10s of milliseconds delay in the RF >>> propagation to the other station). >>> >>> >>> Jim, W6RMK >>> >> >> >> Jim, I think your leading comment just summed it up. I AM a long time >> CW operator, CW contester, and CW DX chaser. I KNOW what good QSK is, >> and what it sounds like. > > Just to probe a bit from a different viewpoint, so maybe some light > will go on in a software designers head.. > > when you say "sounds like" are you referring to what you (the sender) > hears or what you hear from the other side? > > > SDR-5000 + PowerSDR do not yet deliver it. >> Latency is not the issue (well, maybe a little). Smooth and rapid >> transition from T to R is the issue and the shortcoming. > > Is it the transition from T to R.. i.e. an analog radio, even with a > T/R relay, might have some saturation or blocking, and it will come > out of saturation non-instantaneously (affected by the one or two AGC > loops typical). Not only that, but it's not the same for all > frequencies in the passband. For instance, most variable gain > amplifiers have a fair amount of change in phase shift with gain > setting, so as the gain of the receiver chain adjusts, there's a > simultaneous phase shift going on, which changes the relative phases > of the audio frequencies. > > The current SDR implementations tend to "hard switch", with any > softening probably due to downstream bandpass filtering in the > (digital) audio chain. Not to mention that the noise reduction > processing might have some unusual or idiosyncratic sounds. > > Maybe what's needed is some shaping of the receive signal during the > transition, to soften the attack? > > > If there is a >> way to overcome it, I am receptive to learning how. I'll believe it >> when I hear it in my QSK operating. >> > > From a theoretical standpoint, it should be possible, so we have the > classic problem of a behavior that hasn't been well described > analytically, so it's tough to duplicate, but you'd know it when you > heard it. > > Rob Sherwood has also commented on how the AGC of modern radios that > use a lot of DSP in the back end doesn't provide the same subjective > quality that traditional radios provide. I suspect that this is in > the same class of problems. There's some psychoacoustics here that > are difficult to characterize. > > I think that in both cases (your QSK and Rob's AGC) it's not the > linearity of the receiver/transmitter chains necessarily, but the > saturation and gain behavior. > > > One should also not discount the fact that people almost always prefer > the "sound" that they're used to: i.e. the comments about CDs sounding > harsh compared to analog LPs, even though the CD is technically a more > accurate representation. It is subjective after all, and all the > skilled CW ops I know have distinct preferences that they've arrived > at over years of use. And, which they would have a very tough time > describing with any precision, other than by examples or the same sort > of process as trying to describe subtle aspects of wines. > > A similar problem is faced by folks designing DSP guitar amps and > trying to find mathematical representations of, for instance, a > Marshall stack with 2 4 driver cabinets. > > This is one of the more interesting (and frustrating) aspects of > software radios. You know that the creation medium is so incredibly > flexible, if you could only figure out how to do it. > > Jim, W6RMK > > _______________________________________________ > FlexRadio Systems Mailing List > FlexRadio@flex-radio.biz > http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz > Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ > Knowledge Base: http://kb.flex-radio.com/ Homepage: > http://www.flex-radio.com/ > _______________________________________________ FlexRadio Systems Mailing List FlexRadio@flex-radio.biz http://mail.flex-radio.biz/mailman/listinfo/flexradio_flex-radio.biz Archives: http://www.mail-archive.com/flexradio%40flex-radio.biz/ Knowledge Base: http://kb.flex-radio.com/ Homepage: http://www.flex-radio.com/
