Jerry has brought up an important point. We CW ops believe true QSK means hearing between dots at high speed. I thought so myself until I began looking closely at the performance of box-based rigs.
There is an easy calculation that shows why true QSK is difficult: R/T + T/R - ES = Band Sound where R/T is time it takes to mute receiver and begin transmitting T/R is time it takes to stop transmitting and fully activate receiving ES is element spacing ES is 30ms at 40wpm ES is 40ms at 30wpm ES is 60ms at 20wpm Hit the key. It takes about 10-15ms to get a waveform started. Release the key. It takes about 15-20ms minimum for T/R turnaround; most rigs take 30 or more. That means in the best possible case R/T plus T/R turnaround takes 25ms. I measured the response of my 950SDX: R/T = 13ms T/R = 19ms That means no Band Sound at 40wpm. I measure 10ms of Band Sound at 30wpm, but subjectively that isn't enough to call useful. The 950SDX is an old radio, you might say. But if you look at the ARRL reviews the numbers are equal to or better than newer rigs. So, what is the rig that can really do QSK? The K3? Maybe, but it's a DSP rig too. Send me a tape :) 73 Ed W2RF On 14 May 2008 at 11:59, Jerry Flanders wrote: > Thanks, Ed. BTW, what you describe as QSK is usually referred to as > "semi break in", or "Semi QSK" by CW ops. There is a world of difference. > > For the guys and gals out there who may not understand the > distinction, CW ops refer to QSK as the ability to actually hear > activity on the band between dits at a reasonable speed. Modern > radios that actually do true QSK can do it at 30-50 WPM. > > I look forward to purchasing another 5000a (first was sent back for > poor CW performance) if and when new software actually allows it to > perform to this standard. I am pretty sure the 5000a hardware will > allow this, but the following quote from Frank Brickel's April 26 > post in the then-current "CW QSK ability" thread eliminated my hope > that the current PowerSDR could _ever_ provide QSK: "I think this > line of discussion has run its course of usefulness. Development > effort is being focused on doing it right, not patching the current > system, which is basically unfixable in a systematic and maintainable way. " > > If I understand Frank correctly, we will not see what CW ops call QSK > in PowerSDR/Windows. Ever. > > Jerry W4UK > > At 07:34 AM 5/14/2008, Ed Russell wrote: > >Hi Jerry, > > > >It's a 5k. I don't think they apply to the 1k without a little > >coding. > > > >73 Ed W2RF > > > >On 13 May 2008 at 22:14, Jerry Flanders wrote: > > > > > What radio are you using, Ed? > > > > > > Jerry W4UK > > > > > > At 07:29 PM 5/13/2008, Ed Russell wrote: > > > >I thought I was finished with PwrSDR QSK a couple of days ago, but > > > >then I had a few more thoughts... > > > > > > > >There is a new version in the SVN branch w2rf\bin\release > > > > > > > >My favorite settings are DSP 4096/256 at 96Khz/512. What are yours? > > > > > > > >I honestly think that these latest changes take QSK about as far as > > > >it can go with the current architecture. Hopefully, someone will > > > >prove me wrong :) > > > > > > > >73 Ed W2RF > _______________________________________________ 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/
