Some of the previous conversations have been about not using square waves, not using dividers, which on a QSD radio is not correct, they function better with a square wave.
You have no been here long but I have brought that out in the past that a diode mixer benefits from very hard drive, essentially turning the diodes on and off as quickly as possible to minimize distortion. The QSD detector uses switches that are either on or off, we try to minimize the in-between transition period, except compared to diodes they do not require the excessive power that a hard driven DBM requires. At 08:11 AM 4/10/2006, you wrote: >Double balanced diode ring mixers love a square wave LO. Transition >through the diode knee is faster making less distortion. fc > >KD5NWA <[EMAIL PROTECTED]> wrote: You are thinking in terms of analog >mixers, Digital QSD mixers are a >whole other world. QSD mixers have to have a square wave clock, and >function way better than a analog mixer if given a low phase noise >"digital" clock. If they are given an analog sine wave for a clock, >you would have to turn that back into a digital signal which can >introduce jitter, so when possible it's best to keep the clock >digital as much as possible. In a well designed QSD system a clock >divider will improve the phase noise figures not make it worse. > > >Food for thought. > > >At 04:03 PM 4/8/2006, you wrote: > >An addendum to my info: > > > > From this paper, I gave You the internet-adress, You can clearly see > >and take some consequences for receiver constructing. > > > >1.1. If one has an oscillator with phase-noise, You not only mix the > >oscillator not only with the incoming frequency, but also with the > >phase-noise of the oscilltor. It is something like a synchronous > >mixing with a lot of frequencies and a lot of mixing products. The > >less the bandwidth of the phase-noise the better for quality of mixing > >result. > > > >1.2. At mixing You mix a strong signal (the oscillator-signal) with a > >very little one, the incoming signal. Partly You have to filter the > >product. > > > >1.3. You should avoid all solutions with phase noise inclusive > >solutions with ic-dividers. > > > >1.4. The better the signal of the mixing process, the better the > >result. Because of that, to gain ultimate quality, You should forget a > >lot of solutions and change to a dds-circuit with a very high > >working-frequency. All other solutions have a lack of quality, to > >reach ultimate success. > > > >1.5. The alternative could be a quartz-osciallator, but one is not > >able to change the frequency in a wider range. > > > >1.6. My "feeling is" even concepts with I,Q-solutions could be better, > >if a fast dds-circuit is used. > > > >1.7. Having a rectangular signal meens a lot of filtering.... and a > >lot of useless noise. > > > >One can see, that using a fast dds-circuit is at the moment even for > >traditional receveiver concepts in let me say AM, SSB and other > >modulation-types is "state of the art" and You miss-use time and > >effort for other versions. > > > >I will look for answers coming. In the meantime, I will work with my DRT1. > > > >An incoming signal is always not a digital one even, if its > >constructed digital by modulation as DRM. > > > >Wolfgang > > > >--- In [email protected], "Wolfgang Hartmann" > ><[EMAIL PROTECTED]> wrote: > > > > > > Hallo to all, especially to Dan. > > > > > > Here is an email adress, wher You can find some informations in german > > > language. > > > > > > http://www.elexs.de/clock3.htm > > > > > > You see the phase-noise and the noise carpet of several designs. > > > > > > They have a lot more on DRM, Elektor-receiver. > > > > > > Wolfgang > > > > > > > > > > > > > > > > > > > > > > > > >Yahoo! Groups Links > > > > > > > > > > >Cecil Bayona >KD5NWA >www.qrpradio.com > >"Windows the worlds most successful software virus" > > > > SPONSORED LINKS > Ham radio Craft hobby Hobby and craft supply > >--------------------------------- > YAHOO! GROUPS LINKS > > > Visit your group "soft_radio" on the web. > > To unsubscribe from this group, send an email to: > [EMAIL PROTECTED] > > Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service. > > >--------------------------------- > > > > > >[Non-text portions of this message have been removed] > > > > > > > >Yahoo! Groups Links > > > > Cecil Bayona KD5NWA www.qrpradio.com I fail to see why doing the same thing over and over and getting the same results every time is insanity: I've almost proved it isn't; only a few more tests now and I'm sure results will differ this time ... [Non-text portions of this message have been removed] Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
