Yes, absolutely. The faster the convergence, the more likely disturbances to the carrier from fading and interference from other signals, noise, and low frequency modulation will impact it.
Bob On Sun, Dec 18, 2011 at 5:06 PM, Chuck ONeal <cdon...@comcast.net> wrote: > Speeding up convergence of the SAM would be great as a selection in DSP > to set it for one's operating style on AM. Fast AM break-in QSO's are > sometimes difficult when folks are spread out hundreds if not thousands of > cycles! > > Question: Would there be the same compromise that occurs in hardware > synchronous detection, (like the Sherwood sync detector box) between > reduced convergence time and increased intermodulation distrotion products > produced by low audio frequencies? > > Thanks, > Chuck, K1KW > > > ----- Original Message ----- From: "Bob McGwier" <n...@flex-radio.com> > To: <ke...@3950.net>; <flexradio@flex-radio.biz> > Sent: Sunday, December 18, 2011 1:19 PM > > Subject: Re: [Flexradio] FlexRadio Digest, Vol 80, Issue 17 > > > >> We could speed up the convergence, making it act faster in the case of >> QSO's and not broadcaster's. >> >> It was my own bias and ignorance which led me to set it long for >> broadcast dx'ers. >> >> This could be a possible enhancement. I will toss it in the ring as an >> add on to possibly the dsp tab and if we get past that possibly one of the >> buttons, settings in the context sensitive control panel but all of this >> has to be added to the "list". >> >> Bob >> >> Sent from my Verizon Wireless 4G LTE Phone >> >> -----Original message----- >> From: ke...@3950.net >> To: flexradio@flex-radio.biz >> Sent: Sun, Dec 18, 2011 18:09:29 GMT+00:00 >> Subject: Re: [Flexradio] FlexRadio Digest, Vol 80, Issue 17 >> >> On 12/18/2011 12:33 PM, Bob McGwier wrote: >> >>> Absolutely NOTHING. That is the REASON for having the (synchronous AM) >>> >> SAM >> >>> detector. Maybe we should not have included the AM detector at all >>> >> [...] >> >> >> I am glad it is included. Some AM QSOs, especially those involving >> antique gear, have participants separated by many hundreds of Hz, and it's >> nice in such cases not to hear the 'swoop' of the regenerated carrier >> locking in when the stations are breaking back and forth quickly. When >> everyone's very close to zero beat, of course, SAM is much to be preferred. >> >> Let me thank you right now for all the great work you have done with the >> Flex hardware and software. As I said in another venue recently "...doing >> all the filtering and demodulation with perfect mathematical accuracy in >> software not only gives you tremendous dynamic range and filtering >> capability, but it makes the recovered audio almost supernaturally >> clean-sounding. Listening to a Flex into a good sound system for the first >> time is like discovering that pillows had been strapped to your speakers, >> and gravel had been stuck to your voice coil, for all these years -- and >> finally removing them." >> >> I wonder if Flex, or anyone with the ability to do the coding, ever >> considered these four enhancements that definitely interest me: >> >> 1. Costas loop detection for receiving pure DSB with suppressed carrier. >> No transmitted carrier is required for a Costas loop sync detector. It >> depends on the audio null in the Q channel for phase lock. It makes DSBSC >> practical and supposedly does better than a carrier lock sync detector when >> propagation is turbulent, even on AM. >> >> 2. Provision for transmission and phase-locked reception of SSB with a >> pilot carrier down 20 dB or so. This was used by TMC for HF SSB broadcast >> relay gear and gave SSB a clarity, with perfectly aligned harmonics, that >> current ESSB techniques cannot (though they can come close with rubidium or >> GPS frequency standards). >> >> 3. Use of "selectable sideband sync detection" using the phasing >> technique to cancel the interference in either the upper or lower sideband >> of an AM signal. (Since there is no significant desired audio in the Q >> channel, the desired audio is _not_ cancelled from either sideband.) This >> gives a 6 dB s/n advantage over the "drag the filter edge" technique of >> chopping off one sideband when it is interfered with. This would also lend >> itself to a fantastically effective kind of binaural reception on AM: LSB >> interference in the left headphone channel; USB interference in the right >> channel; desired AM audio -- and _nothing but_ desired AM audio -- in the >> center. I have experienced this and it allows the brain to process the >> signal in a way that allows _much_ better intelligibility. >> >> 4. Adding the ability to see the modulated RF (really IF) on the receiver >> scope, instead of just the demodulated audio. This tells you a lot about >> the received signal, especially on AM, and would be a very valuable tool. >> >> >> With best Yule wishes, >> >> >> Kevin, WB4AIO. >> >> ______________________________**_________________ >> FlexRadio Systems Mailing List >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/**mailman/listinfo/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/<http://www.mail-archive.com/flexradio%40flex-radio.biz/> >> Knowledge Base: http://kc.flexradio.com/ Homepage: >> http://www.flexradio.com/ >> >> ______________________________**_________________ >> FlexRadio Systems Mailing List >> FlexRadio@flex-radio.biz >> http://mail.flex-radio.biz/**mailman/listinfo/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/<http://www.mail-archive.com/flexradio%40flex-radio.biz/> >> Knowledge Base: http://kc.flexradio.com/ Homepage: >> http://www.flexradio.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://kc.flexradio.com/ Homepage: http://www.flexradio.com/
