Actually I built analog dividers and it doesn't fix the issue at all as itsthe relationship from local to the reference. A slip is a slip and the chart recorders track them. But we stray from the question on msk. Regards
On Sun, Aug 17, 2014 at 5:27 PM, Alexander Pummer <[email protected]> wrote: > > if you use analog way to divide the 120kHz that will prevent an > incidentally flip of the phase > 73 > Alex > > On 8/17/2014 2:21 PM, paul swed wrote: > >> Robert >> Yes indeed the lm3900 is a great part. The last opamp is a 100hz BPF. >> The RCs perform a phase shift and I will tend to believe that at the >> bandpass filter it is a full wave rectified signal. Only a guess. >> Here is the part I don't get. How does that remove the msk? Mask is FSK >> and >> you can see the shifts in spectrumlab. >> Rick per your comment yes the doubling of the carrier does remove the BPSK >> that was the earliest approach studied applied and then rejected as when >> teh carrier was returned to 60KHz any method used left an ambiguity that >> in >> fact could flip randomly due to noise. Not pretty on the strip chart. >> But back to this its msk. I am missing the secret math or something. >> Do I believe this will work if I build it. Absolutely and a 24 Khz rcvr >> ain't all that bad to build. >> Regards >> Paul >> WB8TSL/1 >> >> >> On Sun, Aug 17, 2014 at 4:35 PM, Robert LaJeunesse <[email protected]> >> wrote: >> >> It's simple, but not obvious. The LM3900 is a Norton amplifier, and while >>> it has differential inputs they are current driven. (Most older op amps >>> are >>> voltage driven.) The LM3900 is powered from 10V, so I think of that as >>> just >>> above the maximimum output voltage. Both the upper amplifier and the >>> second >>> lower amplifier have 1M feedback resistors, and + inputs fed 10V by 1M >>> bias >>> resistors. That would bias the output at near the supply rail, turning >>> these stages into something like half-wave rectifiers. Since the first >>> lower stage has a 2M bias resistor it idles at about half supply, and >>> behaves as a simple inverter. If my analysis is correct (and I worked at >>> National when the LM3900 came out, a friend did apps for this odd new >>> part) >>> then the combining of the two outputs produces a negative going full wave >>> rectification of the signal. The fourth LM3900 stage looks like an >>> inverting bandpass filter, but I'd have to dig out some reference books >>> to >>> determine its behavior in more detail. As for the 100-200 switch I'm >>> confused, why would the bandpass frequency be lowered for the higher >>> modulation rate? >>> >>> Bob LaJeunesse >>> >>> >>> Sent: Saturday, August 16, 2014 at 2:56 PM >>> From: "Kenneth G. Gordon" <[email protected]> >>> To: "paul swed" <[email protected]> >>> Cc: [email protected] >>> Subject: Re: [time-nuts] Cutler NAA on 24.0kHz.... >>> On 16 Aug 2014 at 13:35, paul swed wrote: >>> >>> Kenneth on the opamps that is correct. >>>> But I put little U's to indicate phase. They actually represent the top >>>> >>> half of >>> >>>> the input cycle. >>>> >>> Yes, I saw those, but unless I am mistaken, you didn't add a "U" after >>> the >>> second opamp, which would have returned the phase to the input's. >>> >>> In the top path it inverts once. >>>> >>> I see twice: once through the first op amp and again through the second >>> one. >>> The second one then outputs to the IF. >>> >>> Anyway, to me, it is a very interesting and simple circuit. >>> >>> I LIKE "simple". I am a great believer in the KISS principle. >>> >>> Ken W7EKB >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >>> >>> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to https://www.febo.com/cgi-bin/ >> mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
