Update Have received the 5.9904 MHz xtals and when put into a circuit can easily be tuned to 5.99000 Mhz div by 100 = 59.900 Khz and creates the 100 Hz output. I need to figure out the correct injection setting for the SA612 mixer and in general the correct and reasonable system settings. But it looks pretty good I can easily see the phase shifts and do not need a big complicated HP 3335 generator. Regards Paul WB8TSL
On Tue, Sep 23, 2014 at 8:23 PM, Bob Camp <[email protected]> wrote: > Hi > > If the idea is to decode in software in order to “de-psk” with a switch, > then things are indeed easier. > > My *guess* is that the loops in most WWVB systems are tolerant of noise > bursts already. If not, they would have a hard time with the normal RX > environment. There are a number of ways to build a PLL and make that > happen, even with long time constants involved. They probably used one or > more of the common approaches. > > So here’s a plan: > > 10 MHz / 168 = 59.532xxxx KHz > > 168 is 8 x 7 x 3. That’s two 4 bit programable divider chips and a divide > by 8. With 10 MHz in, it does not have to be very fast. There are (cheap) > CPU chips that will do it on a PWM output. If it’s DIP packages, one > 74AC161’s should do the job for the programable sections. You would need a > NAND gate for each of the programable sections as well. The divide by two’s > can be done several ways. I’d put one at the tail end and the other two at > the front end. > > The 467 Hz note is slow enough to be pretty easy to process with a simple > CPU. > > Bob > > > > On Sep 23, 2014, at 11:54 AM, paul swed <[email protected]> wrote: > > > Wow. What 8 hours can do for responses. > > > > Great comments and appreciated. A piece of the puzzle appears to have > > gotten lost from the start of the process. > > > > This down converter system. Only detects phase change. It is not intended > > to be a phase locked oscillator system that replicates what the old > radios > > have. > > > > Its output flips a signal path to invert or not invert the incoming wwvb > > signal that feeds the old radios. > > There is no need for an instantaneous response in the flip circuit. .3-.5 > > seconds seems fine for the old radios. Want to see if I can get down to > > .1-.2 sec. > > > > Pretty sure from what I have seen so far there is no need to lock the LO > > nor must it be some precise offset of 100 Hz or anything else. > > In watching this on a scope with a stable local 100 Hz reference not > locked > > to anything. The phase changes were obvious and useful. > > > > One of the comments in the thread was that you could use a good local > > reference and adjust for the LO drift. I do believe thats the case. I am > > pretty good at dividing in decades. ;-) But getting ahead of the other > > criteria. Simple as possible. > > OK time to fix the HP3335a that failed. Lost my LO for the moment. > > > > Regards > > Paul. > > WB8TSL > > > > > > > > On Tue, Sep 23, 2014 at 7:37 AM, Bob Camp <[email protected]> wrote: > > > >> Hi > >> > >> Actually stability isn’t the main problem with the progamables. The > issue > >> is usually phase noise ad spurs. Often they use odd multi modulo divides > >> rather than a PLL. That gives them a low cost chip, but the output > spectrum > >> is pretty poor. Figuring out if you have a “bad one” or not is tough > from > >> many data sheets. It’s rare that cheap XO’s come with phase noise and > spur > >> plots. > >> > >> Bob > >> > >> On Sep 23, 2014, at 12:04 AM, Hal Murray <[email protected]> > wrote: > >> > >>> > >>> [email protected] said: > >>>> Did try lots of frequencies and divider math to come up with a simple > LO > >>>> scheme for 61 or 59 KHz. Messy. > >>> > >>> There are companies that will make a crystal or oscillator at any > >> frequency > >>> you want at a not silly price. Delivery is not overnight. > >>> > >>> Beware: There are several companies selling instant delivery of > >> oscillators > >>> running at any frequency you want. They are using a programmable PLL > so > >> you > >>> won't get the stability you expect from a crystal. > >>> > >>> -- > >>> These are my opinions. I hate spam. > >>> > >>> > >>> > >>> _______________________________________________ > >>> 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. > _______________________________________________ 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.
