Re: [time-nuts] WWVB d-psk-r down conversion method
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 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 = 59.532 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 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 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 > wrote: > >> > >>> > >>> paulsw...@gmail.com 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 -- time-nuts@febo.com > >>> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >>> and follow the instructions there. > >> > >> ___ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow
Re: [time-nuts] WWVB d-psk-r down conversion method...
On 9/23/14, 10:11 AM, Alexander Pummer wrote: there is an interesting side effect with that phase modulation: in case the crystal filter is "narrow enough" --to use for the old AM format-- the phase change creates an additional AM modulation, if you take in consideration that effect by the decoding the modulation, you could recover the time information "despite" of the presence of the PSK. Question: as fare as I am informed there is no chip/system available to correctly decode the new signal form, what was the purpose of the whole modulation format change? The old AM format was happy with cca 200Hz bandwidth to recover the time information, which was utilized in many professional receivers, which used a crystal filter for 60kHz, for the PSK format the required bandwidth is at least five times wider, so crystal filter would be problematic and much more costly, the higher required bandwidth brings also more noise actually where is the advantage of the new modulation scheme? These days I suspect nobody would use a crystal filter. You'd digitize at some useful rate and implement your filter in software. The real question would be how many bits do you need in the ADC and how fast do you run it. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
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 = 59.532 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 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 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 wrote: >> >>> >>> paulsw...@gmail.com 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 -- time-nuts@febo.com >>> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
According to the NIST documentation there were a couple of motivations... 1. BPSK is easier to receive in high noise environments so they say. 2. The new format supports sending additional information in addition to the time of day. The other messages are interleaved into each minute and they take a long time to receive. Mike Harpe On Tue, Sep 23, 2014 at 1:11 PM, Alexander Pummer wrote: > there is an interesting side effect with that phase modulation: in case > the crystal filter is "narrow enough" --to use for the old AM format-- the > phase change creates an additional AM modulation, if you take in > consideration that effect by the decoding the modulation, you could recover > the time information "despite" of the presence of the PSK. > Question: as fare as I am informed there is no chip/system available to > correctly decode the new signal form, what was the purpose of the whole > modulation format change? > The old AM format was happy with cca 200Hz bandwidth to recover the time > information, which was utilized in many professional receivers, which used > a crystal filter for 60kHz, for the PSK format the required bandwidth is at > least five times wider, so crystal filter would be problematic and much > more costly, the higher required bandwidth brings also more noise > actually where is the advantage of the new modulation scheme? > 73 > Alex > > On 9/23/2014 9:16 AM, Burt I. Weiner wrote: > >> Charles, >> >> If I recall correctly, the original point of the d-psk-r was to cause the >> clocks to again read the correct time, not maintain their use as a >> frequency standard. I have a Symmetricom 8170 that I used to use only as a >> clock to tell the time of day. Since WWVB's addition of the PSK coding, >> it's only good to watch the pretty blinken lights. >> >> Burt, K6OQK >> >> >> >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
OK this is shifting to an Xtendwave discussion and the magical chips. Been trying to get some for a long time. They had some bare dies earlier this year. But thats a bit small for me to work on. I don't really have any intent to use the Xtendwave chip for this project. Maybe one day. I can see how it could be useful. Just this project has taken on a life of its own and I want to wrap it up and get my old radios running again. Silly as that may be considering good ole GPS and the Jackson Labs GPDSOs. Regards Paul WB8TSL On Tue, Sep 23, 2014 at 5:55 PM, Alexander Pummer wrote: > > > Hi Brooke, > I hope that you are right with that chip, and despite the name change of > the company -- now Xtendwave -- and recovering they will deliver something > some times. I can see that with correlation and averaging schemes the > signal to noise ratio of data, perhaps constant frequency could be > improved, but I would be very interested to see of the mathematical model > of improving the signal to noise ratio of timing. > Regards > Alex > > > On 9/23/2014 1:08 PM, Brooke Clarke wrote: > >> Hi Alex: >> >> Sometime in the future there will be chips that will decode the new >> signals (note the "s" on the end of that last word). There are a number of >> frame times the longest one of which takes 17 minutes and is transmitted >> only once per day. This format offers 23 dB modulation gain compared to >> the 1 minute time frame transmission that the current clocks use. There >> are a total of 5 different modulation formats that will be transmitted over >> different time frames. In the end everyone should have a clock with more >> frequent updates (on the West coast I might need to wait overnight for a >> clock to sync after a battery change) and more accuracy. >> http://prc68.com/I/Loop.shtml#PhaseMod >> >> Have Fun, >> >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
Hi Alex: There's not a requirement that Xtgendwave make the chip. The modulation format is published by NIST and anyone can make a receiver. I would hope there's some Time Nuts that would be interested in doing this rather than trying to remove the phase modulation. It's my understanding that by using the fast (100 bits/second - 10 second frame time) signal you can get more precision than possible using the old WWVB signal. Note: The Xtgendwave patents spend a lot of time and effort compensating for the poor quality of the watch crystal. If it's in spec but not exactly on frequency, then decoding a signal that's 17 minutes long is a big problem. For time nuts use where we have a precision LO all that goes away and instead we could be looking at how to get more precision and at the same time more updates. Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Alexander Pummer wrote: Hi Brooke, I hope that you are right with that chip, and despite the name change of the company -- now Xtendwave -- and recovering they will deliver something some times. I can see that with correlation and averaging schemes the signal to noise ratio of data, perhaps constant frequency could be improved, but I would be very interested to see of the mathematical model of improving the signal to noise ratio of timing. Regards Alex On 9/23/2014 1:08 PM, Brooke Clarke wrote: Hi Alex: Sometime in the future there will be chips that will decode the new signals (note the "s" on the end of that last word). There are a number of frame times the longest one of which takes 17 minutes and is transmitted only once per day. This format offers 23 dB modulation gain compared to the 1 minute time frame transmission that the current clocks use. There are a total of 5 different modulation formats that will be transmitted over different time frames. In the end everyone should have a clock with more frequent updates (on the West coast I might need to wait overnight for a clock to sync after a battery change) and more accuracy. http://prc68.com/I/Loop.shtml#PhaseMod Have Fun, ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
Hi Brooke, I hope that you are right with that chip, and despite the name change of the company -- now Xtendwave -- and recovering they will deliver something some times. I can see that with correlation and averaging schemes the signal to noise ratio of data, perhaps constant frequency could be improved, but I would be very interested to see of the mathematical model of improving the signal to noise ratio of timing. Regards Alex On 9/23/2014 1:08 PM, Brooke Clarke wrote: Hi Alex: Sometime in the future there will be chips that will decode the new signals (note the "s" on the end of that last word). There are a number of frame times the longest one of which takes 17 minutes and is transmitted only once per day. This format offers 23 dB modulation gain compared to the 1 minute time frame transmission that the current clocks use. There are a total of 5 different modulation formats that will be transmitted over different time frames. In the end everyone should have a clock with more frequent updates (on the West coast I might need to wait overnight for a clock to sync after a battery change) and more accuracy. http://prc68.com/I/Loop.shtml#PhaseMod Have Fun, ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
Hi Alex: Sometime in the future there will be chips that will decode the new signals (note the "s" on the end of that last word). There are a number of frame times the longest one of which takes 17 minutes and is transmitted only once per day. This format offers 23 dB modulation gain compared to the 1 minute time frame transmission that the current clocks use. There are a total of 5 different modulation formats that will be transmitted over different time frames. In the end everyone should have a clock with more frequent updates (on the West coast I might need to wait overnight for a clock to sync after a battery change) and more accuracy. http://prc68.com/I/Loop.shtml#PhaseMod Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html http://www.prc68.com/I/DietNutrition.html Alexander Pummer wrote: there is an interesting side effect with that phase modulation: in case the crystal filter is "narrow enough" --to use for the old AM format-- the phase change creates an additional AM modulation, if you take in consideration that effect by the decoding the modulation, you could recover the time information "despite" of the presence of the PSK. Question: as fare as I am informed there is no chip/system available to correctly decode the new signal form, what was the purpose of the whole modulation format change? The old AM format was happy with cca 200Hz bandwidth to recover the time information, which was utilized in many professional receivers, which used a crystal filter for 60kHz, for the PSK format the required bandwidth is at least five times wider, so crystal filter would be problematic and much more costly, the higher required bandwidth brings also more noise actually where is the advantage of the new modulation scheme? 73 Alex On 9/23/2014 9:16 AM, Burt I. Weiner wrote: Charles, If I recall correctly, the original point of the d-psk-r was to cause the clocks to again read the correct time, not maintain their use as a frequency standard. I have a Symmetricom 8170 that I used to use only as a clock to tell the time of day. Since WWVB's addition of the PSK coding, it's only good to watch the pretty blinken lights. Burt, K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
Paul wrote: This down converter system. Only detects phase change. * * * Its output flips a signal path to invert or not invert the incoming wwvb signal that feeds the old radios. Ahhh, you are just building a phase detector to trigger an inverter. That's where I hadn't followed you. As you note, the potential drawback of this approach is the length of time it takes to switch the inverter in or out after each phase shift: 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. Depending on the stability of the disciplined oscillator (inside the old radio), you may need to do better than that. If the old radio uses an OCXO and a very slow discipline loop, 100mS may be good enough. But if it uses a TCXO or a naked crystal and the loop has to be fast enough to help stability in the 1S region, you may need to switch faster to avoid the PLL partially tracking the short burst of anti-phase. Since analog PLLs are hard to make with long time constants (so the loops in the old radios are probably not as slow as you'd like), I suspect you'll see an improvement with faster switching. Of course, you can run the 60kHz carrier through an all-pass filter before the phase switch to delay it if you need to, but you need to watch dispersion vs. temperature if you do that. 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. For that application, correct. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
Alex wrote: The old AM format was happy with cca 200Hz bandwidth to recover the time information, which was utilized in many professional receivers, which used a crystal filter for 60kHz, for the PSK format the required bandwidth is at least five times wider, so crystal filter would be problematic and much more costly, the higher required bandwidth brings also more noise actually where is the advantage of the new modulation scheme? The changes were made to make today's consumer "atomic clocks" more robust, not to help any kind of "professional" receivers (whether time or frequency). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
it could be that the intention was good , but there is no reliable "atomic clock" and the company which promised the chip still no t delivered any usable, as I learned from two of my clients which are in the were business of making "atomic clocks" 73 Alex On 9/23/2014 11:06 AM, Charles Steinmetz wrote: Alex wrote: The old AM format was happy with cca 200Hz bandwidth to recover the time information, which was utilized in many professional receivers, which used a crystal filter for 60kHz, for the PSK format the required bandwidth is at least five times wider, so crystal filter would be problematic and much more costly, the higher required bandwidth brings also more noise actually where is the advantage of the new modulation scheme? The changes were made to make today's consumer "atomic clocks" more robust, not to help any kind of "professional" receivers (whether time or frequency). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
OK Goal of teh d-psk-r is to correct the phase shift so any of the radios will work without modification. Be it time or frequency. However for those with just a need for time like the spectracoms, the remodulator circuit does that job very well and has been in use for over 1.5 years. Darn simple. It was updated about march of this year with a discussion on various wwvb atomic clock modules that will work. The d-psk-r will correct the phase issue and allow the Fluke 207 tracor 599, HP 117 etc to work a byproduct of that method is that it allows the time units to also work. I have released some analog d-psk-r approaches and even a direct hack into the spectracom phase receivers. (I hate internal hacks. But if you only had one receiver it makes a lot of sense.) Have shared all of that over time with Time-Nuts. Some folks closer to wwvb then me have used the frequency doubling method. Lucky them all manners of that method fail pretty badly over time on the East Coast. Alex is right as I learned the really narrow Xtals actually loose the signal for numbers of cycles at the phase flip since they are 60 Khz +- a few Hertz. It gaps actually. Burt Make up a remodulator and you are back in business with the 8170. Its great to see those panalplex displays correctly running again. Regards Paul. WB8TSL On Tue, Sep 23, 2014 at 1:11 PM, Alexander Pummer wrote: > there is an interesting side effect with that phase modulation: in case > the crystal filter is "narrow enough" --to use for the old AM format-- the > phase change creates an additional AM modulation, if you take in > consideration that effect by the decoding the modulation, you could recover > the time information "despite" of the presence of the PSK. > Question: as fare as I am informed there is no chip/system available to > correctly decode the new signal form, what was the purpose of the whole > modulation format change? > The old AM format was happy with cca 200Hz bandwidth to recover the time > information, which was utilized in many professional receivers, which used > a crystal filter for 60kHz, for the PSK format the required bandwidth is at > least five times wider, so crystal filter would be problematic and much > more costly, the higher required bandwidth brings also more noise > actually where is the advantage of the new modulation scheme? > 73 > Alex > > On 9/23/2014 9:16 AM, Burt I. Weiner wrote: > >> Charles, >> >> If I recall correctly, the original point of the d-psk-r was to cause the >> clocks to again read the correct time, not maintain their use as a >> frequency standard. I have a Symmetricom 8170 that I used to use only as a >> clock to tell the time of day. Since WWVB's addition of the PSK coding, >> it's only good to watch the pretty blinken lights. >> >> Burt, K6OQK >> >> >> >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
there is an interesting side effect with that phase modulation: in case the crystal filter is "narrow enough" --to use for the old AM format-- the phase change creates an additional AM modulation, if you take in consideration that effect by the decoding the modulation, you could recover the time information "despite" of the presence of the PSK. Question: as fare as I am informed there is no chip/system available to correctly decode the new signal form, what was the purpose of the whole modulation format change? The old AM format was happy with cca 200Hz bandwidth to recover the time information, which was utilized in many professional receivers, which used a crystal filter for 60kHz, for the PSK format the required bandwidth is at least five times wider, so crystal filter would be problematic and much more costly, the higher required bandwidth brings also more noise actually where is the advantage of the new modulation scheme? 73 Alex On 9/23/2014 9:16 AM, Burt I. Weiner wrote: Charles, If I recall correctly, the original point of the d-psk-r was to cause the clocks to again read the correct time, not maintain their use as a frequency standard. I have a Symmetricom 8170 that I used to use only as a clock to tell the time of day. Since WWVB's addition of the PSK coding, it's only good to watch the pretty blinken lights. Burt, K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method...
The whole point of the d-psk-r is to remove the random phase shifts caused by the new psk modulation scheme and create a signal that the phase locking receivers could use for frequency standard purposes. -Chuck Harris Burt I. Weiner wrote: Charles, If I recall correctly, the original point of the d-psk-r was to cause the clocks to again read the correct time, not maintain their use as a frequency standard. I have a Symmetricom 8170 that I used to use only as a clock to tell the time of day. Since WWVB's addition of the PSK coding, it's only good to watch the pretty blinken lights. Burt, K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] WWVB d-psk-r down conversion method...
Charles, If I recall correctly, the original point of the d-psk-r was to cause the clocks to again read the correct time, not maintain their use as a frequency standard. I have a Symmetricom 8170 that I used to use only as a clock to tell the time of day. Since WWVB's addition of the PSK coding, it's only good to watch the pretty blinken lights. Burt, K6OQK From: Charles Steinmetz Subject: Re: [time-nuts] WWVB d-psk-r down conversion method Paul wrote: >The goal is to remove the psk so the old phase tracking receivers can work. Yes, I understand that. But you want them to work like they originally did, with the disciplined oscillator in the phase tracking receiver phase-locked to the WWVB carrier (or else you may as well just ignore WWVB entirely and generate your own 60kHz carrier). Once you add an LO/BFO, the signal you end up with is NOT locked to the WWVB carrier -- it is locked to some frequency that is determined by both WWVB and the LO/BFO (whch means, it is only as accurate and stable as the LO/BFO). So the whole benefit of receiving WWVB in the first place is lost. [In the special case of a TRF receiver, with no LO/BFO, the signal will remain locked to WWVB.] >Whats good about this as I just typed to Bob the signal is slow and easy to >work on. > From what I have seen the phase tracking receivers have a fairly long time >constant. So the fact that the phase detect and flip occurs 1/10 of a >second later should not have any effect on these radios. It's got nothing to do with how fast or slow the signal you end up with is, or how easy it is to work on. If the frequency and phase of that signal are not uniquely dependent on the WWVB carrier frequency and phase, then the oscillator you discipline will not be disciplined to the precision of WWVB -- it will be disciplined to no better than your own LO/BFO. [Also note that the phase flips at one second intervals no matter what frequency you translate it to -- that is not a unique feature of the 100Hz recovered carrier.] As Alex pointed out, you could in theory use a LO/BFO that is, itself, derived from the disciplined oscillator, and in which the loops will not lock unless the IF and LO have the correct values. But, as Alex also points out, such a scheme will have about the same complexity as a Costas loop. The Tracor itself uses a crude variant of this strategy, in which the LO is guided "huff-n-puff" style in steps of 1/100 of a cycle, some steps above and some below the correct frequency. But when you are starting with a signal that is already orders of magnitude less stable than a GPS signal, it is just rude to throw away even more stability with that sort of approximation. Furthermore, all of this would need to happen outside of the old-school phase tracking receiver, so you'd end up building your own external phase tracking receiver just to run the old phase tracking receiver. Best regards, Charles Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net www.biwa.cc K6OQK ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
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 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 wrote: > > > > > paulsw...@gmail.com 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 -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
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 wrote: > > paulsw...@gmail.com 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 -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
Paul wrote: The goal is to remove the psk so the old phase tracking receivers can work. Yes, I understand that. But you want them to work like they originally did, with the disciplined oscillator in the phase tracking receiver phase-locked to the WWVB carrier (or else you may as well just ignore WWVB entirely and generate your own 60kHz carrier). Once you add an LO/BFO, the signal you end up with is NOT locked to the WWVB carrier -- it is locked to some frequency that is determined by both WWVB and the LO/BFO (whch means, it is only as accurate and stable as the LO/BFO). So the whole benefit of receiving WWVB in the first place is lost. [In the special case of a TRF receiver, with no LO/BFO, the signal will remain locked to WWVB.] Whats good about this as I just typed to Bob the signal is slow and easy to work on. From what I have seen the phase tracking receivers have a fairly long time constant. So the fact that the phase detect and flip occurs 1/10 of a second later should not have any effect on these radios. It's got nothing to do with how fast or slow the signal you end up with is, or how easy it is to work on. If the frequency and phase of that signal are not uniquely dependent on the WWVB carrier frequency and phase, then the oscillator you discipline will not be disciplined to the precision of WWVB -- it will be disciplined to no better than your own LO/BFO. [Also note that the phase flips at one second intervals no matter what frequency you translate it to -- that is not a unique feature of the 100Hz recovered carrier.] As Alex pointed out, you could in theory use a LO/BFO that is, itself, derived from the disciplined oscillator, and in which the loops will not lock unless the IF and LO have the correct values. But, as Alex also points out, such a scheme will have about the same complexity as a Costas loop. The Tracor itself uses a crude variant of this strategy, in which the LO is guided "huff-n-puff" style in steps of 1/100 of a cycle, some steps above and some below the correct frequency. But when you are starting with a signal that is already orders of magnitude less stable than a GPS signal, it is just rude to throw away even more stability with that sort of approximation. Furthermore, all of this would need to happen outside of the old-school phase tracking receiver, so you'd end up building your own external phase tracking receiver just to run the old phase tracking receiver. Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
paulsw...@gmail.com 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 -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
yes Charles you are right, but you could use a trick as you derive the LO from the high stabile oscillator which is locked to the down-converted carrier the IF, and the loop is locked only if the IF and the LO frequencies having the correct value, but that loop change the feedback polarity depend on what site is the LO of the desired value, it needs an acquisition help and will it be not much less complicated than a Costas loop 73 Alex On 9/22/2014 4:56 PM, Charles Steinmetz wrote: Paul wrote: One of the methods suggested for working with the wwvb psk is down converting to a lower frequency. When experimenting with NAA I had built a 24 Khz receiver that down converted that signal to a 100 Hz base band. It was a minor effort to shift it to 60 Khz by changing the LO. * * * for 100 Hz the LO must be at 60.1 or 59.9 Khz. Or synthesize it etc. * * * Not sure there is a real need to lock the LO at all. I'm not sure I understand how this helps. I thought the point of removing the PSK was to reconstitute a version of the original unmodulated carrier, so it can be used to discipline an oscillator at some convenient frequency (the PSK needs to be removed because it upsets the PLL phase detector). That works (in theory) with a TRF receiver, because the received carrier IS the tx carrier that is locked to a standard at the transmitter (modified by the propagation delay and delay variation, and then by doubling/squaring). But once you convert the received frequency by using a LO (or BFO, whichever you want to call it), the recovered carrier frequency is dependent on BOTH the tx frequency AND the LO/BFO frequency. You have lost the link to the tx frequency standard. Am I misunderstanding the goal of the exercise? Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
Hi Ok, well then, here’s a thought - 10 MHz divided by 164 is 60.975. Hz. 165, 166, 167 and 168 are also “close enough” to give you a reasonable tone out of the converter. That assumes you are after a 10 MHz standard at the end of all this. The fact that the tone frequency is something really weird isn’t as big a deal once you convert it to digital bits. More or less - make the LO something easy, lock it up, and do the rest with software. Bob On Sep 22, 2014, at 7:59 PM, paul swed wrote: > Bob > You missed nothing really. 100 Hz because thats what the NAA radio used > with the tracor doubler. So when I moved it to wwvb that was the baseband > signal. > Now that said I liked the 1 second phase flips at 100 Hz delay. Dog slow > and perfectly OK to resolve the phase flip and I can use my favored uproc. > > Whats funny is that any crystal close to anything existed. > Digikey says they have a 6.1Mhz xtal but when selected goes to 6.144 MHz. > I was amazed that both mouser and digikey had the 5.9904 xtals and both > stocked a variety of cases. Must be some story about whatever that > frequency is. > Did try lots of frequencies and divider math to come up with a simple LO > scheme for 61 or 59 KHz. Messy. > Regards > Paul > WB8TSL > > > On Mon, Sep 22, 2014 at 7:42 PM, Bob Camp wrote: > >> Hi >> >> Is it really that much harder to process a 1 KHz note out of a direct >> conversion receiver than it is to process a 100 Hz note? >> >> Put another way - you already have a crystal filter in the front end of >> the “radio” right? It will do a better job knocking down an “adjacent >> channel” 2 KHz away than one 200 Hz away. Even without the crystal filter, >> the only likely thing you are trying to reject is noise. Effectively the >> “no filter” approach degrades your signal to noise by 3 to 6 db depending >> on the type of noise you are dealing with. >> >> I’m asking because I may have missed something that makes 100 Hz “magic” …. >> >> Bob >> >> On Sep 22, 2014, at 6:15 PM, paul swed wrote: >> >>> One of the methods suggested for working with the wwvb psk is down >>> converting to a lower frequency. When experimenting with NAA I had built >> a >>> 24 Khz receiver that down converted that signal to a 100 Hz base band. >>> It was a minor effort to shift it to 60 Khz by changing the LO. I liked >>> what I saw. Essentially a simple direct conversion receiver with about 42 >>> DB of gain. >>> The PSK flips at every 1 second depending on the data and is 1/100Hz >>> delayed from the wwvb flip due to the down conversion process. This makes >>> the further processing very reasonable in just about any micro. >>> But the LO is a mess. Not bad if you have an HP3335a as I did till last >>> week. (Another project to repair) for 100 Hz the LO must be at 60.1 or >> 59.9 >>> Khz. Or synthesize it etc. Starting to get seriously ugly. >>> Or jump to a 1 Khz with 59 or 61 KHz. But I hated the idea of mixers and >>> filters. >>> >>> Any Time-Nuts seen those crystals or oscillators around lately? Seriously >>> missing from the general haunts. >>> >>> But turns out and heavens knows why there are plentiful 5.9904 MHz xtals >>> around. I ordered 5 from Mouser $ .46 ea. >>> 5.9904/100 = 59.904 as a LO and suspect it can be moved to the correct >>> frequency not that it has to be. >>> Not sure there is a real need to lock the LO at all. >>> So an exciting bit of news. >>> Regards >>> Paul >>> WB8TSL >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com >>> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
Charles The goal is to remove the psk so the old phase tracking receivers can work. Whats good about this as I just typed to Bob the signal is slow and easy to work on. >From what I have seen the phase tracking receivers have a fairly long time constant. So the fact that the phase detect and flip occurs 1/10 of a second later should not have any effect on these radios. Regards Paul WB8TSL On Mon, Sep 22, 2014 at 7:56 PM, Charles Steinmetz wrote: > Paul wrote: > > One of the methods suggested for working with the wwvb psk is down >> converting to a lower frequency. When experimenting with NAA I had built a >> 24 Khz receiver that down converted that signal to a 100 Hz base band. >> It was a minor effort to shift it to 60 Khz by changing the LO. >>* * * >> for 100 Hz the LO must be at 60.1 or 59.9 Khz. Or synthesize it etc. >>* * * >> Not sure there is a real need to lock the LO at all. >> > > I'm not sure I understand how this helps. > > I thought the point of removing the PSK was to reconstitute a version of > the original unmodulated carrier, so it can be used to discipline an > oscillator at some convenient frequency (the PSK needs to be removed > because it upsets the PLL phase detector). That works (in theory) with a > TRF receiver, because the received carrier IS the tx carrier that is locked > to a standard at the transmitter (modified by the propagation delay and > delay variation, and then by doubling/squaring). But once you convert the > received frequency by using a LO (or BFO, whichever you want to call it), > the recovered carrier frequency is dependent on BOTH the tx frequency AND > the LO/BFO frequency. You have lost the link to the tx frequency standard. > > Am I misunderstanding the goal of the exercise? > > Best regards, > > Charles > > > > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
Paul wrote: One of the methods suggested for working with the wwvb psk is down converting to a lower frequency. When experimenting with NAA I had built a 24 Khz receiver that down converted that signal to a 100 Hz base band. It was a minor effort to shift it to 60 Khz by changing the LO. * * * for 100 Hz the LO must be at 60.1 or 59.9 Khz. Or synthesize it etc. * * * Not sure there is a real need to lock the LO at all. I'm not sure I understand how this helps. I thought the point of removing the PSK was to reconstitute a version of the original unmodulated carrier, so it can be used to discipline an oscillator at some convenient frequency (the PSK needs to be removed because it upsets the PLL phase detector). That works (in theory) with a TRF receiver, because the received carrier IS the tx carrier that is locked to a standard at the transmitter (modified by the propagation delay and delay variation, and then by doubling/squaring). But once you convert the received frequency by using a LO (or BFO, whichever you want to call it), the recovered carrier frequency is dependent on BOTH the tx frequency AND the LO/BFO frequency. You have lost the link to the tx frequency standard. Am I misunderstanding the goal of the exercise? Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
Bob You missed nothing really. 100 Hz because thats what the NAA radio used with the tracor doubler. So when I moved it to wwvb that was the baseband signal. Now that said I liked the 1 second phase flips at 100 Hz delay. Dog slow and perfectly OK to resolve the phase flip and I can use my favored uproc. Whats funny is that any crystal close to anything existed. Digikey says they have a 6.1Mhz xtal but when selected goes to 6.144 MHz. I was amazed that both mouser and digikey had the 5.9904 xtals and both stocked a variety of cases. Must be some story about whatever that frequency is. Did try lots of frequencies and divider math to come up with a simple LO scheme for 61 or 59 KHz. Messy. Regards Paul WB8TSL On Mon, Sep 22, 2014 at 7:42 PM, Bob Camp wrote: > Hi > > Is it really that much harder to process a 1 KHz note out of a direct > conversion receiver than it is to process a 100 Hz note? > > Put another way - you already have a crystal filter in the front end of > the “radio” right? It will do a better job knocking down an “adjacent > channel” 2 KHz away than one 200 Hz away. Even without the crystal filter, > the only likely thing you are trying to reject is noise. Effectively the > “no filter” approach degrades your signal to noise by 3 to 6 db depending > on the type of noise you are dealing with. > > I’m asking because I may have missed something that makes 100 Hz “magic” …. > > Bob > > On Sep 22, 2014, at 6:15 PM, paul swed wrote: > > > One of the methods suggested for working with the wwvb psk is down > > converting to a lower frequency. When experimenting with NAA I had built > a > > 24 Khz receiver that down converted that signal to a 100 Hz base band. > > It was a minor effort to shift it to 60 Khz by changing the LO. I liked > > what I saw. Essentially a simple direct conversion receiver with about 42 > > DB of gain. > > The PSK flips at every 1 second depending on the data and is 1/100Hz > > delayed from the wwvb flip due to the down conversion process. This makes > > the further processing very reasonable in just about any micro. > > But the LO is a mess. Not bad if you have an HP3335a as I did till last > > week. (Another project to repair) for 100 Hz the LO must be at 60.1 or > 59.9 > > Khz. Or synthesize it etc. Starting to get seriously ugly. > > Or jump to a 1 Khz with 59 or 61 KHz. But I hated the idea of mixers and > > filters. > > > > Any Time-Nuts seen those crystals or oscillators around lately? Seriously > > missing from the general haunts. > > > > But turns out and heavens knows why there are plentiful 5.9904 MHz xtals > > around. I ordered 5 from Mouser $ .46 ea. > > 5.9904/100 = 59.904 as a LO and suspect it can be moved to the correct > > frequency not that it has to be. > > Not sure there is a real need to lock the LO at all. > > So an exciting bit of news. > > Regards > > Paul > > WB8TSL > > ___ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] WWVB d-psk-r down conversion method
Hi Is it really that much harder to process a 1 KHz note out of a direct conversion receiver than it is to process a 100 Hz note? Put another way - you already have a crystal filter in the front end of the “radio” right? It will do a better job knocking down an “adjacent channel” 2 KHz away than one 200 Hz away. Even without the crystal filter, the only likely thing you are trying to reject is noise. Effectively the “no filter” approach degrades your signal to noise by 3 to 6 db depending on the type of noise you are dealing with. I’m asking because I may have missed something that makes 100 Hz “magic” …. Bob On Sep 22, 2014, at 6:15 PM, paul swed wrote: > One of the methods suggested for working with the wwvb psk is down > converting to a lower frequency. When experimenting with NAA I had built a > 24 Khz receiver that down converted that signal to a 100 Hz base band. > It was a minor effort to shift it to 60 Khz by changing the LO. I liked > what I saw. Essentially a simple direct conversion receiver with about 42 > DB of gain. > The PSK flips at every 1 second depending on the data and is 1/100Hz > delayed from the wwvb flip due to the down conversion process. This makes > the further processing very reasonable in just about any micro. > But the LO is a mess. Not bad if you have an HP3335a as I did till last > week. (Another project to repair) for 100 Hz the LO must be at 60.1 or 59.9 > Khz. Or synthesize it etc. Starting to get seriously ugly. > Or jump to a 1 Khz with 59 or 61 KHz. But I hated the idea of mixers and > filters. > > Any Time-Nuts seen those crystals or oscillators around lately? Seriously > missing from the general haunts. > > But turns out and heavens knows why there are plentiful 5.9904 MHz xtals > around. I ordered 5 from Mouser $ .46 ea. > 5.9904/100 = 59.904 as a LO and suspect it can be moved to the correct > frequency not that it has to be. > Not sure there is a real need to lock the LO at all. > So an exciting bit of news. > Regards > Paul > WB8TSL > ___ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] WWVB d-psk-r down conversion method
One of the methods suggested for working with the wwvb psk is down converting to a lower frequency. When experimenting with NAA I had built a 24 Khz receiver that down converted that signal to a 100 Hz base band. It was a minor effort to shift it to 60 Khz by changing the LO. I liked what I saw. Essentially a simple direct conversion receiver with about 42 DB of gain. The PSK flips at every 1 second depending on the data and is 1/100Hz delayed from the wwvb flip due to the down conversion process. This makes the further processing very reasonable in just about any micro. But the LO is a mess. Not bad if you have an HP3335a as I did till last week. (Another project to repair) for 100 Hz the LO must be at 60.1 or 59.9 Khz. Or synthesize it etc. Starting to get seriously ugly. Or jump to a 1 Khz with 59 or 61 KHz. But I hated the idea of mixers and filters. Any Time-Nuts seen those crystals or oscillators around lately? Seriously missing from the general haunts. But turns out and heavens knows why there are plentiful 5.9904 MHz xtals around. I ordered 5 from Mouser $ .46 ea. 5.9904/100 = 59.904 as a LO and suspect it can be moved to the correct frequency not that it has to be. Not sure there is a real need to lock the LO at all. So an exciting bit of news. Regards Paul WB8TSL ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
