John had not seen this before. It is a AM decoder. But its an interesting start if you are less than 1000 miles from wwvb. Regards Paul
On Mon, Oct 12, 2020 at 6:52 AM John C. Westmoreland, P.E. < j...@westmorelandengineering.com> wrote: > Paul, > > Doesn't the post by Chris Howard above appear to be a good/great starting > point? > Seems like that approach could be extended. > > https://github.com/chris-elfpen/Teensy4WWVBsdr > > 73's, > John > AJ6BC > > > On Sun, Oct 11, 2020 at 9:23 AM paul swed <paulsw...@gmail.com> wrote: > > > Good morning to the group. Both Rodger and I can answer the last question > > on the questionable bits very well. > > I have 7 antique devices spectracoms truetime fluke tracor Dymec etc. > > They handle it very well each has at least a 2 second integration time. > The > > dpskr has always taken advantage of this fact. Literally we have run days > > without flips in the charts. Even in summer. > > Some surprises in doing this. Numbers of bits that could change don't > seem > > to. Then some of the bits have a really odd pattern but they follow the > > pattern. Thats been coded into the dpskr. In fact anything over several > > years we have figured out are coded in. > > One thing we did not do was automatic change from summer to winter > offsets. > > Its really a PIA so just not that excited when this happy switch flipper > > can do it in 1 second. > > > > The other bit of fun for the magical new DPS wwvb receiver is after you > get > > the bits you must decode them and its nothing like the AM code. Its a M/N > > FEC code. Its all in the NIST papers but was fun coding and I imagine > every > > bit as fun decoding. The dpskr software at least gives you hints to the > > process. > > > > Here is an offer. Anyone that gets the BPSK bits working through a > SDR/DPS > > arduino/STM cheap chip. Please no $100 FPGA development kits. > > I will be happy to dig into the decoder. The solution needs a 1pps and > the > > bit. > > Whats really funny about the wwvb bpsk is that there has never been sort > of > > a open development platform. Anyone who has played with the ES100 will > run > > into some issues that are annoying for a time nut to tinker with. > > Regards > > Paul > > > > On Sun, Oct 11, 2020 at 10:39 AM Bob kb8tq <kb...@n1k.org> wrote: > > > > > Hi > > > > > > The “simple” approach is to generate the full modulation pattern > > > for the signal based on a “known good” time source. There are a > > > couple of ambiguous bits so it will only be close. Feed that into > > > your inverter and the result will be (near) clean WWVB. Since you > > > never demodulate the WWVB, there isn’t a lot to the RF side …. > > > > > > There will be some drops and pops. The question will be just how > > > well this or that antique device deals with them. > > > > > > Bob > > > > > > > On Oct 10, 2020, at 10:01 PM, paul swed <paulsw...@gmail.com> wrote: > > > > > > > > The additional article John sent us is a pretty good read. Having > > > soldered > > > > all the little wires together with heat shrink, I can see the > advantage > > > of > > > > the epoxy approach. > > > > > > > > A consideration for the discussion. So far its been about the various > > > tried > > > > and true methods for a RF frontend. But the real challenge that is in > > > front > > > > of us is the software that uses that frontend. How about a very easy > to > > > > build a phase flipper so that those that are software inclined do not > > > need > > > > to deal with the frontend to get going. The dpskr has a phase flipper > > in > > > it. > > > > But it can be even simpler than that. > > > > > > > > A 60 KHz logic signal ( divide 6 Mhz down or anything else thats > easy) > > > > Feeds an inverter to generate the 180 degree phase. A gate to select > 0 > > or > > > > 180 degrees. All of the gates/inverters can actually be a single quad > > > > nand gate. A D flip flop with the clock from the 0 degree 60 KHz > logic > > > > level. Your data into the D input. The D flip flop synchronizes the > > data > > > to > > > > the clock. On the output you can filter the signal or not and cut the > > > level > > > > down or not. > > > > Its a BPSK source. > > > > Granted in a pure gate approach the actual bpsk flip will not be the > 2 > > X > > > 60 > > > > KHz for 1/2 cycle. But in real receivers the 120 KHz never comes > > through > > > > the various stages and filters. So no real harm. This also doesn't > > supply > > > > the AM signals 14-17 db modulation. But its good enough to allow > > software > > > > to be developed and its simple. > > > > Good luck > > > > Paul > > > > WB8TSL > > > > > > > > On Sat, Oct 10, 2020 at 2:05 PM John Magliacane via time-nuts < > > > > time-nuts@lists.febo.com> wrote: > > > > > > > >> For WWVB reception, I use a single turn of 40-conductor ribbon > cable, > > > >> configured as a 40-turn loop, brought to resonance with a parallel > > > >> capacitance, that differentially drives an instrumentation > amplifier. > > No > > > >> electrostatic shielding is needed to eliminate e-field pickup with > > this > > > >> approach. > > > >> > > > >> The antenna hangs in my attic with thumbtacks and does a commendable > > > job, > > > >> day or night, 1622 miles east of WWVB. See attached JPEG image. > > > >> > > > >> The March 2017 issue of "Circuit Cellar" magazine described an > > > "improved" > > > >> version of my antenna/preamp combination (which I haven't looked > > into). > > > >> See attached PDF document. > > > >> > > > >> During my early experimentation, I realized that the preamp would > need > > > to > > > >> have a high dynamic range in order to perform well in the high-noise > > > >> environment that is LF. And if the preamp is going to feed a > > receiver > > > >> through any reasonable length of coax, it will need to be able to > > drive > > > a > > > >> high capacitance load as well. > > > >> > > > >> > > > >> 73.000 de John, KD2BD > > > >> _______________________________________________ > > > >> time-nuts mailing list -- time-nuts@lists.febo.com > > > >> To unsubscribe, go to > > > >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > >> and follow the instructions there. > > > >> > > > > _______________________________________________ > > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > > and follow the instructions there. > > > > > > > > > _______________________________________________ > > > time-nuts mailing list -- time-nuts@lists.febo.com > > > To unsubscribe, go to > > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > > and follow the instructions there. > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.