[time-nuts] WWVB Dephaser Question

[paul swed]

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 at 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 at lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>