The noise was lower late at night when more gadgets were off,
which I'm sure is why the automatic clocks you can get now do
their synchronizing late at night.

I thought the reason they sync'ed at night was because of propagation.

I've occasionally "played" with an "atomic clock" by setting it INcorrectly,
and each has always sync'ed within 10 minutes at ANY time of the day, except
for one which was inside a metal building; it finally sync'ed about noon.

I'm near Topeka, KS, some 400+ miles east and a little south of Boulder, CO.

--Myron, W0PBV.
--
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTX). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

Roy Lewallen wrote:

I played with that many, many moons ago. The bugaboo is local noise --
QRM from all kinds of devices running from mains power, switching,
arcing, and sparking. The noise was lower late at night when more
gadgets were off, which I'm sure is why the automatic clocks you can get
now do their synchronizing late at night. So I suggest looking at each
architechture for its noise immunity and how it responds when it does
get a burst of noise. Absolute minimum bandwidth is an advantage from a
noise standpoint, as long as it's not so narrow that it rings for too
long when hit with an impulse. A PLL with long loop time constant might
be a good idea, since it should maintain synchronization through a noise
burst. Other than those generalities, I don't have much to offer. I
built up a simple receiver long ago that allowed me to see the binary
code on a scope, but only late at night. I never pursued perfecting it
to the point where it would be reliable. WWVB increased its power
between then and now, but it's probably still not a piece of cake.

Roy Lewallen, W7EL

Joel Kolstad wrote:
I've been thinking about building a WWVB (time code on 60kHz) receiver, and
wanted to get some suggestions for the architecture. Poking around the web
some, I did find one receiver where the guy built a synchronous detector
using a PLL and VCXO to phase-lock to the 60kHz carrier. Nice idea --
especially since he wanted the 60kHz carrier as a synchronization signal.
However, I just want the time data... so... wouldn't it be easier to build a
mixer at, e.g., 59kHz and then use an envelope detector to get a loud/quiet
audible (1kHz) tone (WWVB reduces power by 10dB to signify 0 bits in its
time code)? It seems to me that this approach avoids the need for the PLL
and VCXO, which is a nice 'reduction' in complexity. Also, since I'll have
a microcontroller around to decode the time code anyway, it can easily
generate the 59kHz signal.

Thanks,
---Joel Kolstad



I would suggest using a shielded loop antenna to help with the local noise
problem.
The loop is directional so it could be oriented to reduce at least one source of
noise.

Bill K7NOM

Bill Janssen wrote:
I would suggest using a shielded loop antenna to help with the local
noise problem.
The loop is directional so it could be oriented to reduce at least one
source of noise.

I was planning to use a coil wound on a ferrite bar core to reduce the
overall size of the antenna, but the web does show people successfully using
large 'air core' loops, as you've suggested. I was thinking of shielding
the ferrite bar antenna by placing it in something along the lines of a
copper pipe with the edge slitted, but apparently it might be bet to enclose
the antenna in a U-shaped piece of metal, such that, oh, say, 1/4 of the
broadside of the antenna is still exposed? I'm not sure why this should
matter, though?

---Joel

Bill Janssen wrote:
I would suggest using a shielded loop antenna to help with the local
noise problem.
The loop is directional so it could be oriented to reduce at least one
source of noise.

I was planning to use a coil wound on a ferrite bar core to reduce the
overall size of the antenna, but the web does show people successfully using
large 'air core' loops, as you've suggested. I was thinking of shielding
the ferrite bar antenna by placing it in something along the lines of a
copper pipe with the edge slitted, but apparently it might be bet to enclose
the antenna in a U-shaped piece of metal, such that, oh, say, 1/4 of the
broadside of the antenna is still exposed? I'm not sure why this should
matter, though?

---Joel

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"Roy" =3D=3D Roy Lewallen writes:

Roy The noise was lower late at night when more gadgets were off,
Roy which I'm sure is why the automatic clocks you can get now do
Roy their synchronizing late at night.

I thought the reason they sync'ed at night was because of propagation.

Interesting.

Jack.
=2D --=20
Jack Twilley
jmt at twilley dot org
http colon slash slash www dot twilley dot org slash tilde jmt slash
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Roy Lewallen wrote:

I played with that many, many moons ago. The bugaboo is local noise --
QRM from all kinds of devices running from mains power, switching,
arcing, and sparking. The noise was lower late at night when more
gadgets were off, which I'm sure is why the automatic clocks you can get
now do their synchronizing late at night. So I suggest looking at each
architechture for its noise immunity and how it responds when it does
get a burst of noise. Absolute minimum bandwidth is an advantage from a
noise standpoint, as long as it's not so narrow that it rings for too
long when hit with an impulse. A PLL with long loop time constant might
be a good idea, since it should maintain synchronization through a noise
burst. Other than those generalities, I don't have much to offer. I
built up a simple receiver long ago that allowed me to see the binary
code on a scope, but only late at night. I never pursued perfecting it
to the point where it would be reliable. WWVB increased its power
between then and now, but it's probably still not a piece of cake.

Roy Lewallen, W7EL

Joel Kolstad wrote:
I've been thinking about building a WWVB (time code on 60kHz) receiver, and
wanted to get some suggestions for the architecture. Poking around the web
some, I did find one receiver where the guy built a synchronous detector
using a PLL and VCXO to phase-lock to the 60kHz carrier. Nice idea --
especially since he wanted the 60kHz carrier as a synchronization signal.
However, I just want the time data... so... wouldn't it be easier to build a
mixer at, e.g., 59kHz and then use an envelope detector to get a loud/quiet
audible (1kHz) tone (WWVB reduces power by 10dB to signify 0 bits in its
time code)? It seems to me that this approach avoids the need for the PLL
and VCXO, which is a nice 'reduction' in complexity. Also, since I'll have
a microcontroller around to decode the time code anyway, it can easily
generate the 59kHz signal.

Thanks,
---Joel Kolstad



I would suggest using a shielded loop antenna to help with the local noise
problem.
The loop is directional so it could be oriented to reduce at least one source of
noise.

Bill K7NOM

I played with that many, many moons ago. The bugaboo is local noise --
QRM from all kinds of devices running from mains power, switching,
arcing, and sparking. The noise was lower late at night when more
gadgets were off, which I'm sure is why the automatic clocks you can get
now do their synchronizing late at night. So I suggest looking at each
architechture for its noise immunity and how it responds when it does
get a burst of noise. Absolute minimum bandwidth is an advantage from a
noise standpoint, as long as it's not so narrow that it rings for too
long when hit with an impulse. A PLL with long loop time constant might
be a good idea, since it should maintain synchronization through a noise
burst. Other than those generalities, I don't have much to offer. I
built up a simple receiver long ago that allowed me to see the binary
code on a scope, but only late at night. I never pursued perfecting it
to the point where it would be reliable. WWVB increased its power
between then and now, but it's probably still not a piece of cake.

Roy Lewallen, W7EL

Joel Kolstad wrote:
I've been thinking about building a WWVB (time code on 60kHz) receiver, and
wanted to get some suggestions for the architecture. Poking around the web
some, I did find one receiver where the guy built a synchronous detector
using a PLL and VCXO to phase-lock to the 60kHz carrier. Nice idea --
especially since he wanted the 60kHz carrier as a synchronization signal.
However, I just want the time data... so... wouldn't it be easier to build a
mixer at, e.g., 59kHz and then use an envelope detector to get a loud/quiet
audible (1kHz) tone (WWVB reduces power by 10dB to signify 0 bits in its
time code)? It seems to me that this approach avoids the need for the PLL
and VCXO, which is a nice 'reduction' in complexity. Also, since I'll have
a microcontroller around to decode the time code anyway, it can easily
generate the 59kHz signal.

Thanks,
---Joel Kolstad