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

Jack Twilley ) writes:
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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.

I thought the reason WWVB was so low down in the spectrum was so propagation
was fairly constant.

Michael VE2BVW

Jack Twilley ) writes:
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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.

I thought the reason WWVB was so low down in the spectrum was so propagation
was fairly constant.

Michael VE2BVW

At 60 kHz, there shouldn't be any difference between daytime and
nighttime propagation. Certainly the ionosphere isn't involved.

Roy Lewallen, W7EL

Jack Twilley wrote:
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"Roy" == 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.

At 60 kHz, there shouldn't be any difference between daytime and
nighttime propagation. Certainly the ionosphere isn't involved.

Roy Lewallen, W7EL

Jack Twilley wrote:
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Hash: SHA1


"Roy" == 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.

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)

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)

On Sat, 04 Oct 2003 18:06:23 -0700, Roy Lewallen
wrote:

At 60 kHz, there shouldn't be any difference between daytime and
nighttime propagation. Certainly the ionosphere isn't involved.

Roy Lewallen, W7EL

Don't forget the daytime LF/MF attenuation in the D-layer, by
preventing it from reaching the E-layer, which sets the LUF (Lowest
Usable Frequency). At night, the D-layer disappears, thus, the signal
can reflect from the E or F layer.

At least the 77,5 kHz Maiflingen standard time transmitter in Germany
is usable to about 2000 .. 2500 km from the transmitter during the
night at least in the winter. However, during the summer nights, the D
layer is in constant sunlight all night nearly 1000 km south of the
arctic circle, which may explain the worse conditions during summer
night, but of course the number of lightnings is also higher during
the summer, increasing the band noise.

Paul OH3LWR

On Sat, 04 Oct 2003 18:06:23 -0700, Roy Lewallen
wrote:

At 60 kHz, there shouldn't be any difference between daytime and
nighttime propagation. Certainly the ionosphere isn't involved.

Roy Lewallen, W7EL

Don't forget the daytime LF/MF attenuation in the D-layer, by
preventing it from reaching the E-layer, which sets the LUF (Lowest
Usable Frequency). At night, the D-layer disappears, thus, the signal
can reflect from the E or F layer.

At least the 77,5 kHz Maiflingen standard time transmitter in Germany
is usable to about 2000 .. 2500 km from the transmitter during the
night at least in the winter. However, during the summer nights, the D
layer is in constant sunlight all night nearly 1000 km south of the
arctic circle, which may explain the worse conditions during summer
night, but of course the number of lightnings is also higher during
the summer, increasing the band noise.

Paul OH3LWR

I'm not at all an expert on propagation. So are you saying that
propagation of 60 kHz signals is via ionospheric skip? E or F layer? I
didn't think the LUF ever got anywhere near 60 kHz at any time.

Roy Lewallen, W7EL

Paul Keinanen wrote:
On Sat, 04 Oct 2003 18:06:23 -0700, Roy Lewallen
wrote:


At 60 kHz, there shouldn't be any difference between daytime and
nighttime propagation. Certainly the ionosphere isn't involved.

Roy Lewallen, W7EL


Don't forget the daytime LF/MF attenuation in the D-layer, by
preventing it from reaching the E-layer, which sets the LUF (Lowest
Usable Frequency). At night, the D-layer disappears, thus, the signal
can reflect from the E or F layer.

At least the 77,5 kHz Maiflingen standard time transmitter in Germany
is usable to about 2000 .. 2500 km from the transmitter during the
night at least in the winter. However, during the summer nights, the D
layer is in constant sunlight all night nearly 1000 km south of the
arctic circle, which may explain the worse conditions during summer
night, but of course the number of lightnings is also higher during
the summer, increasing the band noise.

Paul OH3LWR