atomic clocks
 

The current crop of atomic clocks are inexpensive and largely disposable. But
the following might be of interest.

If the clock refuses to sync, check to see if the ferrite antenna is loose and
rattling. I've found that if it isn't sitting "vertical", it doesn't pick up
enough signal.

These clocks generally sync around midnight. But whoever wrote the firmware
didn't think to attempt a sync when the batteries were installed. So if you
don't want to wait forever, manually set the clock to 11:55 PM (or
thereabouts). You should have sync within a few minutes.

atomic clocks
 

On 21/06/2014 15:54, William Sommerwerck wrote:
The current crop of atomic clocks are inexpensive and largely
disposable. But the following might be of interest.

If the clock refuses to sync, check to see if the ferrite antenna is
loose and rattling. I've found that if it isn't sitting "vertical", it
doesn't pick up enough signal.

These clocks generally sync around midnight. But whoever wrote the
firmware didn't think to attempt a sync when the batteries were
installed. So if you don't want to wait forever, manually set the clock
to 11:55 PM (or thereabouts). You should have sync within a few minutes.

I read this a few years ago, but it begs the obvious question. How do
they know without an even more accurate clock to gauge it against?
So their clock cannot be the most accurate - a paradox.

atomic clocks
 

On 21/06/2014 19:19, N_Cook wrote:
On 21/06/2014 15:54, William Sommerwerck wrote:
The current crop of atomic clocks are inexpensive and largely
disposable. But the following might be of interest.

If the clock refuses to sync, check to see if the ferrite antenna is
loose and rattling. I've found that if it isn't sitting "vertical", it
doesn't pick up enough signal.

These clocks generally sync around midnight. But whoever wrote the
firmware didn't think to attempt a sync when the batteries were
installed. So if you don't want to wait forever, manually set the clock
to 11:55 PM (or thereabouts). You should have sync within a few minutes.

I read this a few years ago, but it begs the obvious question. How do
they know without an even more accurate clock to gauge it against?
So their clock cannot be the most accurate - a paradox.

http://www.npl.co.uk/news/npls-atomi...-most-accurate

atomic clocks
 

"William Sommerwerck" wrote in message
...
The current crop of atomic clocks are inexpensive and largely disposable.
But the following might be of interest.

If the clock refuses to sync, check to see if the ferrite antenna is loose
and rattling. I've found that if it isn't sitting "vertical", it doesn't
pick up enough signal.

These clocks generally sync around midnight. But whoever wrote the
firmware didn't think to attempt a sync when the batteries were installed.
So if you don't want to wait forever, manually set the clock to 11:55 PM
(or thereabouts). You should have sync within a few minutes.

My wris****ch does once in 24h - 01:00 IIRC.

All the desk clocks I have sync every hour, and all sync on battery
replacement.

A few years ago, the UK 60kHz MSF service moved from Rugby to anthorn, loads
of people in the South have since been complaining about flaky MSF
reception, including me - which is a little odd as I bought all my clocks in
Lidl, they're all German made and almost certainly pick up the Frankfurt
77kHz DCF.

atomic clocks
 

"N_Cook" wrote in message ...
On 21/06/2014 15:54, William Sommerwerck wrote:

These clocks generally sync around midnight. But whoever wrote
the firmware didn't think to attempt a sync when the batteries were
installed. So if you don't want to wait forever, manually set the clock
to 11:55 PM (or thereabouts). You should have sync within a few minutes.

I read this a few years ago, but it begs the obvious question. How do
they know without an even more accurate clock to gauge it against?
So their clock cannot be the most accurate -- a paradox.

"Midnight" is what //your// clock thinks is midnight. It doesn't have to be
the least-bit accurate, because the clock will sync at the local time written
in the firmware. Then the clock will be accurate.

The "more-accurate" clock is the NIST atomic clock. Once your clock syncs with
the NIST clock, it is within 15 ms (or so) of the "absolute" time.

atomic clocks
 

On Sat, 21 Jun 2014 07:54:27 -0700, "William Sommerwerck"
wrote:

The current crop of atomic clocks are inexpensive and largely disposable. But
the following might be of interest.

As usual, I disagree.

If the clock refuses to sync, check to see if the ferrite antenna is loose and
rattling. I've found that if it isn't sitting "vertical", it doesn't pick up
enough signal.

I beg to differ here. WWVB 60 KHz is vertically polarized with the H
(magnetic) field running parallel to the ground. It's a magnetic
loop, which works on the H field, not the E field. Pointing the loop
up and down does not work.
http://softsolder.com/2010/01/02/wwvb-groundwave-signal-is-vertically-polarized/
Turning it vertically is just as bad as aiming a bar end
directly at Colorado: the signal drops right into the noise.
So it is written, so it must be.

Also:
"NEW IMPROVED SYSTEM FOR WWVB BROADCAST" (2010???)
http://www.jks.com/wwvb.pdf
Starting on Pg 3, it describes the optimum antenna orientation.
For optimum reception the ferrite rod should be oriented
broadside towards Fort Collins.
Also take care not to point the ends of the rod towards Colorado.

I've done measurements with various rod and loop antennas. There's no
simple answer to optimum reception. Big antennas pickup more signal,
but also more noise, resulting in the same signal to noise ratio as a
relatively small antenna. What seems to work best is E field
shielding to get rid of locally generated noise, and a high Q loop, to
remove interference. However, I don't recall trying a vertically
oriented ferrite rod antenna, but I'll see what it does (maybe
tonite).

Also, it's quite useful to compare your reception with the official
monitoring stations:
http://tf.nist.gov/tf-cgi/wwvbmonitor_e.cgi
(If the graphs don't show, fix your Java).

These clocks generally sync around midnight.

Local time, Ft Collins CO time, or UTC time? Optimum times and
durations (dark path) vary depending on location and season:
http://tf.nist.gov/stations/wwvbcoverage.htm
http://tf.nist.gov/tf-cgi/wwvbgraph_e.cgi?5682905007 (left coast)

WWVB Radio Controlled Clocks: Recommended Practices for Manufacturers
and Consumers (2009 edition)
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903649
See Section 4.B. Synchronization by Radio at Assigned Times on Pg 12.
Table 2 has the local times and duration for various receiver
locations.
Attempting synchronization on the hour at midnight, 1 a.m.,
and 2 a.m. guarantees a dark path at all United States

But whoever wrote the firmware
didn't think to attempt a sync when the batteries were installed.

I again beg to differ.

WWVB Radio Controlled Clocks: Recommended Practices for Manufacturers
and Consumers (2009 edition)
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903649
See Section 2A on Pg 11
When a RCC is first turned on, it will begin looking for a
signal and attempt to synchronize.

It takes a while for the PLL to find the signal, especially when the
receiver is going on and off with the power saver. The algorithm is a
bit complex, but it will sync within about 15 minutes if you have a
signal. Check out the beginning of the C-Max CME6005 flow chart:
http://www.c-max-time.com/tech/software6005.php
Again note that it will try immediately to obtain a signal and sync.
With a test generator and ideal no-noise conditions, it will usually
sync in about 5 minutes after power on.

So if you
don't want to wait forever, manually set the clock to 11:55 PM (or
thereabouts). You should have sync within a few minutes.

Or, just plug in the battery after midnight or when the NIST predicts
there will be signal, and it will sync fairly quickly.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

atomic clocks
 

On Sat, 21 Jun 2014, Ian Field wrote:



"William Sommerwerck" wrote in message
...
The current crop of atomic clocks are inexpensive and largely disposable.
But the following might be of interest.

If the clock refuses to sync, check to see if the ferrite antenna is loose
and rattling. I've found that if it isn't sitting "vertical", it doesn't
pick up enough signal.

These clocks generally sync around midnight. But whoever wrote the firmware
didn't think to attempt a sync when the batteries were installed. So if you
don't want to wait forever, manually set the clock to 11:55 PM (or
thereabouts). You should have sync within a few minutes.

My wris****ch does once in 24h - 01:00 IIRC.

My Casio Waveceptor, that will actually sync to different time signals
depending on where the watch is, it will check for a signal at midnight,
and then if it doesn't sync, keep checking for a few hours on the hour
until it does sync, or it stops for the day.

That is actually better than the clocks I have, which generally try to
sync about 3 or 4am, and if that fails, doesn't try until the next day at
that time.

The clocks and watches all need to be oriented right, I can think of only
one time that I had the watch on at the right time where it sync'd up
okay.

Michael

All the desk clocks I have sync every hour, and all sync on battery
replacement.

A few years ago, the UK 60kHz MSF service moved from Rugby to anthorn,
loads of people in the South have since been complaining about flaky MSF
reception, including me - which is a little odd as I bought all my
clocks in Lidl, they're all German made and almost certainly pick up the
Frankfurt 77kHz DCF.

atomic clocks
 

On Sat, 21 Jun 2014 12:48:37 -0700, Jeff Liebermann
wrote:

On Sat, 21 Jun 2014 07:54:27 -0700, "William Sommerwerck"
wrote:

If the clock refuses to sync, check to see if the ferrite antenna is loose and
rattling. I've found that if it isn't sitting "vertical", it doesn't pick up
enough signal.

I beg to differ here. WWVB 60 KHz is vertically polarized with the H
(magnetic) field running parallel to the ground. It's a magnetic
loop, which works on the H field, not the E field. Pointing the loop
up and down does not work.
http://softsolder.com/2010/01/02/wwvb-groundwave-signal-is-vertically-polarized/
Turning it vertically is just as bad as aiming a bar end
directly at Colorado: the signal drops right into the noise.

Mo
WWVB Radio Controlled Clocks: Recommended Practices for Manufacturers
and Consumers (2009 edition)
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903649
See Section 3.F. Pg 9.
Antenna Orientation
Most RCC antennas are directional and achieve maximum gain
when they are positioned broadside to the transmit antenna
in Fort Collins, Colorado.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

atomic clocks
 

On Sat, 21 Jun 2014, William Sommerwerck wrote:

The current crop of atomic clocks are inexpensive and largely disposable. But
the following might be of interest.

If the clock refuses to sync, check to see if the ferrite antenna is loose
and rattling. I've found that if it isn't sitting "vertical", it doesn't pick
up enough signal.

I've never had that problem but since I'm probably close to the "limit" of
the signal from Colorado, I do find I have to orient the clocks and
watches the right way each night.

These clocks generally sync around midnight. But whoever wrote the
firmware didn't think to attempt a sync when the batteries were
installed. So if you don't want to wait forever, manually set the clock
to 11:55 PM (or thereabouts). You should have sync within a few minutes.

My watch starts trying to sync at midnight (and if it fails, every hour on
the hour till about 4am), but the clocks only try to sync at about 3 or
4am each night. I have four clocks, they all work that way.

One weird thing, and it seems to vary with the clock, I find the "sync"
button may not work. Maybe it's just because I'm trying it at the wrong
time, but late at night I can press the button and it's not sync'd up the
next day. Taking out the batteries, and putting them back, does make them
sync, three at least, and that gets the right time. It's an odd thing,
because I've had some of the clocks go out of sync some times, and they
don't resync until I take out the batteries. But they all have sync
buttons.

Michael

atomic clocks
 

"Jeff Liebermann" wrote in message
...
On Sat, 21 Jun 2014 07:54:27 -0700, "William Sommerwerck"
wrote:

If the clock refuses to sync, check to see if the ferrite antenna
is loose and rattling. I've found that if it isn't sitting "vertical",
it doesn't pick up enough signal.

I beg to differ here. WWVB 60 KHz is vertically polarized with the H
(magnetic) field running parallel to the ground.

I've twice had the antenna come loose, and on both occasions, restoring it to
its original vertical orientation within the case brought back reception.


I don't recall trying a vertically oriented ferrite rod antenna,
but I'll see what it does.

Let us know. I'm curious.

I have another atomic clock with an external antenna. I'll set it up so it's
vertical, and see what happens over the next day or two.

atomic clocks
 

"

I have another atomic clock with an external antenna. I'll set it up so
it's vertical, and see what happens over the next day or two.


Surely 'atomic clock' is the wrong term for these devices ? As I understand
it, an atomic clock is a laboratory time-standard instrument based on the
decay rate of some atomic isotope, usually caesium ? The devices to which
you are referring are radio-synchronised clocks (also referred to, again
wrongly in my opinion, as "radio controlled clocks" ), deriving their
synchronisation from data broadcast from a number of low frequency
transmitters around the world. Otherwise, in between the synchronisation
times, these clocks are just free-running, much like any other clock.

http://en.wikipedia.org/wiki/Atomic_clock

Arfa

atomic clocks
 

On Sun, 22 Jun 2014 02:10:36 +0100, "Arfa Daily"
wrote:

I have another atomic clock with an external antenna. I'll set it up so
it's vertical, and see what happens over the next day or two.

Surely 'atomic clock' is the wrong term for these devices ? As I understand
it, an atomic clock is a laboratory time-standard instrument based on the
decay rate of some atomic isotope, usually caesium ? The devices to which
you are referring are radio-synchronised clocks (also referred to, again
wrongly in my opinion, as "radio controlled clocks" ), deriving their
synchronisation from data broadcast from a number of low frequency
transmitters around the world. Otherwise, in between the synchronisation
times, these clocks are just free-running, much like any other clock.

http://en.wikipedia.org/wiki/Atomic_clock

Well, at the end of the WWVB chain, there is a cesium standard
oscillator feeding the station.

Yep. Even the NIST doesn't like the term.
WWVB Radio Controlled Clocks: Recommended Practices for Manufacturers
and Consumers (2009 edition)
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903649
See 9.B. Use of "Atomic Clock" Nomenclature Pg 34.
... we contend that use of the term "atomic
clock" is technically incorrect and misleading to
consumers, and its usage should be avoided. Unless
there is actually an atomic oscillator inside the
RCC (such as a cesium or rubidium oscillator), we
recommend that the term "radio controlled clock"
be used to correctly describe the product. Labeling
products or documentation with the term "atomic timekeeping"
is also considered acceptable.

Good luck stuffing this genie back into the bottle.

Incidentally, the easiest way to check your signal strength is to just
cram an oscilloscope into the clock module and look at the decoded
data. This should offer some clues as to what to look for:
http://www.leapsecond.com/pages/sony-wwvb/
(Note that the loopstick is horizontally mounted.)
According to the NIST, to obtain reliable updates, the decoded SNR
should be 20 dB or better. That should be easily visible on a scope
and what I'll try tonite.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

atomic clocks
 

On Sun, 22 Jun 2014, Arfa Daily wrote:



"

I have another atomic clock with an external antenna. I'll set it up so
it's vertical, and see what happens over the next day or two.


Surely 'atomic clock' is the wrong term for these devices ? As I understand
it, an atomic clock is a laboratory time-standard instrument based on the
decay rate of some atomic isotope, usually caesium ? The devices to which you
are referring are radio-synchronised clocks (also referred to, again wrongly
in my opinion, as "radio controlled clocks" ), deriving their synchronisation
from data broadcast from a number of low frequency transmitters around the
world. Otherwise, in between the synchronisation times, these clocks are just
free-running, much like any other clock.

It may be the wrong term, but it's common useage now. Most people don't
know what it's about anyway, other than that they keep time, so they won't
be mislead into thinking there's a cesium standard inside. They are aware
of "sync'ing up" so I don't think they have any problems once they get it.

Michael


http://en.wikipedia.org/wiki/Atomic_clock Arfa

atomic clocks
 

On Sat, 21 Jun 2014, Jeff Liebermann wrote:

On Sun, 22 Jun 2014 02:10:36 +0100, "Arfa Daily"
wrote:

I have another atomic clock with an external antenna. I'll set it up so
it's vertical, and see what happens over the next day or two.

Surely 'atomic clock' is the wrong term for these devices ? As I understand
it, an atomic clock is a laboratory time-standard instrument based on the
decay rate of some atomic isotope, usually caesium ? The devices to which
you are referring are radio-synchronised clocks (also referred to, again
wrongly in my opinion, as "radio controlled clocks" ), deriving their
synchronisation from data broadcast from a number of low frequency
transmitters around the world. Otherwise, in between the synchronisation
times, these clocks are just free-running, much like any other clock.

http://en.wikipedia.org/wiki/Atomic_clock

Well, at the end of the WWVB chain, there is a cesium standard
oscillator feeding the station.

Yep. Even the NIST doesn't like the term.
WWVB Radio Controlled Clocks: Recommended Practices for Manufacturers
and Consumers (2009 edition)
http://www.nist.gov/customcf/get_pdf.cfm?pub_id=903649
See 9.B. Use of "Atomic Clock" Nomenclature Pg 34.
... we contend that use of the term "atomic
clock" is technically incorrect and misleading to
consumers, and its usage should be avoided. Unless
there is actually an atomic oscillator inside the
RCC (such as a cesium or rubidium oscillator), we
recommend that the term "radio controlled clock"
be used to correctly describe the product. Labeling
products or documentation with the term "atomic timekeeping"
is also considered acceptable.

Good luck stuffing this genie back into the bottle.

Incidentally, the easiest way to check your signal strength is to just
cram an oscilloscope into the clock module and look at the decoded
data. This should offer some clues as to what to look for:
http://www.leapsecond.com/pages/sony-wwvb/
(Note that the loopstick is horizontally mounted.)
According to the NIST, to obtain reliable updates, the decoded SNR
should be 20 dB or better. That should be easily visible on a scope
and what I'll try tonite.

One of my clocks has a "signal strength indicator". There's a symbol on
the display, and though it looks more like a microwave dish, the more
curved lines displayed the stronger the signal. If there's no indicator,
it didn't sync up.

But other than orienting the clock so it does get the signal, rarely do I
miss a sync, and that's almost ten years after I got the first atomic
clock. It also depends on the clock, the $2.00 at a garage sale one seems
finicky compared to the Radio Shack ones.

That said, remember they changed the transmission to some extent. They
now transmit a phase modulated signal, an attempt to do away with noise
problems "at the extreme points of the transmit area", and I'm not sure
how that's worked out, or how common the clocks are that can take
advantage of it. And I'm not sure how much, if any, the new method causes
problems with old clocks.

Michael

atomic clocks
 

N_Cook wrote:
On 21/06/2014 15:54, William Sommerwerck wrote:
The current crop of atomic clocks are inexpensive and largely
disposable. But the following might be of interest.

If the clock refuses to sync, check to see if the ferrite antenna is
loose and rattling. I've found that if it isn't sitting "vertical", it
doesn't pick up enough signal.

These clocks generally sync around midnight. But whoever wrote the
firmware didn't think to attempt a sync when the batteries were
installed. So if you don't want to wait forever, manually set the clock
to 11:55 PM (or thereabouts). You should have sync within a few minutes.

I read this a few years ago, but it begs the obvious question. How do
they know without an even more accurate clock to gauge it against?
So their clock cannot be the most accurate - a paradox.

Various station clocks are put up against portable clocks that are
referenced to an average of multiple clocks. At least that's how they used
to do it. You were not supposed to put two clocks next to each other for
long. They would slew together.
I used to sync my wind up wris****ch against a cesium standard. I also set
my frequency counter against a 1mHz output right off the system.

I like my analog dial radio clock. The hands move real fast when it syncs
from switches from dst. Stepper motor hands.

Greg

atomic clocks
 

On Sat, 21 Jun 2014 12:59:42 -0700, "William Sommerwerck"
wrote:

I don't recall trying a vertically oriented ferrite rod antenna,
but I'll see what it does.

Let us know. I'm curious.

It's midnight. The clock synced at about 11:30 PDST (7:00 UTC) so I
now have enough signal. Yep, that matches the monitoring station
signal strength:
http://tf.nist.gov/tf-cgi/wwvbgraph_e.cgi?5683005001

However, there's a problem. I don't have a storage scope or DSO
handy. The sweep rate needs to be very slow (about 0.5 sec per
division) in order to see the 1 baud data. I also have a nasty
headache which means I'm not going to setup a better camera tonite. To
be continued another evening.

I disassembled an Oregon Scientific, by Integrated Display Co of Hong
Kong, "Time Machine". Connections we
+VE +5v but works at +3v.
GND Ground
DCF Data out
PON Ground to Power On
I moved the PON wire and soldered it to GND to continuously enable the
clock electronics (in the antenna module). I soldered wires to the
data out and gnd pads, and reassembled the receiver. The wires went
to a scope input. Temporary photos:
http://802.11junk.com/jeffl/WWVB%20test/

When there was sufficient signal, the waveform on the scope was a
clean and slow moving 1 baud signal. However, when the signal was
weak, there were many more transistions, also known as noise. The
difference was very obvious.

When the loopstick was horizontal and perpendicular to the approximate
direction of Ft Collins CO, the signal was clean and slow moving 1
baud data. When either end of the loop was pointed at Ft Collins CO,
it became quite noisy. It was a very pronounced change, but only over
a fairly small (about +/- 10 degree) arc. Pointing the loopstick
vertically was pure noise with no visible signal. Like I said,
vertical is not going to work (trust me for now).

I'll try to produce some scope photos tomorrow evening. Two aspirin
and some sleep first.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

atomic clocks
 

On Sun, 22 Jun 2014 00:23:47 -0700, Jeff Liebermann
wrote:

It's midnight. The clock synced at about 11:30 PDST (7:00 UTC) so I
now have enough signal.

Argh. That should be:
The clock synced at about 11:30 PDST (6:30 UTC)...

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

atomic clocks
 

William Sommerwerck wrote:

I've twice had the antenna come loose, and on both occasions, restoring it to
its original vertical orientation within the case brought back reception.

I just took one of these apart, it projects the time on the ceiling, which
broke but the antenna is horizontal in the unit, not vertical.

Plus I don't think it has a regular "time" to sync the clock, it like the
outdoor thermometer has a radio tower/signal indicator on the display when
it's seeking the WWV, and it just seems to come on at random. Maybe once
every couple hours.

Maybe it tries to sync all the time and the indicator comes on when it
catches the signal or something.

-bruce

atomic clocks
 

"Jeff Liebermann" wrote in message
...

The ones I have handy is an Oregon Scientific "Time Machine" from
about 1998. It uses the same Temec chip at Radio Shack and was
probably made by Integrated Display Co of Hong Kong, which made the
Radio Shack clocks. I have three of these (various mutations) all of
which work quite well when I move the antenna away from common noise
sources. Nothing works when it's near my computah, hi-fi, or strip of
wall warts full of switchers. Even on my RF workbench, I have to turn
off a few instruments that have switchers running continuously.

I have two of those Oregon Scientific clocks. They have thick antennas about
5" long. I turned the antennas upright last night, and neither lost sync. I'll
let them sit that way for a few more days.

Oddly, the La Crosse unit that provoked this posting lost sync last night.
(The sync annunciator is off.) I realize that its antenna is mounted with the
wrong orientation -- but that's the way the unit is designed.

Yes, I'm aware that these //should// be called "radio-controlled" clocks.

atomic clocks
 

"Jeff Liebermann" wrote in message
...

When the loopstick was horizontal and perpendicular to the approximate
direction of Ft Collins CO, the signal was clean and slow moving 1
baud data. When either end of the loop was pointed at Ft Collins CO,
it became quite noisy. It was a very pronounced change, but only over
a fairly small (about +/- 10 degree) arc. Pointing the loopstick
vertically was pure noise with no visible signal. Like I said,
vertical is not going to work (trust me for now).

I trust you. It's working for me (with the same unit) at the moment. I'll let
it sit another couple of days.


I'll try to produce some scope photos tomorrow evening.
Two aspirin and some sleep first.

Don't worry about it. There's no reason not to believe your measurements.

atomic clocks
 

Michael Black har bragt dette til os:
On Sun, 22 Jun 2014, Arfa Daily wrote:



"

I have another atomic clock with an external antenna. I'll set it up so
it's vertical, and see what happens over the next day or two.


Surely 'atomic clock' is the wrong term for these devices ? As I understand
it, an atomic clock is a laboratory time-standard instrument based on the
decay rate of some atomic isotope, usually caesium ? The devices to which
you are referring are radio-synchronised clocks (also referred to, again
wrongly in my opinion, as "radio controlled clocks" ), deriving their
synchronisation from data broadcast from a number of low frequency
transmitters around the world. Otherwise, in between the synchronisation
times, these clocks are just free-running, much like any other clock.

It may be the wrong term, but it's common useage now. Most people don't know
what it's about anyway, other than that they keep time, so they won't be
mislead into thinking there's a cesium standard inside. They are aware of
"sync'ing up" so I don't think they have any problems once they get it.

Michael

The clock's accuracy is based on a cesium standard (or some other
atomic timebase)

Whether the standard is inside the clock itself, or some hundred
kilometers away, controlling or sync'ing over radio is just a matter of
detail. :-)

I don't know if the clock itself learns the frequency of its own
crystal oscillator. It should be fairly easy to determine the count of
oscillations of the internal crystal per "external day", and make the
proper adjustments to make the clock more accurate when running free,
unsync'ed.

--
Husk kørelys bagpå, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

atomic clocks
 

On Sun, 22 Jun 2014, William Sommerwerck wrote:


Yes, I'm aware that these //should// be called "radio-controlled" clocks.

ON the other hand, there is historical precendence.

Didn't Heathkit call it's WWV controlled clock "The World's Most Accurate
Clock"?

I suppose it was, to some extent, since I gather it made small adjustments
to the internal master clock so even when there was no signal, the time
was closer to "exact" than if it just relied on the radio signal.

But, it got all that accuracy from WWV, so the naming was "inaccurate"
too.

Michael

atomic clocks
 

On Sun, 22 Jun 2014 07:04:46 -0700, "William Sommerwerck"
wrote:

I have two of those Oregon Scientific clocks. They have thick antennas about
5" long. I turned the antennas upright last night, and neither lost sync. I'll
let them sit that way for a few more days.

http://atomicelmer.topcities.com/clocks/reviews.html
http://atomicelmer.topcities.com/clocks/
I don't think you'll see much using the front panel indicator. If you
don't mind drilling a hole in the case for some wires, and moving one
wire, methinks the effects of cross polarization will be far more
obvious with a scope on the data line. I'll post better photos later.

Oddly, the La Crosse unit that provoked this posting lost sync last night.
(The sync annunciator is off.) I realize that its antenna is mounted with the
wrong orientation -- but that's the way the unit is designed.

Model number? I don't know much about their clocks, but watching
friends do battle with their weather stations makes me wonder about
their overall quality.

Yes, I'm aware that these //should// be called "radio-controlled" clocks.

Start with LaCrosse and their "Atomic Time":
http://www.lacrossetechnology.com/clocks.php


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

atomic clocks
 

"Michael Black" wrote in message
news:alpine.LNX.2.02.1406221058010.23474@darkstar. example.org...
On Sun, 22 Jun 2014, William Sommerwerck wrote:

Yes, I'm aware that these //should// be called "radio-controlled" clocks.

On the other hand, there is historical precendence.

Big hand or small hand?


Didn't Heathkit call its WWV-controlled clock
"The World's Most Accurate Clock"?

Just "Most-Accurate Clock". But it's the same thing.


I suppose it was, to some extent, since I gather it made small adjustments
to the internal master clock so even when there was no signal, the time was
closer to "exact" than if it just relied on the radio signal.

It switched small capacitors across the crystal in and out to trim the time
keeping. It also had an adjustment for the distance to WWV, to account for the
delay.

Heath sent one and I reviewed for Elektor. Once it synched up, it worked quite
well. Interestingly, I had to replace the carbon trim pots with ceramic
trimmers, to get reliable synching.

atomic clocks
 

"Jeff Liebermann" wrote in message
...

Oddly, the La Crosse unit that provoked this posting lost sync last night.
(The sync annunciator is off.) I realize its antenna is mounted with the
"wrong" orientation -- but that's the way the unit is designed.

Model number? I don't know much about their clocks, but watching
friends do battle with their weather stations makes me wonder about
their overall quality.

Pretty much all of them. Mine is the WS-811561 .

It came with a solar-powered "outdoor" temperature sensor. Though the Pacific
Northwest is not the best location for solar-powered anything, it's worked
perfectly for (I would guess) 18 months. Contrary to what the instructions
say, you don't have to reset the remote sensor before installing the clock's
battery. You can wait until the clock syncs up, then reset the remote sensor.

atomic clocks
 

"Leif Neland" wrote in message ...

I don't know if the clock itself learns the frequency of its own
crystal oscillator. It should be fairly easy to determine the count
of oscillations of the internal crystal per "external day", and make
the proper adjustments to make the clock more accurate when
running free, unsync'ed.

As mentioned in another post, the Heath "MAC" did this. I don't think any
current radio-controlled clock does.

Outside of making the unit more expensive, and improving the accuracy to an
degree most users don't need, I think the main reason it's been dropped is
that the switch to low-frequency broadcasts makes for more-reliable reception.
The Heath had a receiver that switched among the 5, 10, and 15MHz time
signals. Reception varied quite a bit between day and night.

--
Husk kørelys bagpå, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

atomic clocks
 

"William Sommerwerck" wrote in message
...
"N_Cook" wrote in message ...
On 21/06/2014 15:54, William Sommerwerck wrote:

These clocks generally sync around midnight. But whoever wrote
the firmware didn't think to attempt a sync when the batteries were
installed. So if you don't want to wait forever, manually set the clock
to 11:55 PM (or thereabouts). You should have sync within a few minutes.

I read this a few years ago, but it begs the obvious question. How do
they know without an even more accurate clock to gauge it against?
So their clock cannot be the most accurate -- a paradox.

"Midnight" is what //your// clock thinks is midnight. It doesn't have to
be the least-bit accurate, because the clock will sync at the local time
written in the firmware. Then the clock will be accurate.

All my clocks start at midnight and consequently attempt to sync.

What I have noticed is, some you have to manually short the battery
terminals to discharge the reservoir cap on the PCB so it doesn't remember
the previous time. One clock in particular must have a reverse polarity
protection diode, as shorting the battery terminals doesn't do any good. The
only thing I can do is leave the battery out for a while to force a resync.

atomic clocks
 

"Jeff Liebermann" wrote in message
...
On Sat, 21 Jun 2014 23:19:11 -0400, Michael Black
wrote:

One of my clocks has a "signal strength indicator". There's a symbol on
the display, and though it looks more like a microwave dish, the more
curved lines displayed the stronger the signal. If there's no indicator,
it didn't sync up.

Ummm... it doesn't indicate signal strength. It indicates if there
was a successful update

That is the case with all the clocks I have - the Casio Waveceptor dish
tower symbol is made up of individual segments that drop out with falling
signal strength.

atomic clocks
 

On Sun, 22 Jun 2014, Ian Field wrote:



"William Sommerwerck" wrote in message
...
"N_Cook" wrote in message ...
On 21/06/2014 15:54, William Sommerwerck wrote:

These clocks generally sync around midnight. But whoever wrote
the firmware didn't think to attempt a sync when the batteries were
installed. So if you don't want to wait forever, manually set the clock
to 11:55 PM (or thereabouts). You should have sync within a few minutes.

I read this a few years ago, but it begs the obvious question. How do
they know without an even more accurate clock to gauge it against?
So their clock cannot be the most accurate -- a paradox.

"Midnight" is what //your// clock thinks is midnight. It doesn't have to be
the least-bit accurate, because the clock will sync at the local time
written in the firmware. Then the clock will be accurate.

All my clocks start at midnight and consequently attempt to sync.

What I have noticed is, some you have to manually short the battery terminals
to discharge the reservoir cap on the PCB so it doesn't remember the previous
time. One clock in particular must have a reverse polarity protection diode,
as shorting the battery terminals doesn't do any good. The only thing I can
do is leave the battery out for a while to force a resync.

I haven't thought about that, but taht might explain why I have problems
resync'ing one of the clocks (actually, part of a "weatherstation".

Michael

atomic clocks
 

"Bruce Esquibel" wrote in message
...
William Sommerwerck wrote:

I've twice had the antenna come loose, and on both occasions, restoring
it to
its original vertical orientation within the case brought back reception.

I just took one of these apart, it projects the time on the ceiling, which
broke but the antenna is horizontal in the unit, not vertical.

Plus I don't think it has a regular "time" to sync the clock, it like the
outdoor thermometer has a radio tower/signal indicator on the display when
it's seeking the WWV, and it just seems to come on at random. Maybe once
every couple hours.

Maybe it tries to sync all the time and the indicator comes on when it
catches the signal or something.

All my clocks try to sync on the hour every hour, my Casio Waveceptor tries
to synch every 24h - if it fails, it will re try on the hour every hour
until 4am.

If the dish tower symbol in the display isn't showing - the time is only as
accurate as the onboard crystal and any cumulative drift since the last time
it synched.

atomic clocks
 

On Sun, 22 Jun 2014, Ian Field wrote:



"Jeff Liebermann" wrote in message
...
On Sat, 21 Jun 2014 23:19:11 -0400, Michael Black
wrote:

One of my clocks has a "signal strength indicator". There's a symbol on
the display, and though it looks more like a microwave dish, the more
curved lines displayed the stronger the signal. If there's no indicator,
it didn't sync up.

Ummm... it doesn't indicate signal strength. It indicates if there
was a successful update

That is the case with all the clocks I have - the Casio Waveceptor dish tower
symbol is made up of individual segments that drop out with falling signal
strength.

That's a good example, though I'm not sure I've noticed except after I
bought the watch some years back, it's kind of small.

Jeff is right, some or many of those indicators are just indicators, they
flash when trying to sync up, and if they sync up, the indicator remains;
it disappears if it didn't sync up.

Three of the clocks here have no signal strength indicator, the big Radio
Shack wall clock does, and as you point out, so does the Casio Waveceptor.

Michael

atomic clocks
 

"Michael Black" wrote in message
news:alpine.LNX.2.02.1406221335020.23870@darkstar. example.org...
On Sun, 22 Jun 2014, Ian Field wrote:



"Jeff Liebermann" wrote in message
...
On Sat, 21 Jun 2014 23:19:11 -0400, Michael Black
wrote:

One of my clocks has a "signal strength indicator". There's a symbol
on
the display, and though it looks more like a microwave dish, the more
curved lines displayed the stronger the signal. If there's no
indicator,
it didn't sync up.

Ummm... it doesn't indicate signal strength. It indicates if there
was a successful update

That is the case with all the clocks I have - the Casio Waveceptor dish
tower symbol is made up of individual segments that drop out with falling
signal strength.
That's a good example, though I'm not sure I've noticed except after I
bought the watch some years back, it's kind of small.

Jeff is right, some or many of those indicators are just indicators, they
flash when trying to sync up, and if they sync up, the indicator remains;
it disappears if it didn't sync up.

Three of the clocks here have no signal strength indicator, the big Radio
Shack wall clock does, and as you point out, so does the Casio Waveceptor.

I didn't need glasses when I bought the Casio - but I'd notice if most of
the symbol was missing.

atomic clocks
 

On Sun, 22 Jun 2014 09:07:46 -0700, "William Sommerwerck"
wrote:

Just "Most-Accurate Clock". But it's the same thing.

Heath model GC-1000 I assume.
https://www.youtube.com/watch?v=c8fD_3MgfDw
I have one that I'm "rebuilding". The biggest change is replacing the
overheating 7805 linear regulator with a switching regulator
equivalent.
http://www.amug.org/~jthomas/gc1000.html
http://www.ebay.com/itm/261243604047
I've already replaced all the crappy electrolytics.

It switched small capacitors across the crystal in and out to trim the time
keeping. It also had an adjustment for the distance to WWV, to account for the
delay.

Yep. Dip switches on the bottom. 16 propagation delay settings, in
1.25 msec increments. I'm about 1200 miles from Santa Cruz CA to Ft
Collins CO. At 186 miles per msec for the speed-o-light, that's 6.5
msec delay. However, the maximum delay is 18.75 msec, which limits
the range to 3600 miles from Ft Collins CO.

Heath sent one and I reviewed for Elektor. Once it synched up, it worked quite
well. Interestingly, I had to replace the carbon trim pots with ceramic
trimmers, to get reliable synching.

Oh... I didn't know about that. I'll see if makes a difference on
mine. Some adjustments might be drifting.

Not bad for 1984 technology.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

atomic clocks
 

"Michael Black" wrote in message
news:alpine.LNX.2.02.1406212237410.22338@darkstar. example.org...
On Sun, 22 Jun 2014, Arfa Daily wrote:



"

I have another atomic clock with an external antenna. I'll set it up so
it's vertical, and see what happens over the next day or two.


Surely 'atomic clock' is the wrong term for these devices ? As I
understand it, an atomic clock is a laboratory time-standard instrument
based on the decay rate of some atomic isotope, usually caesium ? The
devices to which you are referring are radio-synchronised clocks (also
referred to, again wrongly in my opinion, as "radio controlled clocks" ),
deriving their synchronisation from data broadcast from a number of low
frequency transmitters around the world. Otherwise, in between the
synchronisation times, these clocks are just free-running, much like any
other clock.

It may be the wrong term, but it's common useage now.

Common or not, that still doesn't make it right ...

Most people don't know what it's about anyway, other than that they keep
time, so they won't
be mislead into thinking there's a cesium standard inside.

I'm sure they don't, but most of us on here are engineers of one kind or
another, and we *do* know better, so we ought not to be helping to
perpetuate this wrong description ...

Arfa

They are aware
of "sync'ing up" so I don't think they have any problems once they get it.

Michael


http://en.wikipedia.org/wiki/Atomic_clock Arfa

atomic clocks
 

"Leif Neland" wrote in message
...
Michael Black har bragt dette til os:
On Sun, 22 Jun 2014, Arfa Daily wrote:



"

I have another atomic clock with an external antenna. I'll set it up so
it's vertical, and see what happens over the next day or two.


Surely 'atomic clock' is the wrong term for these devices ? As I
understand it, an atomic clock is a laboratory time-standard instrument
based on the decay rate of some atomic isotope, usually caesium ? The
devices to which you are referring are radio-synchronised clocks (also
referred to, again wrongly in my opinion, as "radio controlled
clocks" ), deriving their synchronisation from data broadcast from a
number of low frequency transmitters around the world. Otherwise, in
between the synchronisation times, these clocks are just free-running,
much like any other clock.

It may be the wrong term, but it's common useage now. Most people don't
know what it's about anyway, other than that they keep time, so they
won't be mislead into thinking there's a cesium standard inside. They
are aware of "sync'ing up" so I don't think they have any problems once
they get it.

Michael

The clock's accuracy is based on a cesium standard (or some other atomic
timebase)

Whether the standard is inside the clock itself, or some hundred
kilometers away, controlling or sync'ing over radio is just a matter of
detail. :-)

Gotta disagree with you on that one. The thing at the far end is an "atomic
clock". The thing that we are talking about, even though it is synced to
that atomic clock, is not one itself. It is an ordinary bog-standard
free-running clock, with a radio and a bit of data decoding circuitry in it,
to sync it to the real atomic clock once a day

Arfa



I don't know if the clock itself learns the frequency of its own crystal
oscillator. It should be fairly easy to determine the count of
oscillations of the internal crystal per "external day", and make the
proper adjustments to make the clock more accurate when running free,
unsync'ed.

--
Husk kørelys bagpå, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.

atomic clocks
 

On Sun, 22 Jun 2014 00:23:47 -0700, Jeff Liebermann
wrote:

I'll try to produce some scope photos tomorrow evening. Two aspirin
and some sleep first.

I took some more photos.

Time Machine:
http://802.11junk.com/jeffl/WWVB%20test/Time-Machine.jpg
Black and white wires sticking out of case on the left are the added
data wires.

Time Machine PCB:
http://802.11junk.com/jeffl/WWVB%20test/Time-Machine-PCB.jpg

Loopstick antenna:
http://802.11junk.com/jeffl/WWVB%20test/antenna.jpg
The Temec chip is under an epoxy blob on the PCB.

Receiver board connections:
http://802.11junk.com/jeffl/WWVB%20test/connections.jpg

Signals using a different camera.

Loopstick horizontal and perpendicular to Ft Collins CO:
http://802.11junk.com/jeffl/WWVB%20test/loopstick-perpendicular-to-WWVB.jpg
The screen width is 2 seconds or 2 digits wide showing two consecutive
"1" bits.

Loopstick horizontal pointed at Ft Collins CO:
http://802.11junk.com/jeffl/WWVB%20test/end-pointed-at-WWVB.jpg
The increased number of transitions are noise. Such a signal will not
decode properly.

Loopstick vertical:
http://802.11junk.com/jeffl/WWVB%20test/loopstick-vertical.jpg
Pure noise and no signal.

Bottom line is that the loopstick should be mounted horizontally and
perpendicular to Ft Collins CO. Vertical mounting does NOT work.


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558

atomic clocks
 

"Jeff Liebermann" wrote in message
...

Heath sent one which I reviewed for Elektor. Once it synched
up, it worked quite well. Interestingly, I had to replace the
carbon trim pots with ceramic trimmers, to get reliable synching.

I didn't know about that. I'll see if makes a difference on mine.
Some adjustments might be drifting.

The drift shows up as the unit taking "too long" to sync, or not synching at
all. If you're not having a problem, why waste your time?

When I lived in Bellevue, WA, there was a periodic noise burst that kept the
unit from synching. What it was, I don't know. It might have come from a
traffic-light controller.

atomic clocks
 

"Jeff Liebermann" wrote in message
...

Loopstick vertical:
http://802.11junk.com/jeffl/WWVB%20test/loopstick-vertical.jpg
Pure noise and no signal.

Bottom line is that the loopstick should be mounted horizontally and
perpendicular to Ft Collins CO. Vertical mounting does NOT work.


Interesting. I have the Time Machine and the Time Machine with a projection
clock. With the loopsticks vertical, neither has yet lost sync

That is... the sync annunciator (or what I interpret to be the sync
annunciator) in the display is still visible.

Both show the same time, which is unlikely if either had lost sync.

"Of course" an antenna's orientation should match the signal's. Why the La
Crosse only works when it doesn't, and it doesn't seem to matter for the
Oregon Scientific products -- I don't know.

atomic clocks
 

"Arfa Daily" wrote in message
...


"Leif Neland" wrote in message
...
Michael Black har bragt dette til os:
On Sun, 22 Jun 2014, Arfa Daily wrote:



"

I have another atomic clock with an external antenna. I'll set it up
so it's vertical, and see what happens over the next day or two.


Surely 'atomic clock' is the wrong term for these devices ? As I
understand it, an atomic clock is a laboratory time-standard instrument
based on the decay rate of some atomic isotope, usually caesium ? The
devices to which you are referring are radio-synchronised clocks (also
referred to, again wrongly in my opinion, as "radio controlled
clocks" ), deriving their synchronisation from data broadcast from a
number of low frequency transmitters around the world. Otherwise, in
between the synchronisation times, these clocks are just free-running,
much like any other clock.

It may be the wrong term, but it's common useage now. Most people don't
know what it's about anyway, other than that they keep time, so they
won't be mislead into thinking there's a cesium standard inside. They
are aware of "sync'ing up" so I don't think they have any problems once
they get it.

Michael

The clock's accuracy is based on a cesium standard (or some other atomic
timebase)

Whether the standard is inside the clock itself, or some hundred
kilometers away, controlling or sync'ing over radio is just a matter of
detail. :-)

Gotta disagree with you on that one. The thing at the far end is an
"atomic clock". The thing that we are talking about, even though it is
synced to that atomic clock, is not one itself. It is an ordinary
bog-standard free-running clock, with a radio and a bit of data decoding
circuitry in it, to sync it to the real atomic clock once a day

All of my desk clocks sync on the hour every hour - my Casio Waveceptor
watch does it every 24h - if it fails it tries again on the hour for the
next 3 or 4 hours.

atomic clocks
 

On Mon, 23 Jun 2014 05:29:50 -0700, "William Sommerwerck"
wrote:

"Jeff Liebermann" wrote in message
.. .

Loopstick vertical:
http://802.11junk.com/jeffl/WWVB%20test/loopstick-vertical.jpg
Pure noise and no signal.

Bottom line is that the loopstick should be mounted horizontally and
perpendicular to Ft Collins CO. Vertical mounting does NOT work.


Interesting. I have the Time Machine and the Time Machine with a projection
clock. With the loopsticks vertical, neither has yet lost sync
That is... the sync annunciator (or what I interpret to be the sync
annunciator) in the display is still visible.

I suspect the loss of lock delay is rather long. It would not do to
have the sync indicator flashing on and off as the signal fades in and
out. Besides, the receiver is only powered on for 5 minutes. If you
don't mind tearing it apart, just ground the PON (power on) line, and
monitor the output with an oscilloscope. No need to use the sync
indicator.

Incidentally, with a 1 baud data rate, an LED attached to the data
line should give a tolerable visual indication of signal quality. On
the Temic[1] chip, the output is rather high impedance, so something
like a CMOS buffer will be needed.
http://psn.quake.net/wwvbsdr.html
I might modify mine into something like that when I have time.

Both show the same time, which is unlikely if either had lost sync.

I beg to differ. Reception could be miserable and the sync indicator
probably won't show a problem for 24 hours. I think (not sure) that
it really means that it hasn't received an update for 24 hrs.

"Of course" an antenna's orientation should match the signal's. Why the La
Crosse only works when it doesn't, and it doesn't seem to matter for the
Oregon Scientific products -- I don't know.

I've seen worse RF design mistakes. I couldn't find a teardown of the
WS-811561 or any similar La Crosse radio clock. One possible problem
is that it's impossible to test a WWVB clock in China as the signal
doesn't go that far. It's possible that they designed and tested it
using a simulator, which will not have the cross polarization problem.
Just guessing.


[1] Temic was bought by Atmel in 1998:
http://www.cpushack.com/2011/02/05/atmel-buys-mhs-again-the-twisted-history-of-atmel-temic-and-mhs/

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558