atomic clocks

  • Thread starter William Sommerwerck
  • Start date
"Jeff Liebermann" wrote in message
news:njvcq95icpvggqrvt4vp5vl7u3c43re09d@4ax.com...

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).
Click to expand...

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.
Click to expand...

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

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 křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.
 
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.
Click to expand...

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
 
On Sun, 22 Jun 2014 07:04:46 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> 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.
Click to expand...

<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.
Click to expand...

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 jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
"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.
Click to expand...

Big hand or small hand?


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

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.
Click to expand...

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.
 
"Jeff Liebermann" wrote in message
news:kvrdq9551svvf6uoviead134umo8pgb66q@4ax.com...

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.
Click to expand...

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.
 
"Leif Neland" wrote in message news:mn.b3eb7de6c7e48bab.130671@neland.dk...

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.
Click to expand...

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 křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.
 
"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lo4k3p$ng8$1@dont-email.me...
"N_Cook" wrote in message news:lo4ic7$auq$1@dont-email.me...
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.
Click to expand...

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.
 
"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:5ojcq9lcf3ag4penuar9j83aj3g844dfta@4ax.com...
On Sat, 21 Jun 2014 23:19:11 -0400, Michael Black <et472@ncf.ca
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
Click to expand...

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.
 
On Sun, 22 Jun 2014, Ian Field wrote:

"William Sommerwerck" <grizzledgeezer@comcast.net> wrote in message
news:lo4k3p$ng8$1@dont-email.me...
"N_Cook" wrote in message news:lo4ic7$auq$1@dont-email.me...
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.
Click to expand...
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
 
"Bruce Esquibel" <bje@ripco.com> wrote in message
news:lo6eoe$c67$1@remote5bge0.ripco.com...
William Sommerwerck <grizzledgeezer@comcast.net> 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.
Click to expand...

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.
 
On Sun, 22 Jun 2014, Ian Field wrote:

"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:5ojcq9lcf3ag4penuar9j83aj3g844dfta@4ax.com...
On Sat, 21 Jun 2014 23:19:11 -0400, Michael Black <et472@ncf.ca
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.
Click to expand...
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
 
"Michael Black" <et472@ncf.ca> wrote in message
news:alpine.LNX.2.02.1406221335020.23870@darkstar.example.org...
On Sun, 22 Jun 2014, Ian Field wrote:



"Jeff Liebermann" <jeffl@cruzio.com> wrote in message
news:5ojcq9lcf3ag4penuar9j83aj3g844dfta@4ax.com...
On Sat, 21 Jun 2014 23:19:11 -0400, Michael Black <et472@ncf.ca
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.
Click to expand...

I didn't need glasses when I bought the Casio - but I'd notice if most of
the symbol was missing.
 
On Sun, 22 Jun 2014 09:07:46 -0700, "William Sommerwerck"
<grizzledgeezer@comcast.net> 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.
Click to expand...

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.
Click to expand...

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 jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
"Michael Black" <et472@ncf.ca> 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.
Click to expand...

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
Click to expand...
 
"Leif Neland" <leif@neland.dk> wrote in message
news:mn.b3eb7de6c7e48bab.130671@neland.dk...
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. :)
Click to expand...

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 křrelys bagpĺ, hvis din bilfabrikant har taget den idiotiske
beslutning at undlade det.
Click to expand...
 
On Sun, 22 Jun 2014 00:23:47 -0700, Jeff Liebermann <jeffl@cruzio.com>
wrote:

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

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 jeffl@cruzio.com
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558
 
"Jeff Liebermann" wrote in message
news:10qeq95jchlhr6rhvg8vtimnq10j12in1p@4ax.com...

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.
Click to expand...

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.
 
"Jeff Liebermann" wrote in message
news:1skfq9pr23olbr1e0793glaavhhod4v8hg@4ax.com...

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.
 
"Arfa Daily" <arfa.daily@ntlworld.com> wrote in message
news:NsKpv.56803$7m3.46486@fx11.am4...
"Leif Neland" <leif@neland.dk> wrote in message
news:mn.b3eb7de6c7e48bab.130671@neland.dk...
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
Click to expand...

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.
 
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