radio time code clock error

[N_Cook]

Anyone any insight into this error? Yesterday , coincidently? the
longest day. Set the alarm function for 06:30. Luckily woke just after
06:00 and decided to get up . Synchronous mains clock read 06:08 but
radio-code clock read 04:08, minute and seconds agreeing with another
radio-code clock but it had decided to go east 2 time zones. Still like
that about 07:00 but on returning in the evening the erroneous clock had
reset itself. How to predict when this error will reoccur? any
amelioration, plenty of LCD contrast so presumably the batteries are ok?

 

[Jeff Liebermann]

On Mon, 22 Jun 2015 07:40:09 +0100, N_Cook <diverse@tcp.co.uk> wrote:

Anyone any insight into this error? Yesterday , coincidently? the
longest day. Set the alarm function for 06:30. Luckily woke just after
06:00 and decided to get up . Synchronous mains clock read 06:08 but
radio-code clock read 04:08, minute and seconds agreeing with another
radio-code clock but it had decided to go east 2 time zones. Still like
that about 07:00 but on returning in the evening the erroneous clock had
reset itself. How to predict when this error will reoccur? any
amelioration, plenty of LCD contrast so presumably the batteries are ok?

Nope. My clocks are just fine. Sometimes my WWVB based clocks go
nuts from RF noise in the shop. They then reset themselves after
midnight, when 60 KHz propagation is best. In the UK, you're probably
using MSF.
<http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/msf-radio-time-signal>
They do have some scheduled outages, but that's not the problem this
time:
<http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/msf-outages>
Offhand, I would guess(tm) that your unspecified model radio clock has
a dying battery. My various clocks do some rather strange things when
the battery is low.

You might want to fasten your seat belt on June 30th.
<http://www.dailymail.co.uk/sciencetech/article-3131840/The-longest-day-Leap-second-make-61-second-minute-end-June-experts-warn-break-internet.html>
<http://www.wired.com/2015/01/leap-second-rattle-internet-theres-plot-kill/>
<http://money.cnn.com/2015/01/13/technology/leap-second/>
The good news is that you'll get an extra second of sleep during the
night of June 30th.

More:
<http://www.leapsecond.com/java/nixie.htm>
<http://802.11junk.com/jeffl/crud/GPS-vs-UTC.jpg>

At the tone, the time will be:
<http://www.leapsecond.com/java/gpsclock.htm>
Ummm... never mind.

--
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

 

[N_Cook]

On 22/06/2015 08:16, Jeff Liebermann wrote:

On Mon, 22 Jun 2015 07:40:09 +0100, N_Cook <diverse@tcp.co.uk> wrote:

Anyone any insight into this error? Yesterday , coincidently? the
longest day. Set the alarm function for 06:30. Luckily woke just after
06:00 and decided to get up . Synchronous mains clock read 06:08 but
radio-code clock read 04:08, minute and seconds agreeing with another
radio-code clock but it had decided to go east 2 time zones. Still like
that about 07:00 but on returning in the evening the erroneous clock had
reset itself. How to predict when this error will reoccur? any
amelioration, plenty of LCD contrast so presumably the batteries are ok?

Nope. My clocks are just fine. Sometimes my WWVB based clocks go
nuts from RF noise in the shop. They then reset themselves after
midnight, when 60 KHz propagation is best. In the UK, you're probably
using MSF.
http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/msf-radio-time-signal
They do have some scheduled outages, but that's not the problem this
time:
http://www.npl.co.uk/science-technology/time-frequency/products-and-services/time/msf-outages
Offhand, I would guess(tm) that your unspecified model radio clock has
a dying battery. My various clocks do some rather strange things when
the battery is low.

You might want to fasten your seat belt on June 30th.
http://www.dailymail.co.uk/sciencetech/article-3131840/The-longest-day-Leap-second-make-61-second-minute-end-June-experts-warn-break-internet.html
http://www.wired.com/2015/01/leap-second-rattle-internet-theres-plot-kill/
http://money.cnn.com/2015/01/13/technology/leap-second/
The good news is that you'll get an extra second of sleep during the
night of June 30th.

More:
http://www.leapsecond.com/java/nixie.htm
http://802.11junk.com/jeffl/crud/GPS-vs-UTC.jpg

At the tone, the time will be:
http://www.leapsecond.com/java/gpsclock.htm
Ummm... never mind.

Not specified as litterally no name/model on it. Casio watch, I
compared it to , was fine . At least I now know not to rely on
"no-name" and use it in alarm mode with another alarm clock. If it went
erroneous "to the west" it would not be so problematic

 

[Ralph Mowery]

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:mm8aj3$o5i$1@dont-email.me...

Anyone any insight into this error? Yesterday , coincidently? the longest
day. Set the alarm function for 06:30. Luckily woke just after 06:00 and
decided to get up . Synchronous mains clock read 06:08 but radio-code
clock read 04:08, minute and seconds agreeing with another radio-code
clock but it had decided to go east 2 time zones. Still like that about
07:00 but on returning in the evening the erroneous clock had reset
itself. How to predict when this error will reoccur? any amelioration,
plenty of LCD contrast so presumably the batteries are ok?

As the minuits agree, but the hours are off, I would look for a setting as
to which time zone the clock is set for.

 

[malua mada!]

I have an Oregon Scientific alarm clock that has five prominent buttons on its face: Clock, UP, DOWN, ALARM, ZONE.

I have hit the zone button by mistake before.
It steps through the 4 US time zones.

 

[N_Cook]

On 22/06/2015 14:59, Ralph Mowery wrote:

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:mm8aj3$o5i$1@dont-email.me...
Anyone any insight into this error? Yesterday , coincidently? the longest
day. Set the alarm function for 06:30. Luckily woke just after 06:00 and
decided to get up . Synchronous mains clock read 06:08 but radio-code
clock read 04:08, minute and seconds agreeing with another radio-code
clock but it had decided to go east 2 time zones. Still like that about
07:00 but on returning in the evening the erroneous clock had reset
itself. How to predict when this error will reoccur? any amelioration,
plenty of LCD contrast so presumably the batteries are ok?

As the minuits agree, but the hours are off, I would look for a setting as
to which time zone the clock is set for.

I've never seen an option to change country of use, or any legend like
LON for London as in the Casio. Automatically seems to selct UK , the
strongest signal? along with automatic daylight saving changes.
Just pressed reset to remind me that no country option comes up and
within 10 minutes had sync'd with the Casio , in effect.
Tried Google Images but this one not seen in the first 3 pages of pics
of silver desktop "radio controlled" LCD clocks

 

[N_Cook]

So perhaps that was the failure mechanism. Rugby went down for
maintainence or its signal got locally shadowed/echoed/interferred with
and if Darmstadt was a stronger/clearer? signal , perhaps reset itself
to CET time for a while. The Casio having a preset station option , it
may loose updating but it would not try to find another code source.

 

[N_Cook]

On 22/06/2015 16:25, N_Cook wrote:

So perhaps that was the failure mechanism. Rugby went down for
maintainence or its signal got locally shadowed/echoed/interferred with
and if Darmstadt was a stronger/clearer? signal , perhaps reset itself
to CET time for a while. The Casio having a preset station option , it
may loose updating but it would not try to find another code source.

Ah, CET is in advance of GMT (BST - 1 ) not behind, and I doubt there is
a transmitter for the Cape Verde Islands.

 

[Bob F]

N_Cook wrote:

Anyone any insight into this error? Yesterday , coincidently? the
longest day. Set the alarm function for 06:30. Luckily woke just after
06:00 and decided to get up . Synchronous mains clock read 06:08 but
radio-code clock read 04:08, minute and seconds agreeing with another
radio-code clock but it had decided to go east 2 time zones. Still
like that about 07:00 but on returning in the evening the erroneous
clock had reset itself. How to predict when this error will reoccur?
any amelioration, plenty of LCD contrast so presumably the batteries
are ok?

I have a clock that has been off by 1 or 2 hours a couple of times. I just
figured that it made a mistake interpreting the received signal, perhaps due to
interference. It has corrected by the next day each time.

 

[N_Cook]

On 23/06/2015 02:09, Bob F wrote:

N_Cook wrote:
Anyone any insight into this error? Yesterday , coincidently? the
longest day. Set the alarm function for 06:30. Luckily woke just after
06:00 and decided to get up . Synchronous mains clock read 06:08 but
radio-code clock read 04:08, minute and seconds agreeing with another
radio-code clock but it had decided to go east 2 time zones. Still
like that about 07:00 but on returning in the evening the erroneous
clock had reset itself. How to predict when this error will reoccur?
any amelioration, plenty of LCD contrast so presumably the batteries
are ok?

I have a clock that has been off by 1 or 2 hours a couple of times. I just
figured that it made a mistake interpreting the received signal, perhaps due to
interference. It has corrected by the next day each time.

Did the errors occur overnight or during the day when you could more
likely get local interference?
Looked inside and only identifying features are these overlay numbers on
the 2 boards
ykf14547 ad085220 ad085211
otherwise little more than 2 crystals and 2 black epoxy humps over RF
end and LCD handling SM chips

 

My "radio time code" system never fails: I have a shortwave
radio, tune in time signals at 5, 10, 15, or 20mHz, and set
all my clocks and watches at the beep.

Works like a charm!

 

[N_Cook]

On 23/06/2015 09:21, thekmanrocks@gmail.com wrote:

My "radio time code" system never fails: I have a shortwave
radio, tune in time signals at 5, 10, 15, or 20mHz, and set
all my clocks and watches at the beep.

Works like a charm!

How do you know if there is a digital relay link somewhere in the
transmission train?
I used to rely on the teletext time that came with the VITS of analogue
TV, but all gone belly-up with digital MUX. In the UK we have the
ridiculous business of the genuine radio pips relayed onto the "radio"
sections of MUX TV, can be up to 10 seconds out via the codec delays.

 

[Ralph Mowery]

"N_Cook" <diverse@tcp.co.uk> wrote in message
news:mmb5tv$9b6$1@dont-email.me...

On 23/06/2015 09:21, thekmanrocks@gmail.com wrote:
My "radio time code" system never fails: I have a shortwave
radio, tune in time signals at 5, 10, 15, or 20mHz, and set
all my clocks and watches at the beep.

Works like a charm!


How do you know if there is a digital relay link somewhere in the
transmission train?
I used to rely on the teletext time that came with the VITS of analogue
TV, but all gone belly-up with digital MUX. In the UK we have the
ridiculous business of the genuine radio pips relayed onto the "radio"
sections of MUX TV, can be up to 10 seconds out via the codec delays.

If using a short wave receiver the signal is being picked up direct from a
station in the US. The only delay is the time it takes for the signal to
get to you by radio which is around the earth about 7 times in one second
and the delay of the sound from the speaker to you rear.
Both are much faster than you cn hit a button on the clock to set the time.

 

[Jeroni Paul]

N_Cook wrote:

Anyone any insight into this error? Yesterday , coincidently? the
longest day. Set the alarm function for 06:30. Luckily woke just after
06:00 and decided to get up . Synchronous mains clock read 06:08 but
radio-code clock read 04:08, minute and seconds agreeing with another
radio-code clock but it had decided to go east 2 time zones. Still like
that about 07:00 but on returning in the evening the erroneous clock had
reset itself. How to predict when this error will reoccur? any
amelioration, plenty of LCD contrast so presumably the batteries are ok?

I live in a fringe reception area for the german time signal at 77.5kHz and have many clocks that use this signal but because a marginal reception they do not always sync. The curious thing about this is every night I have a different set of clocks sync, they seem to decide at random when the signal was good enough.

The oldest one is 13 years old and is an alarm clock I check daily, in these years I have had it three times take an incorrect time/date probably from interference. It either takes the right time or does not sync, three times in 13 years seems not bad for the simple parity bit protection the protocol uses.

I think, however, it is somewhat dangerous to have the clocks sync at night *after* you have checked they are set correctly, so if bad reception sets wrong data they will fail to wake you up at the right time.

 

Jeroni Paul wrote: "The oldest one is 13 years old and is an alarm clock I check daily,
in these years I have had it three times take an incorrect time/date probably from
interference. It either takes the right time or does not sync, three times in 13 years seems
not bad for the simple parity bit protection the protocol uses.

I think, however, it is somewhat dangerous to have the clocks sync at night *after* you have
checked they are set correctly, so if bad reception sets wrong data they will fail to wake you
up at the right time. "


Enough reasons for me not to use the freakin' things...

I've got the best time sync source of all, courtesy
the NIST and WWVB!

 

[Michael Black]

On Sat, 27 Jun 2015, Jeff Liebermann wrote:

On Sat, 27 Jun 2015 14:38:33 -0700 (PDT), Jeroni Paul
JERONI.PAUL@terra.es> wrote:

I live in a fringe reception area for the german time
signal at 77.5kHz

Spain? According the coverage map at:
http://www.ptb.de/cms/en/ptb/fachabteilungen/abt4/fb-44/ag-442/dissemination-of-legal-time/dcf77/reach-of-dcf77.html
Yes, the signal is probably not very strong and you're in the skywave
only region.

and have many clocks that use this signal but because
a marginal reception they do not always sync.

That sounds like the older amplitude modulated system. DCF77 also
transmits a phase modulated signal,
https://en.wikipedia.org/wiki/DCF77#Phase_modulation
which works better for weak signal due to better processing gain. I'm
in the USA and have not tried it with over-the-air DCF77, but have
played with simulators and with WWVB, which also has a phase modulated
BPSK signal. The problem is that the technology seems to be patented
and chips are not forthcoming. Also, the addition of BPSK modulation
caused some old WWVB receiver chips to fail. No clue what the
situation was with DCF77 but it might be worth checking.

The curious thing about this is every night I have a different set
of clocks sync, they seem to decide at random when the signal was
good enough.

Kinda sounds like you're getting some local interference. It doesn't
take much computah or switcher noise to trash the signal, especially
when it's weak in the first place. If your devices have a loopstick
for an antenna, they are directional, with the strongest signal
perpendicular to the loopstick. I was having random updates until I
moved my WWVB clock away from several switching power supplies.

The oldest one is 13 years old and is an alarm clock I check daily,
in these years I have had it three times take an incorrect time/date
probably from interference. It either takes the right time or does
not sync, three times in 13 years seems not bad for the simple parity
bit protection the protocol uses.

It's a bit more than just the parity bit. Some chips require that the
correct time be received successfully more than once before it will
sync. This is a function of the chip design.

I think, however, it is somewhat dangerous to have the clocks sync
at night *after* you have checked they are set correctly, so if
bad reception sets wrong data they will fail to wake you up at
the right time.

Sorry, but you don't have a choice as to what time to sync.
Propagation at VLF frequencies works best after midnight in the USA. I
think it's the same for a north-south path, but I'm not sure. Note
the increases in coverage area after midnight for WWVB:
http://tf.nist.gov/stations/wwvbcoverage.htm
http://www.febo.com/time-freq/wwvb/sig-strength/
I couldn't find something similar for DCF77.

I thought low frequencies were used by WWVB (and WWVL before it) because
it was all ground-wave, and well penetrating.

If it was on shortwave, you would be stuck with a given frequency for a
givne time, which of course is why WWV transmits on a bunch of
frequencies.

The reason I've seen for late night sync'ing (and which makes sense) is
that in the wee hours of the morning, fewer people are up, thus much less
manmade interference. So the CFLs are turned off, the tv sets are turned
off (probably a bigger issue when they were actually CRTs, all that
horizontal sync frequencies into the deflection coil), lots of other
things that might be on in the daytime are off so they aren't making as
much noise.

I've noticed this. My Casio Waveceptor watch starts looking at midnight
local time, and if I have the CFL on at the time, it likely doesn't sync
up, but will at a later hour (the watch is better than most of the clocks,
since it tries multiple times). COnversely, if I have the CFL off, it
generally will sync at midnight.

And I'm probably at the far edge of the reliable reception area.

Of course, with at least some of the clocks, one does have the option of
pressing button (or putting the batteries back in) so the clock tries to
sync up, no matter what time it is.

Michael

 

[Jeff Liebermann]

On Sat, 27 Jun 2015 14:38:33 -0700 (PDT), Jeroni Paul
<JERONI.PAUL@terra.es> wrote:

I live in a fringe reception area for the german time
signal at 77.5kHz

Spain? According the coverage map at:
<http://www.ptb.de/cms/en/ptb/fachabteilungen/abt4/fb-44/ag-442/dissemination-of-legal-time/dcf77/reach-of-dcf77.html>
Yes, the signal is probably not very strong and you're in the skywave
only region.

and have many clocks that use this signal but because
a marginal reception they do not always sync.

That sounds like the older amplitude modulated system. DCF77 also
transmits a phase modulated signal,
<https://en.wikipedia.org/wiki/DCF77#Phase_modulation>
which works better for weak signal due to better processing gain. I'm
in the USA and have not tried it with over-the-air DCF77, but have
played with simulators and with WWVB, which also has a phase modulated
BPSK signal. The problem is that the technology seems to be patented
and chips are not forthcoming. Also, the addition of BPSK modulation
caused some old WWVB receiver chips to fail. No clue what the
situation was with DCF77 but it might be worth checking.

The curious thing about this is every night I have a different set
of clocks sync, they seem to decide at random when the signal was
good enough.

Kinda sounds like you're getting some local interference. It doesn't
take much computah or switcher noise to trash the signal, especially
when it's weak in the first place. If your devices have a loopstick
for an antenna, they are directional, with the strongest signal
perpendicular to the loopstick. I was having random updates until I
moved my WWVB clock away from several switching power supplies.

The oldest one is 13 years old and is an alarm clock I check daily,
in these years I have had it three times take an incorrect time/date
probably from interference. It either takes the right time or does
not sync, three times in 13 years seems not bad for the simple parity
bit protection the protocol uses.

It's a bit more than just the parity bit. Some chips require that the
correct time be received successfully more than once before it will
sync. This is a function of the chip design.

I think, however, it is somewhat dangerous to have the clocks sync
at night *after* you have checked they are set correctly, so if
bad reception sets wrong data they will fail to wake you up at
the right time.

Sorry, but you don't have a choice as to what time to sync.
Propagation at VLF frequencies works best after midnight in the USA. I
think it's the same for a north-south path, but I'm not sure. Note
the increases in coverage area after midnight for WWVB:
<http://tf.nist.gov/stations/wwvbcoverage.htm>
<http://www.febo.com/time-freq/wwvb/sig-strength/>
I couldn't find something similar for DCF77.





--
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

 

[N_Cook]

On 27/06/2015 22:38, Jeroni Paul wrote:

N_Cook wrote:
Anyone any insight into this error? Yesterday , coincidently? the
longest day. Set the alarm function for 06:30. Luckily woke just after
06:00 and decided to get up . Synchronous mains clock read 06:08 but
radio-code clock read 04:08, minute and seconds agreeing with another
radio-code clock but it had decided to go east 2 time zones. Still like
that about 07:00 but on returning in the evening the erroneous clock had
reset itself. How to predict when this error will reoccur? any
amelioration, plenty of LCD contrast so presumably the batteries are ok?

I live in a fringe reception area for the german time signal at 77.5kHz and have many clocks that use this signal but because a marginal reception they do not always sync. The curious thing about this is every night I have a different set of clocks sync, they seem to decide at random when the signal was good enough.

The oldest one is 13 years old and is an alarm clock I check daily, in these years I have had it three times take an incorrect time/date probably from interference. It either takes the right time or does not sync, three times in 13 years seems not bad for the simple parity bit protection the protocol uses.

I think, however, it is somewhat dangerous to have the clocks sync at night *after* you have checked they are set correctly, so if bad reception sets wrong data they will fail to wake you up at the right time.

Have you had the situation of the displayed time jumping by an hour or two?
As an alarm clock, losing synch and drifting a second or two , to a
background quartz crystal clock, is no great problem

 

[Jeff Liebermann]

On Sat, 27 Jun 2015 23:37:42 -0400, Michael Black <et472@ncf.ca>
wrote:

I thought low frequencies were used by WWVB (and WWVL before it) because
it was all ground-wave, and well penetrating.

The skywave doesn't magically go away at lower frequencies. For
example, here's a study on hearing both WWVB and JJY (Japan) in
Germany, which certainly would require skywave propagation.
<http://df6nm.bplaced.net/LF/MSFgaps/MSFgaps.htm>
See 3rd graph from the top. Unfortunately, I've never bothered to do
any DXing on VLF, but have been told that it's possible to hear Europe
and Japan in California if the conditions are right. VLF DX list:
<http://www.dxinfocentre.com/time-vlf.htm>

Unlike HF (high freq) propagation, which is "bent" by the ionosphere
back towards the ground, VLF frequencies are reflected off the D
layer.
<http://vlf.stanford.edu/research/introduction-vlf>

If it was on shortwave, you would be stuck with a given frequency for a
givne time, which of course is why WWV transmits on a bunch of
frequencies.

Actually, VLF has the same problem. Beyond some distance (which
varies with antenna size and power level), the various time sync
stations become very sensitive to ionospheric layer conditions, which
is mostly controlled by the sun. During the day, skywave propagation
sucks, while ground wave is unaffected. However, when there's dark
over most of the distance between the transmitter and the receiver,
the skywave returns. More on how it works:
<http://solar-center.stanford.edu/SID/activities/ionosphere.html>

The reason I've seen for late night sync'ing (and which makes sense) is
that in the wee hours of the morning, fewer people are up, thus much less
manmade interference.

That would be so nice if it were true, but it's not. It's not man
made interference that causes most reception problems, it's lightning
and atmospheric RF noise that are extremely high at VLF frequencies.
See the graph at:
<https://en.wikipedia.org/wiki/Atmospheric_noise>
<https://en.wikipedia.org/wiki/Atmospheric_noise#/media/File:Atmosphericnoise.PNG>
At 60 KHz, the noise level is about 80dB above the normal thermal
noise. When designing a receiver for 60 KHz, the problem is not the
usual NF (noise figure) and gain, but rather being able to remain
linear and handle the overload produced by the noise. That's why you
often see VLF receiver front ends with heat sinks on the RF
transistors.

Incidentally, the high noise levels is also why you can get away with
using tiny antennas with loss instead of gain. A bigger antenna will
amplify the noise and the signal equally which doesn't improve things.
A bigger antenna also produces more voltage at the receiver input,
which has to handled by an increasingly higher voltage and power input
stage. However, what a bigger antenna might do is increase the Q of
the antenna (i.e. decrease the antenna bandwidth) which would pickup
less off frequency noise, which will help increase the SNR (signal to
noise ratio).

So the CFLs are turned off, the tv sets are turned
off (probably a bigger issue when they were actually CRTs, all that
horizontal sync frequencies into the deflection coil), lots of other
things that might be on in the daytime are off so they aren't making as
much noise.

Look again at the noise graph, and notice the red line added showing
man made noises. At 60 KHz, the man made noise is about equal to the
atmospheric noise.

If you want to pursue such a noise source survey, I suggest you build
a loop resonant at 60 KHz and plug into an oscilloscope looking for
noise. I suggest a very high Q magnetic loop so that it only picks up
noise very close to 60 KHz. Just about anything with a switching
power supply should show up as a noise source. I have some opinions
on CFL lamps, LED lamps, and plasma TVs which I'm not quite sure are
correct, so I'll not comment on those. Let's just say I have some
very quiet LED lamps and some VERY noisy LED lamps.

I've noticed this. My Casio Waveceptor watch starts looking at midnight
local time, and if I have the CFL on at the time, it likely doesn't sync
up, but will at a later hour (the watch is better than most of the clocks,
since it tries multiple times). COnversely, if I have the CFL off, it
generally will sync at midnight.

That sounds about right. The chip, usually made by C-Max uses an
algorithm to determine when to listen. The problem is battery life.
It makes no sense to listen during daylight hours, so it doesn't. If
it sync at midnight, it doesn't try again later. If it fails, it
retries according to some pattern. I used to have the link to the
details, but can't find it right now. This is close but not the one I
was looking for:
<http://www.c-max-time.com/tech/software6005.php>

>And I'm probably at the far edge of the reliable reception area.

Probably true with a wristwatch receiver or consumer device. Not true
with a proper loop antenna, which gets much better range. In the
early 1980's, I setup a WWVB receiver in an area infested with high
electrical noise. None of the commodity WWVB clocks would work. A
shielded loop antenna and overkill coax shielding did the trick.
Something like this, except my loop was circular and about 1 meter
wide:
<http://www.ka7oei.com/wwvb_antenna.html>

Of course, with at least some of the clocks, one does have the option of
pressing button (or putting the batteries back in) so the clock tries to
sync up, no matter what time it is.

I hacked one of clocks to do that so I could make measurements:
<http://802.11junk.com/jeffl/WWVB%20test/>
The receiver inside the antenna has an "enable" line to turn it on and
off. In this device, it's labeled PON. The clock/display/control
chip enables it according to the previously mentioned algorithm. I
tied the line high (after disconnecting it from the clock) so that it
would run continuously. It takes about 3 weeks to kill the two AAA
batteries when running continuously.

Clean signal that will decode correctly:
<http://802.11junk.com/jeffl/WWVB%20test/loopstick-perpendicular-to-WWVB.jpg>
Noisy signal that won't work:
<http://802.11junk.com/jeffl/WWVB%20test/end-pointed-at-WWVB.jpg>
<http://802.11junk.com/jeffl/WWVB%20test/loopstick-vertical.jpg>


--
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

 

[Phil Hobbs]

On 6/27/2015 10:26 PM, thekmanrocks@gmail.com wrote:

Jeroni Paul wrote: "The oldest one is 13 years old and is an alarm clock I check daily,
in these years I have had it three times take an incorrect time/date probably from
interference. It either takes the right time or does not sync, three times in 13 years seems
not bad for the simple parity bit protection the protocol uses.

I think, however, it is somewhat dangerous to have the clocks sync at night *after* you have
checked they are set correctly, so if bad reception sets wrong data they will fail to wake you
up at the right time. "


Enough reasons for me not to use the freakin' things...

I've got the best time sync source of all, courtesy
the NIST and WWVB!

Second best. They adjust those ones to match that yellow thing up in
the sky.

Cheers

Phil Hobbs

(We just had a leap second.)

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC
Optics, Electro-optics, Photonics, Analog Electronics

160 North State Road #203
Briarcliff Manor NY 10510

hobbs at electrooptical dot net
http://electrooptical.net