digital clock near cable box always gaining minutes per mont

[Sam Seagate]

I have three digital clocks in my home that are located in various
rooms. Two of them have accurate timing and may gain or lose a minute
in a year, but the one in the living room near the cable box/ tv gains
3-4 minutes a month. My guess is that its frequency circuit is
interfered with from the cable system. First instinct would be to move
the clock, but unfortunately there is limited space and I can't. Is
there anything I can to do get more accuracy? During my initial
research, I came across postings suggesting adding a low pass filter on
the incoming line to the clock, but not sure.

Any helpful suggestions would be welcome.

Thanks,
Sam

 

[Leif Neland]

Sam Seagate formulerede spørgsmület:

I have three digital clocks in my home that are located in various rooms.
Two of them have accurate timing and may gain or lose a minute in a year, but
the one in the living room near the cable box/ tv gains 3-4 minutes a month.

Have you tried swapping the clocs around, so you know if it is the
clock or the location which is the source of the problem?

--
Je suis Charlie

 

[Pat]

On Mon, 09 Mar 2015 06:34:52 -0400, Sam Seagate
<sseagate55094@yahoo.com> wrote:

I have three digital clocks in my home that are located in various
rooms. Two of them have accurate timing and may gain or lose a minute
in a year, but the one in the living room near the cable box/ tv gains
3-4 minutes a month. My guess is that its frequency circuit is
interfered with from the cable system. First instinct would be to move
the clock, but unfortunately there is limited space and I can't. Is
there anything I can to do get more accuracy? During my initial
research, I came across postings suggesting adding a low pass filter on
the incoming line to the clock, but not sure.

Any helpful suggestions would be welcome.

Thanks,
Sam

Most inexpensive clocks count the cycles (frequency) of their power
source. Excessive noise on the line can cause extra cycles to be
counted. The power supply in the cable box could be adding noise to
the power line. If so, a filter can help with that. Technically, it
would be a low pass filter (as you said) because it lets through the
60 Hz (or 50 Hz) power, but filters the higher frequency noise.
However, you might have trouble finding something appropriate called
that because the term loss pass filter is used for RF applications.
Search for power line noise filters.

 

[mike]

On 3/9/2015 6:45 AM, Pat wrote:

On Mon, 09 Mar 2015 06:34:52 -0400, Sam Seagate
sseagate55094@yahoo.com> wrote:

I have three digital clocks in my home that are located in various
rooms. Two of them have accurate timing and may gain or lose a minute
in a year, but the one in the living room near the cable box/ tv gains
3-4 minutes a month. My guess is that its frequency circuit is
interfered with from the cable system. First instinct would be to move
the clock, but unfortunately there is limited space and I can't. Is
there anything I can to do get more accuracy? During my initial
research, I came across postings suggesting adding a low pass filter on
the incoming line to the clock, but not sure.

Any helpful suggestions would be welcome.

Thanks,
Sam

Most inexpensive clocks count the cycles (frequency) of their power
source. Excessive noise on the line can cause extra cycles to be
counted. The power supply in the cable box could be adding noise to
the power line. If so, a filter can help with that. Technically, it
would be a low pass filter (as you said) because it lets through the
60 Hz (or 50 Hz) power, but filters the higher frequency noise.
However, you might have trouble finding something appropriate called
that because the term loss pass filter is used for RF applications.
Search for power line noise filters.

I don't doubt that you can come up with an example, but I think it's
unlikely that the average digital clock works that way.

I think it's unlikely that the cable box is interfering.

If the clock synchronizes with WWVL, the location may interfere
with acquiring that signal.

I'd wager the clock is busted.
Move it and see.

 

[Phil Allison]

Pat wrote:

I am not talking about "atomic clocks". I am talking about regular
old clocks like people sit on their nightstands. Most of them sync to
the power line frequency. By most, I mean over 90%. Many have
battery backup and keep lousy time when running on battery.

I think it's unlikely that the cable box is interfering.

If the clock synchronizes with WWVL, the location may interfere
with acquiring that signal.

** Even that is very unlikely, given the OP's story, as the transmission is modulated with a code that regularly tells the clock what time it is.

Which is not consistent with a steady loss or gain.



.... Phil

 

[micky]

On Mon, 09 Mar 2015 12:25:16 -0700, mike <ham789@netzero.net> wrote:

On 3/9/2015 6:45 AM, Pat wrote:
On Mon, 09 Mar 2015 06:34:52 -0400, Sam Seagate
sseagate55094@yahoo.com> wrote:

I have three digital clocks in my home that are located in various
rooms. Two of them have accurate timing and may gain or lose a minute
in a year, but the one in the living room near the cable box/ tv gains
3-4 minutes a month. My guess is that its frequency circuit is
interfered with from the cable system. First instinct would be to move
the clock, but unfortunately there is limited space and I can't. Is
there anything I can to do get more accuracy? During my initial
research, I came across postings suggesting adding a low pass filter on
the incoming line to the clock, but not sure.

Any helpful suggestions would be welcome.

Thanks,
Sam

Most inexpensive clocks count the cycles (frequency) of their power
source. Excessive noise on the line can cause extra cycles to be
counted. The power supply in the cable box could be adding noise to
the power line. If so, a filter can help with that. Technically, it
would be a low pass filter (as you said) because it lets through the
60 Hz (or 50 Hz) power, but filters the higher frequency noise.
However, you might have trouble finding something appropriate called
that because the term loss pass filter is used for RF applications.
Search for power line noise filters.

I don't doubt that you can come up with an example, but I think it's
unlikely that the average digital clock works that way.

I think it's unlikely that the cable box is interfering.

If the clock synchronizes with WWVL, the location may interfere

I think only a smal fraction of clocks work that way, "In 2011, NIST
estimated the number of radio clocks and wristwatches equipped with a
WWVB receiver at over 50 million.[3]" http://en.wikipedia.org/wiki/WWVB

I have 12 clocks and watches and if the average person has only 4,
that's 1.2 billion in the US alone, 50+ million of which use WWVB.

with acquiring that signal.

I'd wager the clock is busted.
Move it and see.

 

[amdx]

Dang newfangled devices, mom had the same clock on the kitchen wall for
45 years. I oiled once in 1972 cause it got noisy. Did I mention grama
Pillars had it about 10 years before mom put on the kitchen wall.
Mikek




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This email has been checked for viruses by Avast antivirus software.
http://www.avast.com

 

[Pat]

On Mon, 09 Mar 2015 12:25:16 -0700, mike <ham789@netzero.net> wrote:

On 3/9/2015 6:45 AM, Pat wrote:
On Mon, 09 Mar 2015 06:34:52 -0400, Sam Seagate
sseagate55094@yahoo.com> wrote:

I have three digital clocks in my home that are located in various
rooms. Two of them have accurate timing and may gain or lose a minute
in a year, but the one in the living room near the cable box/ tv gains
3-4 minutes a month. My guess is that its frequency circuit is
interfered with from the cable system. First instinct would be to move
the clock, but unfortunately there is limited space and I can't. Is
there anything I can to do get more accuracy? During my initial
research, I came across postings suggesting adding a low pass filter on
the incoming line to the clock, but not sure.

Any helpful suggestions would be welcome.

Thanks,
Sam

Most inexpensive clocks count the cycles (frequency) of their power
source. Excessive noise on the line can cause extra cycles to be
counted. The power supply in the cable box could be adding noise to
the power line. If so, a filter can help with that. Technically, it
would be a low pass filter (as you said) because it lets through the
60 Hz (or 50 Hz) power, but filters the higher frequency noise.
However, you might have trouble finding something appropriate called
that because the term loss pass filter is used for RF applications.
Search for power line noise filters.

I don't doubt that you can come up with an example, but I think it's
unlikely that the average digital clock works that way.

I am not talking about "atomic clocks". I am talking about regular
old clocks like people sit on their nightstands. Most of them sync to
the power line frequency. By most, I mean over 90%. Many have
battery backup and keep lousy time when running on battery.

I think it's unlikely that the cable box is interfering.

If the clock synchronizes with WWVL, the location may interfere
with acquiring that signal.

WWVL has been off the air over 40 years ago. I think you mean WWVB.
But, the OP never mentioned it was that type of clock. However, if it
is, use are right about location and RF noise being the likely
problem.

I'd wager the clock is busted.
Move it and see.

 

[Jeff Liebermann]

On Mon, 09 Mar 2015 06:34:52 -0400, Sam Seagate
<sseagate55094@yahoo.com> wrote:

I have three digital clocks in my home that are located in various
rooms. Two of them have accurate timing and may gain or lose a minute
in a year, but the one in the living room near the cable box/ tv gains
3-4 minutes a month.

Exchange either of the working clocks with the one in the living room
and see if the problem remains with the clock or the location. Repair
by substitution is a well known technique.

My guess is that its frequency circuit is
interfered with from the cable system.

Nope. Cable modems operate at 50-1000 MHz at signal levels that are
unlikely to interfere with your unspecified maker and model of digital
clock. Similarly, the signals on the cable system are much higher
than the 50/60 Hz clock frequency used by the clock. Were it possible
for a cable box to radiate a signal sufficient to affect a digital
clock, it would never pass FCC incidental radiation testing.

First instinct would be to move
the clock, but unfortunately there is limited space and I can't.

I think you'll find an AC extension cord to be a useful tool for
testing.

>Is there anything I can to do get more accuracy?

Certainly. You can accurately disclose the maker and model number of
the various clocks and nearby devices so that we can better guess what
you have happening.

During my initial
research, I came across postings suggesting adding a low pass filter on
the incoming line to the clock, but not sure.

That might be a good fix AFTER you determine if it's the location of
the specific clock that's the problem. The fix usually follows the
diagnosis, not the other way around.

For AC power, there are two types of radiation, conducted and
radiated. Your clock might be overly sensitive to either or both.

Conducted noise and signals arrive via the AC power line, which then
drives the counter in your digital clock. This noise and spurious
signals come from any device plugged into the AC power line. Motor
noise is most commonly known to cause clocks to miss or add a few
beats. Powerline intercoms, switching power supplies, ferroresonant
line regulators, DC desk lamps, light dimmers, electronic ballasts,
and other powered devices that might inject noise, signals, or
distortion onto the 50/60 Hz power line, can all be potential
culprits.

It might also be radiated noise and signals. For example, some AC
transformers have a substantial radiated field. I had an antenna
rotator control box that was good for adding about a minute to a
nearby digital clock while it was turning the rotator. It might also
be that your unspecified model clock is more sensitive to these fields
that your other clocks. Try moving the clock away from anything with
a power supply or wall wart.

There are various pieces of test equipment and procedures that can be
used to identify potential sources of noise or interfering signals. I
don't want to recommend anything with so little information as it will
surely be a waste of time. However, if you want to go sniffing,
borrow or rent a "power quality meter" and see what's on your AC power
line.
<https://www.google.com/search?q=power+quality+monitor&tbm=isch>
If you see glitches like these:
<http://www.powersight.com/HTML/PRODUCTS/Software/PSM-i%20Power%20Quality.html>
<http://reliabilityweb.com/index.php/print/Dont_Underestimate_PQs_Impact_on_Reliability_and_Process_Uptime>
on your AC power, there's your likely culprit.

--
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

 

[Trevor Wilson]

On 10/03/2015 10:26 AM, Pat wrote:

On Mon, 09 Mar 2015 12:25:16 -0700, mike <ham789@netzero.net> wrote:



I am not talking about "atomic clocks". I am talking about regular
old clocks like people sit on their nightstands. Most of them sync to
the power line frequency. By most, I mean over 90%. Many have
battery backup and keep lousy time when running on battery.

**Some may do so. Back in 1994, I visited the US. Part of my mission was
to buy SWMBO (was my girlfriend at the time) a decent clock radio. I
went to Walmart and asked the assistant to show me a Sony I liked the
look of (Australian price - $125.00, US price - $29.95). Here in AUS our
line frequency is 50Hz, so converting a US clock radio can be a
challenge (given the value of the product). I plugged it in, set the
time, then unplugged for a couple of minutes. The time was still
correct. I, therefore, determined it probably used a crystal locked
frequency source (hardly surprising, given the fact that the clock radio
is microprocessor controlled). When I got it back home, I swapped out
the power transformer for a 240VAC unit and the clock radio is still
running perfectly today. It keeps almost perfect time (it gets adjusted
for daylight savings time each year), even after the rare blackout
lasting several hours.

And yes, it does use a proper crystal for time-keeping.




--
Trevor Wilson
www.rageaudio.com.au

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[isw]

In article <mdks25$726$1@dont-email.me>, mike <ham789@netzero.net>
wrote:

On 3/9/2015 6:45 AM, Pat wrote:
On Mon, 09 Mar 2015 06:34:52 -0400, Sam Seagate
sseagate55094@yahoo.com> wrote:

I have three digital clocks in my home that are located in various
rooms. Two of them have accurate timing and may gain or lose a minute
in a year, but the one in the living room near the cable box/ tv gains
3-4 minutes a month. My guess is that its frequency circuit is
interfered with from the cable system. First instinct would be to move
the clock, but unfortunately there is limited space and I can't. Is
there anything I can to do get more accuracy? During my initial
research, I came across postings suggesting adding a low pass filter on
the incoming line to the clock, but not sure.

Any helpful suggestions would be welcome.

Thanks,
Sam

Most inexpensive clocks count the cycles (frequency) of their power
source. Excessive noise on the line can cause extra cycles to be
counted. The power supply in the cable box could be adding noise to
the power line. If so, a filter can help with that. Technically, it
would be a low pass filter (as you said) because it lets through the
60 Hz (or 50 Hz) power, but filters the higher frequency noise.
However, you might have trouble finding something appropriate called
that because the term loss pass filter is used for RF applications.
Search for power line noise filters.

I don't doubt that you can come up with an example, but I think it's
unlikely that the average digital clock works that way.

If the clock is in a box that plugs into an outlet (oven, microwave, TV,
VCR back in the day), odds are that it counts cycles of the power line.

It's easy to tell; just set it precisely and then monitor it for a few
weeks. If it keeps "perfect" time, it uses the power line; if it slowly
drifts ahead or behind, it's using a crystal for a time base.

Isaac

 

[Leif Neland]

Phil Allison sendte dette med sin computer:

Pat wrote:

I am not talking about "atomic clocks". I am talking about regular
old clocks like people sit on their nightstands. Most of them sync to
the power line frequency. By most, I mean over 90%. Many have
battery backup and keep lousy time when running on battery.

I think it's unlikely that the cable box is interfering.

If the clock synchronizes with WWVL, the location may interfere
with acquiring that signal.


** Even that is very unlikely, given the OP's story, as the transmission is
modulated with a code that regularly tells the clock what time it is.

Which is not consistent with a steady loss or gain.

Unless the clock is unable to synchronize, and therefore are
free-running.

My digital radio-controlled clocks are only sync'ing once every 24
hours, usually at 3am, where the radiowaves supposedly travel the best
and the noise is the lowest.

Btw, I've had an analog (i.e. with hands, not digits) clock.
It's funny to see it change time in and out of DST; the hands spin
around like crazy, moving either 1 or 11 hours ahead in a few minutes.

Leif

--
Je suis Charlie

 

[mike]

On 3/9/2015 4:38 PM, Phil Allison wrote:

Pat wrote:

I am not talking about "atomic clocks". I am talking about regular
old clocks like people sit on their nightstands. Most of them sync to
the power line frequency. By most, I mean over 90%. Many have
battery backup and keep lousy time when running on battery.

I think it's unlikely that the cable box is interfering.

If the clock synchronizes with WWVL, the location may interfere
with acquiring that signal.


** Even that is very unlikely, given the OP's story, as the transmission is modulated with a code that regularly tells the clock what time it is.

Which is not consistent with a steady loss or gain.



... Phil

I had to move an atomic clock because the clock couldn't sync with WWVB
in that location. Don't know whether it was interference or plain old
loss of signal...and I didn't care. I moved the clock.

 

[micky]

On Mon, 09 Mar 2015 17:29:44 -0500, amdx <nojunk@knology.net> wrote:

Dang newfangled devices, mom had the same clock on the kitchen wall for
45 years. I oiled once in 1972 cause it got noisy. Did I mention grama
Pillars had it about 10 years before mom put on the kitchen wall.
Mikek

I know what you mean. My mother had a clock that also had a 60 minute
timer since before I was born. Maybe when it was 50 years old it
stopped working but I found the motor part (that say between the two
poles of the electromagnet, copper colored with a cupola on one side and
one simple gear coming out the other side. I replaced that, cleaned
everything on the face of the clock, cleaned the dirt out of the grooves
on the knob, and it looked and worked good as new. I have it now but
I'm not using it.

I don't know what I'm waiting for. The microwave has a timer but it
beeps so quietly I can't hear it when the tv or radio is on, and one
always is. Nor can I use the timer when I'm cooking in the microwave.

The stove has a timer too, analog, but harder to read and harder to set.

 

[Michael Black]

On Tue, 10 Mar 2015, mike wrote:

On 3/9/2015 4:38 PM, Phil Allison wrote:
Pat wrote:

I am not talking about "atomic clocks". I am talking about regular
old clocks like people sit on their nightstands. Most of them sync to
the power line frequency. By most, I mean over 90%. Many have
battery backup and keep lousy time when running on battery.

I think it's unlikely that the cable box is interfering.

If the clock synchronizes with WWVL, the location may interfere
with acquiring that signal.


** Even that is very unlikely, given the OP's story, as the transmission is
modulated with a code that regularly tells the clock what time it is.

Which is not consistent with a steady loss or gain.



... Phil



I had to move an atomic clock because the clock couldn't sync with WWVB in
that location. Don't know whether it was interference or plain old
loss of signal...and I didn't care. I moved the clock.

Orientation is important, at least when you're out near the limits of
coverage. I thought it mattered to be near a window, but sometimes I've
forgotten to take my watch off and so long as I orient it properly at the
bedside, it syncs up fine.

I have four clocks and 1 watch, and I can't think of a time when they all
missed the signal the same night.

Michael

 

[Michael Black]

On Tue, 10 Mar 2015, Leif Neland wrote:

Phil Allison sendte dette med sin computer:
Pat wrote:

I am not talking about "atomic clocks". I am talking about regular
old clocks like people sit on their nightstands. Most of them sync to
the power line frequency. By most, I mean over 90%. Many have
battery backup and keep lousy time when running on battery.

I think it's unlikely that the cable box is interfering.

If the clock synchronizes with WWVL, the location may interfere
with acquiring that signal.


** Even that is very unlikely, given the OP's story, as the transmission is
modulated with a code that regularly tells the clock what time it is.
Which is not consistent with a steady loss or gain.
Unless the clock is unable to synchronize, and therefore are free-running.

My digital radio-controlled clocks are only sync'ing once every 24 hours,
usually at 3am, where the radiowaves supposedly travel the best and the noise
is the lowest.

WWVB is at 60KHz because groundwave reception is very wide. So
transmission is generally reliable, unlike higher frequencies that might
vary with time.

The clocks have generally picked 3am because with most people asleep, a
lot less local electronics is on. It would be mostly sleeping power
supplies, rather than the equipment turned on.

My Casio Wavecepter starts checking the time at midnight, and will try on
the hour until it gets a signal. SO long as I have taken it off and put
it on its stand early enough, it generally syncs up at midnight, though if
it misses, it has other chances still. The clocks do only seem to do it
at 3am, so they can miss the sync.

Michael

 

[Jeff Liebermann]

On Tue, 10 Mar 2015 08:45:44 -0700, mike <ham789@netzero.net> wrote:

I had to move an atomic clock because the clock couldn't sync with WWVB
in that location. Don't know whether it was interference or plain old
loss of signal...and I didn't care. I moved the clock.

Probably a mixture of both. Switching power supplies that operate
around 60 KHz can cause problems. Positioning of the WWVB receive
antenna is also somewhat critical. If you're in a bad signal area,
you might have problems getting updates. Mine has to be across the
room from the computers or it doesn't work. You can check if your
area is having signal strength problems at:
<http://tf.nist.gov/tf-cgi/wwvbmonitor_e.cgi>
(Java required).


--
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

 

[Pat]

On Tue, 10 Mar 2015 14:01:10 -0400, Michael Black <et472@ncf.ca>
wrote:

My Casio Wavecepter starts checking the time at midnight, and will try on
the hour until it gets a signal.

Michael

Mine always starts checking at 4:00 am. 99% of the time, the last
synced time is 4:03AM on the day I am checking. I wonder why mine is
different than yours. Does it vary by time zone? I am in the eastern
time zone so at 4:00 am, it is well past midnight along the entire
signal path.

Pat

 

[amdx]

On 3/10/2015 11:23 AM, micky wrote:

On Mon, 09 Mar 2015 17:29:44 -0500, amdx <nojunk@knology.net> wrote:

Dang newfangled devices, mom had the same clock on the kitchen wall for
45 years. I oiled once in 1972 cause it got noisy. Did I mention grama
Pillars had it about 10 years before mom put on the kitchen wall.
Mikek

I know what you mean. My mother had a clock that also had a 60 minute
timer since before I was born. Maybe when it was 50 years old it
stopped working but I found the motor part (that say between the two
poles of the electromagnet, copper colored with a cupola on one side and
one simple gear coming out the other side. I replaced that, cleaned
everything on the face of the clock, cleaned the dirt out of the grooves
on the knob, and it looked and worked good as new. I have it now but
I'm not using it.

Ya, when I went home one Christmas and saw the clock was gone, I was
disappointed, I would have attempted a repair, just because.
Mikek

 

[Michael Black]

On Tue, 10 Mar 2015, Pat wrote:

On Tue, 10 Mar 2015 14:01:10 -0400, Michael Black <et472@ncf.ca
wrote:


My Casio Wavecepter starts checking the time at midnight, and will try on
the hour until it gets a signal.

Michael

Mine always starts checking at 4:00 am. 99% of the time, the last
synced time is 4:03AM on the day I am checking. I wonder why mine is
different than yours. Does it vary by time zone? I am in the eastern
time zone so at 4:00 am, it is well past midnight along the entire
signal path.

Pat

Then it can't be timezone. I'm in the east too. I recall the manual even
stating it starts checking at midnight.

Try watching it at midnight, there will be an indicator that it's
checking. Maybe you have local noise so it doesn't sync up until 4am. It
will check on the hour until it does sync (well I dont' think it keeps
checking after a certain hour, but I don't know when it stops).

Mine is 8 or 9 years old, I got it for $20 at a department store. Maybe
they've changed the design in more recent times. WWVB has changed it's
format, so now one can get the time signal with a non-AM format of
modulation. Newer receivers are supposed to use the newer format.

Michael