[time-nuts] How accurate are cheap radio controlled clocks?

[Dr. David Kirkby]

I've got one of the cheap radio-controlled clocks? I was listing to radio 4 the 
other day and herd the time signal. The radio controlled clock was about 3 
seconds off. I was a bit surprised it was so far off. I'm just wondering how 
accurate these things are.



--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Brooke Clarke]

Hi David:

I've got a number of the WWVB clocks and can see a few of them at the 
same time.  It's common that they disagree by a few seconds.


Have Fun,

Brooke Clarke
http://www.PRC68.com


Dr. David Kirkby wrote:
I've got one of the cheap radio-controlled clocks? I was listing to 
radio 4 the other day and herd the time signal. The radio controlled 
clock was about 3 seconds off. I was a bit surprised it was so far 
off. I'm just wondering how accurate these things are.





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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[J. Forster]

WWVB clocks look at the Time Code treansmitted by WWVB, not at the carrier
which is used for precision timing.

-John

==


> Hi David:
>
> I've got a number of the WWVB clocks and can see a few of them at the
> same time.  It's common that they disagree by a few seconds.
>
> Have Fun,
>
> Brooke Clarke
> http://www.PRC68.com
>
>
> Dr. David Kirkby wrote:
>> I've got one of the cheap radio-controlled clocks? I was listing to
>> radio 4 the other day and herd the time signal. The radio controlled
>> clock was about 3 seconds off. I was a bit surprised it was so far
>> off. I'm just wondering how accurate these things are.
>>
>>
>
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> time-nuts mailing list -- time-nuts@febo.com
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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Ron Smith]

I have two r-c clocks in the house and they both keep accurate time. One 
clock is made by KLIK, the other by STAIGER - both from ARGOS.


The second-hand moves at the very moment I hear the pip, or as exactly as 
the eye can tell. But I do not use Radio 4. Instead I check my times using 
the pip sequence from RWM's time service broadcasts on either 4.996 or 9.996 
MHz (good signal strengths in UK).


There is a danger with broadcasters these days that their studio source goes 
through digital buffering and will be subject to delays. The time difference 
between identical broadcasts via analogue circuits and digital circuits is 
in the order of two seconds.
BBC time pip accuracy can be checked by listening to them at the same time 
as listening to RWM.


Ron
G3SVW




- Original Message - 
From: "Dr. David Kirkby" 
To: "Discussion of precise time and frequency measurement" 


Sent: Saturday, June 25, 2011 8:19 PM
Subject: [time-nuts] How accurate are cheap radio controlled clocks?


I've got one of the cheap radio-controlled clocks? I was listing to radio 
4 the other day and herd the time signal. The radio controlled clock was 
about 3 seconds off. I was a bit surprised it was so far off. I'm just 
wondering how accurate these things are.



--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Eamon Skelton]

On 25/06/11 20:19, Dr. David Kirkby wrote:

I've got one of the cheap radio-controlled clocks? I was listing to
radio 4 the other day and herd the time signal. The radio controlled
clock was about 3 seconds off. I was a bit surprised it was so far off.
I'm just wondering how accurate these things are.


Typically better than 1s. If there is interference or the radio is disabled,
it won't be able to receive the time signal. Switch mode PSUs and CRT TVs
or computer monitors can interfere with the 60kHz time signal.

The clocks with an LCD display usually have an indicator which shows
signal strength if the clock successfully updated in the last hour.
If you have reception problems, try moving the clock. The built-in
ferrite rod is very directional.

Were you receiving Radio 4 on LW or via a digital service. You could
easily see a 3s delay on digital radio or TV.






--
Linux 2.6.32


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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[David Martindale]

On Sat, Jun 25, 2011 at 12:19 PM, Dr. David Kirkby
 wrote:
> I've got one of the cheap radio-controlled clocks? I was listing to radio 4
> the other day and herd the time signal. The radio controlled clock was about
> 3 seconds off. I was a bit surprised it was so far off. I'm just wondering
> how accurate these things are.

I have a Casio watch that syncs to WWVB when I leave it near a window
overnight.  There's an indicator on the display that shows if it
synced sometime since midnight today (local time), as well as a mode
that will tell you the last time it did successfully sync.  So far,
whenever it has synced today, the difference between it and a
NTP-synced computer time display has always been a fraction of a
second.  Not zero, but well below a half second.  (And when comparing
to a computer, remember that graphics cards and LCD monitors may add
multiple frames of delay).

If the watch doesn't sync for a few days, its timekeeping slowly
drifts but it still takes days to accumulate one second of error.
When I first purchased it, it was 25 seconds fast but the status
display said that the last successful sync was about 8 months ago, so
the internal crystal is likely good to about 3 seconds per month.

On the other hand, I have often heard over-the-air time beeps from
radio stations that are off by 5 seconds or more, usually late.  I
don't know if they are generated by the studio's own clock that is
hand-set and not very accurate, or if the beep is accurately generated
at the mixing board but then fed through something that causes a
significant delay.  (For example, live radio programs have a
multi-second delay between studio and transmitter so they can bleep
out "bad words" that a caller might say before they are broadcast).
So I wouldn't trust a radio time beep for anything without first
comparing it to another source.

 Dave

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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Charles P. Steinmetz]

John wrote:


WWVB clocks look at the Time Code treansmitted by WWVB, not at the carrier
which is used for precision timing.


The ones I have do not monitor WWVB constantly -- they do it once a 
day in the middle of the night (signal permitting), at which time 
they synch up and update an oscillator correction factor based on how 
far they were off since the previous update.  Mine seem to stay 
within 500 mS over 24 hours compared to 1PPS "ticks" from a 
Thunderbolt (subject to the resolution limits of using my eyes and 
ears as the two measurement inputs and the comparator between my 
ears), which is as close as the Lady Heather display clock on my system.


Perhaps some newer WWVB clocks monitor more often than that, or even 
constantly, but I have not seen any that synch more often than once 
every 24 hours.  On one of mine, you can turn the WWVB Rx off.  The 
instructions indicate that the expected battery life goes up 12-fold 
if you do, which may explain why they don't recalibrate more often.


Best regards,

Charles





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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Had]

Hey Ed,

How are things in the land of mold, mildew and Jamesions?

Best 73,

Had
K7MLR




Typically better than 1s. If there is interference or the radio is disabled,
it won't be able to receive the time signal. Switch mode PSUs and CRT TVs
or computer monitors can interfere with the 60kHz time signal.

The clocks with an LCD display usually have an indicator which shows
signal strength if the clock successfully updated in the last hour.
If you have reception problems, try moving the clock. The built-in
ferrite rod is very directional.

Were you receiving Radio 4 on LW or via a digital service. You could
easily see a 3s delay on digital radio or TV.






--
Linux 2.6.32


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A fine is a tax for doing wrong.  A tax is a fine for doing well.

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that the apparatus, or at least your understanding of it, is
always at fault until demonstrated otherwise." He also says,
"Nature is really unmoved by what I, or anyone else, believes."










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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Dr. David Kirkby]

On 06/25/11 08:45 PM, Eamon Skelton wrote:

On 25/06/11 20:19, Dr. David Kirkby wrote:

I've got one of the cheap radio-controlled clocks? I was listing to
radio 4 the other day and herd the time signal. The radio controlled
clock was about 3 seconds off. I was a bit surprised it was so far off.
I'm just wondering how accurate these things are.


Typically better than 1s. If there is interference or the radio is
disabled,
it won't be able to receive the time signal. Switch mode PSUs and CRT TVs
or computer monitors can interfere with the 60kHz time signal.


I don't think there's an SMPS nearby, but there was a 100 W amateur transceiver.


The clocks with an LCD display usually have an indicator which shows
signal strength if the clock successfully updated in the last hour.
If you have reception problems, try moving the clock. The built-in
ferrite rod is very directional.


Thanks.


Were you receiving Radio 4 on LW or via a digital service. You could
easily see a 3s delay on digital radio or TV.


198 kHz longwave - using a Kenwood HF transceiver which has general coverage 
receive.


--
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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Chris Albertson]

Ideally they are supposed to have less then 1/2 second of drift per
day and this get corrected to the nearest second every night when they
can connect to WWVB.  But some might have more than 1 sec per day
drift and they might not be able to receice the WWV signal.  Try
placing the clock some place far from other electronics, like on the
back yard fence and letting it set there over night

-- 

Chris Albertson
Redondo Beach, California

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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Tom Van Baak]

To see the effect of a WWVB watch self-correct each night:
   http://www.leapsecond.com/pages/Junghans/
The raw data came from an inductive sensor and was compared
aginst a stable 1PPS.

/tvb

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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[David J Taylor]

I've got one of the cheap radio-controlled clocks? I was listing to 
radio 4 the other day and herd the time signal. The radio controlled 
clock was about 3 seconds off. I was a bit surprised it was so far off. 
I'm just wondering how accurate these things are.


David,

Be aware that if listening via digital radio (or worse, digital TV) there 
is a delay in the transmission chain of up to several seconds (DTV).  I 
expect you know that already!  Use the FM signal for best results.


Here, I have a couple of analogue display and a couple of digital display 
"radio clocks".  The digital are both about a quarter of a second slow, 
and the two analogue display clocks are spot-on, as near a damn it.


I'm located in Edinburgh and using the Anthorn 60KHz souce:
 
http://www.npl.co.uk/science-technology/time-frequency/time/products-and-services/msf-radio-time-signal

BTW: the "pips" went missing recently:
 http://www.bbc.co.uk/news/uk-13610203

Hope that helps.

Cheers,
David
--
SatSignal software - quality software written to your requirements
Web:  http://www.satsignal.eu
Email:  david-tay...@blueyonder.co.uk 



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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Dr. David Kirkby]

On 06/26/11 07:25 AM, David J Taylor wrote:

I've got one of the cheap radio-controlled clocks? I was listing to
radio 4 the other day and herd the time signal. The radio controlled
clock was about 3 seconds off. I was a bit surprised it was so far
off. I'm just wondering how accurate these things are.


David,

Be aware that if listening via digital radio (or worse, digital TV)
there is a delay in the transmission chain of up to several seconds
(DTV). I expect you know that already! Use the FM signal for best results.


I was using 198.00 kHz longwave here in the UK. Unless there's some digital 
processing going on before the signal is AM modulated, this can't explain the 
problem.


--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[EWKehren]

I have one of my Junghans Mega next to my computer and use it for ebay  
bidding and it is always better than a second.Bert  Kehren
 
 
In a message dated 6/26/2011 10:23:16 A.M. Eastern Daylight Time,  
david.kir...@onetel.net writes:

On  06/26/11 07:25 AM, David J Taylor wrote:
>> I've got one of the cheap  radio-controlled clocks? I was listing to
>> radio 4 the other day  and herd the time signal. The radio controlled
>> clock was about 3  seconds off. I was a bit surprised it was so far
>> off. I'm just  wondering how accurate these things are.
>
>  David,
>
> Be aware that if listening via digital radio (or worse,  digital TV)
> there is a delay in the transmission chain of up to  several seconds
> (DTV). I expect you know that already! Use the FM  signal for best 
results.

I was using 198.00 kHz longwave here in the  UK. Unless there's some 
digital 
processing going on before the signal is  AM modulated, this can't explain 
the 
problem.

-- 
A: Because it  messes up the order in which people normally read text.
Q: Why is  top-posting such a bad thing?
A: Top-posting.
Q: What is the most  annoying thing in  e-mail?

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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[David J Taylor]

From: "Dr. David Kirkby" 
[]
I was using 198.00 kHz longwave here in the UK. Unless there's some 
digital processing going on before the signal is AM modulated, this 
can't explain the problem.


David,

I'm listening to the Radio 3 FM transmission in Central Scotland.  The 
07:00 pips appear to be spot on when compared to my GPS-locked PC, using 
my simple analog clock program:


 http://www.satsignal.eu/software/disk.html#TinyBen

It sounds as if your radio clock is off, so as others have suggested, try 
positioning it for a clear, interference-free good strength signal and 
retest.


Cheers,
David
--
SatSignal software - quality software written to your requirements
Web:  http://www.satsignal.eu
Email:  david-tay...@blueyonder.co.uk 



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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Will Matney]

I have a cheapie digital "atomic" clock I bought at Walmart several years
ago, and I forget the brand, but it works spot on with my PC's clock. That
is as long as you make sure to place it where the signal is strong enough
for it to update itself. However, it does not update all the time, and
reads the WWVB signal at around 4 in the afternoon and at several times to
sync itself. I think they set it at that time because of signal strength on
the east coast being it strongest about then.

Best,

Will

*** REPLY SEPARATOR  ***

On 6/26/2011 at 5:37 PM David J Taylor wrote:

>From: "Dr. David Kirkby" 
>[]
>> I was using 198.00 kHz longwave here in the UK. Unless there's some 
>> digital processing going on before the signal is AM modulated, this 
>> can't explain the problem.
>
>David,
>
>I'm listening to the Radio 3 FM transmission in Central Scotland.  The 
>07:00 pips appear to be spot on when compared to my GPS-locked PC, using 
>my simple analog clock program:
>
>  http://www.satsignal.eu/software/disk.html#TinyBen
>
>It sounds as if your radio clock is off, so as others have suggested, try 
>positioning it for a clear, interference-free good strength signal and 
>retest.
>
>Cheers,
>David
>-- 
>SatSignal software - quality software written to your requirements
>Web:  http://www.satsignal.eu
>Email:  david-tay...@blueyonder.co.uk 
>
>
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>
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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[David]

I've got one of the cheap radio-controlled clocks? I was listing to
radio 4 the other day and herd the time signal. The radio controlled
clock was about 3 seconds off. I was a bit surprised it was so far
off. I'm just wondering how accurate these things are.

David,

Be aware that if listening via digital radio (or worse, digital TV)
there is a delay in the transmission chain of up to several seconds
(DTV). I expect you know that already! Use the FM signal for best results.

I was using 198.00 kHz longwave here in the UK. Unless there's some digital
processing going on before the signal is AM modulated, this can't explain the
problem.


David,

I'd back what David Taylor says that I casually see my cheap Casio watch 
maintaining sync via the NPL Anthorn 60kHz signal within a second of BBC 
R4 LW pips although it appears we are in the same neighbourhood. I back 
the idea that the clock is not syncing for one of the aforementioned 
reasons (local noise, clock orientation etc). Bear in mind R4 LW at 
Droitwitch is not a single national service, there are two other 
transmitters that tend to be forgotten, the R4 198kHz signal Dave & I 
pick up may be the one transmitted from Westerglen rather than the NPL 
monitored signal from Droitwich (see 1). I've never seen anything 
authoritative regarding how the Scottish transmitters are controlled for 
carrier stability or modulation delay (audio or time code) nor anything 
about mutual interference zones. The NPL reports relate only to 
Droitwich carrier accuracy (2).


For the timenut, remember that R4 LW has a largely forgotten time code 
feature (3) which frees you from having to listen to the pips and John 
Humphrys, I wonder if anyone is monitoring this?


(1) http://en.wikipedia.org/wiki/Droitwich_transmitting_station
(2) 
http://www.npl.co.uk/science-technology/time-frequency/time/products-and-services/droitwich-bulletins

(3) http://downloads.bbc.co.uk/rd/pubs/reports/1984-19.pdf

Regards
David




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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[paul swed]

The clocks are amazingly inexpensive these days typically sub $10. Pretty
amazing and run on 1 aa battery. That said what I have seen is they tend to
stay right on time at least using my ear and a wwv rcvr. Granted if they do
not get sync for several days you do see them start to creep. But not much.
Regards
Paul
WB8TSL

On Sun, Jun 26, 2011 at 2:15 PM, David  wrote:

>
>  I've got one of the cheap radio-controlled clocks? I was listing to
 radio 4 the other day and herd the time signal. The radio controlled
 clock was about 3 seconds off. I was a bit surprised it was so far
 off. I'm just wondering how accurate these things are.

>>> David,
>>>
>>> Be aware that if listening via digital radio (or worse, digital TV)
>>> there is a delay in the transmission chain of up to several seconds
>>> (DTV). I expect you know that already! Use the FM signal for best
>>> results.
>>>
>> I was using 198.00 kHz longwave here in the UK. Unless there's some
>> digital
>>
>> processing going on before the signal is AM modulated, this can't explain
>> the
>> problem.
>>
>>  David,
>
> I'd back what David Taylor says that I casually see my cheap Casio watch
> maintaining sync via the NPL Anthorn 60kHz signal within a second of BBC R4
> LW pips although it appears we are in the same neighbourhood. I back the
> idea that the clock is not syncing for one of the aforementioned reasons
> (local noise, clock orientation etc). Bear in mind R4 LW at Droitwitch is
> not a single national service, there are two other transmitters that tend to
> be forgotten, the R4 198kHz signal Dave & I pick up may be the one
> transmitted from Westerglen rather than the NPL monitored signal from
> Droitwich (see 1). I've never seen anything authoritative regarding how the
> Scottish transmitters are controlled for carrier stability or modulation
> delay (audio or time code) nor anything about mutual interference zones. The
> NPL reports relate only to Droitwich carrier accuracy (2).
>
> For the timenut, remember that R4 LW has a largely forgotten time code
> feature (3) which frees you from having to listen to the pips and John
> Humphrys, I wonder if anyone is monitoring this?
>
> (1) 
> http://en.wikipedia.org/wiki/**Droitwich_transmitting_station
> (2) http://www.npl.co.uk/science-**technology/time-frequency/**
> time/products-and-services/**droitwich-bulletins
> (3) 
> http://downloads.bbc.co.uk/rd/**pubs/reports/1984-19.pdf
>
> Regards
> David
>
>
>
>
>
> __**_
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Re: [time-nuts] How accurate are cheap radio controlled clocks?

[Ron Smith]

David,

I think Radio 4 on 198 kHz is straight through analogue - no digital 
buffering with its inherent delays. Yesterday afternoon (1200 UTC I think), 
I listened to the BBC pips from Droitwich at the same time as the pips from 
RWM on 9,996 kHz, and I watched the second-hand of my Steiger 
radio-controlled clock. All three were in exact synchronism - no error 
between them, as closely as the ear and the eye could tell.


Are there different ways these radio-controlled clocks are synched to time 
signals? I have never seen any perceivable error between my clocks and 
analogue broadcast "pips" from MSF, RWM or WWV, so I don't think the synch 
scheme is a corrective one. I will try keeping one of my clocks in a Faraday 
screen for a while to see how far it drifts in terms of time.


I know of the other two 198 kHz transmitters at Westerglen and Burghead, but 
don't know whether they have the same accuracy as Droitwich's frequency 
standard. Do they carry the same phase modulation as Droitwich for 
teleswitching?


Ron, G3SVW
Manchester






- Original Message - 
From: "Dr. David Kirkby" 
To: "Discussion of precise time and frequency measurement" 


Sent: Sunday, June 26, 2011 3:22 PM
Subject: Re: [time-nuts] How accurate are cheap radio controlled clocks?



On 06/26/11 07:25 AM, David J Taylor wrote:

I've got one of the cheap radio-controlled clocks? I was listing to
radio 4 the other day and herd the time signal. The radio controlled
clock was about 3 seconds off. I was a bit surprised it was so far
off. I'm just wondering how accurate these things are.


David,

Be aware that if listening via digital radio (or worse, digital TV)
there is a delay in the transmission chain of up to several seconds
(DTV). I expect you know that already! Use the FM signal for best 
results.


I was using 198.00 kHz longwave here in the UK. Unless there's some 
digital processing going on before the signal is AM modulated, this can't 
explain the problem.


--
A: Because it messes up the order in which people normally read text.
Q: Why is top-posting such a bad thing?
A: Top-posting.
Q: What is the most annoying thing in e-mail?

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