OT accurate time checks?

How accurate is the time given on Windows? Also how about digital radio and freesat, I guess there is a time delay at least on the last 2. I notice that the pips are rarely used these days, and apart from the Olympics I cannot remember the last time I heard Big Ben broadcast.

Reply to
Moonraker
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Radio 4 pips on FM are accurate to a few milliseconds, depending on how far you are from the radio.

Big Ben on FM or AM radio is sort of accurate to a second or so. It can be heard most days on Radio 4 at 5 P.M., as well as other times. Occasionally, to their great embarrassment, you can hear the announcer talk over the start of the chimes.

Timechecks such as the pips on any digital broadcast networks are sort of right, although always late, with a variable delay due to the processing latency at various stages in the chain, and in the case of satellite relays, delayed further by at least twice the light speed delay (i.e. 238.8 milliseconds) due to the Clarke Orbit the satellites are in.

Internet time servers can be extremely accurate, if you use a program that calculates the packet delays and compensates for them.

For a cheap, quick and accurate time signal, use a GPS receiver's time. This will be UTC accurate to within the speed of light delay from LEO, which is of the order of 10 milliseconds. Clever software can compensate for these delays, if you want to be *really* fussy.

Reply to
John Williamson

I never get to hear the beginning of the PM programme. Do they have Big Ben then? I know they have it at 6pm at the start of the news.

A couple of years ago Big Ben was being repaired so they had birdsong instead. It wasn't as accurate.

Reply to
Andrew May

How accurate is the time given on Windows? Also how about digital radio and freesat, I guess there is a time delay at least on the last 2. I notice that the pips are rarely used these days, and apart from the Olympics I cannot remember the last time I heard Big Ben broadcast.

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Don't know about freesat, but my freeview box is accurate to about a second (when compared with my radio signalled clock)

tim

Reply to
tim.....

Possibly not, I was having trouble remembering which it was. I know I hear it most evenings when I'm listening to Radio 4, though. ISTR they play it at either 9 or 10 PM, too.

Obviously. How d'you expect a bird to tell the time without a watch? :-)

Reply to
John Williamson

Moonraker :

Not especially. My everyday timepiece is an MSF wall clock, which agrees to the second with the pips on Radio 4 FM. I just watched the minute click over on my Windows taskbar, and according to the wall clock it was a couple of seconds late.

Reply to
Mike Barnes

In article , Moonraker writes

Depends on how accurate your motherboard's clock is. If the CMOS battery is running low, it will lose time.

Windows can set the time from an Internet time server. On XP, the procedure is to right-click on the clock, Adjust Date/Time, Internet Time, enter 0.uk.pool.ntp.org into the box, then click Update Now. OK your way out and Windows will set the time from a server regularly. Of course, you need to be online for it to work.

Reply to
Mike Tomlinson

if you have a windows NTP client installed or windows does this by default, you should be with 10-20ms of 'correct'

Reply to
The Natural Philosopher

If you use NTP on Windows then I would guess the time would be pretty accurate.

"NTP can usually maintain time to within tens of milliseconds over the public Internet"

Reply to
Mark

It's pips at 5 and BB, as you say, at 6.

Reply to
Nick

This program will keep your Windows time spot on.

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Reply to
Peter Crosland

In article , Mike Tomlinson scribeth thus

Look up Atomic.exe small prog that pings a ntp server every day.

Its also there in Windows 7 ..

Reply to
tony sayer

Provided that you are on FM or AM. MSF Rubgy or DCF77 ULF clocks are accurate to within range to transmitter/speed of light.

Modules to output a pulse per second are offered by the likes of Maplin for slightly more than the cost of an entire radio self setting clock!

Galleons is abouut the easiest unsure of price these days:

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Internet time servers can be extremely accurate, if you use a program

eg

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> For a cheap, quick and accurate time signal, use a GPS receiver's time.

It all depends how accurate you need it to be. Systems for VLBI have local hydrogen maser clocks synchronised to global timeservers. Precise timestamping observations makes looking for fringes easier when the individual telescopes data are later combined in the correlators.

Regards, Martin Brown

Reply to
Martin Brown

Sadly not on Windows - see

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'The W32Time service cannot reliably maintain sync time to the range of 1 to 2 seconds. Such tolerances are outside the design specification of the W32Time service.'

A 3rd part app ought to behave somewhat better.

Mathew

Reply to
mathewjamesnewton

Then take into account the effects of some software. The version of Opera that I'm running atm causes the clock to gain by about 5s between the

2-minute-interval ping of npl.
Reply to
PeterC

Some birds are really accurate. I mean the Cuckoo is famous for being spot on ;-)

Reply to
Graham.

On Tue, 21 Aug 2012, "Moonraker" writ:

As I write my Windows 7 PC is within 500 milliseconds of UTC.

Reply to
Percy

On Tue, 21 Aug 2012, "John Williamson" writ:

How can this be if the final "pip" is 500 milliseconds long?

How many GPS devices show the time to anything less than a second?

Reply to
Percy

The time reference point is the end of the last pip. Technically, the last zero crossing of the signal. I can set a digital watch to within less than a frame of video with practice using the pips.

None that I know of, but the time changes on the display and the serial output at the same time as the reference signal does. You can use a PLL to synchronise any time point you wish within that second.

Reply to
John Williamson

That's standard procedure now, and has been for a year or so.

Certainly at 1800 and midnight, (Pips at 1700*, not Big Ben) the intention was, barring accident to broadcast all the bongs uninterrupted.

Now, the standard practice is to start reading the news headlines after the first bong and fade them out after the third.

In both the above schemes the silence between the end of the forth quarter chime and the first chime is filled with a station ID, time check and "Good evening".

At midnight on New Year's Eve all 12 bongs are played in full, thank goodness, but they still fill that poignant pause with an announcement. Total sacrilege IMHO.

  • The 1700 pips on weekdays is followed by the start of "PM" which used to have a theme tune, which was dropped around the time of 9-11 and never re-instated. Some of us die hard R4 listeners imagine we can still hear it.
Reply to
Graham.

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