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Time Standard

Black Hole

May contain traces of nut
#1
Through my activities elsewhere, I've been comparing the time standard on my HDR-FOX (note - not the HD-FOX sans aerial avec Internet time source... how many G points does that get me?) with MSF Rugby (one of the sources of atomic time which radio-controlled clocks pick up).

Rugby agrees with the pips on analogue radio (digital radio runs about a second behind mainly due to the decoders in the receiver - pips will be pointless when they turn off analogue). Curiously the clock on my RDS radio is a second fast! The time display on BBC NEWS is also within a few seconds (3 in my case, again there are digital decoder delays in the path).

It's a different story with my HDR-FOX I-Plate and screen saver clocks though. I have measured them as 31 seconds fast. This presumably has implications for manual timer recordings and padding recordings, also for any time logs used in the custom software.

It would be useful to get a survey over a selection of HD/HDR-FOXes, and also over a period of time. Bring up the screen saver clock by pausing a live channel and waiting a few minutes for it to appear (this gives a six-digit representation of system time) and compare it with atomic time or analogue pips, then post your results.
 

Brian

Administrator
Staff member
#2
Through my activities elsewhere, I've been comparing the time standard on my HDR-FOX (note - not the HD-FOX sans aerial avec Internet time source... how many G points does that get me?) with MSF Rugby (one of the sources of atomic time which radio-controlled clocks pick up).

Rugby agrees with the pips on analogue radio (digital radio runs about a second behind mainly due to the decoders in the receiver - pips will be pointless when they turn off analogue). Curiously the clock on my RDS radio is a second fast! The time display on BBC NEWS is also within a few seconds (3 in my case, again there are digital decoder delays in the path).

It's a different story with my HDR-FOX I-Plate and screen saver clocks though. I have measured them as 31 seconds fast. This presumably has implications for manual timer recordings and padding recordings, also for any time logs used in the custom software.

It would be useful to get a survey over a selection of HD/HDR-FOXes, and also over a period of time. Bring up the screen saver clock by pausing a live channel and waiting a few minutes for it to appear (this gives a six-digit representation of system time) and compare it with atomic time or analogue pips, then post your results.
I would be surprised if your radio controlled clocks still get their signal from Rugby, as the transmitters were switched off and demolished back in 2007 when the service was relocated to Anthorn in Cumbria.
 

Brian

Administrator
Staff member
#4
Didn't know that, thanks, I've always called it MSF Rugby (on 60kHz, IIRC?).
I only found out about a year ago when I purchased another radio controlled clock, and it mentioned that the UK signal came from Anthorn.
Have you tried comparing two or more rc clocks alongside each other? I have noticed that there can be a discrepancy of more than 1 second between them.
 

Ezra Pound

Well-Known Member
#5
The differences are due to different ways the clock handles the data and also how often it synchronises with the atomic clock, some every hour, some every day etc. here are 6 that vary by 2 seconds some MSF60 (still called MSF after the move from Rugby) some the German DCF77
MSF.jpg
 
OP
OP
Black Hole

Black Hole

May contain traces of nut
#6
Well, OK (clearly I shall have to compare my MSF with careful transit observations) but we're only talking a few seconds. My HDR is out by 30 seconds!
 

Trev

The Dumb One
#7
I've got two MSF clocks (analog display) that both show the same time and tick at exactly the same time (as far as I can tell). Both are about half a second fast compared with my internet synchronised computer clock. My 9200 FV box is about 3 seconds slow. Havn't compared my Foxsat yet
 

Ezra Pound

Well-Known Member
#12
My screensaver (and Humax Time Stamp) was 5 Seconds behind atomic, however as I suspected it did reduce to only 2 Seconds slow after a 'real' power cycle. I think real time is only extracted from the TV signal after a disconnect from the Mains power
 

Luke

Well-Knwοn Мember
#14
HD-Fox-T2 was 34 seconds fast last time I looked (Mainly Sudbury with a bit of Crystal Place). Most of the recordings are AR so that's probably why I have no noticed any earlish cut-offs.
 

af123

Administrator
Staff member
#15
Don't forget that the HD/HDR stashes the current time of day in the front panel processor (Micom) on shutdown and reads it back on boot. I would imagine there is some variance in the accuracy of the Micom's time of day chip.
It does presumably then update the time from the aerial feed if there is one.
 
OP
OP
Black Hole

Black Hole

May contain traces of nut
#20
Dunno yet, something I intend to monitor. The current delta between screensaver time and MSF has reduced to 27 secs lead, similar to the observed change in the fan timebase.