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Time Standard

Discussion in 'HDR-FOX T2 Freeview Recorder' started by Black Hole, May 14, 2012.

  1. Black Hole

    Black Hole Felonius Gru

    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.
     
  2. Brian

    Brian Administrator Staff Member

    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.
     
  3. Black Hole

    Black Hole Felonius Gru

    Didn't know that, thanks, I've always called it MSF Rugby (on 60kHz, IIRC?).
     
  4. Brian

    Brian Administrator Staff Member

    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.
     
  5. Ezra Pound

    Ezra Pound Well-Known Member

    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
     
  6. Black Hole

    Black Hole Felonius Gru

    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!
     
  7. Trev

    Trev The Dumb One

    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
     
  8. 4291

    4291 Well-Known Member

    My HD-FOX T2 screensaver clock is 36 seconds ahead of MSF clock (digital) time.
     
  9. Andrew Benham

    Andrew Benham Member

    Interesting. Screensaving BBC1 (standard definition) from Crystal Palace shows 55 seconds ahead of MSF.
     
  10. 4291

    4291 Well-Known Member

    TV i-plate on BBC 2 SD about 5 seconds behind MSF.
     
  11. Trev

    Trev The Dumb One

    My FV TV is about 4 sec slow and my Sieko watch is about 0.5 seconds ahead of MSF. Beat that.
     
  12. Ezra Pound

    Ezra Pound Well-Known Member

    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
     
  13. 4291

    4291 Well-Known Member

    My iPad is spot on. :)
     
  14. Luke

    Luke Well-Known Member

    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.
     
  15. af123

    af123 Administrator Staff Member

    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.
     
  16. Black Hole

    Black Hole Felonius Gru

    The drifts are so great it would seem not!
     
  17. Black Hole

    Black Hole Felonius Gru

    Over a period of 8 hours the fan timebase has drifted by 4 seconds.
     
  18. Wallace

    Wallace Slightly Pickled

    Wow...:rolleyes:
     
  19. Ezra Pound

    Ezra Pound Well-Known Member

    Does the time correct itself if you power cycle the Humax?
     
  20. Black Hole

    Black Hole Felonius Gru

    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.