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Old 09-07-2013, 02:13 AM   #1
ejonesss
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tivo clock time base ac line or crystal osc

i was wondering where does the tivo box get it's time base for the clock?

i am talking about the time of day clock used to record by not the logic clock used by the cpu and other chips.

i know some clocks use the hum of the ac line and counts the waves that's why take that clock and use it over seas or connect to an inverter or ups it can tell the wrong time.

does tivo use the ac line or a crystal oscillator or divide the cpu logic clock?

i notice shows getting cut off so i wonder if there is a time drift.

has anyone reverse engineered or tore down a tivo 4 power supply and seen anything that connects the ac line to the mother board.


i have the tivo along with other stuff on a cyber power 1000 va ups witch has frequency matching that will maintain a constant 60 hz up to 5 hz on both sides of a frequency drift and line conditioner that will maintain constant voltage even when other items on the same line sags or surges the voltage like air conditioner or refrigerator
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Old 09-07-2013, 02:56 AM   #2
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The old Series 2 models got the time whenever it called in for the schedule.
I am guessing that the new models use a internet time server.

No idea on the timebase, but, it better NOT be from the AC power since that is no longer a valid method to keep good time in the USA.

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Old 09-07-2013, 05:00 AM   #3
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Quote:
Originally Posted by ejonesss View Post

i notice shows getting cut off so i wonder if there is a time drift.
The shows are cut off because they start too early, i.e. before the hour or half hour. Look at the clock on your computer and you will see the idiot networks start the shows early because they don't realize that most people record shows now and expect the show to start on time. Another example of bad customer service that is rampant in USA.

TiVos get their time from a crystal oscillator that is updated every time the Tivo connects to the Mothership, either by phone line or internet.

Last edited by replaytv : 09-07-2013 at 04:27 PM.
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Old 09-07-2013, 06:40 AM   #4
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I'm pretty sure that it works just like the Time Of Year clock in computers - there's a part of the processor or supporting chip that maintains the time with an oscillator and the coin cell battery for backup. The register is updated by the software periodically - with TiVos, when it contacts the server. There may not even be a crystal in there. It won't have anything to do with the power supply.
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Old 09-07-2013, 07:13 AM   #5
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Shows get upcut or downcut simply because the various networks/channels do not always start their programs at exactly the time they're published. The clocks in your DVRs, especially those with full time internet connections, are very rarely the actual problem.
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Old 09-07-2013, 08:09 AM   #6
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Yep, and I believe this is why TiVo added the option to pad shows when setting up recordings.
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Old 09-07-2013, 10:49 AM   #7
ejonesss
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that's a relief that the clock uses a crystal oscillator.

and i compensate for that by adding a couple minutes on each side of the show
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Old 09-07-2013, 12:14 PM   #8
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Quote:
Originally Posted by ejonesss View Post
that's a relief that the clock uses a crystal oscillator.

and i compensate for that by adding a couple minutes on each side of the show
The TiVo clock gets set at least every 30 hours, and will go off about 2 to 5 sec in that time, if even that much
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Old 09-08-2013, 05:18 AM   #9
ejonesss
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i tried a new move i added 10 minutes on each side of the shows in hopes that because i remember it saying it will clip up to 5 minutes so 10 minutes will insure it gets the show.

also is there a minimum time requirement that 1 show has to be over for before that tuner will free up so marathons can be captured with overlap for example.

the show tickle witch is the person from moonshiners who i think went legal is 30 minutes.

usually the discovery channel will play repeats of the show in the hours leading up to the new episode.

so lets say 7 to 730 pm episode with a 1 minute overlap it should be 659 to 731 pm

729 to 801 pm is episode 2 759 to 831 pm is episode 3 and so on

during 729 to 801 pm both tuners are recording at 732 pm tuner 1 has ended and tuner 2 is still recording

then what should happen at 759 both tuners should be recording again for 3 minutes overlap.

instead for example at 758 or 757 tuner 1 stops leaving that run incomplete while tuner 2 will still get part of the previous episode and all but 1 or 2 minutes of the current episode.






it seems to only happen when both tuners are doing back to back recording and not limited to marathons it could be tickle takes up 2 episodes from 7 to 8 pm and then airplane repo goes from 8 to 9 pm and another show say deadliest catch 10 to 11 and then repeats for the 3 hour later repeat.

Last edited by ejonesss : 09-08-2013 at 05:27 AM. Reason: ascii graphics are not syncing with editor posting real graphic
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Old 09-08-2013, 05:23 AM   #10
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Another example of bad customer service that is rampant in USA.

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