# Daylight Savings



## aerialplug (Oct 20, 2000)

I've every faith that TiVo will handle the change from BST to GMT (or is it UT) tonight.

However, I was wondering how a TiVo would cope with a change in the rules for DST as has happened in the US this year and different dates to the current formula were chosen to change the times.

Does anyone know?


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## threadkiller (Dec 12, 2002)

you've more faith than me then, I always have to reboot mine to get the time right  as to coping if we changed DST, then at a guess it would be down to the central time servers.


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## OzSat (Feb 15, 2001)

I've never had a problem with time changes on TiVo.

Some recording look on times in Sky planner - but always work as they should.


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## cwaring (Feb 12, 2002)

Never a problem here either

Of course, TivoWeb users should note that they have to fully re-start to get TW into the right time-zone again. (I don't think a 're-load' will do it, but I'm sure someone will correct me if I'm wrong )


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## AENG (Dec 20, 2000)

threadkiller said:


> I always have to reboot mine to get the time right


That's odd. No idea why, but if my arithmetic is correct my TiVos have experienced 26 clock changes between them and I don't recall having to intervene at all


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## aerialplug (Oct 20, 2000)

No intervention has ever been required for TiVo only but I've had to restart Tivoweb for the time change to take place. No reboot required, just a restart of Tivoweb.


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## aerialplug (Oct 20, 2000)

Back to the original - time changes for TiVo's clock itself is taken care of by the Linux operating system (which copes well with this).

I wonder however if an operating system modification would be required to correct any changes in the formula that dictates when the clocks change or whether TiVo have already built this into the myworld application.


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## aerialplug (Oct 20, 2000)

Back to the original - time changes for TiVo's clock itself is taken care of by the Linux operating system (which copes well with this).

I wonder however if an operating system modification would be required to correct any changes in the formula that dictates when the clocks change or whether TiVo have already built this into the myworld application.

(third attempt at posting this - "server too busy at the moment")


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## OzSat (Feb 15, 2001)

echo


It has been getting busy past few days.


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## deshepherd (Nov 30, 2000)

If DST dates changed then I think there's just one file that needs to be updated to give the new timezone info

Unix is pretty comprehensive with its timezone data. I was going to include the "src" data here from my Solaris machine ... but its over 800 lines including a discussion of how until GMT was established in 1847 that "London Mean Time" according to 18th century documents was measured from a point which made it 1min 15secs ahead of GMT ... and includes rules to derive a LMT (London Mean Time) which uses this 1:15 offset if the time/date is before 1847 if the timezone is set to "London". Also includes Dublin time and Belfast time that take accoutn of a 25:21 difference that was used at sometimes + diffs between BST and IST!

Basically, with Unix/Linux I don't think changes to DST is an issue!


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## aerialplug (Oct 20, 2000)

A hacked TiVo is no problem, I know and as you say it's a single file change in Unix - but what about all the other people who have never opened their box/


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## Pete77 (Aug 1, 2006)

aerialplug said:


> I've every faith that TiVo will handle the change from BST to GMT (or is it UT) tonight.


I'm sure you meant UTC? Which could of course be the same thing as Casablanca time.



> However, I was wondering how a TiVo would cope with a change in the rules for DST as has happened in the US this year and different dates to the current formula were chosen to change the times.
> 
> Does anyone know?


Surely a change in the rules can be handled by a simple change to the section of the Tivo database that holds the timezone data?

What I still want to know though is why it is logical or rational to put our clocks back less than 2 months before the shortest day on Dec 21st but forward more than 3 months after the shortest day.

If we can wait till the end of October to put the clocks back then we ought to be able to put the clocks forward in mid Feb and bring a welcome early to the winter season.


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## Benedict (Jun 8, 2002)

Pete77 said:


> What I still want to know though is why it is logical or rational to put our clocks back less than 2 months before the shortest day on Dec 21st but forward more than 3 months after the shortest day.
> 
> If we can wait till the end of October to put the clocks back then we ought to be able to put the clocks forward in mid Feb and bring a welcome early to the winter season.


Mainland Europe used to put clocks back at the end of September - certainly up until the early 90s.

It may be to do with the fact that the rate at which the sunrise and sunset times change is not balanced. Even though December 21st is the shortest day it continues to get darker in the mornings into the first week of Jan, although the nights started getting lighter around the 12/13 December. The opposite is true in June.


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## Pete77 (Aug 1, 2006)

Benedict said:


> It may be to do with the fact that the rate at which the sunrise and sunset times change is not balanced. Even though December 21st is the shortest day it continues to get darker in the mornings into the first week of Jan, although the nights started getting lighter around the 12/13 December. The opposite is true in June.


Do you have any reference source on that point with more information.

I was already aware that that the rate of change in the length of day is not constant throughout the 6 month period between the shortest day and longest day and that the length of day changes very little indeed in the 6 weeks before and after the longest and shortest days respectively but at a very rapid rate per day around the equinoxes between mid Feb to mid mid April and mid August to mid October.

However the idea that the days start getting longer and shorter in the morning and evenings at different rates in relation to the longest and shortest days is completely new to me, even as one with an inherent geekish interest in noting and retaining all such types of fact about the natural world.


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## Benedict (Jun 8, 2002)

Pete77 said:


> Do you have any reference source on that point with more information.


Try this.


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## TCM2007 (Dec 25, 2006)

Pete77 said:


> Surely a change in the rules can be handled by a simple change to the section of the Tivo database that holds the timezone data?.


TIVo may be relying on Linux to do this, not its internal code. Even if it were under Tivoapp's control it could be had-coded in the app, not stored in the database.


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