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GPS - Daylight Savings

Old 03-20-2007, 08:58 AM
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Default GPS - Daylight Savings

Anybody else notice that their GPS units did not change time with Daylight Savings? I've checked 1 Lowrance and 2 Garmin units. All 3 units are set to update Daylight Savings automatically.

Is there something we need to do on our end?
Old 03-20-2007, 09:36 AM
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Default Re: GPS - Daylight Savings

http://www.thehulltruth.com/forums/t...141452&posts=4
Old 03-20-2007, 09:39 AM
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Default Re: GPS - Daylight Savings

I'm sure that most of the units out there were programmed before Congress changed the DST dates. They will probably change over on the first Saturday in April if you don't do anything. Otherwise, the company may provide a patch, or you may be able to change the time manually, or you can let it change on its' own if it's not that important to you. If you do anything other than a patch, you'll have the same problem in the Fall.
Old 03-20-2007, 09:43 AM
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Default Re: GPS - Daylight Savings

http://www.garmin.com/support/faqs/faq.jsp?faq=6033
Old 03-20-2007, 10:03 AM
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Default Re: GPS - Daylight Savings

I was hoping that the Satellites would send down the time based on determining my time zone via lat/lon.

Old 03-20-2007, 10:11 AM
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Default Re: GPS - Daylight Savings

HardLivin - 3/20/2007 10:03 AM

I was hoping that the Satellites would send down the time based on determining my time zone via lat/lon.
hmmm....How would the satellites know where you are?

As for the DST issue..I changed my Garmin 3010 to reflect DST time with a check box in the menu..and BAM!

an hour forward.
Old 03-20-2007, 10:52 AM
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Default Re: GPS - Daylight Savings

Hardlivin, you're probably right. I was thinking more along the line of computers. The GPS should update automatically - have had the small, hand-held models automatically change as you drive through different time zones.
Old 03-20-2007, 11:46 AM
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Default Re: GPS - Daylight Savings

Joe - 3/20/2007 10:11 AM

HardLivin - 3/20/2007 10:03 AM

I was hoping that the Satellites would send down the time based on determining my time zone via lat/lon.
hmmm....How would the satellites know where you are?

As for the DST issue..I changed my Garmin 3010 to reflect DST time with a check box in the menu..and BAM!

an hour forward.
I think the whole purpose for GPS is for satellites to "know where your are". As far as the DST update, the newer systems already have the updated software to handle the early time change. Like others though, I initially thought that the satellites were responsible for the time on the units. I too have traveled to different time zones with my GPS and the time was correct.
Old 03-20-2007, 12:08 PM
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Default Re: GPS - Daylight Savings

The reason for my question was I simply thought time was another input provided to the GPS via satellite because my GPS keeps the same time down to the second as my atomic watch which is updated daily via satellite. If it is another input then it would be fair to say that it could also keep up with which lats/lons are within a time zone and update the time appropriately when my time zone changes (like others have mentioned).

The problem is most likely the satellites are based on UTC and actually do send the time in UTC format. The GPS is then responsible for rolling the clock on a particular day and, like every other computer system I deal with, it wasn't ready to roll forward on 3/11 without a patch. Heck this is just a SWAG. The GPS is a black box to me, I know how to use it, just don't know exactly how it works.
Old 03-20-2007, 02:38 PM
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Default Re: GPS - Daylight Savings

Cat O Lies - 3/20/2007 11:46 AM

Joe - 3/20/2007 10:11 AM

HardLivin - 3/20/2007 10:03 AM

I was hoping that the Satellites would send down the time based on determining my time zone via lat/lon.
hmmm....How would the satellites know where you are?

As for the DST issue..I changed my Garmin 3010 to reflect DST time with a check box in the menu..and BAM!

an hour forward.
I think the whole purpose for GPS is for satellites to "know where your are". As far as the DST update, the newer systems already have the updated software to handle the early time change. Like others though, I initially thought that the satellites were responsible for the time on the units. I too have traveled to different time zones with my GPS and the time was correct.
It's not the satellites that know where you are; they spit out the same information to anything listening. The unit does all that cyphering, as for the original question, I think he has forgoten to make sure the DST is updated; unit might need to be reset then DST applied.
Old 03-20-2007, 05:47 PM
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Default Re: GPS - Daylight Savings

"It's not the satellites that know where you are; they spit out the same information to anything listening. The unit does all that cyphering"

Humm, I think your right! That makes perfect sense. I'll buy that for a $1.
Old 03-20-2007, 08:43 PM
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Default Re: GPS - Daylight Savings

As far as changing the time as you travel, that is based on longitude--when you cross the pre programed longitude for the next time zone, the gPS will change the time.
Old 03-21-2007, 12:22 AM
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Default Re: GPS - Daylight Savings

GPS time is transmitted as part of the Nav message. GPS time has not been altered since the birth of GPS on Jan 5/6 1980. GPS time = UTC time @ Jan 5/6 1980. The difference between GPS time and current UTC time (leap seconds) is also transmitted as part of the Nav message. So any receiver is able to determine current UTC time from the transmitted signal.

The local time/zone offset and/or DST settings On/Off/Auto etc have absolutely no function as far as determining position is concerned. Local time/DST settings are simply a user option, shows the user the current time and configurable as required. Changes when travelling through different time zones is totally dependent on how smart the receiver software is. This can get complicated as not all time zones are based simply on longitude.

Regards, Kerry.
Old 03-21-2007, 08:31 AM
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Default Re: GPS - Daylight Savings

In my haste to get everything else patched (servers, destktops, laptops, plcs, pdas, blackberrys) I neglected to think about my own personal equipment. The time on my GPS is not all that important to me so I'll just let it roll forward in a week or two. It's funny how my 4 year old watch knew to roll forward on the right day but my much more expensive and 2 year old GPS did not.
Old 03-21-2007, 07:52 PM
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Default Re: GPS - Daylight Savings

So does your watch know where it is? Do you think if you flew half way around the world the time on the watch would reflect the new location or still be relative to it thinking it is still in the USA?
Old 03-22-2007, 09:01 AM
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Default Re: GPS - Daylight Savings

Kerry - 3/21/2007 7:52 PM

So does your watch know where it is? Do you think if you flew half way around the world the time on the watch would reflect the new location or still be relative to it thinking it is still in the USA?
My watch knows where it is because I tell it what time zone it is in. Nothing automatic there. The watch did however have the intelligence to roll forward on 3/11 where it's only 2 inputs were time from a satellite and knowing what time zone it was set to.
Old 03-22-2007, 07:08 PM
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Default Re: GPS - Daylight Savings

So when you say "time from a satellite", which satellite? GPS satellite or one of the standard geo com sats?
Old 03-22-2007, 09:49 PM
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Default Re: GPS - Daylight Savings

I would guess the kind of satellite that could provide the time least expensively. Either one maybe?? The watch provide no GPS features at all. It simply asks you your time zone and collects the time from a satellite at 5:00 AM EST.

What are your thoughts?
Old 03-22-2007, 10:24 PM
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Default Re: GPS - Daylight Savings

Kerry - 3/21/2007 12:22 AM

GPS time is transmitted as part of the Nav message. GPS time has not been altered since the birth of GPS on Jan 5/6 1980. GPS time = UTC time @ Jan 5/6 1980. The difference between GPS time and current UTC time (leap seconds) is also transmitted as part of the Nav message. So any receiver is able to determine current UTC time from the transmitted signal.



Regards, Kerry.
Thats some great info that means absolutly nothing to the average or for that matter any boater.
Old 03-24-2007, 05:48 AM
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Default Re: GPS - Daylight Savings

stanleywinthrop - 3/23/2007 2:24 PM

Kerry - 3/21/2007 12:22 AM

GPS time is transmitted as part of the Nav message. GPS time has not been altered since the birth of GPS on Jan 5/6 1980. GPS time = UTC time @ Jan 5/6 1980. The difference between GPS time and current UTC time (leap seconds) is also transmitted as part of the Nav message. So any receiver is able to determine current UTC time from the transmitted signal.



Regards, Kerry.
Thats some great info that means absolutly nothing to the average or for that matter any boater.
What it means is GPS doesn't give a stuff about DST, has absolutely no interest in DST, same as me! Time of day on a GPS is totally at the descretion of the user. DST and systems that try and compensate for DST change overs are a complete waste of software rescources, causes more problems than what it is worth.

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