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jighed

lowrance h2o gps

10 posts in this topic

i was wondering if anybody else has this problem. last year ice fishing i was on maple lake in annandale and i have the minnesota chip in my unit. i looked on the unit and it said i was fishing in 15 ft of water but when i drilled the hole and checked with my vexilar it was 32 ft. has anybody ran into this problem. it happened this summer to when i was in the boat on cass lake it wasnt the same depth. is there a way to calibrate this unit or are they always like this?

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Look on the satellites page you will see EPE --ft (Estimated Position Error). This will tell you how far off + or - you could be. I've had readings of upwards of 40+ ft (that I can recall). 40ft off on your position could be the difference between 15 ft of water and 32 ft. of water. Generally the EPE readings that I see are anywhere from 5 to 15 ft. There is nothing you can do to bout a small amount of error. Its built into the signals that the satellites put out however a consistant large error on several different lakes would make me believe that there may be a problem with the GPS.

Also Maple lake is an enhanced DNR map which isn't the most accurate map to start with.

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A lot of the Maps are just standard DNR maps they can be way off, the High Def Maps which are lakes that have been surveyed are much more accurate but are still not perfect and can have mistakes also.

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Don't forget to reset your clock too. If it is still on daylight savings time it should be corrected. The GPS needs the correct time and zone to properly calculate positions.

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I must have missed something in GPS 101. Now I am much more familiar with Garmin's but I don't believe that you set the time on a GPS,(unless the H20 is way different) the sats tell you what time it is. You may have to tell the GPS what time zone you are in, but still does not have anything to do with GPS accuracy. I agree with PierBridge and it is probably the innacuracy of the mapping and not the GPS itself.

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Sorry for the misunderstanding, I'm not sure if the H2O operates the same as some others but generally its true on many GPS units that you need to manually adjust them for daylight savings time changes. The time transmitted by the satellites atomic clock are UTC (Universal Time Coordinated) and provides no correction for daylight savings. When daylight savings time changes (or when you move to a new time zone), you need to go into Setup - Time Format and re-select the time format you are using unless you are using UTC. After selecting the format, you will be given the opportunity to change the time.

As far as the accuracy being off, typically, errors of 30 meters or more are not unusual. Now that Selective Availability has been removed, typical GPS position accuracy is approximately 15 meters (50 feet). It doesn't really matter how accurate the map is if you have that much GPS variance. Its also possible that the maps were made using GPS and were made before the removal of Selective Availability which could in the past degrade the GPS accuracy up to 100 meters.

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I looked and my H2Oc adjusted to daylight savings on its own.

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Most equipment for the US Market is programmed for DST on its own, like vcrs and computers. Of course now that it starts a week early and ends a week late that won't be right.

And if I were surveying a lake I would use the surveyor style differential GPS where a base station at a known location transmits corrections to the portable unit. That provides accuracy better than a few feet I think.

I know a guy indirectly that was using one taking sediment cores in lakes and supposedly he could drop the coring tool down the same hole the next day.

If the WAAS is working on the Lowrance, I think the error is in the tens of feet.

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Quote:

Most equipment for the US Market is programmed for DST on its own, like vcrs and computers. Of course now that it starts a week early and ends a week late that won't be right.


Starting in 2007, DST begins 3 weeks earlier and ends 1 week later, but you can teach your iFinder about that:

In Advanced Mode and after you've aquired a position, Hit Menu twice > System Setup > Set Local Time... > Config DST > Change 'Country (United States)' to 'User Config' > Start Date: second Sunday in March, End Date: first Sunday in November.

My software version is 1.1.0 and still had the old dates. I would imagine the next version will update the default U.S. setting.

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thanks for the info

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