GPS displayed magnetic declination

[Forkeye]

I was just wondering if anyone knows where my Garmin 76csx gets its magnetic declination value from.It has been at 19 degrees east now for a few years,ever since I bought it,but the true declination should be 17 degrees east according to my calculations from paper maps and also according to the online declination calculator at the Geological Survey office.I know I can change it in user declination on my unit,but it is using 19 degrees east to calculate the true reading too,I am just wondering why it never updates itself...... I always have a real compass anyway and never really trust my Garmin compass....Any ideas?

[snowfleurys]

I would guess it uses a very small term algorithm to calculate it from the long & lat.

[+Timpat]

Garmin released an update to the Time Zone Map software to v.10.00 in April 2012. You can find it Here. It updated the timezone database.

 

Ed: Oops, I sent you to the time zone update. But, Garmin had included some kind of update to magnetic declination back in Jan as part of firmware updates (at least on my 62s). This may be included in Your firmware updates so be sure you are have the most current version. Use WebUpdater to check and update.

Edited June 15, 2012 by Timpat

[Forkeye]

I suspect that an internal calculation would be required since the gps basically triangulates its position and does not transmit any signals to any sattilites,this theory kind of indicates that some software update would be required from time to time to correct errors in declination.How often or perhaps never is this issue corrected via an update,which means in time the electronic compass becomes more and more inacurate depending on how fast declination is changing where you are navigating.Probably just better off not buying a compass model and use a hand compass anyway which is exactly how I did things when I had my GPS 12.Or navigate solely by gps .Of course if you buy a new gps every couple of years I guess you will have more acurate readings.

[Forkeye]

Contacted Garmin and they asked me if I have tried new batteries or calibrated the compass...Give me a break...I can get better awnsers from my dog