Lowrance Ifinder Go2

[hurley]

I am brand new to GPS. Today I took my new handheld Ifinder Go2, to my boat. On the journey down the track showed my route to the east of the main A road.

At my boat (which is on an estuary, currently on the hard ) it showed my location as being on the starboard bank, whereas I am on the hard on the port side of the river.

When I returned home I checked the actual co ordinates and other significant landmarks, such as headlands, against those in the background basemap. It appears that all the map features are slightly too far to the west, which will show my actual position as always being to the east of map details.

As I am new to GPS, I have the following questions.

1) Is this normal (the unit has a low detail background base map) ie is this all one could expect ?

2) Is the unit faulty ?

3) Can it be calibrated ?

I am able to get a refund as long as I ring the internet retailer on monday.

Can anyone give me advice ?

Thanks in anticipation.

Kind regards Nick

 

[pvb]

It's possible that your unit is set to the wrong map datum. If you look at the Advanced User Guide, it tells you how to change map datums. Trying a different one may show you as being in the right place!

 

[hurley]

HI I can see where you are coming from. Earlier I tried a few different ones such as British grid but with no noticeable differences.

Its set as default to WGS 84.

Please keep the ideas coming though Cheers

 

[pvb]

Look at the Satellite Page, and check what the EPE is. This is the Estimated Position Error, and is an indication of how far away your indicated position may be from your true position.

 

[exfinnsailor]

Accuracy of some units is +- a couple of meters or more .. You can always find out which bank your near by looking .. Gives you a better idea and far more acurate .. /forums/images/graemlins/smile.gif However if you put the coordinates of a waypoint in you can guarantee you will hit it .. Got a new Ford SMax and thats about 15 meters out on our local road junction .. Blame the yanks .. /forums/images/graemlins/laugh.gif after all they look after it ..

 

[exfinnsailor]

Have you heard the one about the Guy who bought himself a new GPS .. Took it walking .. Put it down and forgot it .. The GPS knows where it is but .... He is still looking for it /forums/images/graemlins/cool.gif

 

[gjeffery]

Probability is that the basemap covers a very large area and is of restricted accuracy; it is a map rather than a plan. It is also likely that the basemap fills in a lot of detail through interpolation, and only shows major features. The basemap will be referenced to WGS84, rather than to a local grid. Detailed plans/maps/charts need large files to cover a limited area. A small area of large scale mapping would fill the memory of your unit. What you are seeing sounds quite normal, and what I would expect. My Garmin GPSMAP60 thinks that Bursledon Station is in the Hamble river!

Regarding accuracy of the instrument, if it is showing an expected error (EPE) of better than say 30 feet, this is probably OK. You would not expect to get a tighter EPE than say 12 feet. Best checks are to take a fix on a position with known WGS84 geographical co-ordinates, eg a trig.