Location error on my 60CSX

My 60CSX consistantly shows my position as being up to 200 feet off from
where my location actually is. While at home, it shows me as being 2 to 3
houses down the street and while driving it shows me as being either east or
west of whatever road I am on, and it changes.

Garmin said i had a corrupt data file and i did a cold reboot outdoor so it
could get a good fix, but it seems to have had no effect.

I use my house as an example since i would like to do some hiking and
geocaching.

Is this error acceptable?

My 60CSx and Nuvi 750 both show my home location as being three houses up
the street from my actual location and I find that Google Earth is off about
the same distance. Makes me wonder if the problem is with the maps and not
the gps units??

There was an area in San Jose, CA, where the maps were off by a couple of
blocks in several map references. Near my home in Lake County, Streets &
Trips maps are off by 200 feet, but I see see my track getting closer and
closer to the road on the map as I get near town.

Is there a GPS benchmark anywhere near you?
GPS Monuments http://www.ngs.noaa.gov/cgi-bin/ds_radius.prl
Enter your location, and then enter a few of the monument locations into
Mapsource, or your GPS, or Google Earth.

--
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5

My 76CSx shows my location correctly, but if I ask either it or
MapSource to find my house by address (using City Navigator NA 2008),
it's off by about the same amount as you report.

I've always suspected that this was because of St. Paul's odd way of
assigning addresses. We don't use block numbers, and addresses don't go
up by two from house to house. Instead, the addresses are determined by
distance from two north-south and east-west streets which were central
at the time the city was being laid out.

My address is 1642 west, and the lot line is 16,420 feet west of Rice
St. My lot is 60 feet wide and the next house to the west is 1648.

I can understand how the map makers might get confused.

--
Bert Hyman        St. Paul, MN        bert@iphouse.com

I would expect that to yield perfect geocoded lookups from mapping
programs, because it is perfectly predictable.

My understanding is that there are a bunch of actual address points in the
Tiger Database in the US. Private mapmakers may or may not expand on this
set of actual points. Addresses between those points are interpolated. In
big cities, this works well, because there are lots of fixed points,
although Tiger only claims +/- 168 feet accuracy anyway. In your case, it
sounds like there should only be three fixed points required for the entire
grid, and the interpolation should be perfect. In rural areas, there can
be a lot of space between fixed points, and the address spacing between
those points can be sporadic.

Google Maps locates my address 685 feet away, but right "on" the street.
Microsoft Live is the same. MS Streets and Trips is off by 700 feet in the
other direction, agreeing with Google Earth. The overlays of my GPS
waypoints is correct in Google Earth. So it is the address geocoding that
is wrong, not unexpected here, where there is a lot of space between
addresses, and not many "corners".

Have you checked to see if Rice Street is accurately located on the maps?
Have you checked to see (maybe with a Google Earth or Mapsource "ruler"),
if you are really 16,420 feet west of Rice? If you run a mapping cursor
along your street, can you tell where the addresses are mapped correctly
and incorrectly?

Can you find a USGS monument in your area, and see if it is mapped
correctly?

--
Clarence A Dold - Hidden Valley Lake, CA, USA GPS: 38.8,-122.5