Garmin GPS - Location error on my 60CSX

Author

Location error on my 60CSX

Neil

2008-01-20, 10:33 am

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?

Earl J

2008-01-20, 12:33 pm

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??

"Neil" <n_martin@comcast.net> wrote in message
news:VridnU0_Kc- s6A7anZ2dnUVZ_gmdnZ2
d@comcast.com...
> 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?
>

James B. Thies

2008-01-20, 3:33 pm

My 60CSX locates me exactly at my home address (and elsewhere) on
TerraServer, USGS, Google, National Geographic TOPO and Mapsource maps. I
wonder if your map datum setting is consistent with your mapping products.

"Neil" <n_martin@comcast.net> wrote in message
news:VridnU0_Kc- s6A7anZ2dnUVZ_gmdnZ2
d@comcast.com...
> 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?
>

Steve Calvin

2008-01-20, 3:33 pm

James B. Thies wrote:
> My 60CSX locates me exactly at my home address (and elsewhere) on
> TerraServer, USGS, Google, National Geographic TOPO and Mapsource maps. I
> wonder if your map datum setting is consistent with your mapping products.
>
> "Neil" <n_martin@comcast.net> wrote in message
> news:VridnU0_Kc- s6A7anZ2dnUVZ_gmdnZ2
d@comcast.com...
>
>
My 76CSx has our house marked dead nuts. It can't be the
map datum as that only comes into play when trying to
coordinate locations between the GPS and a paper topo.

Something sounds fishy here. Is your units firmware up to
date? If you don't have WAAS enabled, try turning it on. It
shouldn't be that far off even without WAAS but it's worth a
shot.

--
Steve

Mike Tordoff

2008-01-20, 10:33 pm

"Steve Calvin" <calvins@optonline.net> wrote in message
news:4793ad68$0$1155
1$607ed4bc@cv.net...
> James B. Thies wrote:
> Steve

In the 60CS (and I assume the 60CSx) in the Setup | Map dialog there is a
setting for 'Lock on road'. Turning this on should solve your problem with
driving east or west of the road you are on.

Mike in Philadelphia

dold@83.usenet.us.com

2008-01-20, 10:33 pm

Earl J <mrekj@comcast.net> wrote:
> 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

Bert Hyman

2008-01-21, 10:33 am

In news:85GdnZeBk- z1DA7anZ2dnUVZ_uGknZ
2d@comcast.com "Earl J"
<mrekj@comcast.net> wrote:

> 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??
>

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

dold@83.usenet.us.com

2008-01-21, 3:33 pm

Bert Hyman <bert@iphouse.com> wrote:
> 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.

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

Bert Hyman

2008-01-21, 10:33 pm

In news:fn2oi0$la9$1@bl
ue.rahul.net dold@83.usenet.us.com wrote:

> Have you checked to see if Rice Street is accurately located on the
> maps?

So far as I can tell, the streets (and other identifiable things) are in
the right place on the Garmin maps. When I'm standing or driving
somewhere with my 76CSx, I'm always properly positioned on the map. The
only thing that doesn't work correctly is a "Find" using an address;
even then, the found spoit is on the street, but misplaced along it.

> Have you checked to see (maybe with a Google Earth or Mapsource
> "ruler"), if you are really 16,420 feet west of Rice?

So far as I can tell, yes, that much is done correctly.

> If you run a mapping cursor along your street, can you tell where the
> addresses are mapped correctly and incorrectly?

Never tried that.

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

Nor that.

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

Tom H.

2008-01-21, 10:33 pm

http://home.att.net/~tbharvey/
"Neil" <n_martin@comcast.net> wrote in message
news:VridnU0_Kc- s6A7anZ2dnUVZ_gmdnZ2
d@comcast.com...
> 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?

Neil,
As others have stated, the most likely source of error is with the mapping
data, not the gps itself. The best way to make shure is to find a benchmark
(again others have mentioned this), but short of that, try plotting the
location of your house on google earth. The easiest way to do that is to
make a waypoint at your home and download to mapsource, then do "view":
"view in google earth..." Tracklogs in Mapsource will also be loaded to
google earth by that method. If the photos in google earth do not match
street locations then you can figure they also have map data problems. Some
mapping programs trace the data to the same source so different programs can
have the same errors. For example Mapsource City select makes the same
error as Mapquest in routing me to a friends house. He lives on street that
dead ends in one location and starts again a couple blocks away. Neither
program shows the break in the street.

Tom

Dale Atkin

2008-01-22, 10:34 am

>
> In the 60CS (and I assume the 60CSx) in the Setup | Map dialog there is a
> setting for 'Lock on road'. Turning this on should solve your problem
> with driving east or west of the road you are on.

As the OP said they were thinking about Geocaching, I would *strongly*
suggest you turn that option off. Basically what that option does, is rather
than have the unit report where it actually calculates itself to be, it
calculates a position for itself, and then looks around and sees if its near
a road. If its near a road, it lies to you and tells you it calculated its
position to be exactly on the road.

My suggestion to the OP would be either the Benchmark idea discussed
previously, or go out and look for a cache (preferably an older one, placed
by an experience cacher...the will avoid coordinate problems).

Dale

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