Why does my GPS show my track being off of the main Hwy and when I'm right on the coast it shows my track in the water? I initialize it each time I'm
down in mex and when I cross into Bajasur. I know the format needs to be changed to co-incide with the Baja Almanac but is there something else that I
need to do? Its a Magellan Meridian. Someone told me I needed to down load from magellan web site.Geronimo - 7-18-2006 at 04:09 PM
I have the same problem with my Meridain along hyw 5 and 3. No help but will also be looking for the answer.
I too will be looking for the answer------
Barry A. - 7-18-2006 at 04:12 PM
-------as I have the same problem.jk - 7-18-2006 at 05:02 PM
The representation of your location on a map on your GPS is subject to lots of error especially in Mexico. I have the same problem with my Garmin
system and navigation charts. There are some techincal issues related to the projection system used to locate the data--there are lots of choices. I
have gotten Garmin to clearly identify the projection system the Baja maps reportedly use and have used the exact same system in my geographic info
system, but it has not solved the problem. Rest assured that whatever is going on, it is not operator error, but some inherent problem with the map
data that we as individuals cannot solve. John K.Axel - 7-18-2006 at 05:27 PM
I just went to the Magellan web site and saw that there is an update for my gps I will give that a go... Now if I could only find some batteriesDavid K - 7-18-2006 at 05:52 PM
Would you believe that the maps are not as accurate as your GPS...
My Garmin also will show me several dozen (or more) feet from the road I am on... IN THE USA OR MEXICO...
The map (any map) is not perfect!bajamigo - 7-18-2006 at 06:26 PM
My Garmin is right on target in the US, but in Mex, where I use Baja Expiditioner maps, the tracking is often way off, even when the unit says it's
accurate to within 13 feet.
Yes, but------
Barry A. - 7-18-2006 at 09:30 PM
Coast lines are static-------they do not move. My GPS tells me that I am not on the coast line-------that is a problem, and it is not the "maps"
fault.
"Yes - but" but...
djh - 7-18-2006 at 09:54 PM
Some coast lines actually do move a little each day, month, year, decade, century... etc.... storms, tides, erosion, alluvial changes, etc. Not a
lot generally, unless compared to continental drift which is slower than the . . . (THAT slow)
Is it likely that your map was likely not originally made with accurate GPS data ? ? In other words it is on paper, or other media, but is it
accurate ??
Some of the "maps" and charts in some early naval and merchant marine (navigation) books I have (from the 1800's) are incredibly accurate.... until
compared with modern GPS data.
I wonder how much can be attributed to the built-in inaccuracies of civilian GPS (intended to reduce targeting accuracy) ? ? Are your GPS location
inaccuracies always on the same (wrong) side of the road....?
You have me wondering now.... Please post your discoveries !
djhbajalou - 7-18-2006 at 10:05 PM
Quote:
Originally posted by Barry A.
Coast lines are static-------they do not move. My GPS tells me that I am not on the coast line-------that is a problem, and it is not the "maps"
fault.
Beg to differ with you Barry A. It is a problem with the map that has been digitized and put into the GPS. I have two map programs that show Baja
roads and they are not shown in the same place when I zoom in real close. And my track is a little off from them.
When comparing GPS locations with paper maps, you must be sure and use the correct datum. Mexican topos are NAD27Mexico not WGS84 which is the
default setting in GPSrs and that diference can be a hundred yards or more.
djh and Lue-----
Barry A. - 7-18-2006 at 10:12 PM
----Yes, always on the same side of the road/coastline. But, I am way over my head in this discussion-----a real GPS novice------and I probably
should pull my head back into my shell and await more learned discussion from you all.
I use a Garmin E-trex Gps, and I am still trying to figure it out.wornout - 7-18-2006 at 10:28 PM
As stated earlier, the GPS is Accurate, the Map is not, that is all there is to it.Al G - 7-19-2006 at 06:40 AM
Talk about someone who knows nothing. Your truly is as confused as they come. What I observed is Todos Santos and my trip to Los Barriles is that
about 95% of the time my tracking was spot on, but at times way off.
It seemed to me that the original lost the satellite, and pick up again later as the line was alway straight even when my tracking agreed with the
road.
Can we send our data in to correct the Baja Expeditioner? Maybe not mine as I would not trust it, because of lack of experience, but some of you could
maybe??Taco de Baja - 7-19-2006 at 07:32 AM
Quote:
Originally posted by Al G
Can we send our data in to correct the Baja Expeditioner? Maybe not mine as I would not trust it, because of lack of experience, but some of you could
maybe??
Yes he welcomes any updates of the "real" location for the roads. They may be reflected in product updates.
____________________
As may have said, the error is not with the GPS, but with the digital maps that have been downloaded into the units. Some of the maps, in Baja, anf
the USA too, are 40+ years old and plot the route of an older road alignment that is not the same as the current paved road.
Some "errors" have to do with the real width of the road, take the I-5 as it enters and leaves Mexico, the real width of this road may be 300 feet,
yet on the GPS it is represented as a line that is probably no more than 20 feet wide, thus depending on where you are, the GPS will indicate it has
20 foot accuracy but you may be 200 feet away from the digitized road in the map.
Some errors have to do with expecting too much accuracy from the units, you can not get sub-meter accuracy without spending a lot more $$$. Think of
trying to weigh a letter to see if you need additional stamps on a bathroom scale and getting peeed off at the post office when they send some of your
letters back for insufficient postage....The scale was not designed to weigh in ounces. Our cheap GPSs are not designed to measure in feet, 10's of
feet maybe.....
Also think of this, a pecil point on a standard US Geological 7.5-minute topographic map is about 20 feet in diameter
C'mon Al
djh - 7-19-2006 at 07:47 AM
No retreats....
This is how we (all of us) learn new things....
I've learned a few GPS lessons the hard way. (navigating on a sailboat, fog moved in - small trickey pass, rips and currents, crew disouriented and
seasick, etc.)
Just keeping my wits, (and building some quick confidence in utilizing my depth and radar instruments for navigating the passage - Chatham Pass for
any of you who know it...) was my challenge du our!
All part of the adventure, my friend~!
djh
nav problems
pacificobob - 7-19-2006 at 09:21 AM
the problem has something to do with the expectations gps has given people. prior to the intro of gps and to a lesser degree loran C , people had to
actually know something to do navagation. these devices convinced people that the only thing required to be a navagator was a coulpe hundred buck to
by a neat little device. i have crossed oceans for a living for the past 25 years, and have used every type of system made. they ALL have errors!
Expectations
MrBillM - 7-19-2006 at 09:30 AM
I bought my Magellan GPS before the "Mapping" units were reasonably priced. Having learned to navigate using Lat/Lon coordinates both in aircraft and
on the water many years ago, it's never been a problem. If I were to buy a new GPS, mapping would not be a consideration. Sometimes we subordinate
too much of our thinking processes to technology.
For some GPS mfgrs
Hook - 7-19-2006 at 09:37 AM
you can introduce an "offset" to what you observe on your chart.
For instance, on my marine-based Furuno, when you are cruising along a shoreline but the chart says you are significantly inland, you can "shift" the
chart by the observed error. It then applies this offset to the display and continues to applies this offset until you make another adjustment or tell
it to return to its default setting.
Check your menus..........maybe there is a similar setting. I would doubt it on a small hand-held type unit, though.Reeljob - 7-19-2006 at 10:18 AM
I thought all newer GPS were pretty accurate. In my plane, I can use the GPS with ground based error correction to do precision approaches to an
airpport. If i turn off the WAS, there is no noticable difference in the accuracy.
The newest aviation Garmin unit (396) can also be used with a ground (Auto) software package (maps) and is very accurate.
If I enter an MX airport (MMLT or MMSL for example) the accuracy is almost perfect. If I enter the Runway heading the intercept bar on the GPS is
dead on the center of the runway.
Maybe some of the older units or other brands are not as accurate.
