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4700 Position Error

MikeLip 0 Points
edited November -1 in Magellan Vehicle Forum
OK, just to concentrate on this problem - and it is a problem!

I read the thread arguing that Magellan does not use WAAS or concentrate on absolute accuracy because the Navteq maps have positional errors, so why bother with tight accuracy? That is a fallacious argument - we are discussing a tolerance stackup problem (as it's called in electronic engineering anyway) and what you do as a manufacturer using components with tolerances beyond your control (as when Magellan uses Navteq maps) is reduce the error you can control as far as possible. Magellan ought to be aiming for zero error - impossible of course, but they can do a lot better that the 4700 seems to.

I say this for this reason; Lets assume (to grab numbers out of the air) the GPS can give you an lat/long accuracy of +/-100 feet. Lets also say your map has an error of +/- 100 feet. You can potentially be 200 feet off! It's better to reduce the receiver error and not add that to the stackup.

I have seen errors this large - the numbers I am using are not completely made up :). My 4700 often places me an estimated 100-200 feet away from an intersection I am stopped at. And it shows streets AHEAD of me that are in fact already pretty far BEHIND me.

I have a Garmin GPS10X bluetooth GPS receiver (WAAS enabled) for my Blackberry that routinely gives me less than 10 feet error. And it runs all day on a charge. When I use mapping software on my BB (Garmin for BB - Navteq maps), it shows me AT the intersection when I stop. It does not show me a half block away, like the 4700 does. Neither does my 755t or 255.

I've even had the 4700 show me on the sidewalk while routing through downtown Painesville OH. It was running right next to my 5310 that placed me nicely at the intersection (yes, I do have bunch of GPSs, why do you ask?)

So, now that I am done whining, I do like the 4700 for it's routing. They did a nice job there. The maps look good too, although map movement is a very herky-jerky affair. If you've seen map movement on a 4350, that's how it SHOULD look - smooth and even. Not jump, jump, paaaaaaaauuuuse BIG JUMP. The new firmware fixed the 3D problem nicely - 2.06 is a must-have upgrade. I really want Magellan to get on the ball with positional accuracy though. I don't want to be told a half black late that I missed a turn! Or even SEE the turn a half block late!

Comments

  • Marc 301 Points
    Do you know for a fact that the 4700 is not WAAS enabled? I know that a couple of ads I have read claim it is.
  • Do you know for a fact that the 4700 is not WAAS enabled? I know that a couple of ads I have read claim it is.
    There is nothing on the Magellan website saying so, nor in the manual. I guess I am assuming if it were WAAS enabled they would say so - I sure would. WAAS is just too cool an acronym for a marketer to pass up! :) WAAS aside though, claimed GPS accuracy seems better than actual performance would indicate.

    I wish I could smoosh the best Garmin and Magellan units together and come up with The Perfect PND(c).
  • niks1 0 Points
    ...
    I have seen errors this large - the numbers I am using are not completely made up :). My 4700 often places me an estimated 100-200 feet away from an intersection I am stopped at. And it shows streets AHEAD of me that are in fact already pretty far BEHIND me.
    When I tested the 4700 and, recently, the 1700, which has almost identical software, they both gave me the same offset as you described.

    ...
    I've even had the 4700 show me on the sidewalk while routing through downtown Painesville OH. It was running right next to my 5310 that placed me nicely at the intersection (yes, I do have bunch of GPSs, why do you ask?)
    I've had it show me standing before the 8-lane wide underpass while I was standing (waiting for the green light) after it. It was pretty annoying but I did not mention this “feature” in my review of the 4700 here in this forum. However, the problem is the same with the Magellan 1700 and I managed to determine that it is not the hardware problem or GPS inaccuracy. I performed a test (see thread-review of the 1700). I used a different software (similar to what’s installed on the Magellan 4370) by booting the 1700 from SD card without touching OEM software on the ‘hard drive’. It always showed correct position of my car. Thus, the problem is with Magellan software. I would guess the problem is either smart zoom or 3D view or both. I did not bother to investigate all these combinations, but any of those I tested were – more or less – bad.
  • I have tried the 2D and also zooming out in 3D and it is still off by about 20 feet. I believe it is software issue an could be adjusted and fixed.
  • I tried turning off 3D and autozoom and the error is still there. Ugh. Back to my 5310 until this gets fixed!
  • After a bit more experimenting, and a comparison with a Maestro 4350 and 5310, I have to conclude this is a software issue. The maps have to be the same - they are coming from the same company, and they are the same age. But the positions are very different. The 4350 (the easier one to compare to since the map scroll is so much better and similar to the 4700) shows me exactly where I am. If I am at an intersection, it shows me at the intersection - not a few seconds away. If I am crossing an overpass, it shows me exactly correct in relationship to the overpass. The 5310 is harder to judge in motion, but when I am stopped it places me right at the intersection - not a long way away from it.

    The position lag error of the 4700 is pretty consistent at an estimated 150-200 feet.

    The 4350 is an absolutely beautiful GPS. Everything is done right on it. The map graphics and updating are smooth and even. The 4700 jerks and scrolls in uneven jumps. The 4350 allows me to set day and night backlight levels. It's responsive and does it's job very, very well. Too bad they ALL CRASH. I am on 4350 #6 and it crashes too. I give up. That's one thing about the 4700 - it doesn't crash.

    Come on, Magellan. Get with it. The units have the potential to hammer Garmin flat and you are wasting it on buggy software.
  • DonF 0 Points
    I find my 4700 quite close. If I am at a destination or address it seems to be right on, but when driving, I thought it lagged too until I got used to looking right at the tip of the arrow in the direction of travel, then it seems to be within the accuracy expected. Being in Canada I am using metric units. Next time out I'll try Imperial, maybe the conversion has something to do with it......who knows. With road widening, and intersection reconstruction changes plus waiting for map updates on my old GPS's, they would show me driving in fields. I still get address's that are SO far off it's funny. These are usually rural and town outskirts where an address was guesstimated and in acres, but now there is a Home Depot or Best Buy there with an actual address.
  • Not even the tip of the arrow is close on mine. It's WAAAAAAAY off.
  • niks1 0 Points

    ... Being in Canada I am using metric units. Next time out I'll try Imperial, maybe the conversion has something to do with it......who knows.
    ...
    I faced the issue while the unit was in metric mode too.
    My impression is that the sounds/commands are in sync with reality, but "video", i.e. the car position is not..
  • DonF 0 Points
    That's strange.........I just got back from a short trip around town and all is good. I never did a firmware update so I'm wondering why some units are out ALL the time. Like I said in a previous post, SOME addresses and a few multi-lane highways and intersections are out but most actual vehicle location, to map screen, are dead nuts on.
  • What firmware version do you have? I did not notice it with 1.27, although I wasn't looking for it. I did notice it after updating to 2.06 for the improved 3D street view.
  • DonF 0 Points
    What firmware version do you have? I did not notice it with 1.27, although I wasn't looking for it. I did notice it after updating to 2.06 for the improved 3D street view.
    My Software ver is 1.27. I've NEVER liked 3D mapping (why I liked the 4700) and as for almost all every firmware updates there is usually glitches at first release so I never updated especially to improve the 3D aspect.
  • I wonder if that's all it is? 2.06 fixed a lot of things, but maybe broke position. I wish I could roll it back and see!
  • DonF 0 Points
    No doubt someone will come back and clarify that.........
  • I have the 2.06 firmware update now and the location was off with the original firmware also. The upgrade did not change how far off mine was. I sent Magellan an email in regards to this directly from their web site and did not even get an acknowledgement that they received the email.
  • Yeah, Magellan isn't real quick to reply. But they will eventually. Thanks - it's interesting to know that the new s/w isn't the problem.
  • I am new to Magellan and portable GPS units.

    I had my 4370 Maestro almost a month.

    When reviewing the satellite table on my 4370, the WAAS satellite (PRN 51) pops up on the list about 5 minutes after turning on the unit.

    With the PRN 51 satellite, the SNR (signal-to-noise) showing is always 0?

    Its elevation above the horizon is always above 40 degrees at my location here in upstate south carolina.

    On my Delorme LT-40 (EarthMate) laptop navivation system, PRN 51 is listed as Satellite No. 138, two ways of listing the same bird.

    The LT-40 is WAAS compatible and shows a good signal from Sat. No. 138 (PRN 51).

    Question to follow ....
  • :?: Question: How can a satellite above the horizon get listed in the table if its signal strength is 0 ?

    When I first turn on the 4370, PRN 51 is not even listed, and doesn't even show up until about 3 or 4 minutes later.

    That doesn't make sense!

    How can the unit identify a satellite as PRN 51 if the signal from that satellite is 0?

    My theory is the unit actually is receiving PRN 51, but incorrectly showing its SNR (signal strength).

    When the unit is first turned ON, the table shows satellites 1-31 all with SNR =0. After a few minutes many of the 1-31 sats listed get deleted from the list.

    Josh
    upstate south carolina
  • Tim 1481 Points
    How can a satellite above the horizon get listed in the table if its signal strength is 0 ?
    It can get listed in the table with a signal strength of 0 if by the almanac information received from the other satellites that particular satellite is expected to be found.
  • Has anyone here gotten a reply back from Magellan yet on whether they acknowledge the position inaccuracy problem or not and if they plan to fix it?

    I also wonder if they plan to improve the text-to-speech clarity at all? I saw a video of this gps on youtube and the text-to-speech on certain words or phrases didn't sound very good at all. Such as "turn list" and "where am I".

    I'm currently looking for a gps unit and would consider the Magellan 4700, but only if these issues were addressed first.
  • Magellan has received my email about the error, but has not replied. It's been several weeks.
  • That's unfortunate that there not addressing this issue. I did a forum search on here and found that this has been reported many times before. One of the threads goes back almost 2 years ago mentioning this problem.


    http://forums.gpsreview.net/discussion/2945/x/p1/;highlight=position+lag

    http://forums.gpsreview.net/discussion/5286/x/p1/;highlight=position+lag

    http://forums.gpsreview.net/discussion/6731/x/p1/;highlight=position+lag

    http://forums.gpsreview.net/discussion/8687/x/p1/;highlight=position+lag


    It certainly doesn't give people looking to buy a gps such as myself much confidence if a company is either unwilling or unable to fix a problem that has been going on for so long.
  • I just picked up a Tomtom 140S and the position is bang on. Also my Garmin and Telenav apps are exactly right. So was my 4350 and various Garmins like 755t and 265.
  • My 4040 is off too. I am past an intersection or a street when it shows me approaching the same.
    This appears only to affect the map; when using for directions it usually notifies me in time to not miss a turn. But I don’t feel like I can trust it 100%.
    My TOMTOM and iPhone (Navigon App) are accurate 99.9% and 98.9 % respectively.
    It will soon be time for a replacement device and the responsiveness of Magellan support will boot it out of the running. I certainly could not recommend the brand with this kind of error.
  • rvoll 0 Points
    Previously, I've owned a number of Magellans, and they have been spot on. But this 4700 has a 150-200 foot lag and it drives me crazy, especially when driving around the city and missing streets. My two Garmins are very accurate, so it isn't a satellite or map issue. I've complained to Mitac, but they don't admit the problem. Stay away from the newer Magellans. I'm giving this one away to one of my kids.
  • MikeLip 0 Points
    I just picked up a Roadmate 1440. It does the same thing. SW version 2.2-something, just updated it. So whatever Magellan is doing wrong, they are consistent about it.
  • Same thing with my maestro 3225,always a little too late :x
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