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  1. #141
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    Quote Originally Posted by rfb View Post
    Hi,

    I will test today in South America - Brazil.

    []'s

    Hi,

    Until now always 8 - 12 meters of accuracy.
    Better, but not like 37XX.

    I discovered that just trees between GPS and sky, the signal decreases by half for the satellites. So accuracy decreases until 16 meters or more and back slowly to 8 - 12 metres of accuracy.

    []'s

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  3. #142
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    Yes, it is the same with me, but overall behaviour of the unit is much better. And on clear sky and standing in one place - really 3 m.

  4. #143
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    Quote Originally Posted by lolypop000 View Post
    Here is the file that @isg talking about

    ***Hidden content cannot be quoted.***
    This is from EU nuvi 37xx --> 34xx with 3m accuracy beside my window i didn't test it on road, but this file test @isg
    p.s.
    @isg
    Thank you for your time and test and for your review
    I will be very surprised if it work
    This ARC.BIN and BEE.BIN files is familiar from the times of the first GPS Chipset Type M HotFix on Nuvi765 (a couple of years later on 2x5 MTK). They were naturally investigated. During time of work the content of this files was constantly changing. Consequently it is the usual cache data for HotFix. Idea of HotFix is instantaneous satellites acquisition if device was ON after relatively small period of time in the same place (internal clock has no time much behind). It worked fine and I never saw at least one non-green band on GPS bar. After using SIRFIII device it was fantastic!!! Naturally I was trying to change this files by files from other device and time of satellites acquisition was a lot more.
    May be if if you do substitute this files a device does not have appropriated data for making of Hot Start and it does Cold Start. Hence the temporary increase of the accuracy take place...
    Last edited by Giomen; 15th February 2013 at 23:29.
    Love your wife? Buy yourself a GPS for answering to her favorite question: "Dear, where are you?".

  5. #144
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    @Giomen

    I dont know anything anymore.
    On some nuvi better accuracy with this file on others don't, on some better accuracy with rxn folder and in other not.
    Some 37xx to 34xx have 3m all the time after converting but other have 15m+ accuracy.
    I realy don't understand anything anymore and i give up for now

  6. #145
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    Quote Originally Posted by lolypop000 View Post
    I realy don't understand anything anymore and i give up for now
    Lol I dont believe it
    [Only registered and activated users can see links. ]
    [Only registered and activated users can see links. ]

    [Only registered and activated users can see links. ]
    You have to navigate to get to the good.
    Nuvi1250/Nuvi 34xx/Nuvi 2200/Nuvi 66/Oregon 600/Galaxy S5 MM 6.0.1/TomTom GO/iGO Nextgen Avic,Basar,Isr.Gift/Navigon
    Please don't flood my pm box with questions you can post on forum!! You won't hear back from me.

  7. #146
    Garmin/GPS Systems GMod.

    Neil's Avatar
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    Quote Originally Posted by lolypop000 View Post
    I realy don't understand anything anymore and i give up for now
    Noooo! If Loly gives up I shall slash my wrists!!!! (Or strangle the next Swan i see on a pond).
    'Thanking Posts' are banned. To thank someone, and/or to see hidden links and content, use the [Only registered and activated users can see links. ] button below left of the helpful post then refresh your browser [F5 key]. 'Thanking Posts' are banned.
    Please don't spam. Posts serving no purpose other than to thank or to ask about hidden links are trashed or deleted, it's GPSPower's policy. Please don't spam.
    [Only registered and activated users can see links. ] should make their first post as a new Intro Thread in [Only registered and activated users can see links. ].

  8. #147
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    Quote Originally Posted by Neil View Post
    @tom1807

    Could you do a test on your 3790? Check accuracy with WAAS/MSAS on and off, and report.
    Sorry for my late feedback.
    I tested with Standard GPS and WAAS (switched between both).
    In both cases my accuracy was 4-5m.
    No difference. I guess it has something to do that I am just 25° north of the equator.
    I am next week in Europe, will test again

  9. #148
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    Yes these files are about switch on prediction (HotFix) not about GPS Accuracy.
    Reason: Data in files gets over-written after a while with the true data from the GPS.
    If you convert 1300 to Jap Hotfix is not as Good as EU/US and takes longer for FIX, But it's still usable.
    I think this is the case with 37>34 Real 34 is a newer device after all.
    Also I think Real 34 is a bit over-optimistic by declaring 3M Accuracy all the time even when weak satellite signals are present.
    The difference between stupidity and genius is that genius has its limits.
    Albert Einstein.

  10. #149
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    @dasilvarsa
    Agree with all that, and particularly your comment regarding the 'over-optimistic' 3 metre accuracy all the time by original 34xx. I've commented before about that and i flat out don't believe it. Same goes for 3590, rock-sold 3m constantly. I reckon it's rigged. Maybe real 3790 is a bit optimistic too at times, but it's somewhat more believable at 3 to 6 metres, as i found in the test of it side-by-side with 3490 convert [Only registered and activated users can see links. ].
    I'm hoping Loly gets over the blues and mods 37xx gps fw into 34xx before I open a vein or strangle an innocent [Only registered and activated users can see links. ].
    'Thanking Posts' are banned. To thank someone, and/or to see hidden links and content, use the [Only registered and activated users can see links. ] button below left of the helpful post then refresh your browser [F5 key]. 'Thanking Posts' are banned.
    Please don't spam. Posts serving no purpose other than to thank or to ask about hidden links are trashed or deleted, it's GPSPower's policy. Please don't spam.
    [Only registered and activated users can see links. ] should make their first post as a new Intro Thread in [Only registered and activated users can see links. ].

  11. #150
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    Quote Originally Posted by tom1807 View Post
    Sorry for my late feedback.
    I tested with Standard GPS and WAAS (switched between both).
    In both cases my accuracy was 4-5m.
    No difference. I guess it has something to do that I am just 25° north of the equator.
    I am next week in Europe, will test again
    About SBAS Waas/Egnos..
    I have researched and made ​​measurements in gps of the SBAS satellites that are tuned in the southern hemisphere. One thing I am absolutely sure: my nuvi 3790/3490 (8GB V8 035 GM OF TC, GPS FW 3:04:03) not tunes WAAS / EGNOS / MSAS .. because I did a lot of measurements side by side with an Etrex 30 and Oregon 450 that officially supports WAAS / EGNOS. At the same time, side by side, while the Etrex and Oregon tuned some SBAS satellite, the 3790 never had the least hint tuning these satellites, which shows very clearly that it is not compatible to this standard. Although it has been said in previous posts that this is a firmware feature'm not sure that is so, because it seems to be mainly a feature of hardware, software secondarily. First, because the 3790/3490 of Neil tunes SBAS satellites and no other 3790 that I have ever seen, and that use the same firmware, can tune SBAS. Second, because the tune of SBAS satellites in gps is in different frequency (slightly higher than 1600 mhz). The standard of our civilian GPS is 1575.42 MHz (L1 frequency). Despite of the Asiatic versions, as of the tom1807's and unusual as of the Neil's case, everything indicates that tuning capacity of WAAS / EGNOS of the 3790 is not available in Western version.

    A question: The SBAS / WAAS can improve or worsen the precision of GPS? It depends, check this:
    “If the receiver is outside of the area where valid TEC map data are provided, the receiver should use the build in standard ionospheric correction and then there should be no difference between WAAS/EGNOS switched on or off in the receiver setup menu in these cases. But since most manufacturers recommend switching WAAS/EGNOS off if not within the area where the signals are provided for, it may be assumed that the receivers do not make full use of all information provided and do not check whether the correction should be used or not. That way, the position may be even worse when WAAS/EGNOS is switched on when no proper correction signal is provided.” (kowoma.de link)


    Another problem already raised: How to know if the SBAS correction system is working?
    According to the Garmin website to improved the accuracy must be below 3 meters, and this is what actually happens with the Etrex30 and Oregon 450, but it is important to note that values ​​are for static or low motion. In Gpsreview forum, indicated by Catymag in post 9, the author convincingly explains the uselessness of WAAS / EGNOS for vehicles in motion, subject to be discussed. Notice in the image, in which the satellites are made corrections appears the letter D of differential correction, which does not occur in the case of Neil, but let's await the images of tom1807.
    Another detail is that the SBAS satellites in the GPS Garmin obey the NMEA standard, in which the numbers of slots PRN satellites going 33-64 (conventer to simply subtract PRN - 87). Interesting is that in the case of Neil appears the
    normal number PRN 193, of the SBAS QZSS japanese.

    List, not complete, of SBAS satellites that I could compile:
    - PRN 122, 125, 133, 134, 135, 138 - USA WAAS (Wide Area Augmentation System)
    - PRN 120, 124, 126, 131- EGNOS (European Geostationary Navigation Overlay Service)
    - PRN 129, 137 - MSAS (Multi-functional Satellite Augmentation System) - Japan
    - PRN 193- 197 - QZSS (Quasi-Zenith Satellite System) – Japan

    So far we are using the empirical method to solve the problem of poor accuracy of converted 3790, the trial and error method that sometimes works and sometimes not. The ideal is to seek to understand why, the cause, for thereafter, more safely be able to find solutions. One explanation for the previously reported rapid loss of accuracy after applying Loly’s method (Predicted Eph, Cold Start) can be: “.. ephemeris information is highly detailed and considered valid for no more than four hours.. The orbital position data, or [Only registered and activated users can see links. ], from the navigation message is used to calculate precisely where the satellite was at the start of the message..” (Wikipedia)

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    Nuvi 2689; 3490; Etrex 30; Oregon 200 (from Approach S5)

 

 
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