Thread: About 37xx converted to 34xx satellites reception accuracy

Originally Posted by isg

........... The bad thing in my case is that even go back to 3790 the accuracy is still questionable.
So count me in camp 2 and soon in camp 3 .....

The only reason i'm not in camp 2 is because i'm not having the accuracy problems you're having. My 1st convert functions well enough and it exhibits none of the behavour you and others are reporting. It seems to me that there may be gps receiver hw differences in the 37x0 productions which it's native fw allows for, but the 34x0 fw either barely copes with [i.e. mine and Caty's and some others] and other hw where it doesn't work well at all [i.e. yours and others].

Originally Posted by catymag

@isg
Reverting to 37xx firmware, in my experience, is enough to get 37xx usual reception.

I can confirm that info by Caty. After converting and reconverting many times, my 1st 3790 returns to reporting 3m precision. NV cleared both before and after conversion/reconversion each time. I haven't yet reconverted the 2nd 3790 [3490_kunix] to find out.

37xx -->34xx and other Nuvis comparison tests are welcome Put them off road.

In fairness, although any comparison is welcome you will probably only show that a 37>34 lacks accuracy compared to any other unit. My old SP 2610 is better than 37>34 anecdotally. All my other units show better precision than 37>34 converts do i.e. 13x0/14x0/1690/2455 etc. I've also done informal tests with 2460 as original and converted to dezl 560 which reports mostly 3m both ways. Also 255/265 converted to 465 doesn't suffer any accuracy loss by casual observation, nor does 40/50 > 42/52. The 37>34 is different. The other 3 conversions will both flash and work equally well with original boot.bin or with the full fw flashed. The 37x0 won't flash using original boot.bin but will flash full 34x0 fw. Whatthe! Weird hey? You bet it is, and my layman's guess is that's simply because the 3790 and 3490 are not completely identical physical hardware. So flashing a 37 to 34 is like trying a kid's pony saddle out on a racehorse, you might get it to go on but it won't work property.

More interesting should be to know if someone has two 37xx to compare,may be one provided by a friend: one 37xx original and a 37xx/34xx.

Well, i still have one virgin 3790 [original & never converted] and 2 x 37>34. The only question is will i do the city test run with the 3490_kunix as 3490_kunix#2, as 3490 with unaltered 34x0 fw, or as 3790.
Suggestions are welcome, but if kunix comes up with another fw mod that's what i'll be using regardless [if it doesn't brick it of course] .

Originally Posted by Neil

Well, i still have one virgin 3790 [original & never converted] and 2 x 37>34. .

Neil ,I lost count of your owned Nuvis ,lol you are our hero

You guys are so verbose I've pumped through my brain so many english words today Not sure I remember all the important things you've said.

Originally Posted by Neil

Suggestions are welcome, but if kunix comes up with another fw mod that's what i'll be using regardless [if it doesn't brick it of course] .

I'm looking at this topic and your accuracy tests. I'm afraid the next mod would require digging into how fw_all.bin processes GPS chip output, as this seems to be the only place which could cause problems. So this won't happen too soon for sure.
I have a thought that maybe 34xx firmware processes signals from MT3328 chip in a different way (maybe somehow retarded way), as this chip is only present in older 34xx devices. It would be very interesting to find such 34xx device (with MT3328 inside) and run 37xx and 34xx firmwares on it and compare the accuracy with other 37xx and 34xx devices.
Also I don't like that using GPS firmware from 37xx with 34xx fw_all.bin makes the accuracy even worse. It could indicate that GPS firmware and fw_all.bin are tightly coupled somewhow and everything is even more complicated.
Also it would be nice to see the output of different levels of GPS chip signals processing. I don't really believe in track log, as it was already processed with different filters and probably adjusted to match the nearest road.

Originally Posted by Neil

The 37x0 won't flash using original boot.bin but will flash full 34x0 fw. Whatthe! Weird hey? You bet it is, and my layman's guess is that's simply because the 3790 and 3490 are not completely identical physical hardware. So flashing a 37 to 34 is like trying a kid's pony saddle out on a racehorse, you might get it to go on but it won't work property.

Yes, they seem to be quite different in some places. But 37xx bootloader doesn't work with 34xx fw_all.bin just because 34xx fw_all.bin is too big, no mystery here, and gfwpack solves this problem by making fw_all.bin smaller, though it's quite useless for us.