About 37xx converted to 34xx satellites reception accuracy

Kanopus · 2nd May 2013, 03:34 PM

@Neil: could you do a test? Turn on hidden tracklog on all your nuvis, take them for a ride and then analyze tracks to see if there are real differences in calculated position. I mean, simply check if this is a real or imagined problem

**kunix** · 2nd May 2013, 04:26 PM

I've found in fw_all.bin of 37xx and 34xx some 32KB piece of data which is probably a GPS firmware.
Here is a 34xx v7.90 firmware that has this piece of data replaced with one copied from 37xx v5.00.
Also the GPS firmware version is increased by one (it's just a hardcoded number not related to the GPS firmware).

If someone is not afraid of sacrificing his 37xx device for the sake of science, then I would like to know if the displayed GPS firmware version has changed and if the GPS accuracy is better (and if it works at all!).

I'm not sure what I've just patched so don't flash it unless you're ready to kill your device!
This won't break pre-boot mode for sure. But I have no idea how GPS chip works with wrong firmware version.
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**dasilvarsa** · 2nd May 2013, 05:32 PM

Does anyone know which gps chip is used in 3490 and 3790. ?
I've read somewhere that 3490 has a combined gps/bluetooth chip but cannot find source of info.

**Giomen** · 3rd May 2013, 02:11 AM

Originally Posted by dasilvarsa

Does anyone know which gps chip is used in 3490 and 3790. ?
I've read somewhere that 3490 has a combined gps/bluetooth chip but cannot find source of info.

I had seen Nuvi 3490 and 3590 with different version of GPS when it come to warehouse at first time. Some sample had a GPS version like 37xx, another had a new version. Sorry but I do not fix this fact on screenshot! So I think SW for 34xx have support for more than one GPS chip...

**kunix** · 2nd May 2013, 05:59 PM

I think it's true. But then it's probably also true for 37xx, as they seem to use the same chip mt3328. This chip name is hardcoded in the firmware as well as the GPS software version (well, I'm not sure yet this number is the GPS SW version, but it totally looks like it is). This is the reason why I was inclined to think that GPS software is embedded in fw_all.bin.

**ana550** · 2nd May 2013, 08:28 PM

**lolypop000** · 2nd May 2013, 08:39 PM

@ana550

Is GPS accuracy better?

**kunix** · 2nd May 2013, 10:05 PM

ana550
Ok, so that number was really a GPS firmware version. Now what about GPS accuracy?
Also I wonder what happened to the letter "u" in the word nuvi. Firmwares on both screenshots are 34xx right? (on 37xx GPS firmware version is somewhere between 2.20-2.60).

**Neil** · 2nd May 2013, 11:01 PM

Can't do any tests today, other big fish to fry. Great work kunix and 'big karhoonies' shown by ana550 in being 1st to try (although i reckon you were in safe hands and i'm prepared to do it too on this weekend).

What 'u' kunix?