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

Originally Posted by Neil

I'm starting to think this is an 'urban myth'. My 3790 has been switched back and forth to 3490 many times. Presently it's 3490. I've never noticed any difference in accuracy from original. I just did a quick side-by-side with a brand new 3590 and accuracy is the same, varied from 3 to 8m. Quite acceptable to me .

Wow! I certainly didn't intend to 'toss a cat among the pigeons' quite as much as the above 'opinion' did. But as bthenr said "the benefits of conversation are good", and anecdotally it seems that ppl are experiencing quite different accuracy with 37>34.

Originally Posted by angelozip

............. In short, for me the question of accuracy remains open (at least in terms of curiosity), indicates to be related to the firmare and the fact is that the 3790/3490 in this respect is below the average of other models from Garmin, the rest of it is great, do not intend to use original firmware.

If in 34xx and 37xx the gps hw is the same, logically a difference in gps fw may explain a real loss of accuracy following conversion. But why? I mean why would garmin use different (as in less efficient) fw in 34 than in 37? Unless there actually are gps receiver hw differences .... i wouldn't think so though.

Originally Posted by rfb

.... About the accuracy, it is NOT a myth!

I tested in the same place just swapping the firmware.
Maybe a difference between the devices can cause this issue.

But, I insist in ask. Is there something that I acn change in some file or inside the firmware to try solve that?

PS: I have a good expertise about Garmin. I'm not a total noob about this...

I don't think anyone posting here on this accuracy question thinks anyone else posting is a noob, but the facts are this: we are reporting experiencing differing [conflicting] accuracy results under different conditions in different parts of the world. For example, rfb states his tests are not contemporaneous. A lot can change as you take the time to reflash. To be accurate, the tests have to be made with 2 units minimum side-by-side at exactly the same time and position, i.e. with identical satellites and climatic conditions. In my case, 37 and 34 possibly only appear to be the same accuracy because they are not tested side-by-side. However, my 34 shows no difference to my 35 when side-by-side. I have just completed a 'real world' test of converted 37>34 & my 3590. 33 mins over 20 km in some stop-start traffic with partly overcast sky (scattered cloud and showery). Accuracy varied from 4 to 8 metres. Not bad for overcast conditions. Same accuracy readings for both, ok i only glanced at them occasionally when i was moving, but certainly when stationary in traffic or at lights the readings didn't differ, except for one unit changing a second or so before the other occasionally. Comparison matches my earlier brief test. I will try to get another 37 and do a side-by-side with the 34 convert to accurately compare the original to the converted.

Originally Posted by lolypop000

Nuvi 3490 and 3790 have different gps FW and this is inside of FW for 3790 and for 3490.
If you compare FW number for GPS in 3790 and 3490, you will see difference.
You can try to extract gps FW from nuvi 3790 FW and then add in FW of nuvi 3490.
When new FW will be out you must then again do all over again.

And this would be the definitive test. Three units, all identical 37xx hw, side by side, one running as converted 34xx, the second as 34xx but with 34 gps fw lifted from 37, the third running as an untouched 37xx. Maybe even have as a 4th unit, an original 34xx. The results would be definately more scientific than anecdotal, be very interesting and maybe would settle this once and for all.