About 37xx converted to 34xx satellites reception accuracy

As our friend Neil said, may be a myth, but although I do not have done a comparative test methodical (and being therefore of questionable value) also observed differences in accuracy between the firmware installed on 3490/3790 (I will not angry if someone disagree, lol..). At the latitude and place where I am and in the averages of observations that I have made with the 3790/3490, "accuracy" has been around for 9 to 12 meters to up, although a few times to have reached 6 meters. Given the imprecision of road maps is perfectly acceptable and usable these values. We also have to admit that there may be variations between these models on a production line, so the need for more rigorous testing to clarify definitively the question (multiple devices, same conditions, etc. ..). But, from what I have observed, I believe that there really difference between the signal quality between the two firmwares, even because the chipsets of 3790 and 3490 are different and should also be the drivers that control and optimize its operation.
Of one thing I am sure, the 3790/3490 (v7.60) is less accurate than the nuvi 2595 (v7.60) because I did a comparison test between the two, on a journey of 1 hour with the vehicle in motion and watching intently values ​​(traveling as a passenger). With both GPS side by side, while the accuracy of the 3790/3490 ranged between 9 and 11 meters to up, of the 2595 was around 3 meters (sorry not having captured images).
By way of curiosity too, despite being among devices of characteristics and goals different, while the Etrex 30 and Oregon 450 maintains precision of 3 meters (without WAAS), the 3790/3490 keeps 10 meters, on average, both side the side and at the same time.
In short, in my simplified tests, but careful, the 3790/3490 is less precise and, despite continuing to be perfectly usable, ideally could maintain the same level of accuracy of his new brothers.

angelozip, may be 2595 was GLONASS enhanced?
Look at bodies of devices: where inside 37xx/34xx place to put a good antenna? They are very slim for this :) 9 meters is not too bad, around 13м шт now in Moscow, Russia...

Quote:

---

Originally Posted by Astx [Only registered and activated users can see links. Click Here To Register...]

angelozip, may be 2595 was GLONASS enhanced? Look at bodies of devices: where inside 37xx/34xx place to put a good antenna? They are very slim for this :) 9 meters is not too bad, around 13м шт now in Moscow, Russia...

---

Astx, was a 2595 USA, normal, without Glonass.
I agree with you, the body of 3xxx are small and slim and the antenna should be lower, the difference may be this, but it seems that the chipsets are different (not sure), which may also explain these variations. For not having doubts, would be necessary to make a comparative test with the 2595 but with the original firmware of 3790. Despite the precision meet our current needs, I wanted to emphasize in the previous post that the 3790/3490 is below of the other models (forgot to mention that also compared with the 1390T and the accuracy of the 3790/3490 was much lower). 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.

Guys,

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... : )

[]'s

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.

Quote:

---

Originally Posted by Neil [Only registered and activated users can see links. Click Here To Register...]

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.

Quote:

---

Originally Posted by angelozip [Only registered and activated users can see links. Click Here To Register...]

............. 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.

Quote:

---

Originally Posted by rfb [Only registered and activated users can see links. Click Here To Register...]

.... 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.

Quote:

---

Originally Posted by lolypop000 [Only registered and activated users can see links. Click Here To Register...]

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.

My Real 3490 (Firmware 7.60) Gets 3 Meter Accuracy in South Africa Clear Sky (All the Time).
If I don't switch it off just use power saver the acquision time is also very fast, Just about 10 seconds.

Just completed the same 20km trip home in reverse. Left the 3590 in the glovebox, and used the 3790>3490 only. Cloud a little less, more few-scattered (2 to 3 eighths of sky covered) whereas outward trip was more like half sky covered. Mostly 5 metres, but sometimes 4 or very occasionally and briefly 6m. Acceptable accuracy and consistent. Very light traffic, only took 20 mins and able to watch the screen safely. So what's different in other users' units from Caty's and my unit, why are some ppl experiencing and reporting such high inaccuracies? I have a good chance to get a 3790 in the next few days to make a proper comparison.

Quote:

---

Originally Posted by lolypop000 [Only registered and activated users can see links. Click Here To Register...]

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.

---

Hi,

Good idea. But is it possible just using the tool provide on internet? Like RGN Tool?
If not, someone have an idea to do that?

[]'s

I will be the tester... : )

Quote:

---

Originally Posted by Neil [Only registered and activated users can see links. Click Here To Register...]

Just completed the same 20km trip home in reverse. Left the 3590 in the glovebox, and used the 3790>3490 only. Cloud a little less, more few-scattered (2 to 3 eighths of sky covered) whereas outward trip was more like half sky covered. Mostly 5 metres, but sometimes 4 or very occasionally and briefly 6m. Acceptable accuracy and consistent. Very light traffic, only took 20 mins and able to watch the screen safely. So what's different in other users' units from Caty's and my unit, why are some ppl experiencing and reporting such high inaccuracies? I have a good chance to get a 3790 in the next few days to make a proper comparison.

---

Hi,

Maybe some units have a hardware difference just on the sattelite reception.....I don't know.

Last month I returned back to 37XX and everyday I verified on satelites page the accuracy 3 ~ 4 meter.
So this month, I flashed with 34XX firmware. On the same places, both tests with clear wether, 10 ~ 14 ~ 20.


I realized that the acuracy with the 37XX during moviment is almost permanent on 3 ~4 metres, but the 34XX is to much worse. Sometimes the error increases to ~ 20 metres....terrible, causing the route change, wrong street....

So let's try to discover this secret!

I am willing to test the ideas.

[]'s