Umi Plus and GPS Signal

ciccios · Post time 2016-11-18 21:01:33

plus_user replied at 2016-11-18 20:39
It would be good if UMI would comment the GPS problem officially.

What should the affected users d ...

there are a lot of people here waiting for the same answer for a loooooong time !
most of the previous Umi devices have the same issue :-)
if you have time you can wait; we say "wait and hope"! but not for too long or your "warranty" will expire.
good luck

GlobuS · Post time 2016-11-19 03:49:36

Edited by GlobuS at 2016-11-19 03:51 \n\nOK, I think I have fix GPS.. I still have to test it outside on the move..
Will let You know later what we have to do..

If I am right there is not so much to do.. Only removing upper plastic cover (near camera) and make antenna little bit bigger.

GlobuS · Post time 2016-11-19 21:30:42

So I have opened UMI PLUS.
Here U san see connections to antennas.

Here U san see connections to antennas.
Here are antennas (GPS on the right side)

But in my oppinion we do not need to remove all the covers and we do not need getting to mainboard.
Only we need to extend antenna.

I didn't take picture where copper tape should be placed (at home I do not have copper tape so I used aluminium foil)

So what need to be done:
On this movie You can see how to remove plastic cover:
https://www.youtube.com/watch?v=MlmyOdQwf6k&t=3s

Only remove this close to camera. You will see one srew which is close to GPS antenna and it is connected to antenna.
Unscew it and put copper tape (it should have connecton with copper part from antenna)
Put the srew back to it's place. Close plastic cover.

I'm thinking about connecting GPS antenna to the body of the phone.

enricof · Post time 2016-11-20 00:48:33

Dear Globis 8
thanks you very much for your post but I don 't understand so much...
I don't understand for your opinion where is the harware issue and how we could improve the gps segnal.
Thanks in advance

Enrico

stedk · Post time 2016-11-20 01:29:38

Hi GlobuS. I just removed the cover and inserted a very thin and long wire under the second screw from the left (the one which is accessible, since the first is covered by plastic and not very accessible). I will try tomorrow if it makes a difference by testing the sat nav and report back to you. Ciao

stedk · Post time 2016-11-20 01:46:37

I am under impression the main cause for the poor accuracy is not gps but agps. Looking at the engineer mode it looks like every time a wifi signal is caught the agps finds a new fix for the position. Tomorrow i will test both with and without wifi so I will be able to test my hypothesis.

Fyodor · Post time 2016-11-20 02:04:19

They use a GPS + WIFI combo antenna.

One is 'receive-only', the other one is 'transmit+receive', no big surprise if any kind of transmission in one antenna interrupts reception in the other antenna, as they are 'combined' into one.

They save space this way, of which there is not much at all behind that plastic cover.

It is also cheaper to have only one antenna instead of two.

Too bad after all this design effort that it does not work satisfactory at all, who wants to mess with a new device, but what else can be done?

Some more reading if anyone is interested in combo antennas (GPS + WIFI) in mobiles.

http://www.jpier.org/PIERL/pierl39/12.13021901.pdf

Fyodor

GlobuS · Post time 2016-11-20 02:47:56

enricof replied at 2016-11-20 00:48
Dear Globis 8
thanks you very much for your post but I don 't understand so much...
I don't underst ...

I'm not so good in waves theory, but I think if we make antenna surface bigger it can help. I know there is seperate branch of science about designing antennas

but hope I am right

Also stedk wrote about catching new fix when wifi is connected..
I started to think maybe main reason of loosing signal is that UMI did something with software and it is not holding gps active all the time..
When switching between apps like MTK (on page with wiev of sattelite connected) and some other, every time he is looking for new satelites and applying new fix
Found some apps on market responsible for keeping gps alive all the time.
will test it

stedk · Post time 2016-11-20 03:35:11

Edited by stedk at 2016-11-20 03:37 \n\nOk, quick test on my balcony with copper wire in place. I set my Umi Plus side by side with my Moto X Play. App: Google maps. With Wifi on: fix almost immediate on both devices. Motorola is off by approx 6 meters and doesn't move around. The blue circle is very small (less than 5 metres). Umi Plus is off by approx 25 mt and after a few seconds stars moving all over the place, even hundred meters from my location (I am not moving). The blue circle is approx 20 meters. With wifi off: no change for Moto X Play. Umi Plus is still off by 25 meters. Blue circle much smaller but STILL the central dot moves around, not quite as much as with wifi on but still not nearly as rock solid as my Moto. Goodbye to my "AGPS is the cause" theory. There is defintely something wrong with this device. For me Umi Plus = paperweight.

Fyodor · Post time 2016-11-20 04:30:02

Edited by Fyodor at 2016-11-20 04:34 \n\n.

This is what I would be very happy to discover under that plastic part.

http://www.lpkf.com/news/press-releases/560/130.htm

As it is now, we are looking at a combo 'GPS+WiFi' antenna.

Like these.

http://www.molex.com/molex/produ ... eTitle=Introduction