GPS fixing problem!

Kobra

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I had earlier used Lukas LK-7950WD GPS (without OBD) and found no problem at all for the GPS fixing.
After starting the engine and the dashcam turning on, then driving , the speed was shown on the LED display of the dashcam. At the time, I used the firmware version 2.3

But recently, I replaced it with QVIA AR790 2 CH installed in the same car with the same film but hardly get the GPS fix. It's kinda annoying to me because I really need the GPS feature.
Currently, the firmware I am using is 3.2.1 (the latest version I guess).

Could anyone help please?
 
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Kobra

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Update: after using the dashcam for around a month, I notice the following additional findings for GPS.
- Surpringly enough, it seemed to take a few days to get the first fix of GPS and the car must be parked in parking mode outdoor with GPS enabled.
- During a trip after getting the first fix, the GPS light is on and off from time to time depending on the environment, but it's much relatively quick to be back on.
- However, after coming back home, I normally off the cam and it would be started over with the first fix again of GPS when started the engine in the morning to go out for work, which it would take again a few days to have the GPS light on.

Anyone may have similar or different experiences, I will be more than happy to hear from you as always.
 
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Kobra

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Nobody has experienced the problem at all?

Any way, I found some info about the expected GPS fixing time for Lukas/QVIA dashcam from FAQ ( http://www.qviadashcam.net/bbs/board.php?bo_table=02_board&sca=GPS#a2 )
It said that
---------------
How long does it normally take to receive the GPS signal?
For the first use, it takes about 15-20 minutes, and after that, it normally takes about 3 minutes. Please be noted that there are some areas such as in a tunnel or around tall buildings where
the GPS signal may get lost.
-----------------

But my case is definitely beyond 20 minutes i.e. a few hours to a few days!
 
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Kobra

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Hardware problem
Oh! short response but shocking me.
Are you using your cunningham's law?
You meant the GPS module, didn't you?
Isn't it about the GPS signal acquisition sensitivity that can be adjusted my manufacturer?
 

jokiin

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Too many ¯\_(ツ)_/¯
If you're seeing 20 minutes to get a signal you have a hardware problem, not something that can be adjusted, hard to know where the problem lies though
 
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Kobra

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If you're seeing 20 minutes to get a signal you have a hardware problem, not something that can be adjusted, hard to know where the problem lies though
My problem is about too long TTFF (Time To First Fix) of the GPS but later fix is quick enough. Therefore, I assume the sensitivity was set too low.
In your opinion, will the problem be relieved or solved by using external GPS signal repeater? Or any other advice?
 

kamkar1

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Do GPS antennas get calibrated ?

I have been wondering this with my GPS Issue.
My antenna do work i can see that plugging it in and that it do get a fix eventually, just weird it have to take so long hence my idea of a poor calibration.
 

kamkar1

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YES Cold Boot as we call it is where the problem is, there are no problems with warm boots where the antenna have a saved set of info to start with.

It is however weird that it is not the same every day, at least not for me. Some days i can drive 40 minutes and not get a fix other days i do get a fix but after a long long time compared to other GPS cameras i have owned.

No doubt it is a hardware problem in the GPS antenna.
 
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Kobra

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YES Cold Boot as we call it is where the problem is, there are no problems with warm boots where the antenna have a saved set of info to start with.

It is however weird that it is not the same every day, at least not for me. Some days i can drive 40 minutes and not get a fix other days i do get a fix but after a long long time compared to other GPS cameras i have owned.

No doubt it is a hardware problem in the GPS antenna.
Yes, I compare the GPS fixing between my current AR790 2CH with my earlier LK-7950WD and found that LK-7950WD's GPS fixing worked very fine.

Is the assumed hardware problem only my dashcam or all AR790 2CH's defect?
 

kamkar1

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not too many users of that model, but i cant say i have heard of the problem before, it is probably your GPS antenna that's out of order too, i tried another GPS on my camera and that was much better and then the other camera i changed GPS with had the slow GPS fix so clearly the problem follow that GPS antenna.

I have now replaced GPS antenna with a old one i had lying around, but today are day #1 with the "new" antenna so further investigating need to be done, but i assume this have fixed my problem.
 
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Kobra

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not too many users of that model, but i cant say i have heard of the problem before, it is probably your GPS antenna that's out of order too, i tried another GPS on my camera and that was much better and then the other camera i changed GPS with had the slow GPS fix so clearly the problem follow that GPS antenna.

I have now replaced GPS antenna with a old one i had lying around, but today are day #1 with the "new" antenna so further investigating need to be done, but i assume this have fixed my problem.
Thanks so much for your feedback. Did you have your AR790 WD's GPS replaced by yourself or manufacturer?
Please feel free to share your further experience.
 
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jokiin

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Too many ¯\_(ツ)_/¯
If cold start is slow it's possibly the RTC battery for the GPS that has failed causing it to download the full ephemeris data each time or it's just some other random problem, not something you can tune out as such
 
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Kobra

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If cold start is slow it's possibly the RTC battery for the GPS that has failed causing it to download the full ephemeris data each time or it's just some other random problem, not something you can tune out as such
Oh! This may seem to be the case. Any advice to fix it?
 

kamkar1

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No i have anther brand of camera.
My first dashcam was a Lukas LK-7500, way back in the good old days.

I am tearing my failing GPS antenna tonight to have a look inside.
 

kamkar1

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Here is parts of the inside of my GPS mouse antenna, the culprit as mentioned are probably the little battery in the left corner.

Will take some work for me to resolve what kind of battery its in mine, besides i think i would be better off investing in a pair of glasses first so i had a chance of reading the text on the battery.

GPS.jpg
 

kamkar1

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No i wasent going to, just curious to take a peek, judging by the behavior i have no doubt its the battery so really not a factory flaw worth putting too much effort into.
And i already have 3 GPS fixes two of them thanks to the DC and covering the primary angles.
And its a long time to the next time change. :)
And i have the GC V1 antenna on the camera and it seem to behave fairly decent too, though it do seem like the DC are the cold boot connection champion of the 3, but its not like the other two trail by a margin that is leading to worries about this.
 
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