GPS Antenna / Time Synchronization

[safedrivesolutions]

So last night I finished an installation of an A139 Pro. I then proceeded to show the customer the video files, where the date was wrong.
I though this was weird as I did the following
-Set the time zone correctly
-time synchronization

So why would it show the wrong date?

We even waited a few minutes to gather more video footage and yet again in Live View
-1. It shows the correct time on video footage but time in top left corner is wrong.

Further puzzled we figured out that because we were underground the GPS antenna had not been synchronized.

Customer took it for a drive and voila
-time is fixed in video folder.

So why are the 2 times different? Why does the time synchronization not fix both times?

In image down below you will see top left corner is GPS time

2023/06/28 is because time synchronization would not correct until dash cam seen GPS

-Please note this firmware is about 2 firmwares old, so not sure if it was corrected in last 2 firmwares.

 

[VIOFO-Support]

So last night I finished an installation of an A139 Pro. I then proceeded to show the customer the video files, where the date was wrong.
I though this was weird as I did the following
-Set the time zone correctly
-time synchronization

So why would it show the wrong date?

We even waited a few minutes to gather more video footage and yet again in Live View
-1. It shows the correct time on video footage but time in top left corner is wrong.

Further puzzled we figured out that because we were underground the GPS antenna had not been synchronized.

Customer took it for a drive and voila
-time is fixed in video folder.

So why are the 2 times different? Why does the time synchronization not fix both times?

In image down below you will see top left corner is GPS time

2023/06/28 is because time synchronization would not correct until dash cam seen GPS

-Please note this firmware is about 2 firmwares old, so not sure if it was corrected in last 2 firmwares.

Do you mean that the time in the left corner is different from the time in the footage before there is a GPS signal? But they are synchronized after receiving the GPS signal out of the underground? For example, the time is 03:41:56 in the left corner, shall we know the start and end time in that video footage? Although you have set the time zone correctly, the GPS can just synchronize the time when there is a GPS signal. So the date is wrong when your car is parked underground without a GPS signal.

 

[safedrivesolutions]

View attachment 66024Do you mean that the time in the left corner is different from the time in the footage before there is a GPS signal? But they are synchronized after receiving the GPS signal out of the underground? For example, the time is 03:41:56 in the left corner, shall we know the start and end time in that video footage? Although you have set the time zone correctly, the GPS can just synchronize the time when there is a GPS signal. So the date is wrong when your car is parked underground without a GPS signal.

Yes that is correct time in corner is different then "Time Synchronization" from customers phone. However when viewing footage on live view it shows time is correct. The time in top corner only corrects when GPS signal is found.

 

[VIOFO-Support]

Yes that is correct time in corner is different then "Time Synchronization" from customers phone. However when viewing footage on live view it shows time is correct. The time in top corner only corrects when GPS signal is found.

The time shown on the corner of this video is 03:41:56, shall we know the start and end time shown in this video footage?

 

[safedrivesolutions]

20:41 was start time

 

[Dashmellow]

So why are the 2 times different? Why does the time synchronization not fix both times?

I believe your problem is TTFF - otherwise known as Time To First Fix. This is simply a normal aspect of how GPS works.

GPS requires clear line of sight in between the device's antenna and the various satellites, free of obstructions. Various conditions can affect the Time to First Fix, including the environment, weather, humidity and whether the GPS device is operating indoors or outdoors.

A GPS receiver requires three sets of data before it can accurately locate itself. (or set the time)

• GPS satellite signals from multiple satellites
• Almanac data
• Ephemeris data

The TTFF is commonly broken down into three more specific scenarios.

GPS Signal Lock - (starts) COLD - WARM - HOT​

If a GPS device is new or has been switched off for extended periods of time it will take longer to acquire these required data sets and get a Time to First Fix.

This occurs because the GPS data is outdated and needs to refreshed, with up-to-date information downloaded to the device. Since the location of GPS satellites are constantly changing due to their varied orbital patterns, a gps enabled device often has to spend time searching for them. It doesn't get all the information at once.

You might notice that when you first start your engine in the morning it may take several minutes for your dash cam to establish a GPS lock. If you stop somewhere and shut down your engine for a period, say on a shopping trip and when you restart your vehicle a little while later you have a GPS signal almost instantly, this is because your device already has the information it requires (HOT). It you leave your vehicle for a longer period of time but not too long it may take a little longer to gain a signal (WARM). If you leave your vehicle overnight the GPS Signal Lock will then be (COLD)

So the likely reason you were seeing two different times is that your GPS Signal Lock was still at the warm phase rather than hot (complete) and had not yet gathered all the data it needed to populate the recording. It was likely still presenting the older time stamp it held in memory.

For a more detailed explanation of TTFF see this Wikipedia LINK.

 

[safedrivesolutions]

My main challenge is why does Time Synchronization not correct overall time of app and dash cam?

 

[Dashmellow]

Have you tried it with a different phone?

Or could there be an issue with the app rather than with the camera?

 

[safedrivesolutions]

Have you tried it with a different phone?

Or could there be an issue with the app rather than with the camera?

Everything works. See the problem is mainly this

1.) what is the point of time synchronization if it does not fix the time?
2.) The only thing that fixes the time is selecting time zone and having GPS see the sky.

 

[Dashmellow]

2.) The only thing that fixes the time is selecting time zone and having GPS see the sky.

As explained, that's how GPS works.

Other than that I don't really know the answer.

Is the app configured correctly?