Horrible lag in GPS data

[roadkill401]

I just got my A119 with GPS hooked up and it seems that I am getting a horrible amount of lag in the GPS data that is embedded into the video.

My hope was that i can use the speed and location data as proof of direction and speed (or more to point not moving) when I come to a stop sign. In my few experiments, I can see on the video that I am not moving, but the speed on the video shows me going at 14km/h. the bit of footage leading up to the slowing down and stopping the speed is at 9km/h, so effectively it makes it look like i was actually speeding up instead of slowing down. There are parts where I know that I got up to 40km/h but the video only shows me travelling at 18km/h.

Is this an issue with the GPS. Could it be that I am not connecting to enough satellites, or that the actual unit is defective?

 

[jokiin]

accuracy will improve with signal quality

 

[roadkill401]

Just wanted to make sure as i have not removed the protective sticky back and stuck it onto the actual wind shield yet. Want to make sure that the unit is tested and working correctly as it's better to send it back in pristine condition as DOA rather than with backing tape removed and the sticky pad gone. I will see about taking it out for a better run tomorrow around the city rather than just around the block where i live.

 

[Sutton]

Just wanted to make sure as i have not removed the protective sticky back and stuck it onto the actual wind shield yet. Want to make sure that the unit is tested and working correctly as it's better to send it back in pristine condition as DOA rather than with backing tape removed and the sticky pad gone. I will see about taking it out for a better run tomorrow around the city rather than just around the block where i live.

No worries about the sticky tape, the seller still takes it back with in 30 days (Amazon)

 

[CaptureYourAction]

Just wanted to make sure as i have not removed the protective sticky back and stuck it onto the actual wind shield yet. Want to make sure that the unit is tested and working correctly as it's better to send it back in pristine condition as DOA rather than with backing tape removed and the sticky pad gone. I will see about taking it out for a better run tomorrow around the city rather than just around the block where i live.

Having it mounted to the windshield should help with reception. How are you using the camera if it's not mounted to the windshield? Just sitting on the dash?

 

[roadkill401]

I did have it sitting on the dash so that I could test out the option to rotate image that was added in V2 of the firmware. Funnily i did get a better GPS signal that lasted the whole way around the block where when i had it tacked onto the windshield with some other 2 sided tape and a bit of masking tape (to figure out where it was best to place it without loosing too much function or field of view through my windshield, the GPS didn't kick in until i had made my way around the block and was pulling back into the driveway.

Needless to say i will have to give it a better test tomorrow in the day when i have some actual time.

 

[jokiin]

if it was upside down GPS would struggle

 

[pcaouolte]

I notice something similar with mine. When viewing the video in Dashcam viewer the GPS data displayed at the top of the screen lags behind the data displayed at the bottom of video by 2 seconds. This causes the speed to be different on the bottom of the screen and in the GPS data when accelerating or decelerating. See photo:
https://drive.google.com/file/d/0By_XmFIeGYw-dmIyQk5QZnNNSVE/view?usp=sharing

 

[jokiin]

the data embedded in the OSD is not real time, the player will read the real time data stream from the GPS so you will see a difference

 

[pcaouolte]

the data embedded in the OSD is not real time...

Agreed. Looking at the videos the embedded GPS data is correct and the OSD data is wrong (it lags behind by between 1 and 2 seconds). Can this be fixed in a firmware update?

 

[jokiin]

It may be able to be improved but they will always be a bit different regardless as the OSD data is not embedded in real time

 

[roadkill401]

Took the car out for a drive and found the gps lag to be rather noticeable. When playing back you can see me stop and the speed still shows counting down. in some cases, you can see the car is stopped but the speed still shows 25km/h and takes 3-4 seconds to get down to 3km/h but by that time i have already started driving again. The clips are 390mb size so they are not as much fun to paste into a message. don't think you could.

 

[jokiin]

Took the car out for a drive and found the gps lag to be rather noticeable. When playing back you can see me stop and the speed still shows counting down. in some cases, you can see the car is stopped but the speed still shows 25km/h and takes 3-4 seconds to get down to 3km/h but by that time i have already started driving again. The clips are 390mb size so they are not as much fun to paste into a message. don't think you could.

that type of lag is not just due to processing delay, that's indicative of poor signal quality, possibly due to interference, other electronics, windscreen material etc

 

[roadkill401]

if it's indicative of poor signal quality, then I would point the finger more towards a bad hardware design or defect inside the unit. I have used tomtom and garmin inside the car and both of those units work without an issue. I have used an iPhone and 3 different vendors of android phones with a GPS inside, and all of them have worked without an issue.

If I run the video file though the Dashcam Viewer app on my Mac, it reports back a different set of information than what is being written to each frame of the mp4 video created. Now one would think that what is on the screen should be the same or better than what an external app can pull from the video. Now the video you can see the moment that my car stops, the GPS info on screen shows that I am still traveling at 35km/h, where Dashcam Viewer shows that I am going at 16km/h. it takes about 1 second for Dashcam viewer to drop the speed to zero, where the information on the screen takes a full 3 seconds. Now I can understand if the firmware of the camera only polls the GPS once a second and so you are not getting a real time update of the speed for each and every frame on the video. But for it to take 2-3 additional updates to get an accurate measurement of your speed is just totally unacceptable.

 

[jokiin]

GPS is polled once per second, the player software looks at the data stream from the GPS, not what is injected back into the video for display which is further delayed, the player software may do its own averaging of the data as well, if updating is particularly slow this is most often poor signal, not as many satellites etc, the more satellites it can see the more accurate the speed display is

phones are not good to judge signal issues as they use A-GPS

 

[roadkill401]

I guess my next test is to see if you select on the settings menu to have the GPS display nothing, if the DashCam Viewer app will still get the GPS information. My reason for getting the GPS option was to have a video proof that you have stopped at a stop sign or a light to challenge bogus traffic tickets. But if the information shown on the video is 3-4 seconds off, and never accurate, then it is doing me more harm that good. I really wish this was more prevalently advertised in the reviews and comments section of Amazon where I purchased from. It feels a lot like it was held as a secret that nobody bothers to talk about. Bit of a disappointment.

 

[jokiin]

video shows if you are stopped or not, no need for embedded speed info to show that, GPS speed is not admissible in court as it's not a calibrated measuring device, that said though you don't want something that's wildly inaccurate making you look bad so not having the speed shown in the video is probably better anyway

you could have an issue there which is affecting reception, whether that be a hardware problem or some outside influence, it won't have been mentioned in reviews if others aren't experiencing the same, the feedback from other users suggest yours is not typical so needs further analysis

 

[Gibson99]

one other factor between the OSD and external players... the camera can't see the future in real-time so it is using PAST data to calculate your speed.

meanwhile external computer-based player software can actually look ahead in the file (effectively looking into the "future") and calculate your speed more accurately. that's my guess as to why you're seeing this difference.

 

[jokiin]

one other factor between the OSD and external players... the camera can't see the future in real-time so it is using PAST data to calculate your speed.

meanwhile external computer-based player software can actually look ahead in the file (effectively looking into the "future") and calculate your speed more accurately. that's my guess as to why you're seeing this difference.

Registrator Viewer does work like this

 

[Nigel]

I think it is not unreasonable for the OSD to average the last few readings to give a more accurate speed when you are traveling at constant speed, even if it does mean there is a short delay in response when you do an emergency stop. It probably wasn't designed for people who always go from 100kph to 0kph in just 2 seconds!