uski
Member
- Joined
- Aug 29, 2016
- Messages
- 34
- Reaction score
- 38
- Country
- United States
- Dash Cam
- Blueskysea A12 + Viofo A119 + Viofo A118C
It's not entirely true, GPS receiver CAN interfere between themselves.
I see 4 interference mechanism :
- GPS receivers are just receivers however they may leak signals through the antenna due to the way the reception works. Because GPS signals are so low power, the high gain of the GPS receivers may amplify the noise from the other GPS receiver and this may be a problem (look for LO interference and LO receiver leakeage on Google, LO = Local Oscillator)
- GPS receivers are electronic devices and as any electronic device they broadcast some electromagnetic noise. Intermodulation may generate frequencies with a frequency very close to the GPS signals, making reception difficult. Some receivers feature anti-jamming algorithms that might mitigate this, but if the noise levels are very high they could saturate the radio front-end and no amount of calculation will be able to remove this noise. This is explained very well here : https://www.u-blox.com/sites/defaul...blox-AntiJamming_WhitePaper_(GPS-X-09008).pdf
It is hence possible that one dashcam produces noise that the other dashcam cannot remove
- Multipath and interference (in wave propagation theory) can be an issue and the signals bouncing from nearby objects around the GPS receiver can cancel each other, creating a small dark spot where the antenna of the victim GPS receiver is placed
- GPS signals are very low power and the antenna needs to be tuned properly so that the signals are receiver properly. Placing any object too close from a GPS antenna may de-tune it. This is the least likely interference mechanism but think about it when installing a GPS receiver.
We're talking about dashcams here where GPS performance is not really important, but if you start comparing GPS performance it is not that easy to do it properly. Do not underestimate environmental factors. Just changing the location of a GPS receiver inside a car can affect its performance. Most of the time there is no problem but it can be surprising.
My day job is to design GPS devices for cars so I unfortunately know too well that many things can go wrong. Recent GPS receivers are much less sensitive to interference than older ones but as we don't know what's inside the dashcams we can't assume they have good antijamming.
With that being said, I do not see any issue with the GPS in the Viofo A119 or A119S. Just wanted to give people a heads up that testing GPS receiver properly is not as easy as putting them next to each other and comparing the output. This A119S dashcam seems outstanding.
Hope this helps
I see 4 interference mechanism :
- GPS receivers are just receivers however they may leak signals through the antenna due to the way the reception works. Because GPS signals are so low power, the high gain of the GPS receivers may amplify the noise from the other GPS receiver and this may be a problem (look for LO interference and LO receiver leakeage on Google, LO = Local Oscillator)
- GPS receivers are electronic devices and as any electronic device they broadcast some electromagnetic noise. Intermodulation may generate frequencies with a frequency very close to the GPS signals, making reception difficult. Some receivers feature anti-jamming algorithms that might mitigate this, but if the noise levels are very high they could saturate the radio front-end and no amount of calculation will be able to remove this noise. This is explained very well here : https://www.u-blox.com/sites/defaul...blox-AntiJamming_WhitePaper_(GPS-X-09008).pdf
It is hence possible that one dashcam produces noise that the other dashcam cannot remove
- Multipath and interference (in wave propagation theory) can be an issue and the signals bouncing from nearby objects around the GPS receiver can cancel each other, creating a small dark spot where the antenna of the victim GPS receiver is placed
- GPS signals are very low power and the antenna needs to be tuned properly so that the signals are receiver properly. Placing any object too close from a GPS antenna may de-tune it. This is the least likely interference mechanism but think about it when installing a GPS receiver.
We're talking about dashcams here where GPS performance is not really important, but if you start comparing GPS performance it is not that easy to do it properly. Do not underestimate environmental factors. Just changing the location of a GPS receiver inside a car can affect its performance. Most of the time there is no problem but it can be surprising.
My day job is to design GPS devices for cars so I unfortunately know too well that many things can go wrong. Recent GPS receivers are much less sensitive to interference than older ones but as we don't know what's inside the dashcams we can't assume they have good antijamming.
With that being said, I do not see any issue with the GPS in the Viofo A119 or A119S. Just wanted to give people a heads up that testing GPS receiver properly is not as easy as putting them next to each other and comparing the output. This A119S dashcam seems outstanding.
Hope this helps
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