[Solved] A129 Duo rear camera interference (after startup)

[DashTube]

Edit: This issue has been solved. Please see the following posts for details:
https://dashcamtalk.com/forum/threa...interference-after-startup.38865/#post-464352

I recently received my first A129 Duo. After I got it installed I noticed that there is lots of interference in the rear camera picture right after engine startup. Interference will disappear in a minute or so and won't appear again on subsequent startups when the car is still warm, but I'm still a little bit concerned about the source. Any ideas?

I didn't notice any interference during the install and alignment, but the engine wasn't running at that time.

I have already tried to attach a ferrite choke on one end of the rear camera cable (didn't had more chokes lying around) but it didn't help. Should I try to add another?

We don't have DAB radio broadcasts here, so it can't be the reason either.

Here is a video where the interference is clearly visible for the most of the time but disappears just a few seconds before end. During the video I rev the engine couple of times and hit the brake pedal but those actions had no visible effect on interference.

2019_0418_222836_058R.MP4

drive.google.com

 

[Harsh]

Could be a faulty rear camera cable.

 

[RavenManiac]

What path did you use to run the cabling for the rear camera? Is it possible that something along the path could be causing the interference? Maybe another electronic device.

 

[BlackboxMyCar]

Is the cable connection loose at all, for the front and rear camera ports? Only thing I can think of is the larger vibrations on a first cold start-up vs. subsequent warmer start-ups, if the issue is only occurring during that situation.

Is the rear wire pinched anywhere along the installation path?

 

[CaptureYourAction]

How are you powering the camera? Are you using the supplied Viofo 12V car adapter and Viofo USB power cable?

Do you have WiFi off?

 

[DashTube]

Thanks for the replies!

I routed the cable via left side (driver side) A-pillar and door sills because I didn't want to mess with the curtain airbags. So it goes like this: Rear view mirror -> A-pillar -> front and rear door sills -> C-pillar -> rear hatch. There is a wire harness next to the rear camera cable almost on its entire length. Probably a gazillion other systems and subsystems are powered and controlled by that wire harness. From keyless entry to rear window washer etc. etc.

Connectors feel ok to me. Not overly tight and not loose either.

Cable is not pinched. It is snug fit but can be pulled back and forth if given some slack aroud tighter spots.

Front camera power cable is from my previous Transcend DrivePro 220 camera (had it over three years, no issues - just wanted rear camera as well). Power adapter is Samsung EP-LN920 Dual Fast Car Charger because I need that Qualcomm Quick Charge 2.0 compatible fast charging for my phone. Rear camera cable is the one that came with the unit.

WiFi should be off. Have to re-check on that but I'm 99.9% sure.

 

[CaptureYourAction]

Try with the supplied 12V car adapter and USB cable. Probably a poor power issue.

 

[DashTube]

Try with the supplied 12V car adapter and USB cable. Probably a poor power issue.

Did a quick test this morning and you are correct. It's a poor power issue. More specifically, a voltage drop issue due to too thin power lines in my Transcend camera power cable. Markings on the cable says it's 26AWGX1P / 24AWGX2C, which means it has 24 AWG or 0.205 mm² wires for power (and 26 AWG wires for data), where as Viofo's original cable has 22 AWG or 0.326 mm² power wires. Thus, Viofo's wires are significally thicker (63 % larger cross-sectional area), which leadst to less resistance and smaller voltage drop.

American wire gauge - Wikipedia

en.wikipedia.org

This was also confirmed in my tests. Here are my results with different power adapter and power cable combinations:

12V adapter ⬇ \ Power cables ➡​	Viofo (22 AWG)​	Transcend (24 AWG X2C)​
Viofo​	OK​	Interference​
Samsung EP-LN920 (QC 2.0 support)​	OK​	Interference​

Table 1: Viofo A129 Duo rear camera interference with different 12V adapter and front camera power cable combinations.