Question for you 'Electronic Gurus' - whoever you may be

DT MI

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Dash Cam
More than my wife thinks I need.
Earlier today I installed a 'spare' G1W-H, battery version, camera in my wife's car as a rear cam. (In part because earlier this week she was rear ended coming home from work - no damage and no injuries so that's good.)

I mounted the camera directly on the rear window/windshield/windscreen using my modified rearview mirror mount (https://dashcamtalk.com/forum/threads/convert-mirror-mount-to-stick-on-mount.11457). The rear glass has the dual function defroster/antenna wires. I used a 12V splitter similar to this - (https://www.amazon.com/gp/B00ULTDWDM) for power as her car has only a single power socket and that was being used for the front camera (A118-C at the moment). All works well with a single exception.

When she first started the car and turned on the radio there was a horrific electronic 'squeal' coming from the radio. It was so bad that it completely overrode the broadcast signal. After a few minutes it began to subside and eventually went away altogether.

Moving forward in time, she went out to run a few errands and when she returned I reviewed the video clips and noticed a pattern. Every time she started the car the 'squeal' came back for a short period then went away. The period was proportional to how long the engine had been shut off.

I thought it may have been an issue with the G1W-H so, having another one not in use, I swapped it and the second camera has the same issue.

(As a side note, with experimentation I eventually determined the 'squeal' only affected the lower frequency AM stations - 580, 760, 800, etc. The lower the frequency the more the interference. By the time I get up to 1270 there is none. I thought initially it may have been caused by corrosion on the splitter/adapter but removing it from the installation did nothing and the problem persisted.)

After thinking about this for a while I came to the conclusion that the charging circuit in the camera is the culprit. Neither G1W-H cameras had been used for at least a month or more and the batteries had to be pretty much depleted. This explains why the initial interferance lasted for quite a long period but subsequent episodes were fairly short and proportional to how long the engine had been shut off. Once the battery is recharged the interference stops.

Now with all that background out of the way here's my question.

Is there any way to eliminate the problem?

With a bit of work I can probably mount the camera somewhere other than directly on the glass but I'm not sure that will be adequate, and I would still have to route the power cord around and alongside the window. Does anyone have any idea of what the 'range' of the interference might be?... Could it be 'transmitted' down the power cord so moving the camera would have no effect unless I also moved the cord?

Both G1W-H cameras have been used in our vehicles before, but as front cameras so they were not located anywhere near the antennas.

(Buying another camera is not an option - yet - given that I already have 5 and only 2 vehicles.) My wife likes to listen to 'talk radio' and has her favorite stations so not using the AM frequencies really isn't an option either.

Thanks in advance for any ideas.
 
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Try clipping a ferrite core inductor to the power cable as close as possible to the camera.

It is probably the switch mode power supply components within the camera converting the 5 volt power into what is needed.

Could also try wrapping the camera in aluminium foil!
 
You could do a short test with the aluminum foil wrap- be sure it's grounded to the car body and don't leave it for overheat reasons. If that works, fabricate a wire screen "faraday cage" similarly so there will be airflow. It needs grounding too. Use a couple ferrite chokes end-to-end on the power cable (the bigger the better because of the low frequency) and locate them as close to the cam as you can. Also upgrade to shielded OFC cables. Another thought is to hard-wire the unit to another circuit- you may have to try several. Where is the radio antenna on the car? Make as much distance between the cam and it as you can. Also a large filter cap like used with car stereos on the cam power positive lead may also help.

After these tricks you might be able to go into the cam and filter, shield, or isolate the offending circuit but that will take more research than I've done. Hopefully her favorite station isn't aligned with a harmonic of the charger circuit, that kind of trouble sometimes can't be resolved. These tricks usually work for Ham radio installs so they should work here.

Phil

PS- yes the interference could come anywhere along the power cord- reroute it.
 
@Nigel and @SawMaster, thanks for the assistance, I appreciate it.

I went to the local Radio Shack (closest retail outlet available) and picked up a couple snap chokes (http://comingsoon.radioshack.com/snap-choke-core/2730069.html) and put them right next to the camera. Unfortunately no success.

For @SawMaster - the antenna/defroster wires are on the rear glass proper.

I'm not sure where the antenna lead is routed. I pulled the power cable for the camera out of the little recesses where I had it tucked into and tried it going straight down the center of the car - again no improvement. This, however, tells me the interference is coming from the camera directly into the antenna wires in/on the glass as versus any type of induction signal in the wiring - correct me if I'm wrong on this.

I like the idea of a faraday cage but it will have to wait for another day. Before then I think I'll work on getting it off the glass and try mounting it further from the antenna, hopefully just a few inches will be enough. For the time being she will just have to put up with the interference for a minute or so when she starts the car.
 
...Before then I think I'll work on getting it off the glass and try mounting it further from the antenna, hopefully just a few inches will be enough...

Well, that didn't work out either. :( With my wife's assistance I moved the camera around the interior of the car and anytime it was within 12-15 inches of the rear window the interference began.

Tomorrow I think I'll move the A118-C from the front to the rear and see if that causes a problem. If it doesn't then I'll probably look for a capacitor camera instead of the G1W-H. Either that or just leave the A118-C as the rear cam and come up with something else for the front.
 
(Edit: looks like you posted while I was writing- if you need that much distance it might be easier to switch cams as you'll probably need shielding inside the cam to cure this otherwise. Also a capacitor-based cam will 'charge' far quicker)

What you're dealing with is a wide-frequency 'hash' versus a single frequency interference and that is much harder to filter out. It seems your best bet will be a camera location further away from the antenna. Can you do a side-window mount facing rearward? Or put the cam directly opposite the window from where it is now? The "faraday cage" isn't likely to help much with such close proximity to the antenna- it attenuates the passage of RF but doesn't stop it entirely. I don't know where the lead-in for the antenna is routed, but that is a coaxial cable and grounded, thus a far less likely suspect since you didn't see it during the install and your actions seem to confirm that it's OK.

Almost all consumer electronics fall under the FCC "Part 15" riles which has no requirements or specifications regarding RF interference incoming or outgoing, and battery chargers are sometimes pretty bad noise generators. Here at home my NiMh battery charger has to be across the room from my Ham gear as it creates a lot of hash which the well-shielded and grounded radios hear all too well otherwise. Your car radio is less sensitive so less distance should work as the simple solution.

As an old friend of mine is fond of saying "You can't always want what you get".

Phil
 
Does it still do it when running on battery with the power cord disconnected?

If not then try a different power adaptor, people have had success with that in the past.

If it still does it on battery then it may be worth checking out the earth connections for the radio and antenna/defroster, poor earths on antennas can be a big problem.

If you were in the UK then I would suggest getting a digital radio, much less likely to be affected.
 
When she first started the car and turned on the radio there was a horrific electronic 'squeal' coming from the radio. It was so bad that it completely overrode the broadcast signal. After a few minutes it began to subside and eventually went away altogether.

(As a side note, with experimentation I eventually determined the 'squeal' only affected the lower frequency AM stations - 580, 760, 800, etc. The lower the frequency the more the interference. By the time I get up to 1270 there is none.

After thinking about this for a while I came to the conclusion that the charging circuit in the camera is the culprit. Neither G1W-H cameras had been used for at least a month or more and the batteries had to be pretty much depleted. This explains why the initial interferance lasted for quite a long period but subsequent episodes were fairly short and proportional to how long the engine had been shut off. Once the battery is recharged the interference stops.
Simple:
1- Stop using the AM band (for one, why are you, or your wife, still using it, in this day and age?) :)
2- Charge the batteries once in a while when the camera's not in use.
 
OK guys, thanks for all the suggestions/advice/hints/etc. - I do appreciate the time and effort. I've temporarily averted the problem by switching the cameras front to back. The A118-C is now mounted on the rear window and the G1W-H is back on the front where it was a few months ago. No interference at all. At least I have time now to get a replacement for the G1W-H.

(Edit: looks like you posted while I was writing- if you need that much distance it might be easier to switch cams as you'll probably need shielding inside the cam to cure this otherwise. Also a capacitor-based cam will 'charge' far quicker)...

Like you were reading my mind. :D

...Your car radio is less sensitive so less distance should work as the simple solution....

The radio in question is really low quality. Just pulling into the garage (wood frame, not metal) it will lose at least 50% of the incoming signal strength. This just makes the 'local' interference that much worse.

...As an old friend of mine is fond of saying "You can't always want what you get"....

A wise friend.

Does it still do it when running on battery with the power cord disconnected?

If not then try a different power adaptor, people have had success with that in the past.

If it still does it on battery then it may be worth checking out the earth connections for the radio and antenna/defroster, poor earths on antennas can be a big problem.

If you were in the UK then I would suggest getting a digital radio, much less likely to be affected.

It does not do it when running on battery.

Problem is not the power adapter (although I did consider that initially) because once the internal battery recharged the interference went away - this pretty much points the 'finger of guilt' straight at the charging circuit in the camera. Also, I'm using the same pair of adapters after switching the cameras and all is good.

...
1- Stop using the AM band (for one, why are you, or your wife, still using it, in this day and age?) :)
...

Send me your phone number and I'll have my wife call you directly and you can convince her to switch. :eek::D

Myself I much prefer either satellite radio (XM/Sirius) or my own music selection on a flash drive.
 
It would take me some research since I've not paid any attention to the internal circuit layout, but there is a chance that the charging circuitry can be shielded inside the cam to reduce or eliminate this. Hadn't thought about this before, but if i put a HF ham rig in the van I will have the same problems :eek: No effect on the VHF FM in there now. The comparatively low sensitivity you experience with an AM car radio is part of the design to reduce interference- the less it 'hears' the easier it is to adequately filter.

Where I live, several AM broadcast stations are simulcast on their FM corporate companions. Might be the same where you live, but there may not be the exact one your wife wants to listen to on FM. It's worth a quick check online and with a radio.

Phil
 
I have a permanent solution - just ordered another A118-C. (12 step program here I come...)

I really needed to not use the G1W-H because it has some reliability issues in my wife's car. She parks outside when at work and the car faces south (no option on this) so the camera is exposed to direct sunlight. On hot, sunny days it will fail to start recording (or start and almost immediately quit) when she comes home. This is a fairly severe environment and I sure the failure is heat related because once the camera cools down it functions normally. The A118-C did not demonstrate that behavior in the month or so it's been in her car.
 
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Does your car use the rear demister as an antenna?
 
I really needed to not use the G1W-H because it has some reliability issues in my wife's car. She parks outside when at work and the car faces south (no option on this) so the camera is exposed to direct sunlight. On hot, sunny days it will fail to start recording (or start and almost immediately quit) when she comes home. This is a fairly severe environment and I sure the failure is heat related because once the camera cools down it functions normally. The A118-C did not demonstrate that behavior in the month or so it's been in her car.
Since the hot weather began here, right around April, I always carry a dark piece of cloth in the car for those situations when I can't park the car in the shade. I put the cloth over the camera and not only it's not exposed to direct sunlight but also prevents it from heating. So far I've never had any problems with it not starting up after being in the sun.
The biggest problem here is the UV radiation indexes, which have been abnormally high in Spring for the last 10-12 years. I know what they can do to plastic things.
The climate changes are here to stay, I tell you.
 
Does your car use the rear demister as an antenna?

Yes.

Since the hot weather began here, right around April, I always carry a dark piece of cloth in the car for those situations when I can't park the car in the shade. I put the cloth over the camera and not only it's not exposed to direct sunlight but also prevents it from heating. ....

I'll keep that in mind but with the A118-C mounted directly on the glass it's really not an option. :(
 
I'll keep that in mind but with the A118-C mounted directly on the glass it's really not an option. :(
But it's a good temporary solution for the G1W-H. ;)
 
2002 Honda Civic EX

If ferrite doesnt help, then probably need a shielded power cable. If that doesnt help, then need EMI coating of unit inner shell to shield interference as in previous posts suggested to do quick DIY test with foil-wrap.
 
ARRRRRGGGGHHHHH!!!!!!

The %&@#()&!!) problem is back!! :mad::mad::mad:

This morning I switched the 2 cameras front to back (as I posted above) and drove the car for about 10 minutes with 3 or 4 ignition on/off cycles and had no interference. This afternoon my wife took the car to run some errands and the problem is back worse than ever.

I'm pretty sure it's related to the power adapter going to the rear camera because I haven't changed that - and unplugging the rear cam makes the interference go away. Is it possible that the unit may have just started failing and is causing intermittent problems? (Like I said it was perfect this morning and terrible this afternoon with nothing changing in between those times.)

I'll be switching to a different power adapter tomorrow - I've had enough 'fun' with this today. :(

Edit: At least now I know that it's not the G1W-H. Some good came out of this.
 
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