Help Needed - Strange Problem with USB and DAB

[Al U]

Hi,

If you have any expertise or experience with this issue I would really appreciate it.

I have a windscreen mounted DAB aerial and a mobius action cam that I am using as a dash cam which is also windscreen mounted. When I use the dash cam I get normal DAB reception but as soon as I plug the mini usb cable in the dash cam to charge it, my DAB signal goes completely. If I pull the mini usb cable out DAB reception immediately comes back. This is really annoying me and it is not my area of expertise and despite googling the issue I have not seen a fix.

Can anyone shed some light on what to do?

[pixelatedJH]

Some dash cam cables come with little supressors on them to stop this - look like a little black cylinder and are meant to stop this problem.

Similar to these

[marshalla]

pixelatedJH said:

Some dash cam cables come with little supressors on them to stop this - look like a little black cylinder and are meant to stop this problem.

Similar to these

This. The cable is acting as an aerial and broadcasting the noise from the charger - which is interfering with the DAB signal. The same noise may also be leaking back into the vehicle's loom, which will also transmit it to the supply for the DAB receiver as well as broadcasting it.

You need a better charger and cable with proper suppression.

[Al U]

Yes I have seen people talk about those on some of the searches I've done. Will be purchasing some soon but not sure it will resolve it. Really hoping someone will come along and say thry know the issue and how to fix it.

[Al U]

marshalla said:

pixelatedJH said:

Some dash cam cables come with little supressors on them to stop this - look like a little black cylinder and are meant to stop this problem.

Similar to these

This. The cable is acting as an aerial and broadcasting the noise from the charger - which is interfering with the DAB signal. The same noise may also be leaking back into the vehicle's loom, which will also transmit it to the supply for the DAB receiver as well as broadcasting it.

You need a better charger and cable with proper suppression.

Ok where should the suppresor go on the cable, does it matter? The cable is a 2M USB cable being run off of a 12V USB charger that is plugged into a new 12V socket that I had installed specifically to power the dash cam.

[marshalla]

Start with the charger - a decent one shouldn't kick out all the noise that the cheap ones do.

[Al U]

Will go and buy some of these tomorrow.

http://www.maplin.co.uk/p/ferrite-clip-on-hem3012-...

I think that putting one at the base of the cable where it meets the charger and one as close as possible to the dash cam will be a good start, hopefully that will solve it. Will definitely make the camera less stealth than it already is but I don't mind if it solves it. Thanks for the suggestions so far.

[pixelatedJH]

I've seen it with a lot of cheap Chinese chargers, but never with genuine branded ones, Belkin ones do fine and run about £10. If you're going to try the suppressor instead, don't think it matters but instructions normally say put it about 5cm from the cigarette lighter end of the USB cable

[Al U]

marshalla said:

Start with the charger - a decent one shouldn't kick out all the noise that the cheap ones do.

The 12V socket is good quality, as is the USB cable. They are not cheap parts, they are installed in a way that makes frequent access difficult due to being totally out of site so I bought decent stuff bearing that in mind.

[wst]

Al U said:

Ok where should the suppresor go on the cable, does it matter?

Not particularly, when fitting them on cables used inside audio mixing kit (Avolites) we just used to put them about 2 finger widths from the connector to keep it tidy and uniform.

[Al U]

Just to clarify I am not using a charger like a tomtom charger for exampe. It is a USB cable, plugged ino a 12V USB plug that is plugged into a 12V socket.

[Gavin0478]

USB output runs at 5V normally not 12V.

[Al U]

Gavin0478 said:

USB output runs at 5V normally not 12V.

Yes I imagine they take that into account when they make USB plugs that plug into a 12V socket.

[Al U]

So, added some ferrites today and a step forward has been made. When stationary with the engine on and everything plugged in, the dab is fully functional. However when I went for a drive, the signal became patchy. This is still progress as before there would be no signal at all.

I was running one ferrite close to the dash cam and one in the dash part of the cable route, so I've moved both as close as I can get them to the dash cam now and will see if it makes it any better on the drive to work tomorrow. Thanks again for the suggestions.

[acme]

Thread resurrection.....

Did the OP get any further with this?

Just installed an Aukey dashcam, using their twin USB socket into the cigarette lighter it cuts all DAB signal, which is a pain as it's not that long ago I installed a Continental DAB radio, apart from anything else I could barely get any analogue signal due to an inbuilt windscreen aerial and the car being old.

Any suggestions, I've three USB sockets and all are the same, I assume the obvious advice is ensure a decent make (Belkin) or one of the suppressors?

Cheers

[DaveCWK]

This is caused by the switching frequency within the DC-DC converter. The ones that have issues will just happen to operate at a frequency that interferes with DAB. There are many off the shelf DC converter chips that these companies use - but a variety of cheap ones off eBay that look a little different & one will likely work fine.

[gizlaroc]

Crap chargers that don't meet the spec they are mean to.

I have tried loads, this is the only one that doesn't interfere with DAB I have found.


https://www.amazon.co.uk/Belkin-Charger-Charging-V...

Now of course they may have changed it since I last bought one.

[acme]

Thanks fellas, appreciate the reply.

A Belkin dual one it'll be