Dash Camera Interference

[Dash-Cam Man]

Dr Doofenshmirtz said:

It's the switching frequency of the buck converter in the power adapter that causes the issues. They typically switch at around 150khz, and although this is miles away from DAB frequencies (~225.648 MHz) the cheaper units still produce enough noise to kill reception.
To confirm it's the power adapter (the bit you plug into the ciggy lighter) simply power the dash cam from the internal battery (not a USB power bank as these contain buck-boost converters which also produce switching noise) - if the radio reception improves, then you will know for sure it's the power adapter.
Fixing the issue usually involves either buying a good quality power adapter, or fitting capacitors on the input and output side, fit a common mode suppression choke on the input and wrapping the thing in tin foil

It's a good explanation. Most of the noise does come off the step down, but we have heard from the manufactures themselves that the MOSFET's do emit a certain level of noise too, which can assist in the killing of DAB.

Even a hardwire installation such as power from the fuse box without any cigarette adapter plug (i.e. chop off the plug, strip back and hardwire directly the red/black wires) won't stop DAB interference for 2 channel setups. Most cars we see everyday, will have the DAB module at the rear of the vehicle, in the trunk, just under your high level brake light. In addition, the DAB aerial in most cars is actually now a part of the rear heated copper lines you see on your rear view glass, and putting a dash camera on the glass or anywhere in the rear trunk, instantly kills DAB.

This is a plus for some people, as a 1 channel hard wire installation of a dash camera shouldn't affect DAB, due to wiring being primarily at the front, however 2 channel customers will almost definitely feel the impact of a dash camera. Wrapping the wire in tin foil tape doesn't help, nor does ferret rings. Fitting a suppressor is actually a good idea, something we haven't tried and may well give a go this week on a Range Rover Sport we have booked in. These vehicles have the DAB and Nav unit in the trunk, and loss of GPS on the Nav unit can also be a consequence of a rear dash camera.

Thanks, Jay

[Dr Doofenshmirtz]

A MOSFET is really just an electronic switch, it's typically the inductor that emits the noise.

[Tomo1971]

Dash-Cam Man said:

Tomo1971 said:

I have been looking at car specific forums (Audi) for DAB issues - the DAB reception is intermittent and wife comments that her car in same areas doesn't suffer. Google seems to bring up a few threads about USB interference - low and behold, cheap USB plug branded as 'Scosche'. Drove around and found a DAB dead spot, took out the USB, DAB came in. Reinserted it, DAB lost.

Happy days.

By removing power to the item which transmits the conflicting frequency on the same bandwidth, you of course would restore DAB, plugging it back in would of course cause the dash camera to power back up and reinitiate the interference, therefore loose DAB. Your test is not conclusive.

Read up on MOSFET chips, you will find your answer there.

Don’t remember saying the usb was connected to anything? It was used for phone charger, issue with my DAB was there since day one, the day the phone charger was used from. Dash cam is hard wired, ironically from a cheap eBay kit but seems to be interference free.

Now I use a griffin powerjolt for the phone charger usb, no interference.