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Thread: DAB Radio interference with Polaris screen

  1. #1
    Join Date
    Feb 2014
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    DAB Radio interference with Polaris screen

    Hi all, just finished fitting up a Polaris NG7 screen above the factory screen in my D4. On the first drive with the screen fitted (just by the way back to the dealer because the screen has a couple of problems ) I notice it was causing the DAB to drop out. Not putting any store in coincidence and knowing that the DAB was fine before I fitted the screen, I took the screen off (left it with the dealer for return to Polaris and I hope a new one that works) and hey presto, perfect reception all the way home.
    I thought the levels of EMF were quite low from screens these days, and, I would have expected the head unit in the instrument panel to have some level of EMF shielding anyway.

    Any thoughts on additional shielding because I have a feeling that when I get the screen back and fit it up I am going to have a problem with the DAB again.

    Thanks

    Peter
    MY13 D4 Nara Bronze HSE, Almond Interior, E-Diff, 20" for the road, 18" GOE for the fun stuff, Traxide, OL Bar, GAP IIDTool, Pioneer Tray, DAB+ and LOGIC 7 ICE retro-fit, Vintage SAV Marchal Driving lights (weird I know but what can I say)

  2. #2
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    Apr 2016
    Location
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    I'd be curious as to what exact part in this Polaris unit would be causing the interference .. could help with some interference I get with my phone charger unit.

    I use a Galaxy Tab with OziExplorer for my GPS usage, and it doesn't cause any issue with my Pioneer DAB capable head unit at all.
    Radio head situated in the normal spot in the centre console, and Galaxy Tab mounted via suction cup to screen sits only mm above it on the flat dash top.

    My Galaxy Tab has a sim slot as well as all the other connections that as common in modern mobile devices, and as said causes no DAB interference at all.

    BUT! .. I also use a magnetic Qi charger for my phone, so it's held magnetically to the holder AND charges wirelessly whilst held there.
    (quick review on this BFC device ... .. awesome!)
    Whilst the BFC holder is connected to a power source but phone not mounted, no interference, so no drop outs.
    With BFC connected and phone mounted, so that phone is charging, once the buffer is used up(about 10-15sec worth), DAB dies.
    Comes and goes in some areas, but on the whole drops out for longer periods than actual reception.
    So the interference issue is solely based on the inductive Qi charging system.

    As said, radio head unit mounted in the normal centre console position, and basically anywhere I mount the Qi charger in the front of the car, it causes the dropouts on the DAB frequency.
    dropouts worse on AM stations(mainly ABS Melb), and a bit less so on Gold 104 and Triple MMM frequencies(that I've tried).

    With Qi charger charging on the back seat, it changes to few dropouts and mainly strong reception.

    I wouldn't have thought that inductive charging interference would have been strong enough considering the pretty low power output of the charger.

    I know that the DAB system uses the low 200Mhz range of the radio spectrum, and I'm thinking would an induction coil generate an interference in that frequency range?

    Other points of note are that this happened with both the glass mounted DAB aerial that came with the unit that I mounted on the rear skylight, and when I cut the coax cable and so fitted a large mast aerial on the bullbar, with a thicker, more insulated coax .. same deal. So it's not aerial .. or both use the same compromised design.

    Does this Polaris thing have other features that may be causing your issue? eg. wireless rear camera receiver or something.
    Cheers,
    Arthur.

    '99 D1 300 Tdi Auto

  3. #3
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    Feb 2014
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    206
    Quote Originally Posted by AK83 View Post
    I'd be curious as to what exact part in this Polaris unit would be causing the interference .. could help with some interference I get with my phone charger unit.

    I use a Galaxy Tab with OziExplorer for my GPS usage, and it doesn't cause any issue with my Pioneer DAB capable head unit at all.
    Radio head situated in the normal spot in the centre console, and Galaxy Tab mounted via suction cup to screen sits only mm above it on the flat dash top.

    My Galaxy Tab has a sim slot as well as all the other connections that as common in modern mobile devices, and as said causes no DAB interference at all.

    BUT! .. I also use a magnetic Qi charger for my phone, so it's held magnetically to the holder AND charges wirelessly whilst held there.
    (quick review on this BFC device ... .. awesome!)
    Whilst the BFC holder is connected to a power source but phone not mounted, no interference, so no drop outs.
    With BFC connected and phone mounted, so that phone is charging, once the buffer is used up(about 10-15sec worth), DAB dies.
    Comes and goes in some areas, but on the whole drops out for longer periods than actual reception.
    So the interference issue is solely based on the inductive Qi charging system.

    As said, radio head unit mounted in the normal centre console position, and basically anywhere I mount the Qi charger in the front of the car, it causes the dropouts on the DAB frequency.
    dropouts worse on AM stations(mainly ABS Melb), and a bit less so on Gold 104 and Triple MMM frequencies(that I've tried).

    With Qi charger charging on the back seat, it changes to few dropouts and mainly strong reception.

    I wouldn't have thought that inductive charging interference would have been strong enough considering the pretty low power output of the charger.

    I know that the DAB system uses the low 200Mhz range of the radio spectrum, and I'm thinking would an induction coil generate an interference in that frequency range?

    Other points of note are that this happened with both the glass mounted DAB aerial that came with the unit that I mounted on the rear skylight, and when I cut the coax cable and so fitted a large mast aerial on the bullbar, with a thicker, more insulated coax .. same deal. So it's not aerial .. or both use the same compromised design.

    Does this Polaris thing have other features that may be causing your issue? eg. wireless rear camera receiver or something.
    Hi ak83, a screen that displays hema maps and tom tom maps from a memory card, 3 selectable camera inputs (all hard wired and I am using only one ) and a front crash camera that also records to a card.
    As you have mentioned I just didn't consider that the screen would have been emitting enough EMF to cause interference but it is.
    Thanks
    Peter
    MY13 D4 Nara Bronze HSE, Almond Interior, E-Diff, 20" for the road, 18" GOE for the fun stuff, Traxide, OL Bar, GAP IIDTool, Pioneer Tray, DAB+ and LOGIC 7 ICE retro-fit, Vintage SAV Marchal Driving lights (weird I know but what can I say)

  4. #4
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    Quote Originally Posted by PeterJ View Post
    Hi ak83, a screen that displays hema maps and tom tom maps from a memory card, 3 selectable camera inputs (all hard wired and I am using only one ) and a front crash camera that also records to a card.
    As you have mentioned I just didn't consider that the screen would have been emitting enough EMF to cause interference but it is.
    Thanks
    Peter
    Curious as to why you think the screen itself is the cause of the interference?

    I'd be more inclined to think some other subsystem of the Polaris unit would be at fault.
    ie. charging system, or another wireless interface.
    When you get your unit back, and assuming that when you ran it the first time it was always powered up .. can you run the unit without any connection to power?(ie. does it have built in battery?)
    Try to run it without power .. could be something like the charging cable that is causing the interference .. not the screen itself.

    Also, try to relocate the unit to another part of the dash/car(if possible) to see if that helps too.

    I've had a look into the unit, and found the wiring diagram for it, and it seems to be 'hard wired'(AFAIK), using a simple setup.
    3 wires yellow, red and black and they appear to enter into a black box of some description, and the wiring to the unit then comes out the side of the box.
    Considering that the unit can accept 12-24v range, I'd say that the black box is doing some voltage conversion/stabilisation at the least.
    This black box would be a prime candidate for shielding as a start point.
    If you installed it, I'd say try wrapping it in some foil as a quick'n'easy preliminary test and see how that changes anything.

    For my issue with my Qi charger, I've been meaning to try wrapping the charger and phone (whilst charging) in some foil just to see if that makes any difference, but ATM I've disconnected the charging power to the unit, as I'm running another device from that power point in the car.
    Should take the time to test it one day tho.

    Back in the day, foil was the material of choice we used to use to cover the GPS antenna dongle unit in the company trucks to avoid be spied on when required!
    Cheers,
    Arthur.

    '99 D1 300 Tdi Auto

  5. #5
    Join Date
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    Hi Arthur, the screen is the first thought simply because of it's location to the head unit and the DAB interference with it there, but you are correct it may be some other factor and certainly the power supply could be a prime culprit. I have not had a chance to experiment with cause yet, I will have to wait until I get the replacement screen.

    The black box you mentioned is a fuse and filter according to a person I spoke to at Polaris. I have put it down in the drivers footwell behind the kick plate, and there is a lot of other wiring running through that area, so yes there is another area to consider. There is no back-up battery, it just runs off the car and while I can move the screen around to assess the screen's impact the final location is a bit restricted due to the forward facing camera.

    Anyway, encouraging to hear that other screens don't cause a problem so there you go.

    Peter
    MY13 D4 Nara Bronze HSE, Almond Interior, E-Diff, 20" for the road, 18" GOE for the fun stuff, Traxide, OL Bar, GAP IIDTool, Pioneer Tray, DAB+ and LOGIC 7 ICE retro-fit, Vintage SAV Marchal Driving lights (weird I know but what can I say)

  6. #6
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    Like I said in my original post:
    Don't assume that proximity is THE major determining factor .. my tablet sits basically in a similar spot(even tho we have different vehicles) .. mm's just above the radio unit and where all the cabling is sandwiched between the radio head and tablet screen.
    But the phone charger that causes my issue, is located only mm's from the drivers door basically on the drivers side A pillar. Call it 1 meter away, with a fair bit of stuff in between too!

    I'd say that considering the 2 power and 1 earth wire coming out of that black box .. it should be more than just a 'filter and a fuse'.
    That it can run on a 24volt source .. it'd have to have a voltage converter of some description. Considering it's basically a WinCE tablet type device, they predominantly run off a 5v system(all that I've ever used did anyhow) .. so I'd say it'd be converting whatever input voltage(in your case 12v/13.8v) .. I reckon down to 5v.

    You could try a ferrite choke device on the cabling, individually trying both the input to the small box and the output from the box to the screen.
    Cheers,
    Arthur.

    '99 D1 300 Tdi Auto

  7. #7
    Join Date
    Feb 2014
    Location
    Adelaide
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    206
    Thanks Arthur, the screen went back to Polaris last week, I was told today that it was faulty and a new one is on the way. I will install it and see what we get, try some of your suggestions if I still get the problem then post the results.

    Peter
    MY13 D4 Nara Bronze HSE, Almond Interior, E-Diff, 20" for the road, 18" GOE for the fun stuff, Traxide, OL Bar, GAP IIDTool, Pioneer Tray, DAB+ and LOGIC 7 ICE retro-fit, Vintage SAV Marchal Driving lights (weird I know but what can I say)

  8. #8
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    Location
    Adelaide
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    Well, new screen fitted today and there is still some interference from something, I have posted some pics here Dash mat no where near as much so I guess that's a good thing but I will try some of the ideas and see if I can get rid of it.

    Peter
    MY13 D4 Nara Bronze HSE, Almond Interior, E-Diff, 20" for the road, 18" GOE for the fun stuff, Traxide, OL Bar, GAP IIDTool, Pioneer Tray, DAB+ and LOGIC 7 ICE retro-fit, Vintage SAV Marchal Driving lights (weird I know but what can I say)

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