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philpugh Lifetime Member
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Joined: Dec 28, 2005 Posts: 2003 Location: Antrobus, Cheshire
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Posted: Tue Jan 27, 2009 12:42 pm Post subject: Mini-USb RDC-TMC and Interference |
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Anyone using the mini-USB RDS-TMC receiver and connecting it to their car aerial?
I have had mine connected for a couple of weeks now but just noticed (this weekend) that when I tuned to an AM station I was getting huge amounts of interference. On investigation it appears to be injected by the RDS-TMC unit. I still get a good lock to the TMC service.
At present for local trips I am unplugging the unit as I am concerned about the (admittedly small) possibility of damage to my car radio.
I have tried a couple of different 12V to 5V mini-USB power supplies but I get the same interference. Everything points to the USB receiver or a totally unrelated but co-incidental earthing problem.
Final solution may have to be a separate external aerial - something I wanted to avoid.
BTW - the same setup (car/aerial/splitter etc) was used for a couple of years with my nuvi 660 without any such problems. All I did was remove the 660's TMC receiver aerial lead and connect the flying lead from the TomTom device.
More investigations this weekend with my trusty 'scope I fear! _________________ Phil |
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G4GVB Regular Visitor
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Joined: Jan 04, 2006 Posts: 233
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Posted: Tue Jan 27, 2009 9:45 pm Post subject: |
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Is it only when you tune to a / any AM station or do you get the interference all over the AM band? Is the interference still there when you are tuned to FM? _________________ GO 750 LIVE v9.430 - v8.753612 EU map
XL 350 MT v9.151 - v8.75366 US Map |
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philpugh Lifetime Member
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Joined: Dec 28, 2005 Posts: 2003 Location: Antrobus, Cheshire
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Posted: Tue Jan 27, 2009 11:00 pm Post subject: |
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All across AM band as far as I can tell.
I think it is affecting FM a little - notice a small amount of noise as if in a marginal signal area which disappears when USB connection unplugged. I suspect the interference is swamping the front end of the RF section of the radio. (It's a JVC BT-22).
I'll get a bit more serious with it this weekend. I have an oscilloscope and scanner - I'll try to see if there is any specific frequency (ies) involved. I wondered if anyone has noticed this or pehaps I have a duff TMC unit. _________________ Phil |
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G4GVB Regular Visitor
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Joined: Jan 04, 2006 Posts: 233
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Posted: Tue Jan 27, 2009 11:05 pm Post subject: |
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It sounds like you know what you are doing, but maybe if your playing try ferrite rings. _________________ GO 750 LIVE v9.430 - v8.753612 EU map
XL 350 MT v9.151 - v8.75366 US Map |
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philpugh Lifetime Member
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Joined: Dec 28, 2005 Posts: 2003 Location: Antrobus, Cheshire
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Posted: Wed Jan 28, 2009 11:26 am Post subject: |
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Thanks for the tip - would have got around to that myself soon! Willlet you know how I get on. _________________ Phil |
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