I’m hoping somebody can help me at this forum. I know it’s not the exact topic but there seems to be experts here. I've got a top of the line 08 SUV with the Infinity® CD/MP3 changer audio system w/ subwoofer & external amplifier and roof mount short antenna. However, the AM reception is terrible and the dealer is currently refusing to address the issue. I’m trying to build a case for them to fix it. I’ve found radio signal strength maps at radio-locator.com that show the signal strengths of area stations. The maps show the 2.5, 0.5, and 0.15 mV/m contours respectively (of the horizontal groundwave propagation only). I would like some clarification if you can provide it with respect to what signal strength I need for good reception in my car.

Should a 08 with an Infinity system receive signals in the 2.5 mV/m range without any problems? Should it receive signals in the .5 mV/m range without any problems? How about at .15 mV/m? I’m not getting good reception within the 2.5 mV/m range. (Note: I understand AM reception fluctuates with the weather and nearby interference, but I’m not talking about that.) At about what signal strength (mV/m) should I start to experience issues since in some cases there is a large gap between the 2.5 mV/m and .5 mV/m contours?

The dealer has been trying to tell me that since few people listens to AM anymore, the stations haven’t invested to keep their signal strength up to the max and nobody gets good reception anymore. They are also telling me that HD radio is causing the problem but I’m experiencing the problem across the dial and the symptoms don’t match what I’ve found on the internet. I’ve been amazed that they can make statements like that with a straight face.

It should be noted that I get more noise on the radio when tuned to a weak signal with the engine on but it’s not the high pitch noise that changes with engine speed. I also get additional noise sometimes when passing under residential power lines. I’m not talking large power distribution lines, I’m talking about local neighborhood power lines.

Thanks for any help you can give me.