Stupid High Pitch Whine

Hello, having some issues with a high pitch whining noise. I have an XM unit hard wired to an A/B switch, the B port has an RCA to mini which runs to an IPOD, the IPOD can run with 0 alternator noise, FM radio is fine, CD player has no alternator noise, only the XM unit. It is hard wired (no cigarette lighter) and I have unplugged it from the A/B switch and run it directly into the back of the head unit, no avail, I have isolated it to the signal coming from the XM unit, which is up behind the dash. Where would I look for this problem? Thanks for any help you can provide!

how is the signal run thru or around the headunit ?

Signal is run into the aux input in the head unit, if it is the IPOD hooked into the 8mm hookup, no noise, when the XM is directed in, engine noise pretty bad.

where is the antenna for the XM running ? Try running the power and ground wires to a different spot

It was installed a while ago (few years) by a shop so I don't know how they ran the antenna, but I think it is up one of the A pillars and out onto the roof. I will need to take the dash apart to get to the power and ground wires, think I may give that a shot, this noise has recently gotten LOTS worse and is slowly driving me to insanity...

try having your battery and alt checked (autozone will do it for free). A weak battey can cause that whine,