Sirius sportster 5 static through auxiliary?

Just got a sportster 5 and after being connected through auxiliary for about 5min it starts to static and has a high pitch squealing sound that gets higher and higher as my rpms go up (my car is manual). The sportster is getting power through the cigarette lighter and my ipod sounds fine through the auxiliary. Could the problem be caused by power fluctuations through the cigarette lighter? How do I fix it?