I have a S60R that radiates broadband noise between 48 and at least 55 MHz, of varying frequency and intensity depending on throttle position only with the engine running. Bypassing the throttle position sensor doesn't seem to help it, and, removing the antenna eliminates the noise from the receiver, so we know where it gets in.
The radio is trunk mounted, and is fed filtered DC via a short, heavy gauge wire from the battery that is located in the trunk. Microphone, speaker, and fiber optic cables run to the front of the car. Antenna is on a "L" bracket on the driver's side rear corner of the trunk opening.
For those who don't know, the Volvo S60R is a multi-computer controlled high performance vehicle that uses controller area network (CAN) to communicate between the computers and many of the accelerometers and other sensors.
Anyone have any thoughts?
Rob
Volvo S60R Low band Noise Problem
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For those who don't know, the Volvo S60R is a multi-computer controlled high performance vehicle that uses controller area network (CAN) to communicate between the computers and many of the accelerometers and other sensors.
Your Volvo is an overgrown Ford. Anyway...
First concern is your grounding, both the radio and the antenna. If the antenna is L-bracketed, that would be a significant concern.
Pull the control head, mic, and speaker, and plug them in in the back. See if the noise continues.
Disconnect the antenna and terminate to a dummy load. Check the noise. That'll tell you if you have an antenna problem.
Provide A+ from a separate power supply with the vehicle running and check the noise. If the noise continues, look at the DC with an o-scope - $10 says you find some AC components from a dying alternator. Ford's had fairly serious issues with bad alternators recently... took 3 tries to get a decent one on an almost-new '03 F150.
Other very likely culprits would be a fuel pump or ignition noise.
Running HF or lowband in a vehicle always has its problems. Narrow it down through process of elimination, then get out your test equipment and start looking for the source.
It is definitely coming through the antenna. Remove the antenna, with or without a dummy load attached, and the problem goes away.
Disconnecting the control head and other cables does not make the noise go away. The incoming DC (post filter) is clean.
I'm suspecting the tank mounted fuel pump, since (1) that is in the general area, and (2) it is dependent on throttle position only with the engine running.
The radio is well grounded, the antenna maybe not as well. The bracket is unfinished stainless, screwed to the car. I'll check some more on the antenna.
I should be able to get it into the shop this weekend and sniff around with the spectrum analyzer. I can see the "noise" from outside the car, but, haven't had time to DF it.
Rob
Disconnecting the control head and other cables does not make the noise go away. The incoming DC (post filter) is clean.
I'm suspecting the tank mounted fuel pump, since (1) that is in the general area, and (2) it is dependent on throttle position only with the engine running.
The radio is well grounded, the antenna maybe not as well. The bracket is unfinished stainless, screwed to the car. I'll check some more on the antenna.
I should be able to get it into the shop this weekend and sniff around with the spectrum analyzer. I can see the "noise" from outside the car, but, haven't had time to DF it.
Rob
I know you don't want to drill holes, but... have you considered installing an NMO mount dead-center of the trunk? Lots more ground plane there - just make sure to run some copper braid from a solid ground point to the trunk lid (the original grounding isn't very good). You might be able to make the majority of your problem vanish by that one simple mod.
I'd concur on the likely diagnosis of the fuel pump. You might Google around... I believe Ford has made noise kits available for certain models in the past - you might get an idea there. I think they're just sticking a good-sized capacitor inline, but I'm not sure of the details. I've been fortunate to avoid most of those problems, although I expect when I install an Icom IC-7000 in my F350 diesel, I'll get to learn more than I want.
I'd concur on the likely diagnosis of the fuel pump. You might Google around... I believe Ford has made noise kits available for certain models in the past - you might get an idea there. I think they're just sticking a good-sized capacitor inline, but I'm not sure of the details. I've been fortunate to avoid most of those problems, although I expect when I install an Icom IC-7000 in my F350 diesel, I'll get to learn more than I want.
Ball-mount and a whip on the rear quarter panel?rodell wrote:This particular vehicle has a trunk lid that goes well past vertical when open, so the hole idea doesn't work. Even a trunk lip is no good. Through the roof is definitely a no go.
I've emailed Volvo Tech Support, too, with plots from outside the car. I'll let them noodle on it awhile, too.
Rob
Good luck getting anyone at the manufacturer to do jack for you. They usually refuse to do anything for vehicles sold for emergency service, much less a typical sedan.
Let us know what you find out...
Problem solved, two contributing solutions.
(1) Volvo provided two CANbus filters - that helped a little. I think it keeps conducted emissions down. I could see the difference on the spectrum analyzer, but, the radio could still see it.
(2) The "unfinished stainless" bracket had a coating of something on it. I cleaned it all off, and retorqued the mount and anchor points.
No more whining noise. No more whining, in general.
Rob
(1) Volvo provided two CANbus filters - that helped a little. I think it keeps conducted emissions down. I could see the difference on the spectrum analyzer, but, the radio could still see it.
(2) The "unfinished stainless" bracket had a coating of something on it. I cleaned it all off, and retorqued the mount and anchor points.
No more whining noise. No more whining, in general.
Rob