GPS - Radio interference

Go Garmin?

hehe... no, seriously - what do you mean by "radio interferance"? I've used GPS's since their inception in my cars, and have never suffered this. What happens? Do you have a problem where you don't get a lock on a minimum number of satellites unless you have your radio turned off? Is it an aftermarket radio or original equipment?

Banjo,

Sounds like the Radio receiver is too close to GPS frequency and doesn't have sufficient filtering.

As the radio is so old and replacement cost is less than another GPS (and still may not fix the problem) I would give the old boom box the heave ho and replace it with a more modern unit. You could even get one with MP3 play capabilities.

What more excuse do you need???

Banjo,

Not clear from your post but I think you are saying the GPS interferes with the radio and this can be a problem with any radio receiver. A GPS is not a passive device as stated here, they are not transmitters but do have a powerful processor chip in them like a desktop PC [or Mac if that way inclined] These processors have clock speeds in the Megahertz rage and can cause interferance over short distances. Not sure in your case but it could be the quality of the radio in which case it will suffer from any type of GPS.

Ken

Welcome to the world of modern computer controlled devices! My Garmin GPSMAP 60CS causes interference on my VHF amateur radio transceiver. It's only on a few frequencies, but it makes them useless.
We have problems with switch mode power supplies and inverters on fishing boats causing problems with some types of radios. In one case, a power supply was radiating enough energy to make a radio deaf to any other boat more that 5 Km away. Turn off the power supply and the radio works 60+ Km. It's a hard thing to diagnose and sometimes impossible to fix.

Crispy, you are right regarding the intent of GPS devices, they are not designed as transmitters but unfortunately due to poor sheilding and maybe design, they end up putting out a lot of rubbish.
It is interesting to consider that if your design and manufacture a TRANSMITTER it must meet all sorts of requirements for spurious noise emission but if you manufacture something other than a transmitter the requrement are far less.
My Garmin 60C plays up with the Nissan CD player if it is close to it and this has been noted in earlier posts.
The power source will have little impact although technically the vehicle battery is a resaonable filter and could therefore reduce the noise on he power cables, however the noise experienced in most likely EMITTED RF and is the same on internal batteries or the vehicle battery via the lighter socket.

Ken