Expert: Cezar L. Palconet - 2/28/2011

Question
QUESTION: hi, i know radio in the car emits radio frequency, if i am playing a cd in the car does it also emit RF? thanks, gia

ANSWER: hi Gia.

A car radio is just a receiver by design, and this may emit radio frequency, but by an extremely low level of emission, and considered negligible, this is from, the local oscillator stage, when playing a CD, the radio has no RF emissions contained in a carrier, however some traces of EME exist from the motor, again this is at a negligible level.

regards.

---------- FOLLOW-UP ----------

QUESTION: interesting, just making sure i understand correctly, radio on in car emits a little rf, but a cd playing in the car cd player does not emit any rf? correct?

also are you saying that a car radio is different than a household radio, when you say it is a just a receiver by design? i dont know what that means, this is all new to me, thanks

Answer
Hi Gia,

Correct, the Rf produced by the receiver is due mainly from the local oscillator that enables you to tune the frequency, in the CD players, it emits a small amount of Electro magnetic emissions EME due to the motor spining at a very high rate.

A household radio, or any radio receiver for that matter, has a form of local oscillator, which enables you to tune the receiver to the desired frequency.

However those levels are so small that only specialized equipment are able to detect them, and are largely negligible to be of any use outside the design parameters.

regards.