[BC] FM Stereo Question

[Jeff Glass]

In a message dated 2/27/2010 4:21:01 PM Central Standard Time, broadcast-request at radiolists.net writes:

>That said, I think going mono would help more than messing with pilot level, but I'm not sure.  I think good mono is better than bad stereo.  I doubt that many people would notice the difference. I do run RDS on the station, so I'd have to fool my RDS encoder into thinking there is a 19 kHz pilot to lock on to. Has anyone done that?  It might be easier (and cheaper) to just buy one of the Pira-CZ RDS encoders, which does not require an external pilot.

>Any suggestions are appreciated.

>TIA

>Chuck Conrad

Chuck,

Nothing wrong with experimenting with mono only; it certainly won't hurt anything. If your signal is getting noisy, then you don't have enough RF to go around. Increasing modulation density is not going to help much.

Playing with the stereo pilot is false economy. Dropping the pilot level will reduce your stereo coverage. Sure, reducing the pilot will in theory, make room for more program modulation, but the stereo receivers will lose stereo lock sooner, the more you reduce the pilot injection. It might not matter much in your case since you are already considering going mono.

It sounds to me like the biggest you're having has more to do with RF coverage. You might want to consider having the antenna checked out to verify that you're getting all the coverage you can. Check the orientation of the antenna on the tower.

I don't think you will be able to make the noisy signal sound clean by doing anything with modulation levels. The exception is if your modulation is much lower than it should be. Check this by listening to your station in a strong signal area and compare your loudness to other stations. You have a modulation density problem if you are tempted to turn the volume up on your radio when tuning from the other signals over to your own station. Grossly weak modulation will make the signal sound hissy. Don't get carried away with using processing to extend your coverage. This is an option but it is limited in effectiveness. You can't use modulation density to take the place of a weak RF signal.

It's always a good investment to have a state of the art audio processor in your system; it's to your advantage to get the most out of your signal. If your philosophy is to provide the loudest signal or the cleanest signal, you must have a good audio processor to do that. This is true for either a stereo station, or a mono station.

Best of luck and do let us know what you come up with.

Jeff Glass
Chief Engineer
WNIU WNIJ
Northern Illinois University