Batboard

i have two tower sites that host various gear on VHF / UHF and 800Mhz.

i am having a terrible time with wideband pulse (BZZZZZ) noise at night with the tower lights. every time they come on, i get a BZZZZ in the receive audio....


any recommendations?

the lights are all commercial, nothing cheap, but i can't remember the name on the boxes at the tower site.

funny, ALL the other users are 800Mhz (cellular and SouthernLinc) but they aren't complaining about noise, so maybe it's just in the VHF/UHF bands...

help!




doug

I believe that the FAA regulates the proper use of the tower lights.

In any case, you could complain to the FCC, but that would undoubtedly annoy the tower owner. You might try to gingerly approach the tower owner (I'm assuming you have a freeby situation---otherwise, drop the frickin' hammer on him!).

This is not at all an uncommon situation to have (bad connections on the towerlamps causing RFI, especially below 800 Mhz).

If this is a commercial site and you are paying big bucks, then it's fair to demand that the tower owner fix this problem. If not, the FCC will be glad to give him a nudge. I'm assuming that the tower lights are the culprit, which could be wrong.

Larry

I had a problem like this a couple of years ago. Turned out the beacon controller had a bad circuit breaker in the box that was arcing over. Not only noisy on VHF but a great fire starter in the right conditions. If the noise is only at night, you could try to be there when the lights come on, measure your noise then shut the breaker off momentarily to verify. NOTE...Murphy's Law says when you try to turn them back on, the breaker lever will break off in your fingers, leaving the tower in the dark so do this at your own risk. If you are near any other site or have high intensity lights nearby, they could be the culprit too. Hell, bad florecent light ballasts can screw things up too. Hopefully, it will be on your site and the tower owner is receptive to your call when it comes in.

Dave

Bzzzzt......................Bzzzzt.........................Bzzzzt....................

Very frustrating.

Some friends had this happen recently. A grading contractor knocked down the city's tower. A new tower was put up to replace it. The new tower lights were bothering everything on the tower.

Apparently the new tower lighting controllers generate this kind of hash. The new beacon came from the factory with internal shielding that is intended to prevent radiaing the noise. However - if the installation isn't done correctly - if the cable feeding the beacon isn't shielded and bonded to the shielding in the beacon - bad things happen.

In this case a local RF guru diagnosed the problem and the tower company paid to resolve it.

A similar observation has been made with some types of strobe controllers. The noise may be wire-carried rather than OTA carried; it might be worth checking where the tower lights tap into power.

I would be willing to bet that it is a strobe system. The long strobe at night, and quick flash in the day. I read something a coupla of days ago about a system that had to run two lighting systems. A strobe during the day, and incandescent at night. This was after they tried a 1800$ for a "RF shield" for the strobe head. BTW way it didn’t work!

If they are strobes at night I have had the same problem. It was bad in a Flashtech system. Had to go to halogen red lights at night in more than one of the sites. If you get a red lamp failure in will failsafe to the clear strobe with a longer pulse at night and you will have the same noise problem

It's starting to sound like a few people think this may be a strobe problem.