Film-Tech Forum ARCHIVE: Question for anyone who knows about FM transmission/reception

This is topic Question for anyone who knows about FM transmission/reception in forum Ground Level at Film-Tech Forum ARCHIVE.

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Posted by Justin Hamaker (Member # 2165) on 06-01-2019, 11:44 PM:

Our drive-in uses FM for the sound. When we closed our season last year the signal was crystal clear over our entire lot. When we opened this year we've had a lot of static, especially in one area of the lot. The entire lot has direct line of sight to the antenna, and the furthest distance is about 400'. Nothing has change in our system that might be causing the static, but we have tried several transmitters and changed the cable on the antenna.

One thing that is making me wonder is we installed a new water pipeline between our cinema and drive-in last year. It wasn't operational until after the drive-in closed last season, so I don't know if this is related. What I do know is the pipeline runs along the outer side of the field which has had the most complaints. The pipeline is 2" Schedule 40 PVC. There is a fiber optic cable and a CAT-6 cable buried in the ditch with the pipeline.

I've checked our frequency to see if there might be interference and that doesn't seem to be the issue.

It does seem like there could be an issue related to the lights along our fence as the static is less pronounced when those lights are off, but the static is still there even when the lights are off.

Any thoughts or feedback would be appreciated.

Posted by Justin Hamaker (Member # 2165) on 06-03-2019, 05:40 AM:

I figured out the source of the static. We had attempted to hook up the VIN channel to use with another transmitter, but found the VIN was bleeding over to the regular channel.

When we gave up on the idea of the VIN channel, I didn't disconnect the wires I connected to the phoenix plug, and this was creating the static. I had left the connections to the RCA plugs in place thinking we might try to get this working at another time.

Posted by Dave Macaulay (Member # 813) on 06-03-2019, 11:51 AM:

I was about to suggest you look for the feedline being chewed through by rodents - that's happened at two DIs I visit. But not this time!

Posted by William Kucharski (Member # 7246) on 06-03-2019, 07:50 PM:

quote: Justin Hamaker
We had attempted to hook up the VIN channel to use with another transmitter, but found the VIN was bleeding over to the regular channel.

VIN? My apologies but my brain isn't decoding that for some reason.

Posted by Justin Hamaker (Member # 2165) on 06-03-2019, 08:09 PM:

Visually impaired narration, or descriptive audio.

Posted by William Kucharski (Member # 7246) on 06-04-2019, 12:04 AM:

Thanks - I knew it was something obvious.