[BC] 9th FM harmonic causing interference

[Barry Mishkind]

Not quite 9th harmonic, but we went through something similar with the FAA here. They were certain that one station was blasting their local ATC channel - after all, they heard the country music ... it had to be us!

We used a SpecAn to show we were clean, but then simply shut 
down the transmitter for a few moments. Interference stayed.
FAA finally brought in someone from LA to DF and located the
problem 15 miles away from us.

At 06:02 AM 2/18/2010, Mike McCarthy wrote:
>pattern, he still insisted it was our problem. The Nextel tech was
>absolutely sure we were pounding his system.  Both his and my SA showed a
>nasty emission at our 9th harmonic.
>
>After shutting down the site, I asked the tech if he still showed the
>problem. He said nothing changed.  His pilot channel was still being
>hammered. I then waved him over to our building and showed a completely
>quiecsent transmitter. Kodak momment.
>
>I received a call a few days later from the tech and the shop foreman
>advising they have egg on their face. Turns out it was a cell site a mile
>away emitting stuff on a channel outside their passband.  I told them no
>problem.  It's an easy mistake to make when one starts debugging IX.