The author is an engineering consultant based in Florida and a veteran of a major broadcast equipment manufacturer.
A few engineers whom I highly respect have weighed in on this subject both for and against the annual occupied bandwidth measurement. Richard Rudman is correct, that old capacitors in some AM transmitters can cause issues (I recently repaired a Gates One that had bad caps in it).
And other issues can cause distortion or noise outside the FCC limits, yet we don’t have annual audio proof requirements. Transmitters can drift out of frequency tolerance but we don’t require frequency monitors any longer or mandate frequency measurements at all. Many things used to be required to be checked daily, weekly, monthly or yearly and are now at the discretion of the licensee (including monitor point readings or in some cases no requirement to read AM antenna base currents).
I remember reading base currents for both day and night patterns once a day in my early years of working as an engineer, and driving around weekly to the monitor points, both with day and night patterns. We don’t do this any longer. We don’t do monthly frequency checks or annual audio proofs of performance. Heck, we don’t even have to check tower lights daily if we have the right type of monitor/alarm equipment!
I think the point here is, all those other things have been relegated to an as-needed basis, the commission putting the burden of compliance on the licensees. Why is one issue more important than another? Interference you say? Overmodulation causes splatter and interference. But we don’t require a station to have a modulation monitor, yet the licensee is expected to be in compliance. An AM station with its directional antenna out of tolerance can cause interference. Again, it is up to the licensee to determine compliance.
I say ditch the requirement and put it in the same category as all the other things that we used to do on a required basis but now only as the licensee deems necessary.
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