The debate on the efficacy of the required NRSC measurement continues. The author is chief engineer for the Cumulus Radio Station Group in Colorado Springs, Colo.
The NRSC-2 required yearly measurement should not have been instituted in the first place. It was made mandatory to add the filter to the air chain ahead of the transmitter to limit the audio modulation bandwidth in the 1980s. But since it was required, it should have had a sunset date of five years. I totally agree with Larry Langford’s premise.
The NRSC-2 is an “Occupied Bandwidth” measurement only and does not require measurement of harmonics, intermod or spurious emissions. All AM stations are required to make this measurement yearly and only a few do not pass causing unnecessary burden to nearly all. I made these measurements as part of a contract engineering business for many years. The NRSC-2 measurement is not a good measure of a stations performance, it was intended to eliminate interference. We as engineers are responsible for all operating parameters at our stations and the occupied bandwidth is only a very small part.
Nowadays, the occupied bandwidth rules have been changed to accommodate the IBOC digital sidebands and the transmitters that transmit IBOC further limit the analog audio bandwidth to 5–8 kHz.
For what it is worth, two of us in the Colorado Springs market have Audemat GoldenEagle monitors and we check all stations in this market for things like occupied bandwidth every week. We notify the appropriate engineer if anything is amiss. Anyone can buy a very good quality HP spectrum analyzer with the required 300 Hz resolution to do this type of measurement for under $1,000 on eBay. Several manufacturers make new spectrum analyzers that can do this measurement for about the same price.
I am not saying “do away with the requirement,” just the required measurement for all stations each year. There simply is no justification for it.
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