The author is director of engineering services for the Alabama Broadcasters Association. This article is excerpted from the Radio World ebook “A New Generation of LPFM.”
The 2023 filing window brought more than 1,300 applications, and more than half of them were “singletons” not in conflict with other applications.
That means a lot of construction permits are being issued. Many of these new broadcasters will seek technical help from their local engineering communities. Here are some things to keep in mind if you are helping a new LPFM station.
It is crucial to follow the terms of the construction permit exactly. You already know that; but LPFM newbies sometimes do not. Antenna location, antenna type, center of radiation above ground and the power level must adhere to the specifications of the CP.
LPFM stations are authorized to operate with an effective radiated power or ERP of 100 watts (0.1 kilowatts) or less, at 30 meters (100 feet) antenna height above average terrain (HAAT). The construction permit will list the licensed ERP and antenna height.
Remember that LPFM stations are not protected from interference from other classes of FM stations. Also remember that a construction permit is required before an LPFM station can be built or operated; the mere filing of an LPFM application does not authorize any construction or operation.
The engineer handling the installation should determine the required transmitter power output or TPO, derived from the gain of the antenna and the loss in the transmission line. This information must be filed with the application for a station license once construction is completed.
Take care with your math. Check and double check all calculations. Many LPFM applications have been dismissed due to incorrect math, bad data or simply typos.
Keep a copy of the calculations determining the required transmitter output power on file with the station license.
Once the facility is built per the construction permit, an LPFM station may begin program tests upon notification to the FCC in Washington, provided that within 10 days thereafter an application for license is filed using Form 319.
The LPFM station must have a properly programmed EAS decoder installed. They must also maintain a “Station Log” per FCC Rules 73.877. Each log entry must include the time and date of observation and the name of the person making the entry.
The following information must be entered in the station log:
- (a) Any extinguishment or malfunction of the antenna structure obstruction lighting, adjustments, repairs or replacement to the lighting system, or related notification to the FAA.
- (b) Brief explanation of station outages due to equipment malfunction, servicing or replacement;
- (c) Operations not in accordance with the station license; and
- (d) EAS weekly log requirements as set forth in the rules.
Even though LPFM signals reach only a few miles, make sure the station is broadcasting with the best audio quality possible. “Get it right at the source,” which means checking all audio sources for correct levels and quality. Quality always wins over quantity.
Many LPFMs air educational or other information, and intelligibility is paramount. Keep this in mind while setting up the audio processor.
LPFMs also are susceptible to damage caused by lightning or power surges, like any other station. Use proper grounding techniques to protect the equipment. A “single point” grounding system and surge suppression on power lines are important.
Finally, don’t forget to document how the system is connected, which will help future engineers.
LPFM operators often are not as well versed in FCC guidelines as their cousins who work at full-power cousins. Any assistance you provide will help in compliance. If questions arise, advise the permittee to contact their legal advisor.
