In this series, we’ve been sharing articles about trends in FM translators and how to get the most out of them.
At Nautel, Jeff Welton has the title of regional sales manager for the eastern United States. He’s better known as a “fixer of problems, provider of solutions.”
Radio World: What’s the most important thing to be aware of when installing or maintaining translators?
Jeff Welton: More than anything, the fact that translators are the least protected broadcast service. Any complaint of interference with a licensed station can result in an order to shut down, so it’s critical to work with your consulting engineer to ensure a blank spot on the dial and to keep an eye on the local spectrum for any construction permits that may be an issue.
Beyond that, the usual guidelines with respect to buying a transmitter apply: long-term support, manufacturer history and reputation, these days whether or not it’s got internal processing.
Also, one thing that lends itself to automating the process is that a lot of transmitters these days have the ability to be programmed so that they can shut down on loss of program audio, which is a requirement for almost any translator except FM translators for AM stations that would normally go off at night. It’s good to be able to have compliance with the rules built in so that it doesn’t require human intervention.
RW: You are famous for your tips and tricks. Can you offer any?
Welton: The tips that would apply to any transmitter installation will apply here. One thing I do notice is that a lot of translator installations can be somewhat more “spartan” in nature. If you wouldn’t let your Class C full-power station’s transmitter sit under three inches of dust in a grain elevator, it’s probably not an ideal solution for a translator transmitter either!
Definitely pay attention to grounding and surge protection — those are easy to overlook and sometimes harder to implement with a smaller transmitter.
More and more, having some level of IP connectivity, whether with dedicated internet or network connections, or via prioritized LTE modem, is beneficial — both for providing a source for telemetry and control and for providing a backup audio source, in the situations where it’s permitted (fill-in translators, for example).
RW: How can a broadcaster go about deciding whether a translator would help them?
Welton: A communications lawyer or consulting engineer will help. But there are a few questions they can ask themselves first. Are there any holes in my main station’s coverage area? Places where the signal seems to drop out due to hills or buildings? Is there an area I should be hitting with a significant population where I could be selling ad inventory that just doesn’t seem to be able to hear us? Do I have a signal that can’t be received for other reasons —AM stations getting high levels of interference from electrical noise, FM HD secondary channels where there aren’t a lot of receivers? Those are the sort of situations that translators are designed to address.
RW: What role do they play with HD Radio multicast channels?
Welton: Some engineers have called it the world’s most expensive STL, but using translators to repeat HD secondary channels is becoming much more common. Because the translator in this case is a fill-in, it can be fed directly from the same source as the HD importer, allowing for a more reliable source than an off-air feed.
It’s also got the benefit of allowing the station to provide analog service to that portion of their audience who might not have HD receivers. While that number is slowly declining year over year, there are still a lot of analog receivers out there, and a translator on an HD secondary gives them a chance to receive a signal that they might not otherwise be able to hear.
RW: What are the major components of an installation?
Welton: Except for the audio source, an FM translator installation is identical to a full-service station, with the same installation considerations. Unless it is a fill-in, it has to be fed from an off-air source, so it does require a receiver, whether integrated into the transmitter or separate, that has good sensitivity and selectivity.
If the receive frequency and transmit frequency are close to each other, filtering may be required. If the translator is a significant distance from the source transmitter, then a higher gain receive antenna may be needed … this could also be the case if there are other transmitters on the same frequency in the vicinity that could be a source of interference. In cases like that, a high gain log periodic or other directional receive antenna can be beneficial.
RW: What complications are caused by being a secondary service?
Welton: Per above, it’s definitely a concern. It’s always a good idea to keep an eye on construction permits and applications in the vicinity of a translator, to ensure there’s nothing coming that could be an issue down the road.
Note that if a licensed service complains about interference from a translator, it’s almost always the translator that goes away, so having contingency plans in place — knowing what other frequencies might be usable, for example — is a good idea. Complaints aren’t all that common, but best to have the insurance in hand, just in case.
RW: What role will translators play in the coming five years in the United States?
Welton: I suspect with the advent of ZoneCasting, you’ll see a lot more on-channel boosters and single-frequency networking arrangements. That comes with its own set of challenges that can provide mixed results, depending on configuration and local topography.
RW: Are there other questions we should be exploring?
Welton: In the area of SFN and boosters, understand that on-channel boosters require careful synchronization of carrier, pilot and audio signal. And there is no magic bullet, there will be areas where objectionable interference is likely in almost all situations.
There are several things that can be used to help mitigate this: adjusting antenna height to improve terrain shielding, using directional antennas to minimize overlap, careful synchronization and stable platforms for both audio and RF transport and generation, using HD vs conventional analog systems, etc. That might almost be worthy of a book on its own!
Read more on this topic in the free ebook “What to Know About FM Translators.”
