Advancements in technology and the emerging popularity of digital two-way radio systems make it increasingly important to be aware of other radio systems around you, particularly when operating within a shared spectrum environment. Not only have the numbers of interference incidences between digital and analog systems increased, they have evolved from the sound of a human voice to that unbearably annoying digital screech or white noise.

And there have even been reports of digital signals triggering the private line tones in analog radios, causing them to inadvertently receive digital transmissions. No matter what is happening, many users are having experiences with their radio systems that they did not have prior to the proliferation of digital technology. Most of the interference is a nuisance, but not prohibited by FCC rules. What can you do?

  • Being armed with the full information about your own radio system and those operating around you can help avoid these problems. For example:  Frequencies assigned to land mobile stations are most commonly available on a shared basis, not for exclusive use, so licensees must learn how to coexist;
  • Each system must be identified by the assigned call sign during each transmission, or once every 15 minutes;
  • Licensees suffering or causing harmful interference are expected to cooperate to resolve the problem by mutually satisfactory arrangements;
  • Licensees should take precautions to avoid causing harmful interference to other co-channel systems;
  • Licensees employing non-voice communications are not relieved of their responsibility to cooperate in shared use of radio channels;
  • Shared environments vary depending on incumbent system loading, distance, technologies and applications;
  • To achieve maximum spectrum efficiency, applicants must know when their analog system is sharing with a digital system (and vise versa), their voice system is sharing with secondary data systems, a trunked system is sharing with a conventional system, or a private carrier system is sharing with private internal systems.

If you need more information, EWA’s new e-Advisory and Channel Use Report can tell you:

  • Parameters of the new or modified system, including emission designator(s), station class codes, and certified channels (exclusive or shared spectrum), plus incumbent/co-channel licensee information within an 80 km (50 mile) radius of the proposed site.
  • Whether the incumbent licensees are operating in analog or digital mode, conventional or any type of trunked system, for voice and/or data purposes.

Like so many fond memories from the good old days, it’s time to realize that full power, wide area, analog-only radio systems are no longer the only systems out there, and sharing with full disclosure about who’s nearby, particularly digital systems, is now essential.