As the weather cools, the leaves fall and the air thins, many installers and integrators don't consider how these changes may affect radio frequencies. This is most relevant when conducting site surveys and Emergency Responder Coverage Enhancement System (ERCES) commissioning. Atmosphere, foliage including trees, leaves and branches, dense building materials and even we as people affect the radio waves trying to make their way from the radio tower to the 2-way radio being used by First Responders in buildings.
As you may know, determining if a building will need an ERCES to support public safety radio frequencies inside buildings requires multiple steps mainly around properly conducted site surveys. In many cases, General Contractors and building owners want all contingencies covered in their initial budgets from the integrators and contractors. Makes sense, right? However, many times these budgets are decided before the foundation of the building is even laid. So how are you to determine if a building needs an ERCES if you can't test inside the building for failing coverage spots?
If you have the floorplans and signal strength readings from the site, you can digitally map the building using design software like iBwave. You can also design a system for full coverage to be safe, but that would require a change order once the actual site survey is conducted, and the system design modified. Also, signal strength readings from the ground are typically not as strong as on top of the building where the donor antenna would be expected to be mounted. You also need to consider environmental factors like the season, humidity in the air as well as developmental factors; like is this area going to see additional buildings being raised in the next few years that may block the signal coming from the radio tower.
ERCES's are not meant to provide FULL coverage inside buildings, they are meant to address only the areas with inadequate signal coverage. This is why it's so important to conduct site surveys at both 20% and 80% building completion. As the building becomes more complete, the Radio Frequencies must compete with more building materials than initially tested for. However, if you see failing areas at only 20% completion, the failing areas will only grow with additional construction. Also, with environmental changes being a factor, site surveys should be conducted in various seasons to account for these changes.
The factors affecting Radio Frequencies are many and varied. Staying aware of how these factors affect your site surveys will help you stay ahead of the competition and make your designs more focused on doing exactly what an ERCES is supposed to do: fix the dead zones for first responder radio coverage in buildings. The outside signal is the most important measurement you will take, so make sure you are aware of where your donor tower is located, and what stands between it and the building. If your line of site is riddled with tall trees, your signal strength readings in the summer may vary widely from the ones you collect in the winter.
For more information about RF behaviors, check out chapter 8 of The Complete ERCES Handbook from the Safer Buildings Coalition. You can also visit our website and consider taking one of our GROL/ NICET Prep courses in 2026.
