We get lots of questions at VPR about reception of our signals: “Why can’t you increase your power?” or “Can you build a station in my town?” or “Why can I get 107.9, but not 90.9?” Some of these questions can be answered technically, and some require legal and regulatory explanations.

FM radio signals are broadcast at high frequencies – 88.1 to 107.9 megahertz. Because these radio signals travel in relatively straight lines, FM reception is best when there is a ‘line of sight’ from the transmitting tower to the receiver. The easiest way to understand an FM radio signal is to compare it to light. Place a lamp on the floor and notice how the light in the room is strong in some areas, but in others, there are shadows from furniture or other obstacles. Vermont’s beautiful mountains present obstacles, and FM signals are shadowed in some places by the landscape. If you move your lamp up higher, it will cover much more area in the room, but there will still be some places in the shadows. After height, the next most important thing is output power. A strong light can be seen further away in the dark.

Similarly, a more powerful FM transmitter can reach more distant areas. Now we get into the non-technical, regulatory part of the equation. In the early days of radio, there were few regulations, and the broadcast landscape was a bit like the ‘Wild West’ – only the strongest survived.

Before long, things got so crowded, and there was so much interference among stations, that the government stepped in to regulate frequency distribution. From this we got the current system of station allocations, which determine how broadcast services are distributed across the nation. These allocations were based on a complex set of rules that determined how close together, and at what power, stations on the same or nearby frequencies could be without causing reception problems for listeners.

Sometimes it is possible to use directional transmit antennas to send the FM signal strongly in one direction, while restricting it in the other direction to keep it from interfering with another station. If you are on the weak side of the antenna, your reception will not be as good as reception in the strong signal area. VPR Classical’s 88.1 FM WNCH and 90.9 FM WOXR use directional transmit antennas. They have strong signals in one direction and lower signal strength in others to protect other stations’ signals. The FCC’s allocation system determines the location and the output power, meaning that some stations are much more powerful than others. For instance, 90.9 and 88.1 are both located on high mountains, but neither of these 2 to 3 Kilowatt stations is as powerful as VPR's 107.9 FM WVPS signal from Mount Mansfield, at 50 Kilowatts.

This complex and interlocking system of allocations means that VPR cannot simply increase power, move a station or build one in your area if it will interfere with another licensed station. However, sometimes opportunities to acquire new frequencies do arise. VPR has recently applied for several frequencies and will keep you informed on the status of these applications.

Furthermore, new technology has allowed us to expand our services in lieu of the limitations of traditional FM radio. In addition to Internet web streaming, new HD (Hybrid Digital) multicast broadcasting has given VPR the ability to provide two or three different program choices on our existing VPR stations. Listeners with an HD radio can hear these additional services, including VPR Classical, on all of our transmitters. While the HD signals are not always as strong as regular FM signals, they provide additional opportunity for our services to be heard by the great majority of our listeners across Vermont. And best of all, the new HD radios will still pick up regular FM broadcasts.

To learn more about improving your reception, visit VPR's Guide to Good Reception. And visit our HD Radio page for a more detailed explanation of HD Radio.