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Trouble with HD Radio

Last Updated: Sep 06, 2016 03:50PM EDT

Can I receive the HD channels everywhere I can hear WAMU 88.5?

Just about. WAMU is at the forefront of HD broadcasting. WAMU transmits the highest power digital signals permitted by the Federal Communications Commission. The HD system was designed to offer a service that permits reception of the analog FM signal along with the new digital signals. This requires a careful balance by our engineers to establish the power of the digital channels so as to maximize coverage without interference to the existing analog service or to stations near the 88.5 frequency in nearby cities and towns. Most listeners within the greater WAMU 88.5 coverage area have reported good results in receiving our digital signals. Our intention is to share the experiences and recommendations of our engineers and listeners who can suggest ways to successfully receive the WAMU 88.5 digital channels. Take a look at the coverage map of the WAMU 88.5 signal. The map gives a general idea of where successful reception is possible. As listeners from farther locations try to receive our signal, special techniques may be required to obtain a strong signal.

Anecdotal experience from listeners and our engineers suggests that listeners within the strong signal area contour on the map should be able to receive an excellent signal with a properly placed indoor dipole antenna. Factors which will affect successful reception include whether or not a listener's location has a direct line-of-sight to the WAMU 88.5 transmitter, located on the campus of American University in northwest Washington, D.C., at Massachusetts Avenue and Nebraska Avenue. Generally speaking, locating any FM radio, including an HD radio, on the side of the building facing the transmitter and as high as possible will yield the best results.

An important factor to remember is that an analog FM signal fades gradually as the distance from the transmitter increases. The signal becomes noisier and there is more interference. With a purely digital signal, there will be either perfect sound or no sound at all. In a strong signal area, the signal will be excellent: no fading, no pops, clicks or hiss, but as the signal drops below a threshold level, the signal disappears completely. In addition, when tuning to a digital signal, there is a delay of about five seconds to capture the signal so there are several seconds of silence before the station is heard.

To minimize this problem, the HD technology is designed to first capture the analog signal and gently blend to the digital signal when you tune to a station broadcasting its primary channel in HD. In areas where the digital signal falls below this critical level, our main channel, WAMU 88.5, reverts to the analog signal. However, the additional digital channels do not have a corresponding analog signal. Therefore, when the signal falls below a certain level on WAMU-HD2, the station will go silent. It may alternate between full sound and no sound depending on the actual signal level. It is important for our listeners to understand this difference between reception of the WAMU 88.5 main channel signal and the WAMU-HD2 digital signals.

Did your HD radio come with a dipole antenna?

Dipole antennas are inexpensive and available at many stores or through online retailers.

A dipole antenna captures an FM signal much better than a simple piece of wire. It also receives signals primarily located 90 degrees to the direction of the extended T portion of the antenna.

Using the coverage map, determine the approximate direction of the WAMU 88.5 transmitter, and point the dipole antenna 90 degrees to the direction of the transmitter. (Try facing the location of our transmitter with outstretched arms holding the ends of the dipole antenna in each hand). Usually the higher the dipole is mounted, the better the reception, and you may need to experiment with several locations. Connect the leads of the antenna to the antenna terminals on the back of the HD radio.

Still having problems receiving the WAMU 88.5 digital signals?

Sometimes relocating the receiver or even trying a connection to a TV antenna or rabbit ears will bring in the signal. Some listeners report that they have found an amplified indoor antenna works for them. However, in many cases the amplified antenna overloads, and interference from nearby strong stations prevents reception of distant stations. If this does not produce an acceptable signal and you are a passionate listener to WAMU 88.5, then it may be necessary to obtain an FM antenna to be mounted in your attic or outside on the roof. FM antennas vary in size and cost depending on the number and type of elements designed to bring in distant signals.

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