Listener FAQ: About listening and reception | WAMU 88.5 - American University Radio

WAMU 88.5 : About

Listener FAQ: About listening and reception

 

What's the first thing to check if I am having trouble receiving WAMU's signal?

One of the easiest solutions to a reception problem, particularly if you are in the metropolitan area, is to move the radio to a different party of the room. Sometimes moving the radio only a few inches or feet will bring in a clear signal. Most portable and clock radios use either a telescopic whip or the AC power cord as an antenna. The whip can be extended, retracted, and rotated to change reception. The ac cord can be moved around and draped across objects for the best signal or wrapped up to reduce signal. If your clock radio has no visible antenna or connections for an antenna then you can assume that the radio is using the power cord for an antenna.

Does my radio need an antenna?

Stereo tuners and receivers require an external antenna (an antenna that is not a part of the radio). Many tabletop and clock radios have connections for an external antenna while allowing you to use the power cord should you not want to use an external antenna.

The antenna connects to either two screw terminals marked 300 Ohm or an "F" connector for coaxial (round) cable located on the back of the unit. A "twin-lead" dipole antenna is usually boxed with a new receiver or tuner. Many people attach this dipole antenna to their new set and then ball it up and stuff it behind the equipment. For strong stations this may work just fine. For many weak stations it will not work. If you don't have an antenna connected to your stereo, a dipole can be purchased or you can make one. The dipole is made of about five feet of flat antenna lead-in wire with the ends bared and twisted together. Another five feet of wire is attached to the center of the first piece of twin-lead at the middle of ONE of the wires by cutting it and baring the wire then twisting it together. If you want to make a dipole yourself specifically tuned for WAMU's frequency of 88.5mHz, the length of the first mentioned piece of twin-lead should be 63 inches. The length of the center piece of wire can be as long as needed to reach the set, but no shorter than five feet.

The dipole has what is called a figure-of-eight reception pattern. It picks up signal on the broad sides of the antenna (and provides some antenna gain) and receives no signal on the ends. If the dipole is stretched out and rotated it is possible to point the antenna for best reception or to "null" a station that is interfering with the desired signal. The disadvantage of the dipole is finding a way to locate it in the room. If you are lucky, the direction of the desired station will correspond with one of the walls in the room and you can simply attach the stretched out twin-lead to the wall. Some people mount the dipole on a "TEE" shaped frame made of wood and position it in the room for best reception. Others have mounted this same frame in the attic. It may be easier to buy a "rabbit ear" antenna like you would use for television reception. The rabbit ear is another form of dipole antenna. Each telescopic section should be adjusted for a length of 31.75 inches. The rabbit ear is often easier to place in the room or on the stereo and can still be rotated for best reception.

There are a number of indoor specialty antennas available for FM reception. Some work very well and some do not. I would make sure that the antenna could be returned before purchasing it.

Why is antenna set-up important?

TV and FM reception is referred to as "line-of-sight." This means the transmitting and receiving antennas must be able to "see" each other. For reception outside of the metropolitan area, a roof or attic mounted antenna is recommended both for the increased height and for the additional antenna gain (increase in signal strength over a reference antenna) that comes with a directional antenna. Line-of-sight reception of WAMU should be good for 50 miles. Hills and mountains may extend this range (providing increased height) or reduce it (as an obstruction between the transmit and receive antennae). Directional antennas may also be mounted in the attic still providing increased height over lower level locations. A directional antenna can also help in reducing co-channel (a station on the same frequency as the desired station but located in a different direction) or adjacent channel stations that are interfering with the desired station. Many people who listen to a number of distant radio stations use a rotator to position the antenna correctly for each station. Directional antennas can be found at Radio Shack as well through many TV and antenna dealers (who will also have higher gain antennas). Be wary of the antenna claims of "reception from 110 miles" etc. Remember that unless you are looking down from the mountains with an unobstructed view or have a high tower for your antenna, curvature of the Earth prevents reception from that distance. Be more interested in whether the antenna has 3 db, 6 dB or 9 dB of gain. The more gain the better for distant stations but, the antenna is going to be larger for each increase in gain.

Will an amplifier help reception?

You should also be aware that an amplifier (pre-amp at the antenna or distribution amp in the house) will not produce a better signal, only antenna gain will give you a better signal over noise. Amplifiers are used to make up for the signal losses in long runs of cable, such as from the roof or tower mounted antenna into the house, or from splitting the signal to feed multiple sets. The amplifier should always be inserted before the loss occurs.

How do I mount an outdoor antenna?

If you install an attic or outdoor antenna, be sure to follow good engineering practices by twisting the twin-lead (flat) cable and mounting on stand-offs or better yet, using coax (round) cable. Remember to always ground the antenna and the lead-in cable. Always use "splitters" or "couplers" for multi-set installations or joining several antennae to one lead-in cable. These practices insure the rejection of unwanted and interfering signals being picked up by the cable (or sometimes retransmitted by YOUR antenna to the neighborhood) and afford protection against lightning. Books on proper antenna and lead-in installation can be found in many libraries or at Radio Shack.

What if I already have a good antenna installation?

There can be a number of causes of interference. Interference in receiving the desired station is often caused through overloading of the radio's first amplifier by a different but nearby station. If you know that you are in an area where a radio or television transmitter is located, this may be your problem. There are several cures for this problem. If the signal of the desired station is more than sufficient, then reducing the level of all signals into the radio, receiver, or tuner will help. On radios with telescopic antennas, you can make the antenna smaller by pushing the sections together. On clock radios, wrap up the power cord as short as possible. With stereo receivers and tuners you will need to install a "pad" between the antenna lead-in and the input connection to the set. Radio Shack makes fixed 6 dB pads for coax (round) cable . They also make an adjustable inline attenuator for coax connections that allows you to reduce the signal until the interference disappears. These pads and the attenuator can be adapted for 300 Ohm (flat) twin lead cable.

If the desired signal is weak (you're a long distance from the station) the best solution is to reduce the signal of the station causing the interference. This is done with a filter and is most easily accomplished on a tuner or receiver with external antenna connections. The cheapest filter is a quarter-wave open stub which you can make at home. If your antenna lead-in is the flat twin lead, start by cutting a length 33 inches long. Bare the wires at one end and attach it to the set's antenna terminals along with the lead-in from the antenna. Now, with the set tuned to 88.5mHz, start snipping off a 1/4 of an inch of the cable at a time until WAMU's signal improves. Stop cutting when the signal sounds good to you. You are tuning the stub filter to the interfering station's frequency. If you know that the interfering frequency is above 100mHz, you can start with 29 inches of cable and save some time in cutting.

A filter can also be made for antenna systems using coax (round) cable but is more involved. A coax filter would require a "TEE" connection (three connections; one for the antenna lead-in, one for a jumper cable to the set and one for the filter). A TEE adapter is not made for the "F" connector used for coax cable so an adapter would have to be made from separate adapters. This would consist of three "F" to "BNC" adapters and one "BNC" TEE. Then the coax is cut as described above for the flat cable, attached to the middle connector on the "BNC" TEE and snipped in 1/4 inch increments as described above.

Some interfering stations may be so strong (VERY close to you) that the open stub filter is not sufficient. There are filters that can be tuned for greater rejection at the offending frequency made by antenna manufacturers such as Winegard, Blonder-Tongue, Channel Master, and Jerrold. These filters are quite expensive however.

What if my antenna is fine, I've eliminated the interference from other station signals and I am still getting interference?

Some interference is intermittent. This can be caused by a nearby amateur radio or CB transmitter. Many of the suggestions recommended in the FAQ above this one can improve reception and also filters are available from Radio Shack for amateur and CB bands.

Intermittent static interference is usually caused by electrical appliances (refrigerator, furnace blower motor, air-conditioner, etc). If this interference is coming into the radio via the AC power line (if it sounds O-K running on batteries, this is the problem), an AC line interference filter (from Radio Shack or many hardware and department stores such as Wall-Mart and K-Mart) can be placed between the wall outlet and the power cord.

Multipath distortion is common in the metropolitan area. It is caused by signal reflections from buildings and is often heard in the car as tics and pops as you drive around or, if you are driving more slowly, as small "areas" of distortion that you drive through. In the home multipath distortion will appear in one area of a room but not if the radio is moved to another part of the room. If your radio sounds distorted, particularly if the distortion comes and goes, one of the tips discussed in the first few paragraphs should clear up the problem.

More detailed information about our tower and coverage area

More detailed information about our tower and coverage area can be found here.

What if my question wasn't answered here?

The engineering staff of WAMU want you to receive the best possible signal from 88-5 FM. If we can be of any assistance with your reception problems, please contact us via email or telephone.

How do I get an HD Radio?

We want to make it easy to find out more about HD Radios, and how to purchase one. For a complete listing of currently available models, go to ibiquity.com. Many Washington, D.C., area vendors currently stock HD Radios, including Circuit City and Radio Shack. Online vendors like Crutchfield also sell HD Radios.

If you'd like your purchase of an HD Radio to benefit WAMU 88.5, you can purchase it from Amazon.com using this link, or purchase it from Radiosophy using this link, and a percentage of the sale will benefit the station.

No matter where you get your HD Radio, please give this exciting new technology a listen. You'll never listen to radio the same way again!

How is an HD Radio different from a regular FM radio?

HD radios sound better

Regular FM radio has the ability to produce high fidelity sound under the right reception conditions. FM frequencies require a line-of-site path between the FM transmitter and the receiver. Hisses, pops, static, and fading occurs because FM signals are reflected from obstructions such as buildings -- or from you when you move around the room where your radio is located.

HD radio differs by using digital technology. This technology minimizes reception problems and offers freedom from the interference descibed above. Also, digital technology allows stations like WAMU 88.5 to squeeze in additional services, thanks to cutting edge compression technology.

HD radios receive more stations than FM radios

Several years ago, WAMU 88.5 installed the equipment necessary to broadcast digital signals, in addition to our regular analog signal. Essentially, this allows us to have three signals in the "space" it take for one. On your HD Radio, these three channels are still found at 88.5 on the dial.

WAMU 88.5-1

This is our flagship channel that you can hear on standard FM radios.

WAMU's Bluegrass Country

WAMU's Bluegrass Country is on-air in HD at 88.5-2. You'll hear all your bluegrass favorites, and live-hosted programs featuring Katy Daley, Ray Davis, and Lee Michael Demsey. This station is also heard online at bluegrasscountry.org, which has served the full-time bluegrass listener since 2001. WAMU's Bluegrass Country is among the first in the nation to offer live programming exclusively for HD Radio.

WAMU-3

Our third channel, WAMU-3, in HD at 88.5-3 serves the dedicated public radio news listener with programming not available on the flagship channel, including extended BBC news coverage and NPR's Talk of the Nation. Our groundbreaking partnership with AAA-public station WTMD continues on this station, where we'll continue to air WTMD's funky, eclectic blend of rock, country rock, blues, folk, and world music, weekdays from midnight to 5 a.m., and weekends from 7 p.m.-5 a.m.

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

Unfortunately, not necessarily: The current digital HD system was designed to offer a service that permits receiving the analog FM signal along with the new digital signals. This requires a careful balance by engineers to establish the power of the digital channels so as to maximize coverage without interference to the existing analog service. Luckily, it takes much less power for a digital signal to cover a specific listening area than its analog equivalent. In order to provide side-by-side analog and digital service in the FM broadcast band, the power of the digital signals is only 1/100th the power of the analog signal. The WAMU 88.5 analog signal has a power of 50,000 watts. Our three-channel digital service has a power of only 500 watts.

Nonetheless, most listeners within the greater WAMU 88.5 listening 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.

Map of HD signal coverage

Expected range for receiving WAMU-2 and WAMU-3
Green: Works with included antenna;
Yellow and Pink: May need an outdoor antenna;
Blue: Difficult, may be possible with outdoor antenna & amplifier;
Gray: Out of signal area

A larger version of the map is available for download (PDF, 1.1MB).

Anecdotal experience from listeners and our engineers thus far 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-site 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. 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, it can take up to 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 main 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-2 or WAMU-3, 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-2 and WAMU-3 digital signals.

I bought an HD radio but I'm having trouble hearing the WAMU 88.5 digital channels.

We suggest you first take a look at our coverage map and determine how close to the limit of the primary signal contour you are. If you are relatively close to our transmitter check the following:

Did your HD radio come with a dipole antenna?

A dipole antenna can be identified by its shape. It is in the form of a T.

A dipole antenna

Dipole antennas are inexpensive and available at many electronic retail stores. 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. 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.

Tune in to either WAMU-2 or WAMU-3 and listen for awhile to ensure you have a strong signal that can be consistently received.

I am 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.

An FM antenna

An example of a typical FM antenna

They are available at some local electronic stores or online. You may need to get assistance for the selection of the antenna and its installation from a professional installer.

I'd like to listen to WAMU's Bluegrass Country and WAMU-3 in my car. What's involved?

Those of us who have installed an HD radio in our cars have been very pleased with the results. Not only can we hear WAMU's Bluegrass Country and WAMU-3, we also hear WAMU 88.5's main signal without multipath distortion – the pops, clicks, and distortion often heard when driving near tall buildings and in hilly areas.

Installing a new radio seems daunting to some; others like their current factory-installed radios. Professional installers available at stores like Circuit City can complete a professional installation of an "after-market" radio such as an HD Radio from JVC or Kenwood in a couple of hours. Templates are available for most car models so the finished installation makes the new HD radio look like it was factory-installed.

Two radio currently endorsed by NPR Engineering that are capable of receiving the extra WAMU 88.5 channels are the JVC KD-HDR1 and the Kenwood KTC-HR100 TR tuner box with KDC-MP625 head unit.

BMW recently announced a factory-installed HD radio options for their 2008 models. It's likely to take several years for a significant number of auto makers to include HD radios in their models. For those who can't wait, the radios mentioned here are great additions to the listening experience in your car.

Any other suggestions?

Several listeners in outlying areas with some technical savvy have added an antenna preamplifier to increase the WAMU 88.5 signal even more. This approach is most effective when the preamplifier is mounted near the antenna. Some experimentation may be needed and results aren't guaranteed. Consider ordering outdoor antennas and amplifiers from a store that has a return policy.

Where can I get more information about receiving HD Radio on WAMU 88.5?

After reading this FAQ, feel free to contact us with your questions. Also, we'd like to hear from you about your experience with digital reception.

Where can I get more general information about HD Radio?

Many car manufacturers are now offering HD radios as standard or optional equipment and after-market HD radios are available for most car models at reasonable prices. The sound quality of our HD channel is outstanding and for listeners who invest in car HD radios multipath fading and distortion that often plagues regular FM listening is a thing of the past.

For a complete listing of currently available models for portable, automobile and in-home listening, go to HDRadio.com.

Online vendors like Crutchfield, Amazon and Best Buy have a large selection of HD radios and players including the Insignia Portable HD Radio player.
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