Some of our listeners do not receive VPR well. Occasionally a listener will call with a complaint that their reception has suddenly and permanently gone bad. Here is a guide to improving poor reception or restoring good reception of VPR. It includes some background information on how FM radio works and common causes of interference, general suggestions for improving reception, specific troubleshooting tips, and a summary that includes specific suggestions for buying and installing an FM antenna.
FM radio is much like television. In fact the FM band is smack in the middle of the VHF TV band. At the frequencies employed, 88-108 MHz, radio waves travel in straight lines, much like a flashlight beam. So any object that gets between your radio's receiving antenna and the radio station's tower will block the beam. For best reception, your radio's antenna should be mounted up and away from nearby obstacles.
Another characteristic of FM and TV radio waves is reflectivity. They can bounce off objects and be deflected by them. This gives rise to ghosts in your TV picture and distorted sound from your FM radio (with digital TV instead of "ghosts" you'd see 'pixelated/frozen' screens, or even no signal at all - the so called Digital Cliff). When you listen to FM in a moving vehicle, you may hear the all-too-familiar flutter caused by intermittent reflections. We call that phenomena picket fencing. Imagine a wooden picket fence with slats going by your car window. The radio waves in the air also exhibit a similar pattern when combined with reflections from multiple pathways (multi-path) from the radio tower to you. Indeed improper placement of a stationary FM radio antenna could result in it being in one of those picket shadows yielding a permanently weak and distorted signal.
Why is reception worse here than in the city?
Well for one, we have enormous objects that can block and reflect FM and TV radio waves. We call them mountains! The land in much of rural New England is very rocky and hilly. And as if that were not enough, radio stations tend to be located in or near the urban populations they are licensed to serve. If you live between them, in rural outlying areas, no station is near you and very few come from the same direction. So for proper reception you really have to re-orient your antenna for each station. A fixed antenna is at best a compromise. It will work for some stations but not for others.
Why is VPR weaker than the local rock station?
VPR does not operate local neighborhood radio stations. To do so would require too many transmitting towers. Instead we are licensed to operate higher power facilities from several strategically placed mountain top towers covering a wide area. Thus our signal, throughout much of the region, is not going to be received as a locally strong signal. Also, we do not compress our sound to the extreme of other stations so that you can enjoy the dynamics of the music as if you were playing the recordings at home. This results in our being perceived as softer than the other stations on the dial.
Some of our listeners are located very close to other radio station towers. Those stations can overload or desensitize your radio so it will have difficulty picking up a more distant signal such as VPR. The best solution is a large, rooftop, directional FM antenna. Called a Yagi or Beam this antenna focuses your reception much like the reflector in a flashlight. Aiming it away from the offending local station and toward one of VPR's transmitting sites will eliminate this problem.
Suggestions for Improving Reception
- Treat your FM reception as you would television.
- At home, put up a good, directional, rooftop FM antenna, the larger the better (they are not expensive).
- Use fully shielded coaxial cable from the antenna to the set, not ribbon cable, and use appropriate adapters to connect it to your antenna and set.
- Consider a rotor to permit you to aim the antenna at the desired radio station.
- Buy the largest FM antenna you can afford. In this case bigger is better!
- Avoid indoor antennas as they are subject to drifting performance as you move about the room and will pick up interference from personal computers, TVs, radios and other appliances.
- The ribbon "T" type antenna that is packed with most hi-fi sets is grossly inadequate and will work with only the strongest local signals.
- Clock radios, portables or boom boxes without terminals for external antennas will not perform well at home unless you are quite close to the radio station or have an unusually clear path to it.
- Most cable companies pay little attention to FM reception so you may find that VPR is not good on the cable. If so, do not connect your FM radio to your cable system. You can usually do better with your own roof top FM antenna.
- Automotive reception is very problematical due to the hilly terrain. Look for car radios that have mono/stereo switches. Best reception is in monaural.
- A few of the premium factory equipped car stereos have diversity antenna reception. Only two after market car radio manufacturers currently offer it. The diversity system uses two antennas on the car and constantly compares reception on both, switching the better one to the radio. This eliminates about 80-90% of the multi-path picket fence distortion of a moving vehicle.
Trouble-shooting Tips for Poor Reception
- Reposition the radio and/or antenna.
- Try another radio.
- Inspect your antenna connections in back of the set and on the roof for looseness and any corrosion.
- Try another antenna.
- Use a battery portable radio to sniff out the source of interference.
- Use it to check out the nearby utility poles, or neighbors house, or your own abode.
- Turn off the power at your main service panel and again listen on your battery radio, did the interference stop? If so the culprit is in your own home.
- Compare your reception to that of nearby friends and neighbors. Are you all having the same problem?
- Keep a log of time of day and day of week for intermittent interference. This can give you clues as to who is producing the interference.
- If your reception has suddenly become poor, ask yourself what might have changed in your vicinity?
Did you alter your antenna connections?
Did you add or remove a set?
Did you move some furniture, especially a metal cabinet?
Did you buy a new appliance?
Is there new construction in the neighborhood?
Did a new radio or TV station go on the air?
Did your neighbor put up a new antenna, maybe for CB?
Has the cable company strung new lines or done any other repairs?
Has it rained a lot?
Was it icy or windy recently?
These can provide clues as to what might have changed.
Indoor antennas of any style are inferior to large roof top Yagi style antennas. For best results put up an FM antenna with a rotor.
Use only shielded type RG-59 coaxial cable between the antenna and the set.
If your set is equipped for only 300 ohm ribbon type cable, buy the appropriate matching transformer to mate it with the coaxial style cable. (Your local TV/ Electronics dealer can help get you the right materials).
If your radio does not have provisions for an external antenna connection, consider replacing it with a better radio that is so equipped.
If you are plagued by interference, prepare to do some detective work. Swap radios and antennas. Talk to the neighbors. Borrow a battery radio and survey your home and the neighborhood for the source of the problem.
If all else fails, send us an email.
Note: This guide was originally published to VPR.net in 2002. VPR President Robin Turnau mentioned it on the air o 3/6/14 during "Your Turn," so we're re-posting it here to the blog.