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FM RECEPTION TIPS

By Jim Perry, Greater Philadelphia Radio Group Engineering Staff
(with help and print references from Marc Wielage, CompuServe CEAudio Forum)
E-Mail to Jim

The Problem...

Every radio and TV station has areas of less-than-wonderful reception. Most of these areas are not a result of a technical deficiency at the station; rather, local topography, including hills, buildings, trees, etc., is usually the culprit. A special case for classical stations is that they tend to adjust their audio for a more "natural" sound, as opposed to more "aggressive" stations which adjust their sound to be as loud as possible at all times. The natural sound of classical music tends to reveal every little reception flaw, while the audio of loud stations masks many ills.

Optimizing reception therefore becomes paramount when listening to classical music. These tips are designed to help you identify the cause of reception problems, choose solutions, and, finally, enjoy great music, regardless of format!

Identifying the Noise

Multipath: Static, noisy, distorted stereo sound, especially when music is playing, that greatly improves when switched to mono. Multipath is the most common source of problems, and is caused by signal reflections from buildings, mountains, trees, etc., just like the "ghosts" in TV reception (before cable). Multipath can occur even in strong signal areas.

Weak Signal: A relatively clear but "hissy" stereo sound, perhaps with some slow fading. The hiss is nearly eliminated when switched to mono.

Strong local station: Pieces of another station's sound splattering over the desired station.

Local interference: Interference from other sources such as two-way radios, Citizens' Band operators, and static buzz from appliances and power poles.

-- or any combination! [Back to Index]

Assessing Your Chances of Success

Predicting local FM reception quality is far from an exact science. Before spending money on elaborate equipment and antennas, a certain amount of experimentation would be prudent. It can be particularly disheartening to spend time and money on a fancy new radio, only to find no real improvement.

To help predict your chances of success, try the following: carry a good, trusted portable radio (with its telescoping antenna fully extended) from room to room, listening to the station of interest. If you can get at least a fuzzy, but listenable signal in any room, chances are good that a rooftop antenna (or even a good indoor antenna) may yield very good results. Or, if you can get the station on your car radio while in the driveway or garage, this is also a good omen. If, on the other hand, you get nearly no reception at all no matter what you try, proceed with caution; a fancy new antenna may be an expensive, but futile, experiment.

Careful tuning and listening are important in determining the type of reception problem you have:

Do you almost always hear the desired station, but it's distorted much of the time? Does the audio improve markedly when the receiver is switched to "mono"? This is a classic description of multipath (see definition above). Experimentation with a "positionable" indoor antenna may cure this problem. Severe multipath may be minimized by a carefully aimed outdoor antenna. Some newer receivers have features that help in reducing the effects of multipath.

When the desired station fades, does another (unwanted) station take its place, or is the channel empty (except for normal "static" and distant weak signals)? If another station on the same channel is coming in almost as strongly as the desired station, your receiver-antenna combination may be having trouble choosing one over the other. A directional outdoor antenna, pointed toward the desired station (and away from the other station) may help.

Is an unwanted station (or "pieces" of its program) interfering much of the time? A strong station on a nearby channel may be "splattering" onto the desired station. As above, a directional antenna pointed at the desired station may help. A good-quality receiver may be the answer as well; check out the "narrow band" feature of better receivers described below.[Back to Index]

Things To Try

The following suggestions are in a decreasing order of preference. And, as you might expect, the more involved solutions are generally near the top of the list. An exception is buying a new receiver; in most cases, this expensive option is a last resort. [Back to Index]

Outdoor Directional Antenna

The almost universal solution to reception problems is a directional outdoor antenna. This antenna, called a "yagi," looks just like a plain TV antenna. There are dozens of different models available in the $25 to $250 price range. Important: this suggestion assumes that the radio you're using has connections for an external antenna (many table radios and most portables do not have such connections). Be sure to check the radio first. Some antenna sources:

	Radio Shack
	(many locations)

	Channel Master
	P.O. Box 1416 Industrial Park Drive
	Smithfield, NC 27577
	(919) 934-9711

	Winegard Co.
	3000 Kirkwood St.
	Burlington, IO 52601
	(319)754-0600

And what may very well be the best FM yagi (used by many broadcasters to solve difficult reception problems), the venerable APS-14, available from:


	Antenna Performance Specialists (APS)
	P.O.Box 9597
	Bolton, CT 06043
	(860)643-2733, 
        E-Mail to Ed Hanlon at APS

In every case, use well-shielded coaxial cable (usually labeled "CATV" or "RG-6) from the antenna to your radio, using appropriate static drains and grounding ("coaxial lightning arrestors") where the antenna's cable enters the house. Lightning arrestors are available from some of the above antenna companies, as well as a full line of high-quality models from:


	Electronics Manufacturing, Inc.
	(800)649-6370,  
        E-Mail to Larry Cagle at EMI

Properly installed connectors are very important; buy the best and install them with care. Although flat twin-lead is theoretically less noisy than coaxial cable, the performance difference is negligible for most home installations. If you have a quantity of twin-lead on hand, give it a try, but the potential benefits of coaxial cable's shielding and ease of installation make it the cable of choice.

You can often get better results by using an inexpensive outdoor antenna with an inexpensive radio than you can by using a fancy indoor antenna with an expensive radio. A well-installed and well-maintained outdoor directional antenna alone can have a dramatic and unmistakably positive effect on FM reception, even with inexpensive or older receivers.

Directional Antenna Considerations:

If an outdoor antenna doesn't work to your satisfaction, it's very difficult to disassemble and repack for return and refund. Some stores may not allow such an antenna to be returned, except for manufacturing defects. In any event, your time and money spent on installation is not recoverable.

If you only listen to one station, or to several stations from the same direction, you can leave the antenna aimed in that direction for best reception. However, if you listen to stations from different directions, you may want to consider an antenna rotor (rotator) to re-orient the roof antenna's position. Before buying a rotor, however, it may be wise to manually optimize the antenna's position for your favorite station, then listen to the other stations. They may come in fine with that particular orientation. If not, good rotors are available from Jerrold, Winegard, and Radio Shack.

For more information on complex antenna installations, read Michael Salvati's excellent series of articles on FM antennas in the January, February, March, and April '78 and the January '79 issue of AUDIO magazine (available in any large library). Also good are Len Feldman's antenna comparison in the January '83 issue of AUDIO and Julian Hirsch's article in the May '85 issue of STEREO REVIEW.[Back to Index]

Outdoor Non-Directional Antenna

Non-directional (omnidirectional) outdoor antennas, such as "turnstiles" and "S-shaped" may be helpful in many instances, and usually give better results than any type of indoor antenna. But if eliminating multipath and/or interfering stations is the goal, a non-directional antenna may not help. Only directional antennas can attenuate contaminating signals from other directions, such as reflections from nearby hills or buildings, or an adjacent- or same-channel interfering station. [Back to Index]

Indoor Antenna

Indoor antennas generally do not work as well as rooftop/attic antennas. In most cases, a very inexpensive rooftop/attic antenna will outperform even the best indoor antenna. Again, experimentation is paramount. After connecting the indoor antenna to your radio, try moving the antenna anywhere its leadwire will allow for best reception. In tough indoor reception areas, it's important to move the antenna and, if necessary, the receiver, around the room or house, searching for a good signal spot. Try anything from a $10 set of plain "rabbit ears" from Radio Shack, to what many critics say is the best indoor model, the $200 Audio Prism APPA-8500, made by:

AudioPrism
2729 152nd Avenue NE
Redmond, Washington 98052
Tel. (425) 869-8482; Fax (425) 869-1873
Contact: Byron Collett at byron@audioprism.com
http://www.audioprism.com/

A visit to a high-end audio store will generally yield at least one or two fancy indoor FM antennas (along with a lot of strong opinions on just about everything to do with FM).

Often, it's very difficult to pick up desired stations inside an office building. The villains here are usually the metal-frame building (which can shield the signals and prevent them from reaching your indoor antenna), fluorescent lighting fixtures (which often produce broad-spectrum electronic noise), and interference-producing devices like computers and other office equipment. In some cases, locating a set of rabbit ears against an outside window can improve office reception. As above, it's important to try the antenna and radio in several locations around the office, sniffing out good signal areas.

Important: One positive thing about indoor antennas is that they're easy to pack up and return to the store if they don't perform. Be sure to determine the store's return policy before you purchase any antenna.[Back to Index]

A Better Receiver

Buying a better radio, receiver, or tuner may be the most expensive route to reception nirvana, and should be considered only if your antenna efforts yielded unsatisfactory results. And there's still no guarantee that a new radio will solve certain reception problems, so determine your return/refund rights before you purchase. Talk to the equipment salesperson about your reception problem to establish in advance why you're considering a new receiver.

A current-model receiver may only marginally improve reception, but may have other features, such as station pre-sets and digital tuning, which will aid in finding your favorite stations. Many "reception" problems turn out to be mechanical tuning difficulties with a hard-to-read or poorly calibrated dial, a problem quickly solved by a radio with digital tuning.

Important radio technical specifications to look for are:

Alternate-Channel & Adjacent Channel Selectivity: this refers to the ability to separate stations close to each other in frequency. Higher numbers indicate better performance.

Usable Sensitivity: the minimum signal strength needed to provide a quiet, undistorted audio (the lower the number of microvolts or femtowatts the better).

Capture Ratio: the radio's ability to select one station over another, based on the difference in their strength; the lower the number, the better.

AM Rejection: doesn't refer to getting rid of AM stations!; rather, this specifies how successfully the radio ignores noise-producing level variations (static, sputtering, etc.) in the incoming signal. The higher this number, the better.

Image Rejection: refers to the radio's ability to suppress internally generated spurious noises and squeals, especially in the presence of strong signals or signals of certain frequencies; the higher the better.

Most modern radios have respectable stereo separation and frequency response, as well as low residual noise and distortion. The real tests are the specifications listed above; these will make the most difference in difficult reception situations. Many better receivers have other features that may help in poor signal situations; see Compromises below. [Back to Index]

Antenna Amplifier

If the basic signal is weak, but otherwise free of multipath distortion and interference, you can sometimes benefit by the use of an RF (Radio Frequency) amplifier in the antenna line. If you live anywhere near a radio or TV station, however, there's a strong possibility that the station may overload the antenna amplifier, causing more problems.

As always, start by trying an inexpensive amplifier, and bring it back if it doesn't help. Considered one of the best is the model 205 "Signal Sleuth" Tunable FM Signal Amplifier from Magnum Dynalab at:


	Magnum Dynalab Corp. 
        http://www.magnumdynalab.com
	8 Strathearn Ave # 9,
	Brampton, Ont. L6T 4L9

	Tel: 800-551-4130   Fax: 905 -791-5583

Magnum also offers a free booklet on FM reception for audiophiles called "Rediscover FM Stereo," and is highly recommended.

[Back to Index]

Compromises

Of course, our goal is crystal-clear stereo reception, but if you can't receive the station cleanly in stereo, switch the tuner or receiver to its mono mode. Often, just switching to mono will substantially reduce noise, static, and multipath distortion.

The best radios provide "narrow I.F. bandwidth" modes, which can effectively notch out nearby interfering stations on the dial. While these modes tend to increase distortion slightly, they can often make a noisy distant station completely listenable.

"High-Blend" is another common feature. This circuit helps multipath and weak signal situations by decreasing the high audio frequencies (where most of the noise is) and by reducing stereo separation.

Sometimes one or several of the above special modes in combination with each other can make a dramatic reception improvement. [Back to Index]

Interference Filters

If you're experiencing local interference problems (static, hiss, crackling, pops, noise, etc.), and are fairly sure it's not multipath, try to find the interference source. Possibilities: arcing high-tension power lines, poorly grounded motors, appliances, spark plugs from passing cars, etc.

In these instances, there is no substitute for an experienced ear. If you know someone with electronics expertise, perhaps a local amateur radio operator, try to arrange a visit. S/he may suggest a number of possible cures, including filters for the interfering devices, as well as on the FM radio's power line, antenna line, and audio cables. Experimentation with grounding some or all of your components may also help.

A large variety of power line filters, and RF (Radio Frequency) filters (for the antenna line and/or audio cables) are available from:


	Electronic Specialists
	171 S. Main Street
	Natick, MA 01760
	(800) 225-4876

If you confirm that a powerful local FM station is preventing your reception of a weak, distant FM station on a nearby frequency, you can use the "narrow IF" modes on good FM radios (described above) to improve selectivity. A last-ditch attempt would be to try a special "notch filter" at the antenna connector, to attenuate the interfering station. The Blonder-Tongue MWT-2b is such a filter, and costs about $140 and is available from:

	Blonder-Tongue Laboratories, Inc.
	1 Jake Brown Road
	Old Bridge, NJ 08857
	(201) 679-4000

	Channel Master
	P.O. Box 1416 Industrial Park Drive
	Smithfield, NC 27577
	(919) 934-9711

The FCC's Web page offers a helpful interference handbook at: http://www.fcc.gov/cib/tvibook.html

Or, call the FCC's Consumer Hotline: 1-888-CALL-FCC

If all else fails, and you have reason to believe that the interference is malicious or illegal, contact the FCC:


	Federal Communications Commission
	Radio-Frequency Interference Dept.
	191 M. Street N.W.
	Washington D.C. 20554
	(202) 632-7260

The FCC is overworked and understaffed, and may not be able to respond immediately (if at all). [Back to Index]

Cable TV/FM Connection

A possible solution, not available to everyone, is your local cable TV company. Although many cable TV systems dropped all FM station carriage some time ago, some systems still carry a few FM radio stations in addition to the TV channels. Check with your local cable company. If they don't offer FM, register your disappointment! Even though FM reception from the cable is often slightly degraded, it's better than none at all. [Back to Index]