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Maximizing Range

Operating range is rarely a problem with Audio-Technica wireless systems. A-T equipment is conservatively designed and carefully manufactured, and includes a comfortable built-in safety margin. In almost all instances, the range will be more than adequate, even when conditions are less than favorable. For unusual applications or when the situation is especially difficult, however, a bit of extra range can become important. Fortunately, there are some simple measures and sensible precautions that can be taken to maximize range.

  • Use better equipment. One of the best ways to maximize the range of wireless systems is to purchase better equipment. Higher-priced systems almost always outperform low-cost systems, including providing greater usable range.

  • Use diversity systems. Diversity receivers are required to achieve maximum range. In typical wireless applications, diversity receivers will provide from two to ten times the range of similar non-diversity receivers. This is because dropouts due to multipath will generally make a non-diversity system unusable long before the signal gets too weak for good reception with a diversity system.

  • Use good alkaline batteries. Use only top-quality, name-brand alkaline batteries. Other types of batteries might not have enough capacity to allow the transmitter to deliver maximum power. In particular, do not use rechargeable batteries, as they usually have a lower output voltage which reduces transmitter power. Make certain to use only fresh, new and unused batteries. Not only will operating life be short with a used battery, transmitter power usually drops at least slightly as the battery nears the end of its life.

  • Choose frequencies carefully. Select interference-free frequencies. Interference, whether it is audible or not, almost always reduces range. Strong interfering signals can reduce the sensitivity of the receiver, making it more difficult to receive the desired signal. Make certain that other frequencies are not closer than the required minimum frequency separation for the system being used.

  • Don't over-squelch. If the squelch control on the receiver has to be set above midrange to prevent noise, there is an interference problem that must be corrected. High squelch control settings can greatly reduce range, sometimes to one-third of what it should be. Digital devices such as computers and signal processors often produce RF noise that interferes with wireless receivers or requires a high squelch setting. Such devices should be mounted as far away from wireless receivers as possible, but certainly no less than 24 inches (60 cm), if maximum range is the goal.

  • Separate transmitters and receivers. Do not allow other wireless transmitters to come near the receive antennas. Strong signals on nearby frequencies can overload the receiver RF circuits, cutting sensitivity and reducing range even when interference does not result. Other high-power RF devices such as two-way radio equipment should never be used in the vicinity of the wireless receivers. Reduced operating range should also be expected when there are high-power television transmitters in the same band nearby.

  • Use remote antennas. Use remote antennas when receivers are rack mounted. The metal frames of the rack will partially block RF signals, usually significantly cutting range. Do not stack receivers on top of each other or directly side-by-side unless remote antennas are being used. Even then, this is not good practice because RF leakage from one receiver can sometimes affect another. When receivers are stacked, attached antennas will be much too close together to be efficient. Antennas that touch each other will not only seriously affect range, but also create a high possibility of interference. For best results, antennas attached to different receivers should be separated by at least 18 inches (45 cm) for VHF, and 6 inches (15 cm) for UHF.

  • Mount antennas high. Mount receive antennas as high as possible, at least 8 feet (2.5 m) above the floor, taking care not to get too close to fixtures, metal framing for suspended ceilings or other metal objects. Do not place the receive antennas next to walls, as there might be pipes, cabling, metal lath or metal studs inside. Make certain that there is a clear, open RF path between the receive antennas and the transmitter at all times. Metal objects between the transmitter and the receive antennas, even ones slightly off to one side, will frequently cut range significantly.

  • Don't coil transmitter cable. On VHF body-pack transmitters, do not wrap excess microphone cable around the transmitter body. This will seriously affect range because the microphone cable is used as the antenna and the coils will effectively short out the RF signal. For much the same reason, do not coil or bundle the microphone cable closer than 18 inches (45 cm) from transmitters. On UHF transmitters, keep the microphone cable well-separated from the small whip antenna.

  • Position transmitter high. Position the body-pack transmitter antenna as high on the body as practical. For VHF transmitters, running the microphone cable up over the upper back and shoulder then back down the front will improve range appreciably. Height is less important for UHF transmitter antennas, but it is still worthwhile to locate the transmitter high on the body when maximum range is the goal. However, a body-pack transmitter should not be worn where it is immediately adjacent to any implanted cardiac pacemaker or AICD device since RF energy may interfere with the normal functioning of such a medical device.

  • Maintain equipment. Consider the possibility that the wireless equipment needs maintenance, especially if the range seems to be less than it once was. If the equipment is more than a year or two old, has been heavily used or has suffered rough handling, it might need a tune-up to return it to peak performance. Wireless transmitters and receivers have internal adjustments that can be disturbed by drops, careless handling and mechanical abuse, causing reduced range and other problems.

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