1. No matter what type of wireless transmitter you have, always be sure you start with a fresh new battery. Battery life will vary from mic to mic as well as from day to day. Its much less painful to install a new battery each time than to explain why you cant be heard.
2. Turn your transmitter is off.
3. Turn your receiver to on.
4. If your system has Automatic Frequency Selection (AFS), press the receiver's "Select" button. It will scan and locate a good frequency automatically for you.
5. Temporarily turn down the receiver's volume or level control on your mixer or amp.
6. Turn on your transmitter.
7. If your system has Automatic Transmitter Setup, press the transmitter's "Sync" button. It will lock on to the receiver's selected frequency. Check the receiver's LED or meter to confirm that it is picking up the transmitter. Turn the receiver's volume control up to a normal level.
8. Adjust the transmitter audio gain. This is the way to getting a good sound and good levels. You may require a small screwdriver for this. Sing or speak loudly into the microphone and increase the gain slowly until the receiver's "RF Level" or meter occasionally flashes to indicate a peak during the very loudest moments.
9. Do a walk-through the performance area while watching the receiver's "Power" LED or RF meter. It should indicate sufficient reception in all areas of coverage. If you see a dropout, reposition the receiver or antenna to improve the reception.

Setting the proper input gain is the absolute most important adjustment on a wireless microphone system. Set it too low will cause the signal-to-noise ratio of the system to suffer (too much noise in the signal). Setting it too high may cause horrible distortion and/or compression of the dynamic range. Adjusting the transmitter input gain is exactly like setting the record level on an analog tape recorder. It is important to consider the features and controls offered on any wireless transmitter that enable accurate gain adjustment.

The transmitter-to-receiver distance has a major effect on the signal-to-noise ratio of a wireless system. When the transmitter is farther away from the receiver, the signal-to-noise ratio gets worse as the transmitter signal gets weaker. When the system is near the limit of its operating range, dropouts in signal will become frequent and a buildup of steady background noise (hiss) will be heard.

The term "diversity" has to be one of the most widely misunderstood concepts of wireless systems. The term simply refers to the use of two antennas to eliminate "dropouts" caused by multi-path phase cancellations (multi-path nulls). Dropouts occur when the transmitter and receiver antennas are in a particular location relative to each other. Moving the transmitter or receiver to a different location can often reduce or eliminate the dropouts. Other objects that move around the room, like people’s bodies, can also change both the reflected and direct signals between the transmitter and the receiver and can make dropouts either more likely. The wavelength of radio signal carriers at VHF frequencies ranges from about 5 to 6.5 feet long. At UHF frequencies, the wavelength ranges from about 12 to 20 inches. The place where a dropout occurs will be larger at VHF frequencies than at UHF frequencies, so antennas have to be moved farther with a VHF system than with a UHF system to reduce or eliminate dropouts. This also means that locating dropout zones during a walk test is a bit easier with a VHF system than with a UHF system.

There are four types of Diversity designs and here is an overview:

• Passive Diversity: This is the addition of a second antenna to a single receiver, placed 1/2 wavelength or more apart. This can be easily done with an outboard combiner and a second antenna. Two combined antennas will gather more RF signal and can reduce dropouts to a small degree. Tests under actual situations have shown that there is little or no improvement in the prevention of dropouts by simply using two antennas.
• Antenna Phase Switching Diversity: The big advantage of this is small size, which explains whyphase switching is used for compact receivers designed for field production. Two antennas are mixed to feed a single receiver, with a phase reversal switch added to the input of one of the antennas.
• Audio Switching Diversity: This technique uses two separate receivers, selecting the audio output of one of the receivers. It is quite effective at overcoming dropouts, but only provides a minor improvement in operating range. The switching action is usually triggered by comparing incoming RF levels and switching to the receiver with the stronger RF signal, which usually produces a better signal to noise ratio in multi-path conditions. This is often called "true diversity," and is probably one of the best methods of reducing dropouts in real life situations.
• Ratio Switching Diversity: Two separate receivers, share a common oscillator and audio circuitry for this method. The audio outputs of the receivers are used simultaneously, being mixed with a "panning" circuit in a ratio controlled by the comparative RF levels at the receivers. The ratio combining process is similar to an audio switching diversity design. The difference between these two techniques can be found in that ratio diversity receiver utilizes both receivers simultaneously, whereas an audio switching type uses only one receiver at a time. These systems can be extrememly expensive and give little advantage over over a good true-diversity system.

DIVERSITY vs. NON-DIVERSITY

In a house of worship situation where there are few if any obstructions between the transmitter and receiver and frequency coordination is relatively simple, it may be best to have a simple VHF, non-diversity system. Sometimes simple is best.

This is another typically misunderstood area of wireless systems. It’s understood that UHF has greater range due to higher power output, and is less susceptible to television interference. Although totally true - there are other things to consider when making this choice.

Power Output
One consideration - in the VHF spectrum from 174 to 216 MHz the maximum allowable transmitter output power is 50mW. But in the UHF band maximum allowable transmitter power is 250mW. Higher output power from the transmitter helps get rid of dropouts and increases operating range, but will cause shorter battery life. The actual effective radiated power is also affected by each different transmitter antenna, so a higher output power does not necessarily mean greater operating range by any means. High-quality VHF transmitters produce the allowed 50mW, for reliable operating range and reasonable battery life. UHF transmitter output power varies much more widely from one brand to another than VHF units. The maximum allowance of 250mW in the UHF spectrum is useful when maximum operating range is the prime concern. 100mW is commonly chosen for UHF transmitters as a good balance between operating range and battery life. Of course.. when batteries improve, this will all be moot. Things change.

VHF & UHF
Wireless mic systems usually operate in several bands from 150MHz to 216MHz, which includes the VHF TV channels 7 through 13, or in the 470MHz to 806MHz UHF band (TV channels 14 through 69). TV channels 60 to 69 (746 to 806MHz) are being re-allocated, as of the date of this writing, for other applications. In addition, *the band from 470 to about 516MHz is also being re-allocated for public safety applications*. The demand for more spectrum usage is increasing while the available spectrum for wireless microphones is decreasing. Above the TV band is another part of the UHF spectrum from 902 to 928MHz. This upper UHF band is a "general purpose" band used by many different users ranging from garage door openers and amateur radio, to home-use cordless telephones. For now, the 902 to 928Mhz band is not a good choice anymore for wireless microphone systems, and certainly not for professional use in traveling applications. Interference is virtually guaranteed in this band. Dont asusme that UHF is always the best.

Choosing A Wireless Mic For Live Performance:

When choosing a wireless mic for live performance, there are a number of factors to consider.

1. The microphone should be rugged and reliable in order to hold up to the rigors of the road - nightly live performance and travel.
2. It should feel comfortable and easy to hold while performing.
3. It should offer good resistance to feedback.
4. It should be able to handle high SPL (Sound Pressure Levels) and deliver a nice clean signal.