FREQUENTLY ASKED QUESTIONS [ SUPPORT ] [ CONTACT ] 
Is UHF better than VHF ?
 

VHF here refers to VHF high band and UHF here refers to UHF high band. The advantage of VHF high band is that the wave propagation through the air is excellent and their ability to pass through non-metallic substances is good. This results in good VHF high band transmission range.

The reduced radio waves propagation of UHF through the air and through non-metallic materials result in less range for comparable radiated power. Another setback for UHF is the increased amount of radio waves reflections by metal objects, resulting in more frequent and more severe dropouts due to multi-path cancellations. This is the reason why UHF non-diversity is not so effective and thus not so advisable. However, diversity is very effective in UHF as the required antenna spacing is minimal.

However, there is certain true that UHF band is less crowded than VHF at the moment, thus it is far less prone to interference.

Another advantage of UHF is that now UHF frequencies are being approved all over the world for wireless microphone usage.

The main economic difference between VHF and UHF is the relatively higher price of the UHF system. This is due to the fact that it is more difficult and hence more expensive to design and manufacture UHF devices.
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Could two transmitters be used on the same receiver ?
  No. The working principle of wireless microphone is radio. Just like radio, every transmitter and receiver is allocated a dedicated frequency of operation. When two transmitters of the same frequency work on the same receiver, it will result in interference.
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Antenna Diversity vs True Diversity
 

Basically, an antenna diversity system is a non-diversity system. The two signals that come in from the two antennas are compared and switched via a simple comparator circuit and the resultant signal is fed into the non-diversity RF circuit for further processing. The rest is non-diversity.

In a true diversity system, two separate tuners processed the two incoming radio signals till the detector circuit before making a comparison by a diversity circuit. It is a much complexed and accurate circuit as compare to that of antenna switching system. True diversity system has a much higher sensitivity than the antenna switching system
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Non-diversity vs True Diversity.
 

Non-diversity receivers are equipped with a single antenna whereas a diversity receiver has two antennas.

In a radio transmission system, radio waves propagate omni-directionally in straight line from the transmitting antenna to the receiving antenna. However, in indoor operation, certain waves may have travel different path, hit some metallic object and reflected to the receiving antenna. The receiving antenna is constantly picking up a varying combination of direct and reflected waves. The direct and reflected waves travel different paths to arrive at the receiving antenna, hence the term multipath. These multipath result in differing levels, arrival times and phase between the waves. The net resultant is the sum of the direct and reflected waves. These waves can reinforce or cancel each other depending on their relative amplitude and phase. This result in degradation or loss of radio signal at certain points. Cancellation of radio signal could occur when the direct and reflected waves are similar in amplitude and opposite in phase and this could happen even when the transmitter is at a relatively short distance from the receiver.

Diversity refers to the general principle of using two antennas to take advantage of the low probability of simultaneous dropouts at two antennas at two locations. There are various diversity techniques and true diversity refers to receiver which have actually two receiver sections and each section possess an antenna, RF and IF stages
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What is Pilotone ?
 

The word Pilotone was coined and originally used by Chiayo in the early 1990s and is now used by many competitors. Most of Chiayo systems are now equipped with Pilotone.

Pilotone is actually a further refinement of the conventional squelch circuitry used in most radio receivers. A sub-audible tone signal ( usually 32.768 KHz ) is modulated into the radio carrier along with the audio signal to act as the code of the transmitter. This enables the receiver to identify the desired radio signal. The receiver will un-mote or been triggered on only when it picks up the radio signal of adequate strength and it detects the presence of the Pilotone signal.

This effectively prevents the possibilities of noise from the system when the transmitter signal is lost or when the receiver is on standby state. Turn-on and turn-off delays are incorporated so that the transmitter power switch operates quietly, eliminating the need for a separate mute switch
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What is the Squelch ( SQ ) for ?
  The squelch control on the back panel of the receiver is preset at the factory, but can be adjusted if one uses the system in a high RF interference area. If there are audio output from the receiver when the transmitter is off, adjust the squelch control ( SQ ) so the system will receive the signal from your transmitter but “ squelch “ or eliminate the unwanted background RF noise. This adjustment can cause a reduction in usable range of the wireless transmitter, so set the control to the lowest position which reliably mutes the unwanted RF signal. For example, if you encounter receiving interference ( other than an operating TV station ), often it can be overcome by adjusting the receiver squelch control ( SQ ).
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What is a compander system ?
 

The word Compander is coined from the two words Compressor and Expander. Basically, it is a noise reduction system. In a wireless microphone system, the audio signal is compressed at the transmitter in a certain ratio say 2:1 before transmitting. This is to lift it above the inherent noise floor of the RF link. For example a 110 dB dynamic range signal is thus transmitted with an effective range of only 55 dB, which is above the 60 dB noise floor of the RF link. In the receiver the signal is expanded in an identical but opposite way in a 1:2 ratio to restore the original signal., giving a radio link with an excellent signal-to-noise ratio.

Could one tells the difference between systems with and without compander noise reduction ? Yes, a system with no compander noise reduction is has much more background noises when the transmitter is about 20m away from the receiver. A system with compander system operates noise free up till 100m
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