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    FAQ
    Frequently asked questions @CHIAYO's product users

    • Wireless mic
    • Wireless amp
    • Infrared mic
    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.

    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.

     

    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.

     

    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.

     

    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.

     

    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 ).
    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.

     

    What is the function of : IrDA : in Chiayo・s wireless microphone system ?
    IrDA stands for Infrared Data Association, it・s a body that set standard for communication between devices (such as computers, PDAs and mobile phones) over short distances using infrared signals.
    Chiayo is the first wireless microphone company that adopted this duplex mode data transferring technology into her wireless microphone system, enabling exchange of data information between transmitter and receiver and vice versa.
    How does IrDA work?
    As IrDA function is in Duplex mode, one can expect transfer of data from two direction, namely from Transmiiter to Receiver as well as from Receiver to Transmitter.
    To do this, first set the required data on either the Transmitter or Receiver, point the IR sensor to each other, press the send key and the data will be transferred from the side where the send key is activated.
    What is the difference of our IrDA system compare to other similar products?
    Chiayo IrDA designed wireless microphone is unique in the sense that it is a 2 ways data exchange system. One can change the receiver data via the transmitter and vice versa.
    What is the purpose of a Repeater transmitter ?
    A repeater Transmitter serves to extend the reception range of the wireless microphone system. It is usually placed in between the Transmitter and the final reception Receiver. Take for example of a QR-2000 system, the Receiver module on the left receives the Rf signal from the wireless microphone on stage, the Repeater transmitter on the right ( different frequency as that of receiver on the left ) get the output signal of the first receiver and transmit it to the 2nd receiver ( same frequency as that of the repeater transmitter ) at a further distance. The system could be extended by using several Repeater transmitter to achieve the longest distance required.
    • As in this car parade, TX0's audio signal goes to RX0. TX1's to RX1, TX2's to RX2, TX3's to RX3. This one-after-one audio transmission enables all cars to broadcast from a sole voice source.
    • As in this stadium, TX0's audio signal goes to RX0. TX1's to RX1, TX2's to RX2, TX3's to RX3. This one-after-one audio transmission enables all areas to broadcast from a sole voice source.
    Do all Chiayo・s Portable Sound Systems using Lead Acid rechargeable battery?
    No, only the Smart 300; Focus 500; Adventure; Challenger 1000 and Victory 2000 series are using Lead Acid rechargeable battery. iTalk personal PA uses AA size NiMH battery and Coach 400 uses Lithium -Ion battery.
    Do I need to charge the battery of my wireless amplifier if it・s intended for a pause of long time?
    Lead Acid battery does not have memory effect. So one can charge the battery at any condition. If one intends to stop using the system for a few months, it is always advisable to give the battery a full charge every month.
    What if I forget to unplug the charging cable from the Portable System after it・s fully charged?
    No problem. All our systems have a built-in an over charge protection circuitry. The system won・t be overcharged if it remained plug in after it・s fully charge.
    What is unique about Chiayo・s wireless portable amplifiers?
    Chiayo・s wireless portable amplifiers such as Challenger and Victory systems could be daisy-chain link ( via Master V Slave link ) to form a much larger system in a much larger crowd. The link could be done by wire or wirelessly via a Repeater transmitter.
    Further, our Challenger and Victory systems could accommodate 4 receiver modules to become a 4 channel wireless system.
    How could I extend the receiving range of my Victory and Challenger Portable Sound Systems?
    You could extend the range of the reception by adding a Repeater Transmitter and a Slave system with the correct frequency matching receiver module.
    • As in this stadium, TX0's audio signal goes to RX0. TX1's to RX1, TX2's to RX2, TX3's to RX3. This one-after-one audio transmission enables all areas to broadcast from a sole voice source.
    How to select a proper frequency of a Repeater Transmitter to ensure an interference-free long range transmission?
    In order to get a long range interference-free Repeater transmission, proper selection of frequency band is of utmost importance. Based on our numerous experiments, it is advisable to select a band which is minimum 30Mhz apart, in fact the wider the separation is better.
    For countries with limited allowed bandwidth, it is advisable to separate the receiver and transmitter channels as far as possible such as choosing CH1 for Transmitter and CH16 for receiver or vice versa. This will give at least a 20 MHz separation between them. If this is still a problem, please install the repeater transmitter further away like clipping it on the extended trolley handle or mount it a distance away on a tripod.
    Are Chiayo・s wireless products affected by the recent FCC changes banning all UHF in the 700 MHz band from use?
    No, Chiayo has wireless products with frequency operate in the 600 Mhz range. Users in America should just choose the 600 MHz range products.
    What is the fundamental difference between an IR microphone compare to the RF ones?
    IR microphone makes use of Infra Red ray as Carrier whereas RF system is using Radio Frequency as Carrier.
    Infra Red transmission technology provides an alternative to the RF transmission we are so used too. Infra Red comes into play when RF meets its limitation in certain applications.
    In a multi-classroom environment when 50-100 rooms need to be fitted with sound reinforcement system with wireless microphone systems, it would be a big challenge to do it economical with non-interference RF channels.
    What are the advantages of an IR microphone?
    1. IR is license free
    2. IR does not penetrate wall and cause interference to the adjacent system.
    3. IR transmitter can move from classroom to classroom as all have the same frequency.
    4. IR is eavesdrop free and nobody can record down the audio from a distance away. It is a more secured than a RF system.
    5. Hygienic. A teacher can carry his/her personal microphone from classroom to classroom.
    Which application is more suitable for IR system?
    As applying reflection of IR rays to transmit audio signals, it could only be used in indoor applications. As IR does not penetrate wall, so it is extremely suitable for use in multi-room school environment or karaoke.
    What is the advantage IR has over the RF system?
    As IR does not penetrate wall, so in fact every classroom could use the same frequency as carrier and this solve the multi-channel interference headache exist in the conventional RF system, which required very accurate and tedious frequency allocation ( thus expensive ) to avoid such problem.
    Further, in the simple IR system configuration, each teacher could keep his / her personal transmitter when going from class to class.
    What care one need to take when using an IR system?
      Please be informed of the limitations of the IR and avoid the followings:
    1. Avoid Outdoor use, since applying IR ray reflection.
    2. Wall and ceiling sensors are recommended and attention should be paid to their installing direction..
    3. Do not face huge glass windows or black walls as IR ray may just pass through it and can not be reflected back to the receiver sensor.
     
    DIY
    Simple DIY trouble shooting
     
    Situation 1GTransmitter is ON, Receiver is ON, but NO RF signal received.
    Possibility AGTransmitter and Receiver are having different frequencies.

    SuggestionGIf this is the case, please change either transmitter or receiver to the correct matching frequency or frequency group. For PLL series, if the frequency group is correct, the channel selected could be wrong on either side. Please verify and select the correct channel.

    Possibility BG The transmitter is faulty

    SuggestionGWhen step 1.1 is verified to be correct, then either transmitter or receiver is faulty. To prove this, please use another functional transmitter ( if any ) of the same model and same frequency to switch on the receiver. If this transmitter of the same frequency could trigger on the receiver, then this prove that the other transmitter is faulty.

    Possibility CGThe receiver is faulty

    SuggestionGWhen steps 1.1 and 1.2 are verified and found no clue, then the receiver might be faulty. To prove this, please use another working receiver of the same model and same frequency to receive the signal from the transmitter. If this receiver could receive signal without any problem, then it proves that the other receiver is faulty.

    Situation 2GA whistling sound is heard when the transmitter is on.
    This is most probably the effect of interference noise.

    When interference does happen, switching on and off the transmitter is usually accompanied by a pop sound. To eliminate this problem, try to make the receiver less sensitive, by turning the squelch control ( SQ ) in clockwise direction until the effect disappear. However, higher squelch settings will decrease the operating range of the system. If this effect still persist despite the maximum position of the squelch control, it means the interference signal is too strong and there is no way to resolve this problem. It is advisable to change the system to another frequency and let this system be used at a different location.

     
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