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Q Common problems and solutions of wireless microphones

A
In the process of using wireless microphones, we often encounter a variety of problems, in general, about wireless microphones, so in the end, the wireless microphones, do you have any questions?

1. Wireless microphones are not compatible

When using wireless microphones, there is always interference between the systems themselves.

Although each system has its own frequency or interval of a few megahertz, intermodulation distortion (IMD) can still cause interference between microphones.

If there is not enough MHZ space between the intermodulation signal and the operating frequency of the device, it is difficult for the receiver to pick up the signal from the transmitter.

Typical phenomena are cross-talk between systems, frequent signal loss or excessive noise and distortion.

Solution: To avoid intermodulation distortion, select a calculated frequency that is compatible with each other.

This requires extensive knowledge of transmitter and receiver design, which wireless system manufacturers have often calculated.

For example, when only eight wireless microphones are used together, thousands of calculations are performed to ensure compatibility between microphones.

Digital can only be allocated frequency, preset 48 UHF optional channels, effectively avoiding signal interference.

2. Wireless microphones are compatible, but not enough

There are different levels of compatibility between frequencies, and if you know what the system is doing, you can be more aggressive in adopting more systems, but the key is how to balance the compatibility of the whole system.

Most frequency compatible software is designed with the important assumption that all receivers are always on or off (even if some transmitters are occasionally turned off) to ensure that none of the receivers pick up intermodulation signals that might cause noise.

Solution: Balance the maximum number of system devices with high performance, and ensure that the compatibility level between frequencies is appropriate for the intended system.

Keep the transmitter at least 10 feet away from the receiving antenna, and if the transmitter's RF output is adjustable, use the lowest transmitting power to cover the desired distance between the transmitter and receiver.

3. The wireless microphone is also subject to interference from other signal sources transmitted in the same spectrum.

The most common is usually television,

Solution: Indoors, avoid interference on 40-50 miles of TV channels.

When working outdoors, it should be kept within a radius of 50-60 miles.

Since the frequency varies from city to city, the appropriate frequency for a wireless microphone depends on the location.

4. Other wireless audio devices such as ear monitors, intercom systems, and non-wireless devices can also cause interference problems.

Digital devices (CD players, computers, and digital audio processors) tend to emit strong rf noise and may cause interference if they are located close to wireless microphone receivers.

Solution: When choosing a wireless microphone frequency, be aware of other wireless audio devices.

The digital device should be at least a few feet away from the wireless microphone receiver.

5. Receiving antenna

The receiving antenna for wireless microphones is one of the most misunderstood areas.

Errors in antenna selection, layout, and wiring can lead to short range of performance coverage areas and low signal strength, leading to frequent drops.

The performance of modern diversified receivers is far superior to that of individual antenna types, but for system performance and reliability to be optimized, antenna selection and layout must be correct.

Solution: To ensure good diversity performance of the system, the antenna space to ensure at least one half wavelength (about 9 inches 700MHz).

6. Unintentional signal obstruction

The human body, which is composed mainly of large amounts of water, can also interfere with radio frequency energy.

In addition, the effective output of the handheld transmitter can be reduced by more than 50% if the user wraps his hand around the external antenna.

Similarly, if the flexible antenna on the transmitter is curled or folded, the signal will also be affected.

Solution: Keep the transmitter antenna fully extended and unblocked to achieve the maximum range of signal transmission to achieve the best performance state.

The voltage is not enough

Transmitter battery life is the primary concern of wireless microphones, users are always trying to reduce the cost of equipment with cheap batteries.

Rechargeable batteries often seem like the ideal solution, but most rechargeable batteries, even when fully charged, provide a voltage 20 percent lower than that of disposable batteries.

Bardl USES AA battery for electricity consumption: low power indicator function;

8. Non-adjustable launcher

The inherent noise and limited dynamic range of FM transmission make analog wireless audio transmission limited.

To overcome this, most wireless microphone systems typically employ two audio processing methods to improve sound quality.

Pre-weighting devices are added to the transmitter and de-weighting devices are added to the receiver to improve the signal-to-noise ratio.

The compressor and receiver expander in the transmitter can increase the dynamic range to over 100dB.

This makes the volume setting very important.

If the audio level is too low, it will sizzle;

If it is too high, it may cause distortion.

Solution: For optimal sound quality, the input gain of the transmitter should be adjusted so that full modulation occurs at the highest volume without distortion.

9. Receiver output level setting error

With so much discussion of frequency, wavelength, and antenna, it's easy to overlook the most basic requirement of a wireless microphone system: to replace the connection between the signal source and the audio system, the receiver is usually equipped with an output level control, which most wired microphones do not.

This provides a better opportunity for a more accurate match between the receiver's output and input.

Solution: The output level, whether microphone level or line level, should be set to the highest practicable level and not exceed the input limits of the sound system, which may be specified on the input channel of the mixer, or can be determined by listening for sound distortion.

10. Wireless microphone setting;

The most vexing problem with wireless systems is that the waves themselves are constantly changing.

Analog and digital television channels have been changing their airwaves ever since the switch to digital television began.

Solution: It used to be easy to know if the VHF channels in your city were odd or even.

However, when people install and use wireless microphones (as well as in-ear listeners, intercom systems, etc.), they now have to regularly check the status of their local spectrum even when they are working in familiar locations.
Q Frequently asked questions and answers about wireless microphones

A

1.Can I use two microphones of the same frequency at the same time

Cannot be used simultaneously.Wireless transmissions cannot "blend" in the air, and receivers cannot mix two transmissions, even at the same frequency.For example, it is impossible for two FM radio stations to send signals on the same frequency.This can cause confusion and lead to audio distortion.In short, each wireless transmitter should have a separate receiver with its own frequency.

2. What is the difference in frequency of the wireless microphone to avoid interference?

It depends, but at least 4MHz.We can't answer that question explicitly here, because it involves complex calculations.In general, cheaper wireless systems require a wide range of frequencies because of their simple receiver design and limited selection.This limits the number of compatible channels.The system with higher price has better filtering, closer distance between channels and more compatible channels.If we say, "You don't want to do the math yourself," we're right.If you need, please contact the manufacturer or agent, they will help you calculate.Most manufacturers have calculated the compatible frequency of each of Shur's wireless features, so you don't have to do the math yourself.

3. UHF is better than VHF, right?

These two frequency segments for wireless microphones have their own advantages and disadvantages.This is determined by the users of the frequency band, the physical characteristics of the frequency band, and the adjustment limits of the frequency band.

The following are the advantages of UHF over VHF:

1) UHF frequency band is not "crowded" with VHF frequency band.

2) UHF with flexible frequency can be used in a wider range.

3) UHF features can provide more compatible systems.[For example, the Schur LX and SC (VHF) systems offer only 12 compatible channels, while the Schur UHF system offers more than 100 compatible channels.]

4) UHF system has higher power output, wider frequency shift, better dynamic range and better signal-to-noise ratio than VHF system.

VHF is superior to UHF in several aspects:

1) VHF system is cheaper.

2) VHF has a larger emission range at a specified transmitting power.

3) VHF signal propagation, even through nonmetallic substances.VHF has a long wavelength and is not easily absorbed by the human body.

4. Can UHF system be compatible with VHF system?

Yes, it is compatible with UHF even if the maximum number of compatibilities using VHF systems is achieved.However, the current VHF antenna 'VHF separator' or VHF antenna distribution amplifier of the UHF receiver cannot be connected.

5. The receiver and microphone have been turned on, but there is no signal receiving.

There are two possibilities:

1) If the receiver and microphone are at different frequency points, please change any of them to the same correct frequency point. If it is PLL type and the frequency range of both is the same, it may be the wrong frequency point. Please change the channel selection to the same correct frequency point.

If the above two frequency points are the same, one of the microphone or receiver may fail. Another microphone of the same model and frequency point can be tested. If the receiver can be activated, the original microphone is the fault;Or test with another receiver of the same model and frequency point. If activated, the original receiver is faulty.

6. What is the reason why the microphone cannot be activated?

Check for weak battery power or filling errors.

7. What if the signal transmission distance is short and the signal is off?

1) Please check whether the antenna is installed correctly.

2) Please check whether the battery weak signal indicator light is on.

8. What is the reason for the sound box's buzzing noise?

1) The microphone may malfunction and affect the appropriate current supply.

(2) Do not share the same socket with AC and other electrical appliances.

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