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.