Nowadays, with the continuous advancement of radio communication technology, the quality and functions of wireless microphone products have reached a relatively mature and practical stage. At present, wireless microphones have become one of the indispensable equipment of KTV, but this equipment sometimes disappoints people when people are playing more fun. Many wireless microphones in KTV will have annoying noises when they are used. If the situation occurs on a professional stage performance, the consequences will be even more serious. What is the reason for this phenomenon? Is there something wrong with your wireless microphone?
In fact, the reason for this line is very simple. The reason is that the sound wave signals appearing around interfere with the wireless microphone receiver. So, how should we solve this problem?
1. Choose a wireless microphone in the UHF or VHF band according to your needs
Are wireless microphones in the UHF band really better than those in the VHF band? The answer is relative, depending on the specific requirements of consumers.
At present, the popular VHF band wireless microphones on the market mainly use quartz oscillators to finely and stably fix the transmitting and receiving frequencies at a certain frequency point, which solves the shortcomings of FM band without frequency stabilization function and large frequency drift. The degree of clutter interference is also greatly reduced. Due to the high frequency, the antenna can also be designed to be hidden, so that the microphone has a beautiful appearance, and the use of online karaoke equipment in hypermarkets is also convenient and safe. At present, this kind of circuit is very mature, the parts are popular, and the price is low, so it has become the best-selling model on the market, and it is also the standard design of wireless microphone systems.
Due to the excessive use of wireless microphones in the VHF frequency band, the problems of mutual signal interference and noise interference from various electrical appliances are becoming more and more serious, often causing frequency "traffic jams". In professional audio engineering, it is necessary to use wireless microphone systems at the same time. The number is also increasing. In order to solve this phenomenon, a wireless microphone with UHF frequency band (main frequency around 800 MHz) and a phase lock and frequency synthesis system has become a better choice for professional engineers. Dozens of frequency points are designed in the frequency synthesis system, allowing users to change at will. The cost of this advanced design is relatively high, so the current UHF band wireless microphone market price is relatively high, and there are fewer energy producing manufacturers. Once UHF frequency band products can be as popular as VHF frequency band and flood the market, there will also be the trouble of VHF frequency "traffic jam". Of course, there will be better ways to replace it at that time.
2. Choose a microphone for phase-locked frequency synthesis
The signal interference problem is the larger technical bottleneck of wireless microphones. The more frequencies the sound card uses at the same time, the more serious the interference problem. To avoid interference, in addition to physically selecting frequencies that do not interfere with each other and avoiding external signal interference, the receiver must also have good selectivity, and the transmitted and received radiation harmonics must be filtered out very cleanly.
Generally speaking, the fixed frequency front-end selection can be made very narrow, and the phase-locked frequency synthesis front-end selectivity must be compatible with the entire variable frequency range, and it cannot be made too narrow. Even if the front-end adopts variable band-pass filtering, it is not as good as the fixed-frequency front-end band pass. Filtering. In situations where there is no need to use multiple frequencies, the phase-locked frequency synthesis wireless microphone is used at a fixed frequency, its anti-interference ability is inferior to that of a fixed-frequency wireless microphone. Because of its variable frequency, the overall anti-interference ability is better than that of a fixed frequency. powerful.
When using multiple frequencies at the same time, such as using a fixed wireless microphone, in the case of strong signal interference and intermodulation interference, it is impossible to arbitrarily change the desired frequency, so it must be replaced as a whole. The phase-locked frequency synthesis microphone has pre-stored dozens of frequencies in the transmitter and receiver, allowing users to change at will, providing dealers and users with very convenient functions, and completely solving the above-mentioned defects.
3. Choose a model with sound code lock and mute function
Generally, receivers have a mute control function. The principle is to set up a noise detection circuit in the receiving demodulation output. When the noise is higher than the noise detection threshold, the mute circuit is closed to achieve the mute effect. Some also use the detection field strength signal to achieve this function. Regardless of the method used, occasionally encounter strong signal interference beyond the mute control during standby, and the receiver mute circuit will also be activated by this impact noise to output huge noise.
In order to solve this defect, the so-called "audio code lock mute circuit" is installed in some high-quality products to suppress it. A password discriminator is also installed inside the receiver. Only when the receiver receives a transmission signal containing a fixed superaudio cipher modulated signal, the microphone can activate the output circuit, so as to prevent the huge noise caused by interference during standby and damage valuables. Sound system. In order to protect the audio system, it is necessary to select a model with a sound code lock and mute function.