How to Solve the Interference Problem of Wireless Microphone?

- Oct 17, 2018-

1. Select a wireless microphone in the UHF or VHF band as needed

At present, the popular VHF band wireless microphones on the market mainly use quartz oscillators to make the frequency of transmission and reception be fixed and fixed at a certain frequency point, which solves the disadvantage that the FM frequency band has no 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 appearance of the microphone is beautiful, and the use of the network karaoke equipment is convenient and safe. At present, such a circuit is extremely mature, parts are popular, and the price is low, so it has become a popular model on the market and a standard design of a wireless microphone system.

Due to the excessive use of wireless microphones in the VHF band, the problems of mutual interference of signals and interference of various electrical noises are becoming more and more serious, often causing a phenomenon of "catch-over" of frequencies, and in professional audio engineering, it is necessary to simultaneously use a wireless microphone system. The number is also increasing. In order to solve this phenomenon, wireless microphones with UHF frequency band (main frequency around 800 MHz) and phase locking and frequency synthesis system have become the better choice for professional engineers. The frequency synthesis system is designed with dozens of frequency points, which can be changed by the user. This advanced design cost is high, so the current market price of wireless microphones in the UHF band is relatively high, and there are fewer manufacturers of energy products. Once the UHF band products are as popular as the VHF band and flood the market, there will also be problems with VHF frequency "cable cars". Of course, there will be better ways to replace them.

2. Select the microphone with phase locked frequency synthesis

The signal interference problem is a large technical bottleneck of the wireless microphone. The more the frequency of the sound card is used at the same time, the interference problem is serious. To avoid interference, in addition to physically selecting the frequency that does not interfere with each other and avoiding external signal interference, the receiver must have excellent selectivity, and the transmitted and received radiation harmonics should 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 is compatible with the entire variable frequency range, and cannot be made too narrow, even if the front end adopts variable band pass filtering and the fixed frequency front end band pass filtering. When the multi-frequency use is not required, the phase-locked frequency is synthesized into a wireless microphone. When it is used at a fixed frequency, its anti-interference ability is inferior to that of a fixed-frequency wireless microphone. Since its frequency is variable, the overall anti-interference ability is stronger than the fixed frequency.

When using multiple frequencies at the same time, if a fixed wireless microphone is used, in the case of strong signal interference and intermodulation interference, the frequency that is desired to be used cannot be arbitrarily changed, and thus the entire station must be replaced. The phase-locked frequency synthesis microphone, which pre-stores dozens of frequencies in transmission and reception, allows the user to change arbitrarily, providing dealers and users with very convenient functions to completely solve the above defects.

3. Select the model with the tone lock mute function

Generally, the receiver has a mute control function, and the principle is to set up a noise detecting circuit at the receiving demodulation output. When the noise is higher than the noise detecting threshold, the mute circuit is turned off to achieve the mute effect. There are also some that use the detection field strength signal to achieve this function. Regardless of the method used, occasionally encountering strong signal interference beyond the mute control during standby, the receiver mute circuit will also be activated by the impact noise to output a huge noise.

In order to solve this defect, a so-called "sound code lock mute circuit" is added to some high-quality products to suppress it. The principle is to add a fixed super audio plus a password modulation signal to the microphone's transmission signal. A password discriminator is also installed inside the receiver. Only when the receiver receives the transmission signal with a fixed super-audio password modulation signal, the microphone can start the output circuit to prevent the huge noise generated by the interference during standby, which damages the valuables sound system. In order to protect the sound system, you must select the model with the tone lock mute function.



MAONO is an innovative designer and manufacturer of Lavalier, Podcasting, Wireless, Shotgun, Recording microphones and accessories for Smartphone, Camera and PC, etc.