The wireless microphone is composed of a number of pocket transmitters and a centralized receiver. Each pocket transmitter has a different working frequency. The centralized receiver can receive voices of different working frequencies from each pocket transmitter at the same time. signal. It is suitable for occasions such as stage podium.
According to the different frequency of use, wireless microphones are generally divided into 3 types, namely FM section, VHF section and UHF section; below we will analyze in detail the advantages and disadvantages of the three types of wireless microphones and suitable places for use.
Frequency band: F M
Everyone knows FM radio, the frequency of FM radio is 88-108MHz. The frequency of wireless microphones in the FM band is higher than 108MHz. Generally between 110-120MHz, so the FM radio signal will not cause interference to the FM band wireless microphone, but it will be interfered by other clutter.
Advantages: simple circuit structure and low cost, which is conducive to the production of manufacturers.
Disadvantages: poor sound quality, frequency will change with time/environmental temperature, poor reception, disconnection, and large interference will often occur. Screaming into the microphone will cause stuttering.
Use occasions: Very low requirements for use, not much requirement for sound quality. An FM wireless microphone can be used in this case where only sound is required.
Channel: V H F
The VHF section is usually referred to as the V section, and the frequency is between 180-280MHz. Due to the high frequency, there is generally little interference. The frequency lock of crystal is adopted, and there will be no frequency conversion, and the receiving performance is relatively stable. V-band wireless microphones generally have two circuits.
The first circuit: only one 2003 integrated IC is used in the high-frequency part. Including: signal reception, radio frequency amplification, frequency mixing, frequency discrimination and so on in one step. Sensitivity is not high, the audio part uses 31101 line. The audio is compressed and expanded, the sound quality is greatly improved compared to FM, and the reception performance is improved by a notch.
Advantages: stable reception. Interruption is rarely seen in short distances.
Disadvantages: the high frequency part is not stable, the audio frequency response is not wide enough, and the effect of professional use is not ideal.
Use occasions: In general households, where relatively stable performance and decent sound quality are required. This type of wireless microphone can be used.
The second circuit: the high-frequency part adopts discrete processing, high-frequency amplification, and intermediate-frequency amplification. Frequency mixing and frequency discrimination. Step-by-step processing, better effect, higher sensitivity, and more stable performance. The audio processing part adopts 571 circuit, which has better sound quality and wider audio frequency response.
Advantages: stable performance and good sound quality.
Use occasions: KTV hall, home, small and medium-sized concerts, ideal effect.
Frequency band: U H F
UHF section is usually called U section, and the frequency is generally 700-900MHz. There is basically no other external frequency that can interfere with such a high frequency. Most U section uses SMD components. The performance is very stable, there are generally three circuits in the U section. The audio principle circuit adopts the latest 571 circuit, and the sound quality is better.
The first type: single frequency.
Similar to the V band frequency circuit, high frequency amplification, intermediate frequency amplification. Frequency mixing and frequency discrimination. Step-by-step processing, high-amplification is divided into several episodes for amplification, audio processing adopts 571 circuit design, and the sound quality is clear.
Use occasions: When it is not satisfied with the V segment, the requirements for use are not very high. Or if there is interference in the environment where the V-segment machine is used, this type of machine can be used.
The second type: adjustable frequency type.
This type of machine is controlled by a microcomputer program. The high-frequency oscillation is controlled by a phase-locked loop (PLL). Generally, there are multiple channels adjustable, and thousands of adjustable frequency points are available for selection. Effectively avoid interference, multiple machines can be used at the same place at the same time without interfering with each other. If there is interference, adjust the frequency point to other frequency points to avoid interference, squelch control. The audio processing adopts a brand-new design with stable performance.
Use occasions: This type of machine is used in many high-end KTV rooms. Small and medium-sized concerts. Or require multiple colleagues to use when singing, the effect is ideal.
The third type: Diversity.
The so-called diversity is diversity reception, one is single-frequency diversity. One is tunable frequency trial diversity. This type of machine has the functions of a U-segment machine, and each channel uses a two-way receiving circuit system. For example, there is a dead point in the receiving system of one channel, and the signal can be received in another channel, which effectively avoids the signal dead zone, greatly improves the technical level of the whole machine, and ensures the stability of the received signal and continuous reception. This type of machine is more advanced wireless microphone. The farthest use distance can reach more than 200 meters.
Use occasions: various large and medium-sized concerts. The use environment is very demanding and the use environment is more complicated. This type of machine is the best choice.