A microphone, whose scientific name is a microphone, is an energy conversion device that converts sound signals into electrical signals. It is translated from Microphone. Also called microphone and microphone. In the 20th century, microphones developed from acoustic-electric conversion through resistance to inductive and capacitive conversion. A large number of new microphone technologies were gradually developed, including microphones such as aluminum ribbon and moving coil, as well as the widely used condenser microphones and electrets. microphone.
Microphones are classified according to the principle of acoustic-electric conversion: electric type (moving coil type, aluminum ribbon type), condenser microphone type (DC polarization type), piezoelectric type (crystal type, ceramic type), electromagnetic type, carbon particle type , Semiconductor type, etc.
According to the force of the sound field, it is divided into: pressure type, pressure difference type, combined type, linear type and so on.
According to the transmission method of electric signal, it is divided into wired and wireless.
Divided by purpose: measuring microphone, vocal microphone, instrument microphone, recording microphone, etc.
According to the directivity, it is divided into: cardioid, sharp heart, super cardioid, two-way (8-shaped), non-directional (omnidirectional).
Electret microphones are small in size and low in cost, and are widely used in telephones, mobile phones and other equipment.
Silicon micro microphones are based on CMOSMEMS technology and are smaller in size. Its consistency will be more than 4 times better than that of electret condenser microphones, so MEMS microphones are particularly suitable for cost-effective microphone array applications, where a better-matched microphone will improve sound wave formation and reduce noise. Laser microphones are used in eavesdropping.
The wireless microphone is composed of several pocket transmitters (which can be put in a pocket, the output power is about 0.01W) and a centralized receiver. Each pocket transmitter has a different working frequency. The centralized receiver can Simultaneously receive voice signals of different operating frequencies from various pocket transmitters. It is suitable for occasions such as stage podium.
The types of wireless microphones can be divided into many different types according to different definitions. Divided by rate, it can be divided into the following 3 types:
a. FM wireless microphone: commonly known as FM refers to the FM 88-108MHz international FM radio frequency band. Early consumer wireless microphones used FM radios to receive. The system was simple and low in cost. However, due to the effects of use, it could not meet the requirements of professional quality. In the 21st century, it can only become a toy for children or students.
b. VHF wireless microphone: It is divided into two types, low frequency and high frequency. The former uses the VHF50MHz frequency band. Because of the low frequency, the antenna length is too long, and it is easy to be interfered by various electrical clutter, so this type of product , Has been replaced by high frequency bands in the 21st century and gradually disappeared from the market. The latter uses the VHF200MHz frequency band. Because of the higher frequency, the antenna is shorter, and it can even be designed as a hidden antenna, which is convenient and beautiful. The clutter interference of the receiver is greatly reduced. The circuit design is extremely mature and the parts are popular and cheap. So it has become a popular model in the market today.
c. UHF wireless microphone: use a wireless microphone with a frequency of 300-3000M. It is the mainstream of microphone applications in the 21st century. Because the interference of V-segment walkie-talkies is avoided, the stability is greatly improved.