First, wireless simultaneous interpretation system
The wireless simultaneous transmission system currently has three modes of low frequency transmission, infrared transmission and ultra-high frequency transmission.
(1) Low-frequency transmission simultaneous transmission system: Also known as electromagnetic induction type interpretation system, it is a loop line in the listening range, which is fed by a high-power audio amplifier to generate a strong audio electromagnetic field. The listener listens to headphones that are driven by the input core coil and amplifier. This system is simple and inexpensive, but has poor sound quality and stability. Because low-frequency electromagnetic fields can penetrate ordinary buildings and thus have poor confidentiality, they are especially suitable for museums, science museums, and some large convention and exhibition centers that require multiple sub-sites to use the same set of simultaneous transmission systems. Disadvantages become advantages.
(2) Infrared transmission simultaneous transmission system: Infrared (IR) refers to electromagnetic radiation with a wavelength exceeding red visible light, and its frequency is above 2 MHz. Infrared rays do not penetrate the wall, so they are confidential and resistant to radio interference and eavesdropping. Due to its stable performance and better sound quality, it has become the mainstream equipment of the simultaneous transmission system. In recent years, a development trend of infrared simultaneous transmission technology has shifted from the earlier BAND II (45 kHz to 1 MHz) frequency band to the higher BAND IV (2 to 6 MHz) frequency band to avoid energy-saving lamps. Interference caused by high frequency driven light sources. In addition, the BAND IV frequency band has wide frequency response characteristics, high signal-to-noise ratio, and less channel interference, which has better sound quality.
(3) UHF transmission simultaneous transmission system: This mainly refers to the broadband-based G-band digital simultaneous transmission system developed in recent years. Compared with the infrared transmission system, the advantage is that the reception is non-directional, unobstructed, and is not easily interfered by the radiation of the energy-saving lamp, and the requirements for the venue environment are relatively loose.
Second, the wireless conference discussion system
There are several types of wireless conference discussion systems:
(1) Conference and discussion system combining wired and wireless transmission
Early introduction of a conference discussion system: the wired transmission mode between the delegates, the chairman and the main control unit, using only the V-frequency or U-band between the main control unit and the audio system (mixer) Wireless transmission. The advantages are low cost and stable performance. However, due to the limitations of use and poor confidentiality, no promotion has been made.
(2) U-band wireless conference discussion system
Each chairman unit and representative unit is an independent gooseneck wireless microphone with different frequencies, and the receiving units are collectively stacked into one small cabinet. The advantages are mature technology, simple structure and low price. The disadvantage is that there is only a mode of free speech, lack of control functions, and the number of units working at the same time is limited and the confidentiality is poor. It is only for economical small meeting rooms.
(3) G-band wireless conference system
Its core technology is similar to the above-mentioned G-band simultaneous transmission system, but its functions are more perfect. The system operates in the 2.4 GHz G-band and can connect up to 200 units to work simultaneously. Adopt DSSS encryption transmission technology; basically have the same functions as the wired conference system: in addition to the operation modes such as "application for speaking", "sound control" and "priority", it also has voting function and 8 channels. Sound interpretation function. It has been adopted by many government agencies and enterprises in China, and its operation effect is good, but the price is relatively expensive.
(4) Infrared conference system
The infrared conference discussion system consists of a central control unit, a transmitting/receiving unit, and a number of representative speaking units. The representative speaking unit includes a transmitter, a receiver, a microphone, a speaker and a rechargeable battery, and communicates with the transmitting/receiving unit installed at a high place through the infrared channel in a two-way communication distance of not more than 7 m. The transmitting/receiving unit is connected to the central control unit via a coaxial cable. In addition to the discussion function, the infrared conference system also has simultaneous interpretation (2 languages) and voting functions.
The infrared conference system is currently considered to be a more promising new conference system. However, there is still a certain gap compared with the wired conference system: the confidentiality and stability are less; the distance between the speaking unit and the receiving unit cannot exceed 5 to 7 m; and the number of units working at the same time is limited.
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