Brève analyse du développement sans fil de l'industrie des systèmes de conférence
Wireless development is the important trend of the conference system industry. With the development of the wireless communication technology development, all main manufacture have concentrated on developing wireless conference products.
Wireless technology can be divided into two types, one is radio frequency transmission and IR transmission. The principle of the radio frequency transmission is that by the induction between electric field and magnetic field, the signal spreads outside quickly and the signal is loaded in the electromagnetic field. However, the principle of IR transmission has essential difference with radio frequency transmission. It relies on the on-or-off of the infrared ray or the change of the intensity to transmit the information. ( the transmit terminal emits the infrared ray in different intensity in according with the information features, the receiving terminal receives the infrared ray and transform it to level signal that carrying the information by the photodiode)
The main application frequency band of wireless radio frequency transmission has VHF, UHF, 5G and etc. VHF is mostly applied in the broadcasting station/ radio and television, aeronautical and marine communication and other long-distance communication, this frequency band is applied in the conference industry rarely. What UHF is applied mostly can be divided into 400MHz-900MHz and 2.4G. The 400MHz-900MHz is usually appled in the radio and television, interphone and ect. 2.4G is appled in the wireless internet. 5GHz frequency band is also applied in the wireless internet. With the limitation of the switch rate of the IR receiving tube , the IR modulation frequency could not be too high, mostly it is within 10MHz. In the application in the conference system, the regular IR frequency band is from 2MHz to 8MHz.
The illustration of main features of all kinds of wireless technology:
One, U frequency band (400MHz-900MHz), its advantage is as follow. It is high diffractive and the signal can cover more easier. Its transmission could not be weaken relatively, low power can enable the long-distance transmission. Because of the data transmission rate is relatively low, it can not meet the demand of digital system that is large amount of data. It is suited to the FM modification technology product that is small-size audio transmission and has small amount of data. Such as wireless voting system, U frequency band wireless microphone. If that frequency band is applied in the conference system, it would be easily interfered and adopted the FM analog modulation. As a result, it can cause crosstalk, noise and other problem.
Two, G frequency band( 2.4G/5G), it has the following advantages such as high data transmission rate, high capacity of signal band, few interference source of 5G. It is suited to the AV product communication that has large amount data, such as wireless discussion system, simultaneous interpretation system, paperless conference, multimedia transmission. G frequency band is the main subject that the current wireless communication technology industry focuses on. It has huge technical expandable space and strong compatibility. Because this frequency band is widely applied in the wireless internet, the main problem of its application in the conference system is how to make sure G frequency band co-exists with WIFI system without any interference.
Three, IR transmission has few interference source and few possibility for the outside malicious source to disturb. However, the disadvantage of it is also apparent, its diffractive ability is weaker. During the transmission, the signal is getting weaker and is easily interfered by the environmental factor and light, which causes the small coverage of the signal. When the IR transmission technology is applied in the conference system, it need to modulated to produced stronger signal emission power in order to overcome the signal weakness during the transmission and provide more reflect energy. As a consequence, it is suited to the one-way communication such as simultaneous interpretation language distribute system. In the application in the conference system, the technical problem is how to set the power and the construct the system.
GONSIN wireless conference system: Since the establishment in 2003, GONSIN has deeply developed the wireless products. In 2003, it launched the wireless digital voting system that was the first one in the world with frequency detection and frequency offset compensation. In 2006, the unique DSSS wireless technology was innovated by GONSIN. By the wireless digital simultaneous interpretation system equipped utilizing DSSS technology, GONSIN won the honor of 2006-2007 National Torch Project. In 2006, it developed 6 channels IR simultaneous interpretation system. With the WIFI technology, GONSON R&D team applied it into conference system and launched GONSIN 1000 Congress Sever. In 2015, GONSIN makes a progressive strike. With wireless technology accumulation, it developed 2.4 G FS-FHSS technology ( frequency selecting, frequency hopping spread spectrum) wireless conference system, launched the paperless application Congress Server GONSIN30000 based on WIFI technology.
The feature of FS-FHSS selecting-and-hopping technology: it uses the 2.4 GHz global frequency band, it do no require certificate. The wireless frequency points are abundant, 80 frequency points could be used; 2.4 GHz has high frequency carrier, the signal diffractivity is relatively weak so that other 2.4 GHz signal could not interfere the conference signal. Adopt FS-FHSS technology, it detect the wireless environment and select the useable frequency point before the conference, during the conference, it hops between the backup frequency points, which can avoid the interference source. It utilizes the efficient digital audio encode and decode technology, one frequency point can transmit 4 channels, it just need two frequency points to transmit 8 channels simultaneous interpretation signals. Because the system occupies relatively less frequency points resource and utilizes the FS-FHSS technology to operate, it can co-work with WIFI and other 2.4GHz system. It applies the digital audio encryption and digital modulation to avoid any interception and malicious interference; the signal transmitting power could be modified in according with the application occasion, the adjusting range is from 50 meters to 500 meters( the customized system can cover 2,000 meters).
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