Transmission distance of wireless audio and video equipment with different transmission power in different environments-EEWORLD

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　　At present, the working frequencies of the commonly used wireless audio and video transmission systems are: 0.9G 1.2G 1.3G 2.4G, etc. Among them, the working frequency of the 0.9G system is close to the frequency of the GSM (big brother) system, so it is best not to use it in cities. The 1.2G system is the most popular, and its ability to penetrate obstacles and diffraction performance are better than the 2.4G system, so it is often used in medium-power transmission systems. 2.4G~2.4835GHz belongs to the S band, which is also called ISM (industry science medical), which is an industrial free radiation band and is not restricted by the Radio Commission, and will not cause harm to human health. This working frequency band has less interference and better image quality transmission effect. It is now more and more popular, but the disadvantage is that the transmission distance is short.

　　Technical features of wireless audio and video transmission system:

　　Wireless audio and video systems use high-frequency electromagnetic wave signals as carriers to transmit audio and video signals, so the transmission effect is limited by the transmission characteristics of electromagnetic waves. Taking 1.2GHZ microwaves as an example, its wavelength is very short, so the diffraction performance is very poor and it is not easy to penetrate obstacles. Therefore, the best transmission environment is: there is no obstruction between the transmitter and the receiver, which is the so-called line-of-sight transmission. The transmission effect of wireless audio and video equipment is also related to several other factors:

　　1. Effective height of transmitter and receiver.

　　Radio transmission theory tells us that the higher the height of the transmitter and receiver, the longer the transmission distance. When conditions permit, the transmitter and receiver should be placed as high as possible, so TV stations and radio stations are built very high.

　　2. The electromagnetic interference intensity of the operating environment.

　　When using wireless audio and video equipment in industrial places with severe electromagnetic radiation, if the transmission frequency of the interference source is close to 1.2G frequency, it will cause serious interference to the equipment. Wireless audio and video equipment modulates the signal in a frequency modulation manner. The demodulator at the receiving end must have a sufficient signal-to-noise ratio to detect useful signals. When the useful signal is submerged in the environmental noise, wireless audio and video transmission cannot be achieved.

　　3. Wireless audio and video equipment requires a good power supply

　　Power supply is the basic guarantee for the normal operation of any circuit. Wireless audio and video equipment also has strict requirements on power supply. First of all, the power supply must meet the working voltage of the equipment. Generally, the voltage is required to be stabilized at 12 volts. Too high or too low will cause the equipment to not work properly. In addition, the ripple coefficient of the power supply must be small enough. When using batteries as power supply, it is necessary to consider that the battery voltage will reduce the transmission power after it drops.

　　Transmission distance of wireless audio and video equipment with different transmission power in different environments

power	A	B	C	D
50mw	100 metres	30 meters	20 meters	50 meters
100mw	200 meters	50 meters	40 meters	100 metres
200mw	400m	70 meters	60 meters	200 meters
700mw	800m	120m	100 metres	400m
1000mw	1000m	200 meters	150m	500m
1. “A” in the table indicates open space with no obstructions. 2. "B" in the table indicates that the interior building material is brick structure. 3. "C" in the table indicates that the indoor building materials are cement grouting structure. 4. "D" in the table indicates that there is a high-rise building blocking the view. The data in the table may have errors depending on whether the rooms are on the same floor and the size of the building.

Reference address：Transmission distance of wireless audio and video equipment with different transmission power in different environments

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