ISM (IndustrialScientific Medical) Band, is defined by ITU-R (ITU RadiocommunicationSector, International Telecommunication Union Radiocommunication Bureau). This band is mainly open to industrial, scientific, medical, three major institutions to use, belong to the FreeLicense, without authorization, only need to comply with a certain transmit power (generally less than 1W), and do not cause interference to other bands can be. Generally speaking, all countries in the world have reserved some wireless frequency bands for industrial, scientific research, and microwave medical applications.ISM frequency bands in various countries are not uniform. For example, in the United States, there are three frequency bands 902-928 MHz, 2400-2484.5 MHz and 5725-5850 MHz, while in Europe, part of the 900 MHz band is used for GSM communication. In Europe, the 900 MHz band is partially used for GSM communications. 2.4 GHz is the same ISM band in all countries***. Therefore, wireless LAN (IEEE 802.11b/IEEE802.11g), Bluetooth, ZigBee and other wireless networks can work in the 2.4GHz band.
The ISM bands designated by ITU-R are as follows:
Frequency range Center frequency Availability
6.765-6.795 MHz 6.780 MHz
13.553-13.567 MHz 13.560 MHz
26.957-27.283 MHz 27.120 MHz
40.66-40.70 MHz 40.68 MHz
433.05-434.79 MHz 433.92 MHz ITU Only Region 1
902-928 MHz 915 MHz ITU only Region 2
2.400-2.500 GHz 2.450 GHz
5.725-5.875 GHz 5.800 GHz
24-24.25 GHz 24.125 GHz
61-61.5 GHz 61.25 GHz
122-123 GHz 122.5 GHz
In fact, in terms of band management for wireless products, this is a very important area. The regulations in this area are not sound in terms of band management for wireless products. 2.4G is a license-free band in different countries, while the following are other different free bands:
l North America: 315MHZ and 915MHZ, 902~928MHZ
l EU: 433MHZ and 868MHZ, and other bands in Japan and Australia.
At present, the 800M and 900M frequency bands in China have been occupied by the GSM cellular mobile network, and most of the products work in 433MHZ, 315M band is the main frequency band of the early wireless remote control products, so the radio magnetic environment in the band is quite complicated, and wireless data transmission is not very reliable, 433M band is not very reliable, because of the new car remote control products. The 433M band is now becoming more and more complex due to the fact that many new automobile remote controls are gradually using this band. Therefore, these two frequency bands are more often used in the transmission of simple data on the wireless remote control. And for water, electricity, gas and other utilities metering data collection, the national radio administration released two application-free wireless metering frequency band (470-510M), dedicated to the wireless data transmission of civil metering equipment.