For data exchange worldwide, so-called unlicensed (ISM - Industrial, Scientific, Medical) radio frequency bands exist. In the Russia, based on the Decision of the State Commission on Radio Frequencies (SCRF) No. 08-24-01-001 dated 28.04.2008 and No. 07-20-03-001 dated 07.05.2007, the frequency ranges 433.075 - 434.750 MHz and 868.7 - 869.2 MHz have been allocated for these purposes. These radiofrequencies may be used without obtaining a special SCRF permit and completely free of charge

For wireless data exchange worldwide, unlicensed (ISM - Industrial, Scientific, Medical) bands are provided. In the RF, based on the Decision of the State Commission on Radio Frequencies (SCRF) No. 08-24-01-001 dated 28.04.2008 and No. 07-20-03-001 dated 07.05.2007, among others, the frequency ranges 433.075 - 434.750 MHz and 868.7 - 869.2 MHz have been allocated for these purposes. These frequencies may be operated without obtaining a special SCRF permit and completely free of charge, provided the requirements regarding bandwidth, radiated power (up to 10 mW in the 434 MHz range and up to 25 mW in the 868 MHz range), and the intended use of the transmitting device are observed.

Legal aspects

Non-specialized (general purpose) devices include short-range devices of general use, including remote control units, telemetry and telecontrol systems, alarm systems, data transmission, and other similar transmissions.

Short-range device – a technical means intended for transmitting and/or receiving radio waves over short distances. Such devices are used on the condition that they do not cause interference to other radio electronic equipment (REE) and do not require protection from interference from other REE.

Main technical characteristics and conditions of use for non-specialized short-range devices

Let us highlight two main points. First – the law does not explicitly restrict the range of communication systems. This means that the use of highly efficient directional antennas and repeaters makes it possible to create radionetworks of considerable length.

Second – in Russia, in the sub-bands 433.075-434.79 MHz and 868.7-869.2 MHz, unlike European standards, there are no limitations on the duty cycle (ratio of reception time to transmission time). This means that theoretically, radiomodems operating in this frequency range can function at a speed 10 times higher than in Europe. In practice, however, it is not always possible to bypass the duty cycle limitation in a radiomodem. Often, the manufacturer rigidly fixes the transceiver operating mode.

Physics of radio wave propagation in 433/868 MHz radio frequencies

It has been experimentally proven that with an increase in radiofrequency, the level of background noise decreases, the antenna radiation efficiency increases, but at the same time the ability of waves to bypass obstacles decreases. The 433 and 868 MHz bands have proven themselves well in dense urban environments. On the one hand, the radio waves in these bands penetrate concrete structures well, on the other hand, they are not as significantly attenuated when passing through brickwork as 2400 MHz (Wi-Fi). For mobile objects, it is preferable to use the frequency band 433 MHz. The band 868 MHz has advantages in range and data exchange speed for stationary networks. The short wavelength of (70 and 35 cm, respectively) allows using compact directional and omnidirectional antennas with high gain.

Application of

The classic fields of application for ISM frequency bands are automation and control systems for household and industrial equipment indoors, monitoring and control of remote parameters and production processes, radio-controlled toys, security alarm systems, and safety systems. All these systems share one feature – a rather limited communication range.

The use of external antennas with high gain, as well as repeaters , opens up new horizons for the use of these radiofrequency resources. For example, the repeater Vector VR-44 MASTER, manufactured by our company, allows organizing a network of portable license-free LPD radio stations with a communication range of up to 15 km.

As for radiomodem communication – the possibilities here are even greater. Some models of radiomodems, such as Spectrum-433 or Conel CDX 800 (868 MHz), can operate as a repeater (relay with time division of reception and transmission). By creating a chain of such radiomodems, one can build fairly large-scale data collection or control networks. In such case, the radio network will not be limited to the territory of the enterprise but may serve facilities located at significant distances.