![]() ![]() ![]() RADIO REGULATIONS OF THE PEOPLE’S REPUBLIC OF CHINA It is not an exhaustive list, but more detail can be found by following the links provided in the table. Worldwide Frequency Allocations Below 1 GHzĪ more-detailed description of the various sub-1-GHz standards is given by Table II. If the received power goes below the minimum power needed to demodulate the signal correctly (called the sensitivity point), the link will break down. It shows that, for a fixed transmit power, P t, the received power will decrease with the square of the distance, d, and the square of the frequency, f (or increase with the square of the wavelength, λ). This equation assumes that both antennas have unity gain. The improvement in propagation range for lower-frequency radiators can be shown by a simplified version of the Friis transmission equation, which relates the power available in a receiving antenna, P r, to the power delivered to the transmitting antenna, P t: The 5.8-GHz band has also attracted some attention-in cordless phones or the 802.11a version of WLAN, for example.įor systems that require both wider range and lower power, however, the sub-1-GHz bands remain compelling due to reduced co-existence issues and greater transmission range, as both of these affect power consumption-an important consideration in battery-powered applications. In fact, it has become the frequency band of choice for such standards as Bluetooth, WLAN, and ZigBee. The 2.4-GHz band is widely used by designers who want to build systems that can operate worldwide. Global SRD Frequency AllocationsĪvailable in Europe/U.S./Canada/Australia/NZ Table I lists the frequency bands available globally. In most cases, the choice is limited to those portions of the spectrum that allow license-free operation given that certain specifications and conditions on usage are met. Automotive, including remote keyless entry and remote car-startingĭesigners of SRD wireless systems need to use great care in choosing the radio’s communication frequency.Telecontrol for home- or other building-automation systems.Among their more popular applications are: One cannot list all the applications of SRDs, because they provide many different services. The term short-range device (SRD) is intended to cover radio transmitters that provide either unidirectional or bidirectional communication and have little capability of causing interference to other radio equipment. Wireless Short-Range Devices: Designing a Global License-Free System for Frequencies <1 GHz ![]()
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