Detector of Free Parts of Radio Frequency Spectrum
This article presents hardware and software, with the help of which it is possible to establish communication sessions on temporarily free parts of the radio frequency spectrum. The efficiency of radio frequency spectrum can be improved by using temporarily free parts of the spectrum. Using temporarily free parts of the spectrum also allows to increase noise immunity, for example, working in FHSS (frequency-hopping spread spectrum) mode, etc. Secondary users’ activity should not disrupt the primary users. For the organization of secondary communication networks it is necessary to implement the detector of free parts of radio frequency spectrum. The decision on a condition of the channel is made by comparison of a threshold and average energy of the channel. Basis for statistically reliable determination of threshold value is the histogram of energy. The histogram represents experimentally measured density of distribution of average energy in the channel for all channels in all range of frequencies. In this article requirements for the detector are presented. There are many variants of the hardware. Methods of analysis are considered. The algorithm of forming a histogram of average energy and the algorithm for determining the threshold value are described in detail.