Noise Characteristics Of Signal Generators Of Radio Transmitters For Wireless Ad-Hoc Communication Networks
This article is devoted to the study of noise characteristics of signal generators of radio transmitters of unmanned aerial vehicles of wireless ad-hoc communication networks. It is noted that the quality of transmitted payload data depends largely on the ability to adapt the speed of their transmission, determined by solutions at the physical level of the OSI network model. Based on the results of the analysis of carrier frequencies and digital modulation methods used for data transmission using unmanned aerial vehicles, a universal approach to signal formation is proposed, combining the advantages of the indirect modulation method with the frequency conversion up using a superheterodyne and the direct digital synthesis method; a generalized block diagram is developed that implements it. It is shown that one of the most important parameters of any signal generation system is the phase noise, for which mathematical models of noise characteristics are obtained. Based on the results of modeling the noise properties of the device, it was found that this scheme is characterized by a level of phase noise in minus 100 - minus 115 dBc/Hz at the offset of 1 kHz from the carrier oscillation for the generated signals in the frequency range of 1200-5800 MHz, which confirms the effectiveness of its use. Ways for further improvement the spectral characteristics of the signal transmitters of unmanned aerial vehicles are proposed. They include optimizing the circuit implementation for lowering the phase noise level, as well as automatic compensation of phase distortions that reduce the level of parasitic discrete spectral components in the output spectrum of the device by 10-15 dB.