VESTNIK of Samara University. Aerospace and Mechanical EngineeringVESTNIK of Samara University. Aerospace and Mechanical Engineering2542-04532541-7533Samara National Research University311810.18287/2541-7533-2016-15-3-124-130UnknownGeneration of signals with prescribed spectral characteristicsBaraboshinA. Yu.<p><span lang="EN-US">Head of Research Laboratory</span></p>bay@soniir.ruMinaevaO. A.<p><span lang="EN-US">engineer</span></p>minaeva.oa@soniir.ruFederal State Unitary Enterprise Radio Research and Development Institute091220161531241302912201629122016Copyright © 2016, VESTNIK of Samara University. Aerospace and Mechanical Engineering2016<p>The main causes of undesirable changes in signal frequency-amplitude characteristics at the output of modern generators are stated in the paper. A functional scheme of the waveform generator is presented. The generator is constructed with the use of home-produced hardware components. A simplified scheme of the on-board transmitting device for the small spacecraft Aist-2 is taken as an example. The operation and interaction of units of the scheme, as well as the principle of generation of signals with various types of modulation are described. The device developed is analyzed. The units that make the most undesirable changes in the frequency-amplitude characteristic of the output signal are identified. A method of combatting bandpass flatness of frequency-amplitude characteristics is described. The spectra of the output signal prior to and after frequency correction are presented. The process of origination of parasitic amplitude modulation in a digital computation synthesizer in the case of generating signals with frequencies close to the Nyquist rate is explained. A method of combatting parasitic amplitude modulation caused by the use of a digital attenuator in the digital computation synthesizer is also discussed. It is shown that the application of the methods proposed makes it possible to develop a special waveform generator that can ensure the required spectral characteristics of the signals.</p>Spectral characteristicwaveform generatoramplitude randomizationbandpass flatnessparasitic modulationdigital synthesizerСпектральная характеристикагенератор радиосигналов специальной формырандомизация амплитудынеравномерность АЧХпаразитная модуляцияцифровой вычислительный синтезатор[1. Savitskaya M.P., Botnar L.B. Analogovye elektronnye ustroystva. Module 1: [Analog electronic devices Module 1: Textbook]. Odessa: Odessa National O.S. Popov Academy of Telecommunications Publ., 2008. 108 p.][2. Mikroskhema integral'naya 1508PL8T. Tekhnicheskoe opisanie [Integrated circuit 1508PL8T. Datasheet]. Moscow: Open Joint-Stock Company Research and Development Center «ELVEES» Publ., 2012. 31 p.]