Instruments and Systems: Monitoring, Control, and Diagnostics Annotation << Back Improving the Noise Immunity of Modem Digital Systems With Amplitude Manipulation YU.M. VESHKURTSEV With the use of new knowledge, the modem of digital systems for different purposes with amplitude manipulation was reconstructed. It is proposed to consider the characteristic function of a guasi – deterministic signal, which is modulated simultaneously with the amplitude in the antiphase by a telegraph message. A demodulator was built for receiving control commands using estimates of the real and imaginary parts of the characteristic function. The noise immunity of a digital system with amplitude manipulation is increased by two orders of magnitude by incorporating a new demodulators operating in the signal – to – noise ratio range of 20 dB. Keywords: amplitude manipulation, characteristic function, demodulator, modem, noise immunity, signal – to – noise ratio. DOI: 10.25791/pribor.07.2019.741 Contacts: E-mail: vym1940@mail.ru Pp. 38-44.