Martynov P. V. Russia Saratov State Technical University named after Gagarin Y.A., Saratov State Technical University named after Gagarin Y.A., 77, Politechnicheskaya st., 410054, Saratov, Russia Аспирантpavel_martynov@list.ru Author's articles Increasing of Information Reliability of Digital Systems with QAM/COFDM-Modulation