FIELD: digital communication systems. SUBSTANCE: during complex filtration, preferably, by Gilbert filters, method involves converting source digital voice signal to complex signal which sampling frequency is decreased. Passing band of corresponding complex filter corresponds to sampling frequency. Resulted complex signal is subjected to phase modulation by means of key signal which is generated by random signal generator. Then it together with pilot signal which has also been phase keyed, is combined by means of addition to encrypted information signal for transmission which is sent together with preamble which serves for synchronization and correction of information signal at receiving side. During receiving method involves new conversion of signal after complex filtration and subsequent down shift of sampling frequency during preamble detection. Thus signal provides clock synchronization of pilot signal which is generated by receiving system and keyed by phase. This signal also provides data for calculation of correction factor for correcting unit. Then decoding stage is initialized. Encrypted information signal after transmission is separated from phase-keyed pilot signal which has been superimposed on it by transmission system by means of addition to synchronized pilot signal which is generated by receiving system. Then resulted phase-keyed encrypted digital signal is decoded by means of detection of key signal which is generated by receiving system. Its clock frequency is controlled by preamble. EFFECT: increased reliability against surveillance, increased quality of voice, good speaker recognition, keeping strict bandwidth range provided by analog radio communication and telephone network. 23 cl, 14 dwg
