FIELD: information transmission. SUBSTANCE: alternating rate data transmission is achieved through in-phase (I) and quadrature (Q) communication channels. Input information signal is transmitted through either I or Q communication channel. Initially, information signal is split into first and second sub-signals, which are transmitted to respectively first and second group encoding devices. First device combines first sub-signal with first group code; second device combines second group signal with second group code, which is orthogonal first group code. Then combined signal which is encoded by group codes is modulated by orthogonal functional signal in order to produce first modulated signal. Pseudorandom in-phase signal (PNI) and pseudorandom quadrature signal (PNQ) in given PN codes are used for spreading first modulated signal to send it to receiver through respectively I or Q channel. EFFECT: estimation of input information signal from modulated carrier signal, which is received through either I or Q communication channel. 30 cl, 14 dwg
