A method of transmitting and decoding biphase coded signals individually representing separate data services and inserted in the line blanking interval of a video signal greatly increases the probability of avoiding the effects of anticoincidence errors. A unique start code is allocated to each of the data services prior to transmitting the video signal. The video signal is separated into the separate data services without field or line windowing. Every pair of biphase elements occurring after the start code is checked for anticoincidence errors, and all wanted bits are stored in a buffer memory. The wanted bits are transferred from the buffer memory to an output memory only when no anticoincidence error has occurred between the start code and the last wanted bit.