INTERLEAVED DIGITAL DATA AND VOICE COMMUNICATIONS SYSTEM AND METHOD

摘要

Digital data is inserted in quiet or "no speech" portions of the PCM encoded voice signal stream when such quiet periods are detected. The digital data is encoded in a two byte pattern in which the scaling bits (VUT) are set high and the sign bit (S) alternates in each eight bit byte. Four bits of each byte are thus reserved for scaling and sign purposes, but the remaining four bits (d7-d4 and d3-d0) are available for data transmission. Setting the three PCM scaling bits high and alternating the sign bit has the effect of indicating to the receiver that voice is not present. Recognition of such a signal by the receiver permits a detector to block the output at a speech terminal and to strip the scale bits from the input two byte patterns and pass the remaining bits as data to a data output.