TRANSMISSION SYSTEM FOR CODED SPEECH SIGNALS AND/OR VOICEBAND DATA

摘要

A digital coder receives (input 100) either speech or voice-band data. When receiving speech this is coded by a digital speech coder (102) and formatted into frames with parity bits (106). If modulated data are present this is recognised by a detector (107) which routes the signals instead via a demodulator (108). Parity bits are generated from the same frame portions but parity is inverted (110) so that a parity checking unit at a receiver (not shown) can readily recognise the change. Preferably means (111) are provided to insert into data frames codewords identifying the start and end and indicating the type of modulation in use. Additional detectors (107) and demodulators can be added for different types of modulation.