COMPATIBLE TRANSMISSION OF ADDITIONAL INF ORMATION IN CONVENTIONAL TVSYSTEMS

A novel modulation scheme MQAM for transmitting an additional data sig nal compatible with conventional television standards (PAL, NTSC, SECA M) is proposed.. MOAM can be described as a synthesis of PM and QAM an d is optimized due to minimum degradation of the TV signal in conventi onal receivers with both synchronous and envelope detection. Computer simulations show that a bit rate of 500 kbit/s and an error 10(-6) can be achieved without annoying interference. First experimental results are in good accordance with the theoretical results about the impairm ent on standards receivers.