Automatic changeover circuit decoding PAL M PAL N and NTSC - uses brightness and vertical sync. signals to detect TV system received

摘要

The equipment comprises a brightness circuit (1) to generate difference voltages dependent on the colour content, a colour difference circuit (2) to generate colour difference signals from a circuit (1), a synchronisation circuit (4) for the processing of vertical synchronisation signals, a frequency detection circuit, 50 or 60 Hz, (5), a control circuit (3) to detect NTSC signals, and a discriminator/switching circuit (6) to differential between PAL-N and PAL-M signals. Offer circuits include demodulators (7,9,11) and oscillators (8,10,12) or NTSC, PAL-M, and PAL-N respectively. USE/ADVANTAGE - TV receiver automatic selection of different systems.