Zweikanalton

Digital on-screen graphic displayed at the beginning of Zweikanalton programmes on ORF 1

Zweikanalton ("two-channel sound") or A2 Stereo,[1] is an analog television sound transmission system used in Germany, Austria, Australia, Switzerland, Netherlands and some other countries that use or used CCIR systems. South Korea utilized a modified version of Zweikanalton for the NTSC analog television standard. It relies on two separate FM carriers.

This offers a relatively high separation between the channels (compared to a subcarrier-based multiplexing system) and can thus be used for bilingual broadcasts as well as stereo. Unlike the competing NICAM standard, Zweikanalton is an analog system.

Zweikanalton can be adapted to any existing analogue television system, and modern PAL or SECAM television receivers generally include a sound detector IC that can decode both Zweikanalton and NICAM.