Matrix H

Matrix H was developed by BBC engineers in the late 1970s to carry quadraphonic sound via FM radio in a way that would be most compatible with existing mono and stereo receivers.

The experimental broadcasts lasted for one year, after which the BBC assessed the public reaction.

Since very few listeners had suitable decoders, the BBC arranged demonstrations at the Langham Gallery in London.

This was based on tolerance zones designed to include modified versions of both Matrix H and the prototype two-channel encoding of Ambisonics, known as System 45J.

Subsequently, the Nippon-Columbia UMX matrix was brought into the standard, leading in 1977 to the UHJ, now associated with Ambisonics.