Review my post #2 above and then click on the link to a number of pdf files related to the Rosen DVD system.

The material is probably the best you will find these days. There are also pdf's on the Land Rover Blue Tooth analogue and fibre optic 2121 related systems.

For whatever reason, the system does not seem to allow me to repost the link referenced in post #2 above, however the already provided link still works.