After a little looking around, I found this term in a Sony glossary,
where the real context should apparently be 'deterministic signal'.
See
http://products.sel.sony.com/semi/glossary.html
A deterministic signal is used in communications systems (by adding it
at the transmitter) to permit the receiver to lock to the original
*information* signal. There are wide varieties of how this is done.
Note that deterministic signal energy is 'wasted' in terms of
communications systems - i.e. the system power efficiency is
transmitted *information* power / total transmitted power.
I am sure many here could elaborate on deterministic signals (I don't
have a huge amount of time right now).
Cheers
PeteS