As mentioned before, we shoot IR from the back of a cinema auditorium
towards the screen where it is scattered to cover the entire auditorium.
In a series of tests, we mounted the IR panel at the back of the Fremont
Theater (
https://www.kcet.org/shows/artbound/the-many-lives-of-the-fremont-theater
) and reflected the IR off the screen. We could receive the IR signal at
each of the approximately 850 seats in the house. The distance from the
emitter to the screen is about 125 feet (40 meters). The IR carries 3 RF
carriers (1.8 MHz FSK, 2.3 MHz FM, and 2.8 MHz FM). The IR emitter and
receivers are shown at
http://www.uslinc.com/index.php?option=3Dcom_virtuemart&Itemid=3D72&vmcchk=
=3D1&Itemid=3D72
..

These systems are used to carry closed captioning, hearing impaired audio,
and visually impaired audio (also called "Audio Description" where there
is a voice describing what is happening on the screen). An advantage to IR
is that it covers the auditorium but does not leak into other auditoriums.
Some competing systems use RF instead of IR. There is currently a lawsuit
where complainants say the equipment at a theater was unreliable. In one
situation listed in the complaint, the user finally got a receiver that
worked. But, instead of getting Audio Description for the movie she wanted
to see (The Imitation Game), she got audio description for "Fifty Shades
of Gray."

Harold


--=20
FCC Rules Updated Daily at http://www.hallikainen.com
Not sent from an iPhone.
--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.