Looking at the latest HUD systems, the symbol generator is a briefcase
sized unit mounted on the cockpit ceiling. can anyone explain how they
work and the reason for the size. What is the impediment/technology
breakthrough required to make them much smaller where they could be
fitted to any aircraft regardless of size. General Motors have a unit
for their cars that's about the size of an orange.
Aviation technology often lags the state of the art by a considerable
margin, because the design process and lifetimes can run to decades.
This is also dictated by the approvals process, which tends to favour
well proven technologies with good track record.
Modern HUD systems probably use a raster scanned display, much like a
computer crt monitor and there's nothing particularly special about
the electronics side of the technology. Small projection quality crt,
symbols in non volatile storage, medium performance embedded processor
and graphics hardware, comms interface and power supply. You could
think of it as a rather special dedicated function pc, but built to a
far higher standard using proven technologies run well within their
ratings.
Small briefcase sized box sounds about right. A couple of decades ago,
it would mnost likely have been several medium sized boxes, with a
separate box just for the symbol generator...