In addition what dnmilikan said about IR, I have to say thtat IR isn't convergent which makes it useless when the distance between TX and RX units is large.
On the other hand there is one problem with a battery powered stand alone TX unit. We are using visible 650nm class II laser (for obvious reasons like alignement) therefore we decided to switch off the laser whenever the beam is broken.
The user doesn't want to see red spots (caused by the laser transmitter) on his/her photos. In order to do this we decide to power everything from the main controller unit.
Yes, there are going to be lot's of cables, but the good news is that the same cable will be used all over the system.
I understand the reasoning behind turning off the laser. The question that still comes to mind for me is what about "hiding" the cables? This seems to something that I would find problematic as a potential purchaser or user? Other then having white cables for photographing a polar bear on ice and snow, how will the cables be hidden? Then if white is used, this color will be very noticable and needing to be addressed in a woodland scene. What about stringing cables through water for photographing gators in the swamp? Will the cables and componants be water proof and not subject to shorting or open circuits? Have you checked into the actual cost of RC componants? I would think that the cost would not be prohibitively expensive, it would afford much more flexibility to an end user other then yourself. How about the technology that already exists with the Mamiya flash triggers? Please understand, I am not intending to find fault with your considerations. My intentions are to raise questions that will challenge the already existant creative potential that you have and to use that potential to the greatest benefit. Good luck. Sounds like a very exciting time for you.
There already is such a gizmo, called a Dahle beam (not sure of the spelling). The way it works is, the animal moves between the transmitter and receiver, and the camera strobe is triggered.