[MPlayer-dev-eng] Opportunity for list members (w/ attach)

[Jan Knutar]

On Wednesday 22 September 2004 00:09, Jeff Gladnick wrote:
> 1) Power will be supplied from li-ion batteries.
> 
> 2) would it really consume that much more power if the CheckForPeople() 
> subroutine ran once every 30 seconds?

Well, if it involves waking up the system, powering up USB bus for camera,
etc, it might. I'm no expert though. To me, a hobbyist, I can think of a numerous
ways off the top of my head to spend less than 3 bucks per unit for some photocell-
like detection. Not including fancy presentation and installation, of course.

In a gondola you'd also have the problem of intensive background light interfering
from all the pretty scenery :) Can be worked around in clever software of course...
Maybe just coupling the "activation" with a sensor for gondola-at-station and a
gondola-door-opened sensor would work, assuming it has a door, and that the door
wouldn't be needlessly opened, etc.

Of course, whether a ready-made already existing unit complete with camera and all
would be cheaper to develop and debug software for, to work in these conditions,
than interfacing and writing some software for a simple hardware sensor, I can't really
tell.

> 3) The controlled environment is the inside of a gondola, as in a ski 
> resort gondola.  So controlled, yes, power access, no.  Any ideas for 
> howto detect that a person has entered the gondola in the cheapest 
> fashion possible are welcome!

If starting from scratch I would probably myself use hardware sensors for
the door and/or pressure switches for the seats.

Also, why Li-Ion? Would a large lead-acid on top of the gondole not be cheaper,
or is Li-ion cheaper in the long run or what? I don't have any quotes for battery
systems available, but atleast on hunch I would assume bog-standard car betteries
are cheaper.