🚀 go-pugleaf

In article <2407.27B2CBE1@ofa123.fidonet.org> rick@ofa123.fidonet.org 
  (Rick Ellis) writes:
>On <Feb 05 09:12> Robert Wier writes:
>
> RW>  What looks like is happening is that there 
> RW>  is an initial burst of information which is complex, followed
> RW>  by much simpler repeats.  
>
>Many remotes do this, some just repeat the entire code, some don't repeat at 
>all, some repeat 2 or 3 times only, ad nauseum.
>
> RW>  I seem to recall that the initial
> RW>  burst is a manufacturer/device ID so that conflicts between
> RW>  different pieces of equipment can be avoided.  The pulses are
> RW>  sent at about 40khz.
>
>There is no real "standard" so it very much depends on what remote you're 
>looking at.  Just about every encoding scheme you can think of has been used and 
>many more you'd never think of.

This looks like a good time to jump in with a question I thought of this 
morning.  I came up with the (probably not very original) idea of "digitizing"
remote control codes with my computer and playing it back via software 
control.  Then not only could I add timing features to my audio/video 
equipment, but I wouldn't have a pile of remotes to deal with.  (No, I don't
like those universal remotes.)

Now, I have a working knowledge of electronics, and I'd done quite a few 
projects, but I know little about the codes used by remote controls.  (I knew
that they tended to be 40kHz, but that's about it.)  Anyway, what is the 
feasability of sampling these codes using basically a phototransistor 
hooked to some input (say a digital joystick port or parallel port)?  I know
that the digital audio samplers for the Amiga (the computer I'd be doing this
with) on average max out at around 56K/sec at 8 bits-per-sample.  Some 
claim to be much faster, but I've never really looked into them.

Basically, my idea was to make 1-bit samples of the phototransistor's state
at up to, say, 50K/sec (I don't know how fast I could push this yet).  I 
would then play back these samples using an IR LED.  At that speed could I 
expect a positive result?  Also, what is the typical length of the code before
it repeats?  I could search for repeating patterns to shorted sample length.

I guess I should ask for some info on the transmission technique.  Is the
signal just a set of bits that are transmitted one per forty-thousandth of
a second, or is another signal modulated at 40kHz, or what?  In that case,
would it make more sense to sample at 40kHz?  It is possible that I could
use the first pulse to sychro-start (to steal a casio keyboard phrase :-)
the sampling.

Am I just plain insane?

Greg
-- 
-------Greg-Harp-------greg@ccwf.cc.utexas.edu-------s609@cs.utexas.edu-------
"Confutatis maledictus                "When the accursed have been counfounded
 Flammis acribus addictis,          == And given over to the bitter flames,
 Voca me cum benedictis." -- Mozart    Call me with the blessed."