🚀 go-pugleaf

 I am involved in a project which involves connecting a HP-95LX
palmtop computer to a local area network via an infra red ( IR ) link.

 The link must be able to support at least 9600 baud. In the figure
below IR Communicator1 and 2 are basically an IR transmitter/ receiver
pair each. 

        Typical Room, ( say 20' by 24' )
   ____________________________________________________
  |                       |____| IR Communicator1      |
  |                                                    |
  |                       /                            |
  |                      /                             |
  |                     /  Communication at 9600 baud  |
  |                    /    using IR                   |
  |                   /                                |
  |              _____                                 |
  |          ____|___| IR Communicator2                |
  |         |        |                                 |
  |         |________|                                 |
  |      palm-top HP95LX                               |
  |                                                    |
  |                                                    |
  |____________________________________________________|

 I need suggestions on how to design and build such a system. Any ideas
you have may be useful to me. So please send them to me. My main difficulty
is with the actual analog/optoelectronics portions of the link. Designing
protocols/error correction etc seems to be the simple part.

 I envisage finally ending up with a system which like the TV remote
system does not need much of an alignment between the remote and the
photodetector in the TV. Only that the remote must face in the 
general direction of the TV.  So I was wondering what kind of power should
the IR LEDs have ? Is a power output of 12mW adequate. Would I need several
LEDs to achieve my goals? Would a photodarlington ( with other circuitry )
do for a detector? The response time figures for photodalingtons seem
to range from 40 microseconds (us) to ~100us. Would normal phototransistors
have sufficient gain to be useful? 


Thanks 

Manish Pandey

***************************************
School of Computer Science,
Carnegie Mellon University,
Pittsburgh, PA 15213-3891.
Ph: (412) 268-3054 (w), (412) 421-8403
-- 

Manish Pandey
SCS-CMU 412-268-3054(w) 412-421-8403(h)
pandey@cs.cmu.edu