🚀 go-pugleaf

In article <83073@sun.uucp> rfm@sun.com (Rich McAllister) writes:
>In article <88Dec26.153341est.10798@ephemeral.ai.toronto.edu>, bradb@ai (Brad Brown) writes:
>>Whether the IR keyboard really worked on the PC-Jr is debatable -- it *was*
>>a cool idea but required a line-of-sight from the keyboard to the computer.
>>This was *not* nice.  If you could put the IR reciever on the NeXT monitor
>>it would be OK, but then you'd still have to worry about paper getting in the 
>>way or the desk covering the LED when you type on your lap.  Give me a nice
>>old wire, just make it long and flexible!
>
>This just means that the IR transmitter was anemic.  A really *bright* IR
>source can bounce off walls, ceilings, etc. to get to the sensor. Think of
>flashing a strobe light in a dark room.  Steve Wozniak's CL9's "Tyron"
>remote control booster is an example.

Heck, you don't really need a booster anyway!  Assuming you're sitting at a
comfortable distance from the monitor, the IR system found in standard TV
remote controls should do quite well.  I've got a remote-controlled TV that
seems to be able to receive signals from the control quite well - in fact,
my last act before bedtime nowadays is to BOUNCE an IR beam off the wall AND
ceiling behind me to switch the TV off!  And this is STANDARD EQUIPMENT!  If
IBM had only taken a look at the systems TV manufacturers use......

>Obviously this makes crosstalk
>between two systems in the same room even worse, but at the cost of a little
>more processing power in the keyboard, one could do a packet-based scheme
>(like Ethernet) to address the keyboard packets and get retransmission after
>a collision.

Sounds feasible, but we may then have to address the problem of response
time.  In a particularly IR-noisy environment (or even with about 3 IR
keyboards sitting next to each other), the delay caused by repeated
retransmissions could become pretty annoying.  Perhaps someone with
experience in designing IR control systems could comment on this?

An alternate solution would be to arrange the receivers appropriately (say,
at right angles).  If you're in a cubicle, there shouldn't be much of a
problem (unless, of course, you accidentally orient your keyboard to fire a
stream of IR pulses that ricochet all over the shop and hit your co-worker's
receiver - but the pulses would probably be too weak or garbled to register
anyway).

>
>--
>Rich McAllister (rfm@sun.com)

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Adrian Ho a.k.a. The Cybermat Rider	  University of California, Berkeley
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