Re: [iPAQ] IrDA Range?

The spec range of irda is under 1m. I know more about the irda hardware
on palm, but ipaq irda hardware may be similar. At least on the palm,
the on period of the transmit diode was fixed by the hardware, so
changing the bit rate just inserted larger or smaller spaces between the
on pulses. The on pulses were very small, since their period was set by
the pulse length required at the highest irda link speed. So getting the
irda hardware to produce the ~40khz signal needed by remote control
protocol resulted in a very low duty cycle waveform. This signal was
more difficult for the IR remote decoder to differentiate from noise,
and so reception became sporadic if the palm was moved outside of a very
small range. For our product, we ended up building an IR module that
clipped onto the serial port of the palm. There are several other models
with the same approach available for palm, but we had some special needs
(extra range, 2 way channel).

Anyways, to summarize, the two problems with using irda for remote:
1) low power IR transmission. This can be ameliorated by changing
resistors, using an external FET drive with bigger diodes, etc.)

2) non-optimal 40khz waveform. This is harder to fix, especially with
some kinds of irda hardware. I'm not sure what the situation is in the
ipaq.

-Holly Gates
 Hardware Engineer
 E Ink Corp.
 http://www.eink.com

Tom_Kirksey@ingersoll-rand.com wrote:
>
> Does anyone know off hand what the range of the IrDA port on the iPaq is?
> It could make a dandy remote control.
>
> Tom
>
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Received on Thu Aug 24 15:29:18 2000