300 lines
7.1 KiB
HTML
300 lines
7.1 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>Beyond IrDA</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Linux Infrared HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Advanced Topics"
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HREF="infrared-howto-c-advanced-topics.html"><LINK
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REL="PREVIOUS"
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TITLE="Power Saving"
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HREF="infrared-howto-s-power-saving.html"><LINK
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REL="NEXT"
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TITLE="IrDA Network Neighborhood"
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HREF="infrared-howto-s-network-neighborhood.html"></HEAD
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><BODY
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CLASS="sect1"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Linux Infrared HOWTO</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="infrared-howto-s-power-saving.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 5. Advanced Topics</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="infrared-howto-s-network-neighborhood.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="sect1"
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><H1
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CLASS="sect1"
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><A
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NAME="infrared-howto-s-beyond-irda"
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></A
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>5.6. Beyond IrDA</H1
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="AEN1459"
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></A
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>5.6.1. Extending Transmission Distance</H2
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><P
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> According to the IrDA specification the range is up to 1 meter. From
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the "IrDA Data Link Design Guide" p. 20 by
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<A
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HREF="http://www.hp.com/go/ir"
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TARGET="_top"
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>Hewlett-Packard</A
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>
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: " In some cases it may be desired to
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increase link distance beyond the 1 meter guaranteed by IrDA. The two
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ways to do this are to increase transmitted light intensity, or to
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increase receiver sensitivity. In order to extend the link distance,
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both sensitivity and intensity must be increased for both ends of the
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IR link. If it is desired to communicate with a standard IrDA device
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that may have minimum transmitter intensity, the receiver intensity
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must be increased. The standard IrDA device may also have minimum
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receiver sensitivity, so transmitter intensity must also be
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increased."
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</P
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><P
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> Andreas Butz wrote: "This might be a silly question, but has anyone an
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idea whether the whole IrDA stack really relies on a two-way
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connection, or whether there are some parts of it that could be abused
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for a one-way connection, ideally for unreliable data? We're trying to
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modify some IR dongles to broadcast information to palm pilots over
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several meters distance (cover a whole room), and since we don't want
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to modify the pilots themselves, and increasing the sensitivity on the
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receiver side seems unlikely to work, we're stuck with a one way
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link.". Please see the mailing list archive for details of the
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discussion.
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</P
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><P
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> Sent by Marc Bury " .. just heard about some
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Philips new scheme for remote controls: they call it IRDA - Control.
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This is supposed to be bi-directional, 75 kbps data rate, multiple
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simultaneous devices (up to 8) and with a minimum 6 meter range!" More
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information at
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<A
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HREF="http://www.irda.org/"
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TARGET="_top"
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>IrDA.org</A
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> .
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</P
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><P
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> The German magazine ELEKTOR issued a guide to build a Long Distance
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IrDA Dongle (20m, RS232, IrDA 1.0),
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<A
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HREF="http://www.elektor.de"
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TARGET="_top"
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>ELEKTOR</A
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>
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5/97 p.
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</P
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><P
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> <SPAN
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CLASS="QUOTE"
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>"The main problem is that you generally have to
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make the receiver more sensitive. Basic physics has the inverse square
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law: the intensity drops with the SQUARE of the distance, so going
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from 1 to 5 meters requires 25x the power (and battery drain on a
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portable device), or 25x the sensitivity (and dynamic range - it still
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has to be able to work at 3 inches). And if you want to do it on the
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other end, it doesn't simply have to be 25x more sensitive, it must
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pick up the tiny IrDA pulse needle in a haystack of florescent lights,
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screen savers, moving shadows ..."</SPAN
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>
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</P
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><P
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> Also laser diodes (pulsable) were recommended by K-H. Eischer: But they
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are more expensive. And the laser diodes are also dangerous if they
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have more than 1 mW. A better solution would be to use lenses to focus
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the beam. There is a minimum of absorbtion in the air (I don't know
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the right frequency) and you should use IR diodes with this frequency.
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</P
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><P
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> James wrote: " Who ever it was wanting to do long distance with IrDA,
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we've tried this before. The best approaches are:
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</P
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><P
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>
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<P
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></P
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><UL
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><LI
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><P
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> wavelan - buy the cards but not the antennas you can make your own
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with equaly good gain as the $9000 type they sell here.
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</P
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></LI
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><LI
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><P
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> microwave - you can pick up X-band doppler radar modules, tune
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them slightly apart and use the your local TX as the LO for the
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incomming RX, the whole thing behaves like ethernet and you can
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hook it onto an AUI port, this may now be illegal.
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</P
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></LI
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><LI
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><P
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> ir - Many people sell kits which transmit video over Ir, they come
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complete with the large fresnel lense you need, they manage about
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4MHz b/w over 100m.
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</P
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></LI
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><LI
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><P
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> laser diodes - when we looked at these they were a pain, I think
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elantec make decent drivers but modulating them was a big pain,
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Steve Carcia had a series on articles on modulating He-Ne lasers
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but be careful they have lots of volts in them that want to get
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out and kill you.
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</P
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></LI
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></UL
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>
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</P
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><P
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> Whatever you choose IrDA might very well be a good choice for a
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protocol, given it's one of the few that sensibly copes with simplex."
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</P
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><P
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> Here are some links to
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<A
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HREF="http://repair4laptop.org/notebook_irda_selfmade.html"
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TARGET="_top"
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>do-it-yourself InfraRed (IrDA) devices</A
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>
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to use with your laptop, notebook, PDA or mobile phone.
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</P
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></DIV
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><DIV
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CLASS="sect2"
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><H2
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CLASS="sect2"
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><A
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NAME="AEN1485"
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></A
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>5.6.2. Upcoming Standards (Bluetooth and IrDA)</H2
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><P
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> "More and more people now think that IrDA and Bluetooth will live
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happily side by side, and the idea of Bluetooth as the IrDA killer
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just don't work anymore. IrDA is still unbeatable in price/performance
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and with the new additions to the standards family like AIR and VFIR,
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it's really good to see that IrDA is moving in the right direction."
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</P
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></DIV
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLPADDING="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
|
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><A
|
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HREF="infrared-howto-s-power-saving.html"
|
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ACCESSKEY="P"
|
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>Prev</A
|
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></TD
|
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
|
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><A
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HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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></TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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><A
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HREF="infrared-howto-s-network-neighborhood.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
|
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><TR
|
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><TD
|
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WIDTH="33%"
|
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ALIGN="left"
|
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VALIGN="top"
|
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>Power Saving</TD
|
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><TD
|
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WIDTH="34%"
|
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ALIGN="center"
|
|
VALIGN="top"
|
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><A
|
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HREF="infrared-howto-c-advanced-topics.html"
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ACCESSKEY="U"
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>Up</A
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></TD
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><TD
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WIDTH="33%"
|
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ALIGN="right"
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VALIGN="top"
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>IrDA Network Neighborhood</TD
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></TR
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></TABLE
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></DIV
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></BODY
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></HTML
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> |