Re: Please Recommend Wireless Protocol and How-To/Tutorial

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Right, the point I was after is that even though TCP/IP has plenty of its
own error correction built-in, it assumes the lower level has a 'reasonable'
bit error rate (perhaps 10^4-10^-6) and using it _without_ further encoding
(i.e., with simple CW/AM/FM) over the typical radio link will kill it.

I mention this primarily because I've been told that approach has been tried
and the progenators apparently surprised at the results... ;-)

Re: Please Recommend Wireless Protocol and How-To/Tutorial

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Ok, almost totally off topic, but did you see the EDN article about
10GbaseT, 10GBPS over copper?  What these guys are doing for error
detection/correction must be orders of magnitude over orders of magnitude
beyond what I am capable of.  To bring it slightly back on topic, I doubt
many of those techniques apply to wireless, unless you are looking at
spread spectrum.  Certainly beyond the OP's request, though.


Re: Please Recommend Wireless Protocol and How-To/Tutorial
On 2 Nov 2004 20:17:35 -0800, (

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Hi, I have had some of my students do such things in the past, I
lecture at the University of Ulster (and am a radio amateur)

A fully fledged protocol that is robust has a lot in it

If all you want to do is pass keystrokes, or some application that
just demonstrates the technology then it is not too difficult.

My students just used three remote stations and demonstrated switching
a relay on and off, sending back their status when asked and sending
back temperatures when asked, all very low volume stuff.

The students spent their time getting the modules going, aerial (i.e
antenna (sic) ) working and handling a crude master slave protocol.

The only "gotcha" ( unexpected feature 8-) ) was that if receivers and
transmittes are close to each other then switching the transmitter on
saturates the receiver and the particular modules we used it took over
half a second before the receiver could receive anything after the
transmitter was switched off.

(the standard fix for this would be to design a little pin diode
switch that shorts out the receiver input so it doesn't see a massive
signal from the transmitter. Or to use distance to separate tx and rx
aerials, there are other fixes...)

The expedient solution was to add a one second delay!

We just used RS232 and the RTS control line to enable the transmitter
(AFAIR). Each transmission was a single line of simple text readable
ASCII, with a end of line sequence of <]><CKSM>CKSM><CR> and a start
of line sequence of <n><[> where n is 1,2,3 or the letter 'M' for
slaves 1,2 or 3 or the master. I used the bracket symbols so that if
you clip a second PC onto the system you can use hyperterminal to
monitor traffic, ( also I implemented the first version of this
protocol on 8-bit apple microcomputers ][ )

Hope that helps, I may have a machine readbale version of the
student's report, but the info above should get you started. I would
only email the report to your prof in any case,

Don't forget to tell the group how you get on!

Regards and good luck
Ian McCrum, MI5AFL, lecturer in Digital systems
Unversity of Ulster.

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