Subject:
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Re: IR transmission, strange coding ?
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Newsgroups:
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lugnet.robotics.rcx
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Date:
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Tue, 6 Nov 2001 00:42:58 GMT
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Viewed:
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1977 times
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Stef Mientki <s.mientki@ids.kun.nl> wrote:
> According to what Kekoa Proudfoot found
> "A '0' is coded as a 417us pulse of 38kHz IR, a '1' bit is
> 417us of nothing."
> ok, nothing wrong with that.
I forget exactly how I measured this. I think maybe I hooked a scope
directly to the LEDs then sent a constant stream of something to the tower
and looked at the waveform on the scope. I don't remember noticing
anything funny with the start and stop bits, but I don't remember looking
either, so something fishy like you described might be going on.
On the other hand, my assumption has always been that the circuitry in the
tower is pretty simple, that the tower does no interpretation of the data,
and that therefore the start and stop bits are coded just the same as all
other bits.
Thinking about this more, I can't see the tower examining the data to tweak
the encoding of the start and stop bits. There are some things we got to
work that would not have worked if the tower did this. In particular, we
got the tower to transmit at a 2x baud rate just fine. If the tower
adjusts the start and stop bits, I'm pretty sure it would have screwed up
the 2x baud rate.
-Kekoa
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Message has 1 Reply:
 | | Re: IR transmission, strange coding ?
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| hi Kekoa, thanks for your answer, About the strange stop bit, I was wrong (John Barnes also mailed me about that, thanks John) it was indeed the parity bit. About the startbit (which is inverted to the data) I'm (almost) absolutly sure, I measured (...) (23 years ago, 6-Nov-01, to lugnet.robotics.rcx)
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Message is in Reply To:
| | IR transmission, strange coding ?
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| hi all, I'm working on what I call an "InfraRed All module" , which should become IR-tower, IR-sensor, IR-audio-remote, etc. Measuring the IR pulses from the IR-tower I encountered the following effects According to what Kekoa Proudfoot found "A '0' (...) (23 years ago, 4-Nov-01, to lugnet.robotics.rcx)
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