Subject:
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Re: IR to FM
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Newsgroups:
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lugnet.robotics
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Date:
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Thu, 31 Aug 2000 22:12:37 GMT
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Original-From:
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Simon Bogaert <SIMON.BOGAERT@ADVALVASstopspammers.BE>
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Viewed:
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1828 times
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<snapped an excellent technical description>
> I have used a small 8051 (single chip) microprocessor to decode these • kinds
> of signals in the past. I converted them into RS-232 so that I could plug
> this into a PC's serial port - which I used to drive a flight simulator
> program that I'd written for a radio controlled model plane!
>
> So it's certainly not impossible that you could do it in software inside
> an RCX with the output of a radio receiver (appropriately
> demodulated/amplified/attenuated/whatever) stuffed into one of the inputs.
> The RCX is quite a bit faster than an 8051 - so this shouldn't be too
> hard.
I wasn't exactly thinking of the RCX doing the smart job of the FM
communication. I imagined more of the RCX just outputting IR signals to an
apparatus that translates them to FM. These radio waves are then picked up
by a second apparatus that translates the FM back to RCX compatible IR
signals, thus enabling the two RCX'es to communicate outside the line of
sight and on a greater distance.
> However, I do think you'd need to use a true machine-code/C approach using
> LegOS or something to do the decoding. The NQC byte-code wouldn't be fast
> enough - and the task scheduler would do bad things to your high precision
> timing.
>
> Getting this to work would actually be rather cool - the radio system
> could easily provide up to 8 analog/switched inputs using only one
> RCX input.
>
> On the other hand, any filtering/protection circuitry that Lego may
> have hung off the RCX inputs might screw things up to the point where
> you can't read the input signal anymore.
Making an RCX the heart of radio comms is indeed a very interesting project.
> Using one of the RCX outputs to drive a radio transmitter ought to
> be possible too. Some RC transmitters have an optional 'buddy box'
> input that lets you slave one transmitter to another so that an
> 'instructor' can take over and fly your model plane if you are
> in danger of crashing it while learning to fly.
>
> The buddy box input is in the same format at the RC output
> signal - except that it's not FM or AM modulated. Again, I'm
> not sure what voltages you'd need - but in principle one
> could connect the output of an RCX to the buddy box input via
> some kind of signal conditioning and some careful timing
> software and have a radio link!
This also is a very interesting project!
> I considered doing this once before (but with a laptop's printer
> port - not an RCX) - so I could teach my computer to fly
> an RC plane...
>
> ...but then sanity prevailed.
>
> :-)
Which wasn't in-sane...
> ** WARNING WARNING WARNING WARNING WARNING WARNING WARNING **
>
> PLEASE DON'T DO THIS UNLESS YOU ARE FULLY AWARE OF
> THE
> EXACT VOLTS, AMPS, OHMS, WATTS, HERTZ,
> BITS AND BYTES OF WHAT YOU ARE DOING!
>
> If you do any of these things and wreck either the RCX, your
> computer or your radio gear, I will not be accepting responsability!
Of course not: doing anything with your RCX that's not in the book of
correct use is at your own risk.
Don't stop constructring...
Simon
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Message has 1 Reply:
 | | Re: IR to FM
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| Hi, Here is a link on ebay for the exact item I was talking about: (URL) Original Message ----- From: "Simon Bogaert" <lego-robotics@crynwr.com> To: <lugnet.robotics@lugnet.com> Sent: Thursday, August 31, 2000 6:12 PM Subject: Re: IR to FM (...) (...) (26 years ago, 2-Sep-00, to lugnet.robotics)
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Message is in Reply To:
| | Re: IR to FM
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| (...) Well, I know a little about the format of Radio control signals of the kind you get in RC planes and cars. There is a signal pattern (which can be either FM or AM depending on the waveband of the radio) that represents a train of pulses that (...) (26 years ago, 29-Aug-00, to lugnet.robotics)
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