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- From: kranburg@hlunx3.uto.dec.com (Otto van Kranenburg)
- Subject: Re: Infrared remote controls
- Message-ID: <1992Dec15.123639.7460@nntpd.lkg.dec.com>
- Sender: usenet@nntpd.lkg.dec.com (USENET News System)
- Reply-To: kranburg@hlunx3.uto.dec.com (Otto van Kranenburg)
- Organization: Digital Equipment Corporation
- References: <of90_cC00UhB465rsp@andrew.cmu.edu>
- Date: Tue, 15 Dec 1992 12:36:39 GMT
- Lines: 63
-
- The infrared signals being transmitted by IR controls are a series of 1 and 0's
- superimposed over a 40 KHZ carrier. The Radio Shack device (if it is the Sharp
- GP1U52X-module I think it is) filters out the carrier and leaves you with the
- series of 0 and 1's. If you count the pulses and plots them out you will
- see the
- differences in signals between various brands of equipment. Sony
- re-transmits
- the same basic signal a number of times while some other brands do it
- just once.
-
- Somewhere on the net there is a description of a device referred to as
- the Xanadu
- Zapper which when connected to the parallel port on a PC can read in the
- signals and
- play them back. There are no source listings in the article allthough
- some hints are
- given how to program. On output the point is to again add in the 40 KHz
- carrier .
-
- In a German PC magasin of last year there was also an article describing
- a similar
- device with again only some basic programming hints. I 've built a
- device which
- actually combines the schematics for the Zapper and the German
- equivalent and
- wrote several drivers. On input I' m sampling (at 80 Khz) app. 40000
- pulses
- which in all cases was a sufficent number. I then analyse the signal and
- in the end
- it requires me to store only about 500 integers (I've have to remember
- only the 0-1
- and 1-0 status changes). For Sony devices it must either be 6 times more
- of I have to
- remember to repeat the signal 6 times on output. On output I reconstruct
- the original
- signal and do a replay at exactly the same frequency as used on sampling
- (with the
- carrier added in).
-
- Anyway I've succesfully used the device to reproduce the output for 4
- different type
- of remote controls. The disadvantage of the way I've done it is of
- course that I have to
- store all the signals.
-
- Allthough I 've taken another approach I do remember that in the German
- magasin they
- did built an output only device as well and programmed it with pulse
- information obtained
- from Sony.
-
- Hope this is of help,
- Otto
-
-
- -
- *****************************************************************
- ** Name : Otto van Kranenburg Organisation:
- ** Email: kranburg@hlunx3.uto.dec.com Digital Equipment BV
- ** P.O.Box 8810
- ** Tel (Office): 31 10 453 8213 3009 AV Rotterdam
- ** Tel (Home ): 31 78 510 245 The Netherlands
- *****************************************************************
-