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From: zabetia@tiger.UUCP
Newsgroups: sci.electronics
Subject: Wireless data link:  How do I modulate?
Message-ID: <177@tiger.Princeton.EDU>
Date: Thu, 12-Mar-87 13:57:11 EST
Article-I.D.: tiger.177
Posted: Thu Mar 12 13:57:11 1987
Date-Received: Sat, 14-Mar-87 09:28:46 EST
Reply-To: zabetia@tiger.UUCP (Mahboud Zabetian)
Organization: Princeton U., EE
Lines: 33
Keywords: high speed, about a mile in  distance


So how would I go about sending the data over the laser, or the LED's?

Should I just pulse them on for a 1 and keep them off for a 0?

Should I constantly send a square wave(on-off-on-off) at about ten times the
frequency of my data and then keep it on for a 1 or off for a 0?  I mean:

data:
	1          ------      ------------		     ------

levels: ?   ------ (no data)			 ------		   --------

	0		 ------            ------      ------ 
	   no bit   bit   bit    two bits   bit   none  bit    bit  no bit

Emitter:
	on - - - - ------      ------------      - - -       ------ - - - -


	
	off - - - -      ------            ------ - - -------      - - - - -


Anybody have better ideas?  How do they do it for fiber optics?

Thank you again for your help.

-- 
Mahboud Zabetian		allegra! --\	zabetia@tiger.princeton.edu
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