[net.video] Teletext -- decode in Radio Electonics

adp@hp-sdd.UUCP (Tony Parkhurst) (03/17/86)

     The latest issue of Radio Electronics has a construction article for
a TeleText decoder.  My questions are: 
	Is it worth it?
	Is it worth spending $200 on the kit?
	Are there any consumer products available to do this?
		(I haven't noticed any yet)
	What kinds of info are typically available?
	In this area, there are 3 channels that seem to have info in the
		vertical refresh band, how does one tell if it is teletext,
		closed caption, or other info?
	Can closed caption info be transmitted on the same channel as teletext?
	...and so on.


			Thanx in advance -- Sparky

caf@omen.UUCP (Chuck Forsberg WA7KGX) (03/24/86)

The R-E Teletext decoder does not decode the CBS signals, which are the
only ones I have seen broadcast in the Portland OR area lately.

lauren@vortex.UUCP (Lauren Weinstein) (03/25/86)

The Radio Shack teletext kit is (I believe) for the World Standard
for-the-public teletext magazine such as the ELECTRA magazine on WTBS.
This is not the same as the system used by CBS, nor is it the same as the 
system used for the high speed interleaved/encoded data channels on 
WTBS used for Stargate.  The kit is ONLY useful for receiving the
public teletext magazine, and, being heavily LSI'd, cannot be modified in any
reasonable manner.

I don't know if the kit includes a decent cable demod or not--if it
doesn't that is a significant cost to consider unless you plan to feed
the kit video from another demod source (like a VCR) -- this may work
if properly tuned but can be very unwieldy.

Commercial versions of a teletext magazine decoder for the World
Standard are available for around $300.

--Lauren--

P.S.  For most vertical interval data systems, a teletext magazine
takes up some number of full lines.  On WTBS, A couple of lines
are devoted to ELECTRA, and a bunch more lines are devoted
to the commercial high speed/encoded data system (which is totally
different than the teletext magazine and much more sophisticated).
Closed captioning lives on line 21 and is separate from all the other
materials.

--LW--