lauren@vortex.UUCP (Lauren Weinstein) (01/30/84)
My initial inquiries to some possible distribution sources have met with luke-warm to warm responses, so it appears that this actually may happen. Note that if a particular site is already in an area that has cable, they will most likely be able to receive data with only the netnews decoder box being needed. Areas without cable would either continue to use conventional telephone techniques or could spring for an RO dish (I can get units that would suffice for slightly over $1000, most likely). Note that the bandwidth of a broadcast vertical interval data signal (assuming 4 video lines used per field) is about 50 Kbytes/sec. This rate is so high that very high levels of redundancy and error-correction could be easily included. The cycle of articles would also repeat at a high rate so that any missed articles could be picked up on the next cycle. This is all in the planning stages, so please don't ask me for too many more details yet... --Lauren--
dya@unc-c.UUCP (02/04/84)
References: vortex.238
Are you sure that you want to use the vertical blanking interval with
cheap satellite receivers? Whose video signal are you going to use ? And
$ 1000 dish/TVRO systems are notorious for differential gain/differential
phase errors, IF phase anomalies, df/dt errors (with resulting cycle slipping
in PLL receivers), horrible DC restoration in the vertical interval, and
so on.
In addition, who is going to give up four lines in the VBI. The easy
way to go is
1) An aural subcarrier (say 7.2 mHz) with 56 kb/s synchronous or
less -- the implementation is trivial; use a 13 foot dish and receiver
with threshold extension;
2) A SCPC satellite, with much lower line charges, running digitally.
In this case, the IF bandwidth can be drastically narrowed, saving money
on dish (and permitting a simple receiver/modem.) The cost for VBI stripping
equipment is nontrivial.....
Performance of $ 1000 and below satellite receiving systems is unacceptable
for plain old video. I don't know what price Lauren was quoting, but even
at the wholesale, 10-99 unit price, the equipment really stinks.
SCPC or 12 gc is the way to go........
--David ( Last of the Analog ) Anthony
akgua!mcnc!(urp,unc-c)!dyadya@unc-c.UUCP (02/04/84)
References: vortex.238
Incidentally, I think it is a great idea, and would love to work with
We have several in the area, and a 5 metre at our own site.
* NO FLAMES FOR USING THE NET FOR COMMERCIAL PURPOSES, PLEASE *
Reply by mail to ( clyde!akgua!mcnc!urp!dya )msc@qubix.UUCP (Mark Callow) (02/05/84)
Your plan for news distribution via cable TV systems in the vertical
blanking interval sounds *exactly* like Ceefax and Oracle the
BBC and ITV teletext systems currently running in Great Britain.
--
From the Tardis of Mark Callow
msc@qubix.UUCP, decwrl!qubix!msc@Berkeley.ARPA
...{decvax,ucbvax,ihnp4}!decwrl!qubix!msc, ...{ittvax,amd70}!qubix!msc