wales@ucla-cs.UUCP (02/10/85)
A couple of weeks ago, I posted some questions regarding cable TV and
25" stereo cable-ready monitors. This message is to summarize what I
found out.
Thanks to the following people who replied to me:
David G. Cantor ucla-cs!dgc
Lauren Weinstein vortex!lauren
??? ihlpm!rfish
Mark Salzman tekigm!marks
Don Doerner unmvax!dd
J. Abeles mhuxm!abeles
H. Reza Taheri ihuxb!reza
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(1) Splitters and Amplifiers:
(a) Each side of a two-way splitter will experience a signal loss of
3.5 to 6 dB from the original signal level. (3 dB, of course,
means that the signal strength is cut in half.) This should not
matter, unless the cable company is sending out an excessively
weak signal to begin with.
(b) Cable amplifiers are available at reasonable cost ($50 or so),
but should not be necessary unless you are feeding lots of
sources from a single cable. You don't need a "broadband" unit
capable of handling UHF, since cable systems don't use UHF.
(c) Unused splitter or amplifier outputs should be terminated with
75-ohm dummy loads.
(d) Typical cable systems offer at least 20 dB isolation between the
user and the system -- and some 60 dB isolation between two ad-
jacent users. Hence, there appears to be no way that use of a
splitter or an amplifier could mess up other customers.
(e) Some cable companies evidently do object to the use of splitters
or amplifiers (unless supplied by the cable company itself at a
price!). I didn't get any feedback at all regarding whether
such policies are in fact legally enforceable.
Is there any procedure for "type-approval" of cable amplifiers
and cable-ready consumer devices (TVs, VCRs, tuners, etc.), such
that said device can be guaranteed not to cause problems on a
cable system, and thus that the cable company can have no valid
grounds for objecting to the device being attached to the cable?
(Sort of like what is done with phones and modems now -- if the
device is FCC-approved, you can connect it to your phone line
even if you didn't buy it from your local phone company.)
(f) Many VCRs have both "VHF in" and "VHF out" cable jacks, and the
output can be set up to come either from the VCR or directly
from the input.
When connecting both a VCR and a cable-ready TV to a single
cable, then, an alternative to using a splitter is to connect
the incoming cable to the "VHF in" jack of the VCR, and then
connect the "VHF out" of the VCR to the TV.
The output from the VCR can then be seen on channel 3 or 4 of
the TV -- or, if the TV has monitor inputs, you would of course
connect to them from the VCR's video/audio outputs.
This approach seems much cleaner than using a splitter. It has
the advantage of providing the maximum possible signal to the
VCR. While there is some insertion loss involved in going into
the TV through the VCR, it is probably no worse than using a
splitter. I would suppose, too, that a setup like this is much
less likely to cause raised eyebrows from a cable-TV service
person on a house call than a splitter would be.
(2) 25" stereo cable-ready monitors:
(a) Stereo capability.
I found out from personal experience while shopping for a new TV
that you have to be VERY careful regarding claims that a TV has
the ability to receive stereo broadcasts. In at least two dif-
ferent places, I had salespeople insist to me that a given set
had "stereo" -- when in fact all it really had was either stereo
monitor inputs or some kind of stereo-simulating circuitry, but
no stereo broadcast reception capability at all.
When trying to decide whether a set has "true" stereo, look for
evidence that it can pick up a "secondary" or "bilingual" audio
channel from a station. Look for an indicator marked something
like "bilingual", "SAP" (secondary audio program), or "audio B",
as well as a switch or push-button that can select either the
regular audio or the secondary audio.
As far as I could tell from fairly exhaustive searching, if a
set doesn't have the above-mentioned "secondary" or "bilingual"
audio facility, it doesn't have stereo broadcast reception cir-
cuitry either, no matter what the salesman tries to tell you.
(b) Cable readiness.
Cable-ready tuners these days seem to have anywhere from 105 to
169 channels (the extra ones beyond the 82 VHF and UHF broadcast
channels correspond to various and assorted small bands of chan-
nels used for cable transmissions). I ran into two schools of
thought:
(1) Get as many channels as possible, so you'll be ready for
anything a local cable company throws at you.
(2) 105 channels is probably all you or your children will ever
need.
As a result, I made the number of channels on the tuner a sec-
ondary issue when looking for a set.
(c) What did I end up buying?
I was initally attracted to some Fisher sets, but changed my
mind after some knowledgable friends indicated some misgivings
about the reliability of Fisher products in recent years.
I fell in love with the Mitsubishi 2566. Some people told me
that Mitsubishi was relatively new and untested in the video
field, while others considered their stuff to be excellent. In
any case, just as I was about to make my purchase, every Mitsu-
bishi supplier in Los Angeles seemed to "dry up" all at once --
absolutely no one had a Mitsubishi 2566 in stock, nor could they
promise one for several weeks to come.
I finally ended up buying an RCA FKC2023. This set has two reg-
ular monitor inputs (video/left/right), as well as an RGB input.
The tuner has 127 channels, and you can switch between the var-
ious input sources via the remote. Further, I can control both
the TV and my VCR (an RCA VJT700) with a single remote. (Oh, as
an aside, the picture is excellent too. :-})
So I'm happy. The only thing I find slightly objectionable with
the 2023 is that, when you switch channels, the tuner takes
about half a second to lock in on the new channel -- but I can
live with that.
I am driving the VCR directly from the incoming cable, with the
TV being fed from the VCR's VHF output (same setup as described
earlier in this message). I could see no difference in picture
quality between this "series" approach and connecting the TV
from the incoming cable via a splitter, by the way.
--
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Rich Wales
University of California, Los Angeles (UCLA)
Computer Science Department
3531 Boelter Hall
Los Angeles, California 90024 // USA
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Phone: (213) 825-5683 // +1 213 825 5683
ARPANET: wales@UCLA-LOCUS.ARPA
UUCP: ...!{cepu,ihnp4,trwspp,ucbvax}!ucla-cs!wales
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