From: rxv9839@ritvax.isc.rit.edu
Subject: Re: Cable reception
Reply-To: rxv9839@ritvax.isc.rit.edu
Organization: Rochester Institute of Technology
Date: Mon, 5 Oct 1992 00:02:18 GMT

In article <BvI9Ey.1qF@ssesco.com>, elmquist@pez.ssesco.com (Chris Elmquist) writes:
>In article <petec.718042450@splat> petec@splat.dell.com (Pete Cruz) writes:
>>I just bought a 46" TV and have now noticed fairly bad reception from my
>>cable company. I had a 27" TV before which "appeared" fine, now I notice 
>>quite a bit of detail difference. And channels very in quality also.
etc etc> (well covered in current posts)
>I think it's common *and* you're getting poor service.  I have the same
>problem but *amazingly* have been able to work with the cable company to
>try to find the cause of the problem.  I called and asked to speak to
>the engineer-in-charge of the headend that serves my neighborhood. I was
>amazed when I actually got to talk to him... and even more amazed when he
>seemed generally interested in the problem. He and several others that work
>for him have come out to the house and actually seen the problem.  Your
>mileage may vary.
>
>For me, I get herringbone interference on channels 37, 38, 39, 40, 41, and 42.
>The herringbone is very visible on larger screened monitors like 27" and less
>noticeable on a 19" and not at all objectionable on a 13".
>
>When the Cable Co. comes out to make measurements... they bring a portable 9"
>TV so that they run it on batteries in the bright sunlight out in the yard.
>For some reason (?? what could it be ??) they have never seen the herringbone
>on the 9" but admit to seeing it on my 27".  
.........

To elucidate this matter just a bit--
Grainess, snow that the original poster was having is a very different problem
in cable than herringbone.  Herringbone can come from loose fittings, impedance
mis-match and other causes, both in your TV and in the cable companies headend
and distribution plant.  You are correct that it is most likely in the headend,
however your TV set is not positively ruled out by the test you describe so
far.  If the cable company has other problems on your line it may be a logical
troubleshooting procedure, rather than easter-egging, that they are using to
correct the problem.  (Not intended as a defense of them, simply an observation
of another possibility.  I'd probably defer to your on-site evaluation if you
have a sound basis for it.)  They probably use battery operated TV's and small
at that for in the field (outside of homes) troubleshooting.  Its a trade-off. 
Most mobile power sources don't treat TV's kindly and can induce more problems
than the systems really have.  Its hard to troubleshoot a noise problem if your
generator is putting glitches all across the TV screen.  And after you have
blown up a TV or two on a poorly regulated power invertor, one opts for a
battery TV.
And here's a helpful tip.  After they're alll done and if you still have
herringbone ask if they have a "sweep" program and can they sweep out to your
house.  It is a process where they insure the flatness of their amplifier
response and can make a big difference in picture quality if it is radically
off.
Bob Vogel

Newsgroups: rec.video.cable-tv