[sci.electronics] Undesired television reception: solution?

uusgta@swbatl.UUCP (4237) (11/15/89)

I'm getting ready to write a scathing letter to my cable television company.

The problem is "ghost" images on network channels, when viewed through the cable 
connection.   After talking to the company, they explain that the downlink
site is miles from my house, and local signals overpower the cable carried
signals.  My suspicion is that this is indicative of poor shielding on their
part; Isn't coax awfully close to a faraday cage?  It also seems that they
could move local channels to another freq on the cable, or boost signal
levels at diffrent points in the city.   They say I should "just connect the
antenne" to watch local channels, a wholly unacceptable answer, especially
during unattended videotaping.

Am I reasonable in my irritation?  Are there other solutions I could suggest?
Is there some minimum quality of service they are required (by whom?) to
provide? Should I wrap my house in tin foil :) ?
-- 
#	---Tom Adams---	| uunet!swbatl!uusgta or uusgta@swbatl.swbt.com
# I collect pre-1930 wireless, electrical and scientific books.
# opinions... Opinions? I don't think I'm allowed to have opinions.

illgen@hq.af.mil (Keneth..Illgen) (11/15/89)

In article <938@swbatl.UUCP> uusgta@swbatl.UUCP (Tom Adams 5-4237) writes:
>I'm getting ready to write a scathing letter to my cable television company.

>The problem is "ghost" images on network channels, when viewed through the cable connection.

     For the sake of your CATV company, I hope they gave you the wrong info.
If the same problem exists for everyone on the system then the CATV people
either need to move their antenna location or take a good look at their cable
plant. Normally ghosts that appear to the left of your picture indicate strong
reception of an off-the-air station at the same frequency. Ghosts to the right
indicate multiple paths to the receiving antenna and an impedance mismatch
on the cable plant. Either case should be fixable by your CATV company.
     If only people in your neighborhood have this problem then my comments 
below are worthy. Otherwise they're not.

>Am I reasonable in my irritation? 
  
     Absolutly! If the CATV signal is allowing that much signal to penetrate
their cable they have a serious problem.     

>Is there some minimum quality of service they are required (by whom?) to
>provide? 

     The quality of the service they have to give you could be enforced by
whoever licensed them (the local government for example). You could report
them to BBB and hope that others have complained. At least that's what I
think.
     The fact that their signal is being distorted by outside elements 
should concern them a lot if the FCC finds out. Because what comes in goes
out. i.e radiated emissions. Particularly those frequencies that ride the
cable that could effect aeronautical frequencies. If you have an airport
near your house call the CATV company and remind them of their respons-
ibilities to the FCC for leakage. For most signal level requirements a
CATV system won't worry about FCC enforcement; but when it comes to 
radiated emissions they'll be all over their cable plant looking for the 
fault (If they're smart; which they don't seem to be.)     

>Should I wrap my house in tin foil :) ?

     Nah!

matthew@sunpix.UUCP ( Sun Visualization Products) (11/16/89)

In article <938@swbatl.UUCP> uusgta@swbatl.UUCP (Tom Adams 5-4237) writes:
}I'm getting ready to write a scathing letter to my cable television company.
}
}The problem is "ghost" images on network channels, when viewed through the cable 
}connection.   After talking to the company, they explain that the downlink
}site is miles from my house, and local signals overpower the cable carried
}signals.  My suspicion is that this is indicative of poor shielding on their
}part; Isn't coax awfully close to a faraday cage?  It also seems that they
}could move local channels to another freq on the cable, or boost signal
}levels at diffrent points in the city.   They say I should "just connect the
}antenne" to watch local channels, a wholly unacceptable answer, especially
}during unattended videotaping.
}
}Am I reasonable in my irritation?  Are there other solutions I could suggest?
}Is there some minimum quality of service they are required (by whom?) to
}provide? Should I wrap my house in tin foil :) ?
}-- 
}#	---Tom Adams---	| uunet!swbatl!uusgta or uusgta@swbatl.swbt.com
}# I collect pre-1930 wireless, electrical and scientific books.
}# opinions... Opinions? I don't think I'm allowed to have opinions.

 
Had the same problem with a local cable company.  (Alert Cable of Cary, NC).
MTV was broadcast on the same channel as a local TV station. Enough people 
got together and complained about this kind of problem and the cable company 
redistributed their selections.

If the cable company complains that they don't have the available free 
frequencies to move a channel to, tell them to suffle the bulletin board 
channels to the frequencies used by local TV stations. Typically BB channels
use Computer generated graphics with colors that are driven so far into 
saturation, that ghosting won't be a problem. Also impress upon them the
goodwill value of a Cable company trying to improve their services.

If this all fails, take up the problem (and these solutions) with your local
goverment.  Most Cable companies are under contract with the local goverment
to provide a specified level of service.  If your local company doesn't meet
those standards, your local goverment will work on your behalf to force 
correction of those problems.


-- 
Matthew Lee Stier                            |
Sun Microsystems ---  RTP, NC  27709-3447    |     "Wisconsin   Escapee"
uucp:  sun!mstier or mcnc!rti!sunpix!matthew |
phone: (919) 469-8300 fax: (919) 460-8355    |

myers@hpfcdj.HP.COM (Bob Myers) (11/17/89)

>site is miles from my house, and local signals overpower the cable carried
>signals.  My suspicion is that this is indicative of poor shielding on their
>part; Isn't coax awfully close to a faraday cage?  It also seems that they

First minor point: coax may or may not be viewed as a "Faraday cage", depending
on whether or not a balanced drive scheme is used (i.e., if the signal return
current is carried over the "shield", than it's not stricly a "Faraday cage.")

Now, major point: regardless of how well the cable company keeps undesired
signals off their cable, they *can* and likely *will* enter either at
the converter box or in your tuner (you don't mention whether you
use an external converter or use a "cable ready" TV).  Consumer electronics
are notorious for poor shielding.

>could move local channels to another freq on the cable, or boost signal
>levels at diffrent points in the city.   They say I should "just connect the
>antenne" to watch local channels, a wholly unacceptable answer, especially
>during unattended videotaping.

If the local channels are on their proper frequency on the cable, then I'm
assuming that your set's tuner is doing all the work - the above comments
apply.  Connecting the external antenna for the local channels may in fact be
the only solution.  Is this really a problem for taping?  How often do you
tape shows from both local stations (which are not available from other
stations on the cable) and cable-only stations, in the same "unattended"
period?

>Am I reasonable in my irritation?  Are there other solutions I could suggest?
>Is there some minimum quality of service they are required (by whom?) to
>provide? Should I wrap my house in tin foil :) ?

Unfortunately, some type of shielding may be the only answer outside of
pulling the antenna swap - wrapping your house in tin foil is, I presume,
unacceptable. :-)



Bob Myers  KC0EW   HP Graphics Tech. Div.|  Opinions expressed here are not
                   Ft. Collins, Colorado |  those of my employer or any other
myers%hpfcla@hplabs.hp.com               |  sentient life-form on this planet.

derek@hppad.HP.COM (Derek Schuurman) (11/18/89)

I had the same problem but I found it was on my end - the cable is
shielded very well but my TV's enclosure is far from a faraday cage! 
( it's plastic in fact! ) and the 300 ohm line that runs from the 
back connection on the TV to the pre-amp/tuner is a perfect antenna 
for any local broadcasts! 

In my case there was nothing wrong with the cable company but merely the
poorly shielded chasis on my own TV.

I have not yet solved the problem - the only solution I can see is to
watch your TV in a "faraday cage"  :^)  :^)

Derek.
 

adams@swbatl.UUCP (4237) (11/20/89)

In article <17660035@hpfcdj.HP.COM> myers@hpfcdj.HP.COM (Bob Myers) writes:
>
>use an external converter or use a "cable ready" TV).  Consumer electronics
>are notorious for poor shielding.
 
TV and VCR are cable ready.  But if these devices are commonly ("notoriously")
poorly shielded why would the cable company not use another frequency for the 
local signals?  Seems a problem designed to occur.o

Several other people have mentioned gathering groups of dissatisfied
cable customers.   I wonder if someone could explain just how that occurred?
Are there already appropriate advocate groups?

>apply.  Connecting the external antenna for the local channels may in fact be
>the only solution.  Is this really a problem for taping?  How often do you
>tape shows from both local stations (which are not available from other
>stations on the cable) and cable-only stations, in the same "unattended"
>period?

Actually, quite often, I'm often grabbing stuff from the local
PBS station as well as all those weird channels that offer scintillating
material on the mating habits of the Iguana but only at the most *inconvenient*
hours.  Always wondered why, Iguana seem at least as interesting as
Dougie Howser. :)

Plus, I forget to reconnect, it's inconvenient, and I feel as though I'm paying
for something I don't receive (no pun intended).

>Unfortunately, some type of shielding may be the only answer outside of
>pulling the antenna swap - wrapping your house in tin foil is, I presume,
>unacceptable. :-)

Where to shield; with what?  I guess it would be easier to just get the
whole house.  Hmmm,  perhaps Christmas tinsel...   illuminated by flashing 
multicolored spotlights in colors appropriate to each holiday. 
-- 
#	---Tom Adams---	| uunet!swbatl!uusgta or uusgta@swbatl.swbt.com
# I collect pre-1930 wireless, electrical and scientific books.
# opinions... Opinions? I don't think I'm allowed to have opinions.