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Video Distribution and Comcast On Demand Services

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Anonymous
December 4, 2004 8:14:43 PM

Archived from groups: comp.home.automation,alt.tv.tech.hdtv (More info?)

I've been doing video distribution in my home for over 7 years. We
have the cable coming in and using a notch filter to delete channels
71-78. We then add a channel using the Triple Play modulator. The
modulator and the cable are combined using a 5-1Ghz splitter/combiner
which goes to another 1Ghz splitter and then to two 8 port 1GHz
splitters. Everything has been working great. We originally had an
amplifer on the system, but it was causing problems when Comcast put
in digital channels. Removing the amplifier fixed the problem of not
receiving digital channels.

However, we can't use Comcast's On Demand Services. If I directly
connect the cable box to the main line (bypassing everything) it
works. But with my setup of splitters/combiners, modulator and notch
filter - it doesn't work - I just get a communications error.
Obviously, my commands are not getting back to Comcast.

I've removed the filter - no change. I've removed the modulator -
still no On Demand services. I've read that you need to ensure the
splitters and combiners support up to 1GHz and mine do.

Anyone have any suggestions? Anyone getting On Demand Services with a
video distribution system?

Thanks
December 5, 2004 6:41:53 AM

Archived from groups: comp.home.automation,alt.tv.tech.hdtv (More info?)

"Mark Vogel" <mark@vogel-denebeim.com> wrote in message
news:fa5d8edd.0412041714.5bdf2520@posting.google.com...
> I've been doing video distribution in my home for over 7 years. We
> have the cable coming in and using a notch filter to delete channels
> 71-78. We then add a channel using the Triple Play modulator. The
> modulator and the cable are combined using a 5-1Ghz splitter/combiner
> which goes to another 1Ghz splitter and then to two 8 port 1GHz
> splitters. Everything has been working great. We originally had an
> amplifer on the system, but it was causing problems when Comcast put
> in digital channels. Removing the amplifier fixed the problem of not
> receiving digital channels.
>
> However, we can't use Comcast's On Demand Services. If I directly
> connect the cable box to the main line (bypassing everything) it
> works. But with my setup of splitters/combiners, modulator and notch
> filter - it doesn't work - I just get a communications error.
> Obviously, my commands are not getting back to Comcast.
>
> I've removed the filter - no change. I've removed the modulator -
> still no On Demand services. I've read that you need to ensure the
> splitters and combiners support up to 1GHz and mine do.
>
> Anyone have any suggestions? Anyone getting On Demand Services with a
> video distribution system?
>
> Thanks

I was installing these boxes for comcast for a few weeks and
was told to try to make sure that with splitters we weren't down
more than 6dB at the box. maybe reduce the number of splitters
youre using one at a time until you figure out how many max you
can have and see if that makes a difference.
Anonymous
December 5, 2004 10:56:30 AM

Archived from groups: comp.home.automation,alt.tv.tech.hdtv (More info?)

"Rob" <rob@nospam.com> wrote in message news:<5svsd.630$cJ4.612@trndny05>...
> "Mark Vogel" <mark@vogel-denebeim.com> wrote in message
> news:fa5d8edd.0412041714.5bdf2520@posting.google.com...
> > I've been doing video distribution in my home for over 7 years. We
> > have the cable coming in and using a notch filter to delete channels
> > 71-78. We then add a channel using the Triple Play modulator. The
> > modulator and the cable are combined using a 5-1Ghz splitter/combiner
> > which goes to another 1Ghz splitter and then to two 8 port 1GHz
> > splitters. Everything has been working great. We originally had an
> > amplifer on the system, but it was causing problems when Comcast put
> > in digital channels. Removing the amplifier fixed the problem of not
> > receiving digital channels.
> >
> > However, we can't use Comcast's On Demand Services. If I directly
> > connect the cable box to the main line (bypassing everything) it
> > works. But with my setup of splitters/combiners, modulator and notch
> > filter - it doesn't work - I just get a communications error.
> > Obviously, my commands are not getting back to Comcast.
> >
> > I've removed the filter - no change. I've removed the modulator -
> > still no On Demand services. I've read that you need to ensure the
> > splitters and combiners support up to 1GHz and mine do.
> >
> > Anyone have any suggestions? Anyone getting On Demand Services with a
> > video distribution system?
> >
> > Thanks
>
> I was installing these boxes for comcast for a few weeks and
> was told to try to make sure that with splitters we weren't down
> more than 6dB at the box. maybe reduce the number of splitters
> youre using one at a time until you figure out how many max you
> can have and see if that makes a difference.

I'll try that. If it is signal reduction at the splitters. What can I do?
Related resources
December 5, 2004 12:07:03 PM

Archived from groups: comp.home.automation,alt.tv.tech.hdtv (More info?)

I am having the same difficulty. I think it is the number of splitters.
Comcast even came in and replaced all splitters. But after they left I
realized that they missed one :)  Then I will see if it works.

The guy that came from Comcast mentioned something about two-way splitters.
I am not sure if he was just talking about 1Ghz splitters or if there is
actually specific splitters that are two-way.

Joe

"Mark Vogel" <mark@vogel-denebeim.com> wrote in message
news:fa5d8edd.0412041714.5bdf2520@posting.google.com...
> I've been doing video distribution in my home for over 7 years. We
> have the cable coming in and using a notch filter to delete channels
> 71-78. We then add a channel using the Triple Play modulator. The
> modulator and the cable are combined using a 5-1Ghz splitter/combiner
> which goes to another 1Ghz splitter and then to two 8 port 1GHz
> splitters. Everything has been working great. We originally had an
> amplifer on the system, but it was causing problems when Comcast put
> in digital channels. Removing the amplifier fixed the problem of not
> receiving digital channels.
>
> However, we can't use Comcast's On Demand Services. If I directly
> connect the cable box to the main line (bypassing everything) it
> works. But with my setup of splitters/combiners, modulator and notch
> filter - it doesn't work - I just get a communications error.
> Obviously, my commands are not getting back to Comcast.
>
> I've removed the filter - no change. I've removed the modulator -
> still no On Demand services. I've read that you need to ensure the
> splitters and combiners support up to 1GHz and mine do.
>
> Anyone have any suggestions? Anyone getting On Demand Services with a
> video distribution system?
>
> Thanks
December 5, 2004 6:39:26 PM

Archived from groups: comp.home.automation,alt.tv.tech.hdtv (More info?)

They need to be 1GHz splitters, the 900MHz result in sporadic problems
with the digital boxes. As far as 2 or 3 way splitters, either are fine,
just
you want to limit the dB losses that occur as a result of using splitters.
You'll note on the three way, two of the outs are -3dB and the third if
I recall correctly is -6dB. Avoid that one if it's running to another
digital
box (or cable modem... a cable modem can only deal with -3dB as far
as I was told when I was a tech for Comcast - keep in mind I was a
contractor and the only training I received was from other contractor
techs, there was nobody who could REALLY answer the questions
available to us).

"Joe" <jmorris651XX@XXhotmail.com> wrote in message
news:Q8qdnZuVdpkdvi7cRVn-pw@comcast.com...
>I am having the same difficulty. I think it is the number of splitters.
>Comcast even came in and replaced all splitters. But after they left I
>realized that they missed one :)  Then I will see if it works.
>
> The guy that came from Comcast mentioned something about two-way
> splitters. I am not sure if he was just talking about 1Ghz splitters or if
> there is actually specific splitters that are two-way.
>
> Joe
>
> "Mark Vogel" <mark@vogel-denebeim.com> wrote in message
> news:fa5d8edd.0412041714.5bdf2520@posting.google.com...
>> I've been doing video distribution in my home for over 7 years. We
>> have the cable coming in and using a notch filter to delete channels
>> 71-78. We then add a channel using the Triple Play modulator. The
>> modulator and the cable are combined using a 5-1Ghz splitter/combiner
>> which goes to another 1Ghz splitter and then to two 8 port 1GHz
>> splitters. Everything has been working great. We originally had an
>> amplifer on the system, but it was causing problems when Comcast put
>> in digital channels. Removing the amplifier fixed the problem of not
>> receiving digital channels.
>>
>> However, we can't use Comcast's On Demand Services. If I directly
>> connect the cable box to the main line (bypassing everything) it
>> works. But with my setup of splitters/combiners, modulator and notch
>> filter - it doesn't work - I just get a communications error.
>> Obviously, my commands are not getting back to Comcast.
>>
>> I've removed the filter - no change. I've removed the modulator -
>> still no On Demand services. I've read that you need to ensure the
>> splitters and combiners support up to 1GHz and mine do.
>>
>> Anyone have any suggestions? Anyone getting On Demand Services with a
>> video distribution system?
>>
>> Thanks
>
>
Anonymous
December 5, 2004 6:39:27 PM

Archived from groups: comp.home.automation,alt.tv.tech.hdtv (More info?)

In article <OYFsd.533$HR4.413@trndny03> "Rob" <rob@nospam.com> writes:

>They need to be 1GHz splitters, the 900MHz result in sporadic problems
>with the digital boxes. As far as 2 or 3 way splitters, either are fine,
>just
>you want to limit the dB losses that occur as a result of using splitters.
>You'll note on the three way, two of the outs are -3dB and the third if
>I recall correctly is -6dB. Avoid that one if it's running to another
>digital
>box (or cable modem... a cable modem can only deal with -3dB as far
>as I was told when I was a tech for Comcast - keep in mind I was a
>contractor and the only training I received was from other contractor
>techs, there was nobody who could REALLY answer the questions
>available to us).

Bzzzt! A 3-way splitter is "electrically" nothing more than two 2-way
splitters ganged together inside a common housing. As such, you will have
only one "high leg" (-3 db) and two "low legs" (-6 db). Actually the
levels will be closer to -3.5 and -7

In any two-way cable system (where we're dealing with both transmitted and
received signals on the same wire) signal splitters are normally
undesirable. Your cable company will generally install something called a
Directional Coupler and connect your cable modem to the "tap" leg and
connect the TV (or a splitter for multiple sets) to the "thru" leg.
Telling them apart (a splitter vs a directional coupler) requires knowing
the difference, because to the untrained person a D/C looks a lot like a
2X splitter.

Insofar as these inline devices go, there's also good ones and junk. On
good ones the back cover is soldered on. On the junk ones the cover is
held on with epoxy. If you've ever worked on a particularly difficult case
of ingress (or egress) radiation, you'll come to recognize the superiority
of the soldered cases.
December 5, 2004 6:39:27 PM

Archived from groups: comp.home.automation,alt.tv.tech.hdtv (More info?)

LOL, I didn't mean two-way in regards to how many splits. I meant two-way
traffic :) 

Although I think Mr. Fixit's response is more accurate in the descriptions.

"Rob" <rob@nospam.com> wrote in message news:o YFsd.533$HR4.413@trndny03...
> They need to be 1GHz splitters, the 900MHz result in sporadic problems
> with the digital boxes. As far as 2 or 3 way splitters, either are fine,
> just
> you want to limit the dB losses that occur as a result of using splitters.
> You'll note on the three way, two of the outs are -3dB and the third if
> I recall correctly is -6dB. Avoid that one if it's running to another
> digital
> box (or cable modem... a cable modem can only deal with -3dB as far
> as I was told when I was a tech for Comcast - keep in mind I was a
> contractor and the only training I received was from other contractor
> techs, there was nobody who could REALLY answer the questions
> available to us).
>
> "Joe" <jmorris651XX@XXhotmail.com> wrote in message
> news:Q8qdnZuVdpkdvi7cRVn-pw@comcast.com...
>>I am having the same difficulty. I think it is the number of splitters.
>>Comcast even came in and replaced all splitters. But after they left I
>>realized that they missed one :)  Then I will see if it works.
>>
>> The guy that came from Comcast mentioned something about two-way
>> splitters. I am not sure if he was just talking about 1Ghz splitters or
>> if there is actually specific splitters that are two-way.
>>
>> Joe
>>
>> "Mark Vogel" <mark@vogel-denebeim.com> wrote in message
>> news:fa5d8edd.0412041714.5bdf2520@posting.google.com...
>>> I've been doing video distribution in my home for over 7 years. We
>>> have the cable coming in and using a notch filter to delete channels
>>> 71-78. We then add a channel using the Triple Play modulator. The
>>> modulator and the cable are combined using a 5-1Ghz splitter/combiner
>>> which goes to another 1Ghz splitter and then to two 8 port 1GHz
>>> splitters. Everything has been working great. We originally had an
>>> amplifer on the system, but it was causing problems when Comcast put
>>> in digital channels. Removing the amplifier fixed the problem of not
>>> receiving digital channels.
>>>
>>> However, we can't use Comcast's On Demand Services. If I directly
>>> connect the cable box to the main line (bypassing everything) it
>>> works. But with my setup of splitters/combiners, modulator and notch
>>> filter - it doesn't work - I just get a communications error.
>>> Obviously, my commands are not getting back to Comcast.
>>>
>>> I've removed the filter - no change. I've removed the modulator -
>>> still no On Demand services. I've read that you need to ensure the
>>> splitters and combiners support up to 1GHz and mine do.
>>>
>>> Anyone have any suggestions? Anyone getting On Demand Services with a
>>> video distribution system?
>>>
>>> Thanks
>>
>>
>
>
Anonymous
December 5, 2004 6:39:28 PM

Archived from groups: comp.home.automation,alt.tv.tech.hdtv (More info?)

"Mr Fixit" <MrFixit@msn.com> wrote in message news:23b6r0dqqg6bfrvr1cga3el036gvpe1oea@4ax.com...
> In article <OYFsd.533$HR4.413@trndny03> "Rob" <rob@nospam.com> writes:
>
> >They need to be 1GHz splitters, the 900MHz result in sporadic problems
> >with the digital boxes. As far as 2 or 3 way splitters, either are fine,
> >just
> >you want to limit the dB losses that occur as a result of using splitters.
> >You'll note on the three way, two of the outs are -3dB and the third if
> >I recall correctly is -6dB. Avoid that one if it's running to another
> >digital
> >box (or cable modem... a cable modem can only deal with -3dB as far
> >as I was told when I was a tech for Comcast - keep in mind I was a
> >contractor and the only training I received was from other contractor
> >techs, there was nobody who could REALLY answer the questions
> >available to us).
>
> Bzzzt! A 3-way splitter is "electrically" nothing more than two 2-way
> splitters ganged together inside a common housing. As such, you will have
> only one "high leg" (-3 db) and two "low legs" (-6 db). Actually the
> levels will be closer to -3.5 and -7

Now, now, one shouldn't try to intimidate others, especially when
one is wrong.

A 3-way splitter is not necessarily built that way.
You can design a splitter to divide power into 3 equal outputs,
if that's what you want (-4.77 dB before losses). Or you can
design the outputs to be any ratio you desire.

Don
Anonymous
December 6, 2004 10:24:34 AM

Archived from groups: alt.tv.tech.hdtv (More info?)

First question how many televisions are you supporting?
If you get the system to work with a straight through (Cable to box)
work backwards and add items into the system (one at a time) this will
be tedious and time consuming but you can probably find the culprit.
I would begin with the notch filter then introduce your other
modulator, and go from there.


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rcbridge
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