[mythtv-users] Pixelation/Bad Recordings HDHR Prime -- I am at my wits end

Wed Aug 28 03:18:11 UTC 2013

On Aug 27, 2013 8:03 PM, "Mike Carron" <jmcarron at starstream.net> wrote:
>
> From: mythtv-users-bounces at mythtv.org [mailto:
mythtv-users-bounces at mythtv.org] On Behalf Of Captain Hook
> Sent: Tuesday, August 27, 2013 7:46 PM
> To: Discussion about MythTV
>
> Subject: Re: [mythtv-users] Pixelation/Bad Recordings HDHR Prime -- I am
at my wits end
>
>
>
> Results are in:
>
>
>
> Original Configuration:  Comcast signal comes in, connects to a
cylindrical object that we believe is a filter.  Goes into a splitter (That
was highly weathered, by the way) which then feeds two cables into my
house.  One of these goes to another splitter and then ultimately to my two
TVs.  The other goes to a line that leads to a splitter that is then
connected to my cable modem and my HD Homerun Prime.
>
> Results:  -0.5 to -4dB (didn't test too many channels)
>
>
>
> Test 1.  Removed the Comcast splitter (#1 in my diagram) which was
outside.  I then pulled the source cable into my house (left on the
cylindrical object which is apparently a filter) and connected the input
into the Motorola amplifier and the outputs into the Comcast splitter that
goes to my TVs (splitter #2 in my diagram) and the other output into the
line that leads to my cable modem and HD HR Prime (through splitter #3).
>
> Results:  +10 to +12dB, depending on channel.
>
>
>
> Test 2.  Removed the Motorola amplifier ( (left on the cylindrical object
which is apparently a filter on the source cable) and replaced this with
another splitter I had from years back that was originally provided by
Comcast.  Loss of -3.5dB per output according to the sticker.  0-1000MHz.
>
> Results:  -0.5 to -5.4dB, depending on channel.
>
>
>
> When the amplifier seemed to add too much signal I thought that maybe the
splitter (#1) was the problem; this doesn't seem to be the case.  I suspect
that the signal will be too high and I will have the same issues if I
continue to use this amplifier.  I guess the other option is to continue
using the same amplifier and either intentionally lower the signal by using
multiple splitters (quick, "duct tape" fix) or get an amplifier with one
with more outputs and ultimately replace two splitters in one shot.  Since
the 4 port amp seems to provide a lower signal amplification, perhaps this
will work?  I suspect that I will still be in the positives regarding
strength so I'm not sure that this will work either.
>
>
>
> For what it's worth, the "cylindrical object" I keep referring to that we
think is a filter has "QLP-16" stamped on it and nothing else.  A quick
Google search did not yield any relevant results.
>
>
>
> On Tue, Aug 27, 2013 at 10:26 PM, Chris Porter <hoodlum7 at gmail.com> wrote:
>
> I suspect there is interference problems or the input into your house
from Comcast is not consistent.
>
> On Aug 27, 2013 6:22 PM, "Captain Hook" <captainhookzero at gmail.com> wrote:
>
>
>
> On Tuesday, August 27, 2013, Chris Porter wrote:
>
>
> On Aug 27, 2013 5:13 PM, "Captain Hook" <captainhookzero at gmail.com> wrote:
> >
> > That strength is without the booster. Here is more info on the booster
if you're interested. Looks like the gain is 10.2-11 dB.
http://www.motorolasolutions.com/web/Business/Products/Cable%20Broadband/RF%20Amplifiers/BDA100/_Documents/staticfile/BDA_Catalog_Specifications.pdf
> >
> > I will definitely take your advice. My plan is to move the HDHR around
and see what the readings are in different areas.
> >
> > Thanks.
> >
> > On Tuesday, August 27, 2013, Chris Porter wrote:
> >>
> >> On Tue, Aug 27, 2013 at 2:56 PM, Captain Hook <
captainhookzero at gmail.com> wrote:
> >>>
> >>>
> >>>
> >>> On Tue, Aug 27, 2013 at 5:51 PM, Chris Porter <hoodlum7 at gmail.com>
wrote:
> >>>>
> >>>> On Tue, Aug 27, 2013 at 2:30 PM, Captain Hook <
captainhookzero at gmail.com> wrote:
> >>>>>
> >>>>>
> >>>>>
> >>>>> On Tue, Aug 27, 2013 at 5:22 PM, Chris Porter <hoodlum7 at gmail.com>
wrote:
> >>>>>>
> >>>>>> On Tue, Aug 27, 2013 at 2:15 PM, Captain Hook <
captainhookzero at gmail.com> wrote:
> >>>>>>>
> >>>>>>> I am not sure how much bandwidth the packet loss test attempted
to push.  This issue occurs when there is only a single recording
happening, if that makes any difference.
> >>>>>>>
> >>>>>>> Here is a link to a diagram of my network.  Yes, my TrendNET 8
port gigabit switch is just an unmanaged switch.  I have a Sonicwall
firewall and a separate Meraki access point (also both connected to the
switch).  My frontend has another switch connected (also a TrendNET), but
that is upstairs.  For what it's worth, my brand new frontend does act
laggy at times with fast forward and loading the recordings screen but this
is fairly rare.
> >>>>>>>
> >>>>>>> http://s21.postimg.org/iuqsauaif/Coax_Wiring_Home.jpg
> >>>>>>>
> >>>>>>> The splitter just prior to my HDHR Prime has alternated between
Monster Cable splitter, Motorola 2 port signal booster, and a splitter I
obtained from Comcast years ago.  All three exhibit this issue.
> >>>>>>>
> >>>>>>>
> >>>>>>> On Tue, Aug 27, 2013 at 5:09 PM, Chris Porter <hoodlum7 at gmail.com>
wrote:
> >>>>>>>>
> >>>>>>>> On Tue, Aug 27, 2013 at 1:57 PM, Captain Hook <
captainhookzero at gmail.com> wrote:
> >>>>>>>>>
> >>>>>>>>> Background
> >>>>>>>>>  I have been having intermittent issues with recording quality
with my HDHomeRun Prime with Comcast cablecard since the inception of this
project. I am really remembering why I gave this HTPC nonsense up years
ago, but I'm already significantly invested in this at this point and I am
determined to see it through.
> >>>>>>>>>
> >>>>>>>>> Issues
> >>>>>>>>>  Intermittent issues with recordings on MythTV. Some recordings
will be perfect, others will have pixelation periodically, others will have
heavy pixelation, yet others will be so bad that the recordings stop during
playback. The same channel will not behave the same twice--sometimes things
are fine, other times they are terrible. This seems to happen on any
channel and do not occur at any particular time of the day or during any
other operations or recordings on my network.
> >>>>>>>>>
> >>>>>>>>> During playback the pixelation occurs at exactly the >
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> >
>
> Okay, so your signal strength is at a negative. If you amplify that you
are amplifying a poor signal.  I suspect If you hooked the HDHR directly to
your splitter #1 this value would be in the positive.
>
> FYI: a perfect reference signal is 0.0 dBmV. You want to keep your signal
as close to the reference as possible. If you go too high you can get the
same kind of problems. Most digital devices consider values between -12 and
+16 dBmV as acceptable.
>
> If you do not feel comfortable replacing splitter #1 with your amp, then
I believe you would get the most value placing the amp directly after it.
Then run any additional splitters off the amp.
>
>
>
> This makes perfect sense. I think I am going to put the amplifier in
place of the first splitter installed by Comcast. It is currently outside
but I can easily bring it inside.
>
>
>
> Oddly enough my signal is now showing:
>
> Signal Strength
>
> 100% (-0.5 dBmV)
>
> Signal Quality
>
> 100% (36.8 dB)
>
> Which really seems to lend credibility to my "intermittent" description.
>
> **
>
> I suggest you check with your Comcast tech guys before connecting your
cable modem to the output of an amplifier. My cable service (Wave
Broadband) techs strongly advise against it.
>
>
>
> mike
>
>
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>

I agree. The only exception to this would be if the cable modem had to be
run off a large dB drop. Then it would be safer to "run" it off the amp.
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