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

Captain Hook captainhookzero at gmail.com
Wed Aug 28 02:46:25 UTC 2013


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 >
>>> _______________________________________________
>>> > mythtv-users mailing list
>>> > mythtv-users at mythtv.org
>>> > http://www.mythtv.org/mailman/listinfo/mythtv-users
>>> >
>>>
>>> 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.
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>>
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