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

Mike Carron jmcarron at starstream.net
Wed Aug 28 07:29:52 UTC 2013


From: mythtv-users-bounces at mythtv.org [mailto:mythtv-users-bounces at mythtv.org] On Behalf Of Chris Porter
Sent: Tuesday, August 27, 2013 8:18 PM
To: Discussion about MythTV
Subject: Re: [mythtv-users] Pixelation/Bad Recordings HDHR Prime -- I am at my wits end

 


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 > _______________________________________________
> > 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.  
>
> **
>
> 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
>
>

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.

**

Just make sure the amp is bi-directional. Some claim to be but actually aren’t. At a minimum it should specify a 0db return. It’s still a better idea to take one branch off the first splitter and route it directly to the cable modem and nothing else.

 

mike

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