[mythtv-users] HD HomeRun Prime, CableCard, LiveTV works

Gary Buhrmaster gary.buhrmaster at gmail.com
Wed Mar 21 14:11:50 UTC 2012


On Tue, Mar 20, 2012 at 23:23, Rick Nickle <ricknickle at hotmail.com> wrote:
....
> Now, even after lengthening them a second time (close to 10000ms now), I’m
> still not getting one particular channel that is popular in the house, but
> maybe the signal strength issue is related to the cable company performing
> the digital switchover that moved me to HDHomeRun in the first place.  I’ll
> keep tweaking the settings, and I think you have all helped me get on track.

Since this problem seems to be with "some" channels,
I suspect a signal issue.

<background>
When the cableco moved to digital, they also (likely) changed
the "real" channels being used to send the signal.  Sometimes
a local issue causes less than desirable signal(s) on that
frequency.  Sometimes it is the outside cable plant, and
sometimes it is the number of new splitters added inside the
house.  Different cable tuners (TVs, STBs, HDHomeruns)
have different sensitivity regarding the RF signal, and some
tuners can lock in to signals others can't.  Note that while
analogue tuners will lock into a poor signal (usually with a
little snow), digital tuners need a signal which is in a
certain range of quality to lock.
</background>

A quick thing to do is to download the command line utilities
that SiliconDust provide, compile them, and then do some
debugging of the signal (if you like GUIs, SiliconDust also
provides one).  Presuming you are in the directory that
you compiled the codes in, and the channel you are
having problems with is <channel>, and the HDHomeRun
id is <HDHR> try something like the following:

  LD_LIBRARY_PATH=. ./hdhomerun_config <HDHR> set /tuner2/vchannel <channel>
  LD_LIBRARY_PATH=. ./hdhomerun_config <HDHR> get /tuner2/status

You may want to issue the last command a couple of times to
see if the output changes over time.

The first command tunes to the virtual channel.  The second will
gets the channel status.

The output of the second command should be something like:
   ch=qam:513000000 lock=qam256 ss=88 snq=100 seq=100 bps=38810720 pps=0

If the status shows "lock=none", the signal cannot be locked
on to.  If the values for snq or seq are not close to 100 (and
the ss a largish value), the incoming signal (to the Prime)
is poor.  Usually the status will show a valid lock in less than
a few seconds (often fractions of a second).

You may want to try this on another channel which works
fine.  See if the numbers look better.

If this is a signal problem, the first thing to do is connect the
HDHomeRun Prime directly to the cable tap on the wall.  See
if the problem goes away.  If so, either you have too many
splitters after the tap, or the signal is really low coming into
your residence.  For the first, you are (clearly) on your own,
and for the second, you should contact the cableco to boost
the signal.

Note that sometimes the cablecos sometimes have problems
with certain frequencies due to outside plant issues, so that
some frequencies will work fine, and others will not.  For
example, It is not at all uncommon for the cablecos to use
the frequencies that are used by OTA FM broadcasters.  If
the cable plant has a leak, in comes the FM signal, and you
may not be able to lock into "some" channels.  In some cases
there may be an (old) attenuator on your drop that was
intended to prevent you from receiving "free" HBO (or cable
modem service).  When the cableco moved the frequencies
around, you are now impacted due to those old attenuators.
In all of these cases the cableco is responsible for fixing
the problem.

I will note that the cableco techs have those $10K meters
that can tell them all this stuff in 30 seconds.  If all else
fails, you might want to call the cableco and tell them you
are having problems tuning some channels, and schedule
an appointment.  The tech who arrives should be able to
use one of those expensive meters, and be able to tell you
in seconds if it is their problem (resolution might take a
bit longer, especially if they have to climb poles to locate
the bad wires).

Good luck.


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