[mythtv-users] Hauppauge WinTV-quadHD TV Tuner Card 1609 and Pixelation

[Stephen Worthington]

On Sat, 16 Feb 2019 18:02:02 -0600, you wrote:

>
>Hi Folks!
>
>I am considering building a new Backend and wondering if the current 
>tuners are better at compensating for varying signal conditions than the 
>old ones. Specifically I’m considering the Hauppauge WinTV-quadHD TV 
>Tuner Card (1609) versus reusing my old HVR-1600 and HVR2250.
>
>I have issues with pixelation: have tweaked the incoming signal to the 
>best of my ability; problem is definitely wind and moving tree branches. 
>Am wondering if a newer tuner (later generation) is able to handle 
>fluctuating signal levels better than the older tuners (early 
>generation). I realize no one can give a 100% answer as reception 
>depends on a number of factors. I’m located in the U.S., so ATSC and OTA.
>
>Thanks!
>
>Barry

If your pixellation is caused by low signal levels, then you will need
to tell us just what your aerial system is like in order to work out
what would be a good solution.  A lot of people get bitten by not
understanding how to set up an aerial system.  Some basics that you
may or may not already know:

1) The quality of the aerial signal can not be improved by anything
you do after the aerial itself.  If the signal quality is such that
only one device directly connected to the aerial does not get a usable
digital signal, the only fix is a better aerial.  Any length of cable,
amplifiers or splitters in the aerial system will degrade the quality
from that available at the aerial.  Eventually, with too much cable or
too many devices in the aerial system, the signal quality can be
degraded beyond the point where a valid digital signal can be
detected, despite proper signal levels.

2) When you have to connect more than one device to an aerial, the
usual means of doing that is to use one or more splitters to split the
aerial signal into multiple paths going to the devices.  However,
splitting the signal means exactly that.  If you use a two way
splitter, each of the outputs of the splitter will get slightly less
than half the signal level of the input.  The "slightly less than" bit
is the loss of signal that happens in the splitter - like everything
electronic, they are not perfect devices and they will lose a little
of the signal in the process of splitting it.  How much depends on the
quality of the splitter.  There are good and bad splitters.  You can
usually get 2, 3 and 4 way splitters at retail outlets.

3) The reason that splitters are used and commonly do work well is
that tuners have a quite wide range of signal levels that they can
work with.  At the upper end, a tuner can be given too much signal and
that can cause reception problems.  That is uncommon, but if you are
in a high signal area and have only one or two devices on your aerial,
it can happen.  Usually, the signal level is too low for the tuner's
specification and it will either fail to tune at all, or will suffer
loss of signal at times, usually causing pixellation where it will
lose some of the incoming data for short (or long) periods.  Tuners
have different specifications.  Some are more "sensitive" than others,
which means that they can work with a lower signal level.  When you
buy a tuner for a PC, the specifications may tell you the sensitivity,
but that number is only useful if you have professional aerial testing
equipment and can measure the signal arriving at the aerial cable
connecting to that tuner.  If you are suffering from low signal
levels, getting a tuner that is more sensitive is one possible
solution.

4) Tuner devices with multiple tuners are available in several
different types.  Some have a separate aerial input for each tuner.
Most have only one input for all the tuners in the tuner device. Where
there is one input per tuner, you need to use external splitters to
give each tuner its signal.  Where there is a single input for
multiple tuners, then there will normally be an internal splitter on
the device.  So if it has two tuners fed from one aerial input, each
tuner will be getting slightly less than half the signal from that
input.  And if it is a quad tuner device, then each of the tuners will
only be getting slightly less than a quarter of the input signal.  So
if you have a signal coming into that device that your TV say (with
only one tuner) can work fine with, the splitting on the tuner device
may well reduce that level to well below what is needed for each of
its tuners.

5) More recently, there have been some new tuner devices which have
only one input but somehow feed that to each of their tuners in a way
that gives them all effectively the same signal level.  I have no idea
how this is done, but I have two tuners that work like that, my
TBS6909 8 tuner DVB-S2 card and my TBS6209 8 tuner DVB-T2 card.  These
are rare and seem to only be cards with greater than 4 tuners.  But
they work well.

6) It is common for people to have a TV that works fine on their
aerial.  They then add a dual tuner device, using a splitter to
provide half the signal to the TV and half to the dual tuners.  The TV
still works fine, but the dual tuners have pixellation.  That is
because the TV has half the previous signal, and is sensitive enough
that it works.  The dual tuners have their own two way internal
splitter, so they only get less than one quarter of the original
signal, which is not enough.  It is worse if a quad tuner device is
added instead of a dual tuner - then each tuner is only getting one
eighth of the original signal.  So it is usually necessary to amplify
the signal going to the quad tuner, or it may be better to amplify
before the external two way splitter, depending on the actual levels
involved.  The commonly available amplifiers are normally
amplifier/splitter combination devices - typically an amplifier with a
two way or four way splitter.  These do work fine, but if your
requirements are not a good match with a two or four way split, you
can go to commercial suppliers for lots of other options, such as a
pure inline amplifier, or a amplifiers with many outputs, 8, 10, 16 or
more.

7) If you have signal level problems, then separate tuners may be a
better option.  If you have a TV and two separate tuners, you can use
a three-way splitter, so each of them gets one third of the available
signal.  If you use a TV and a dual tuner device, you have to use a
two way splitter, giving the TV half the signal, and each of the dual
tuners will then only be getting one quarter of the signal.