[mythtv-users] Network tuners vs. USB Tuners

[James Abernathy]

On Mon, Nov 15, 2021 at 5:23 PM Scott Theisen <scott.the.elm at gmail.com>
wrote:

> On 11/15/21 10:14 AM, James Abernathy wrote:
>
> Thanks, I do have the 1609 model of the WinTV-quadHD PCIe card. I have not
> found that it ever has an issue with too much signal. In this case it was
> the HDHR Quatro that had the pixelation and I think that tuner can be
> overloaded easily.
>
> It's possible, but I would be surprised if you are overloading the RF
> frontend.  The different tuners reacting differently to marginal signals is
> unsurprising.  This could also depend on the internal architecture, i.e.
> 4-way splitter to four tuners or loop through chained amplifiers integrated
> in the tuners.
>
> The HDHomeRuns report three different signal quality metrics:
> https://info.hdhomerun.com/info/hdhomerun_config
>
>    - ss = signal strength. 80% is approximately -12dBmV.
>    - snq = signal to noise quality (based on analog signal to noise
>    ratio).
>    - seq = symbol error quality (number of uncorrectable digital errors
>    detected).
>
> SS is mostly informative (amplitude only), SNQ is more relevant, and SEQ
> is the important one.  These are also shown in the GUI version.
>
> What are these for your stations?
>
> My house is new enough that it has a data closet where every coax or
> cat5e/6 cable is terminated.  So my Clearstream 4Max is directly wired to
> an 8-way splitter in my data closet.
>
> A lossless 8-way power divider is -9 dB. The simple, cheap, and inherently
> broadband resistive divider is -6 dB per stage, however.
>
> If this
> https://www.amazon.com/Antennas-Direct-ClearStream-Multi-directional-Adjustable/dp/B074DYDSNK?th=1
> is your antenna (which looks very funky), its beamwidth in the UHF band is
> 45°.  (I assume this means -3dB ±22.5° from the normal of the antenna
> plane, but I couldn't find a radiation pattern.)
>
> There are only a few unused ports and they all have 75ohm terminators on
> them.
>
> Good, you don't want any reflections from unterminated ports/transmission
> lines.  (Although, that only matters if the divider has poor isolation.)
>
> As I mentioned previously, I think this may be multipath distortion.
>
> https://en.wikipedia.org/wiki/8VSB claims multipath is irrelevant for
> modern receivers.  (Take from that what you will.)
>
> Pointing the antenna toward the PBS station 55 miles away puts me aiming
> at neighboring houses and 45 degrees off the direction to the main towers
> 10 miles away.
>
> What RF channel is the PBS station on?
> https://en.wikipedia.org/wiki/Pan-American_television_frequencies
> https://www.fcc.gov/media/engineering/dtvmaps (You have to click on the
> station to see the RF channel.)
>
> Do you still have good signal on the other channels when pointed at the
> PBS station?
>
> Regards,
> Scott
>

The Clearstream antenna's main feature that I liked was that it was
unpowered. I've experienced a lot of amplifier failures on other antennas
that had an amp in the head of the antenna.

The PBS station is RF 20 and sometimes comes in with partial lock at 35% SS
when the antenna is pointed to the main stations I care most about.

When I point toward the PBS station The other stations are strong (>80%)
but the SNQ and SEQ bounce a lot.  Not completely to zero as with older
HDHR firmware, but the HDHR config gui shows a lot of movement +or- 10%

For now I've taken a practical approach and not worry about the PBS
station.  I hardly ever record anything from there and since I have DirecTV
Stream I can record anything on PBS that interests me there.

Jim A
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