[mythtv-users] HDHomerun signal strength required

[Roger Heflin]

backuppc at sundquist.imapmail.org wrote:
> On Sat, 23 Feb 2008 09:16:56 -0500, backuppc at sundquist.imapmail.org
> said:
> 
>> I will try each antenna individually and
>> tweak the aim to get the best reception and then compare it to when both
>> are hooked up.  If the signal is much weaker when combined, I will try
>> small adjustments to see of steer out of a null for the channels I need.
>> Maybe even set up a second attic mast and separate then laterally.
>>
>> After I get the best aim on the north/norhwest one, I'll see if I can
>> get the big ABC/CBS/NBC towers located not too far to the south out
>> the back of that same antenna.
> 
> Findings:
> 
> Disconnected the south facing antenna, connecting the 50-foot RG-6
> directly to the other antenna's balun.  That antenna (the one aimed
> towards Grand Island/CN Tower) seemed to be aimed well, changing
> direction just made it worse.
> 
> Most interestingly, I got the ABC/CBS/NBC signals "out the back" just
> fine with only one antenna, pointed the other way.
>  
> This is all with the pcHDTV 5500  Here are the results from before (two
> antennas):
> 
> 
> And here's the results with one antenna (with the pcHDTV 5500):
> 
> signal stength:
> 
> channel = 34 freq = 593000000Hz
>  30db       0%         25%         50%         75%        100%
> Signal:     |     .     :     .     |     ._____:_____._____|
> Signal: 051 -------------------------
> 
> channel = 20 freq = 509000000Hz
>  30db       0%         25%         50%         75%        100%
> Signal:     |     .     :     .     |     ._____:_____._____|
> Signal: 014 -------
> 
> channel = 38 freq = 617000000Hz
>  30db       0%         25%         50%         75%        100%
> Signal:     |     .     :     .     |     ._____:_____._____|
> Signal: 077 $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
> 
> S/N:
> 
> channel = 34 freq = 593000000Hz
>  dB     -10        0        10        20        30        40
> SNR:     |         |         |         |         |         |
> SNR: 017 ============================
> 
> channel = 20 freq = 509000000Hz
>  dB     -10        0        10        20        30        40
> SNR:     |         |         |         |         |         |
> SNR: 003 --------------
> 
> channel = 38 freq = 617000000Hz
>  dB     -10        0        10        20        30        40
> SNR:     |         |         |         |         |         |
> SNR: 026 $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
> 
> So about the same.  I took the second antenna out of the attic.
> 
> But the HDHR is disappointing me so far.  Following the Craig's advice:
> 
>>> SiliconDust provides a utility to work with the HDHomeRun that can
>>> help for testing reception. Do a full channel scan on one of the
>>> tuners, which will take several minutes, with:
>>>
>>> hdhomerun_config FFFFFFFF scan /tuner0 scan0.txt
>>>
>>> Focus on the bits of interest with:
>>>
>>> grep -B1 -A1 '8vsb' scan0.txt
> 
> I get:
> 
> SCANNING: 473000000 (us-bcast:14)
> LOCK: 8vsb (ss=59 snq=72 seq=100)
> PROGRAM: 3: 29.1 WUTV-HD
> --
> SCANNING: 581000000 (us-bcast:32)
> LOCK: 8vsb (ss=67 snq=73 seq=100)
> PROGRAM: 3: 23.1 WNLO-HD
> --
> SCANNING: 587000000 (us-bcast:33)
> LOCK: 8vsb (ss=98 snq=89 seq=100)
> PROGRAM: 1: 2.1 WGRZ-HD
> --
> SCANNING: 593000000 (us-bcast:34)
> LOCK: 8vsb (ss=48 snq=48 seq=100)
> PROGRAM: 3: 49.1 WNYO-HD
> --
> SCANNING: 617000000 (us-bcast:38)
> LOCK: 8vsb (ss=70 snq=69 seq=100)
> PROGRAM: 3: 7.1 WKBW-HD
> --
> SCANNING: 623000000 (us-bcast:39)
> LOCK: 8vsb (ss=91 snq=93 seq=100)
> PROGRAM: 5: 4.1 WIVB-HD
> --
> SCANNING: 647000000 (us-bcast:43)
> LOCK: 8vsb (ss=44 snq=43 seq=100)
> PROGRAM: 2: 43.1 WNED-HD
> 
> ...which are somewhat lower.  Perhaps that is understandable because I
> have the splitter in place with the HDHR.  And in fact, I suppose the
> numbers are not all that different for the three I highlight.  But for
> 1,000 KW Fox (channel 14), the discrepancy is greater:
> 
> channel = 14 freq = 473000000Hz
>  30db       0%         25%         50%         75%        100%
> Signal:     |     .     :     .     |     ._____:_____._____|
> Signal: 076 $$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
> 
> vs:
> 
> SCANNING: 473000000 (us-bcast:14)
> LOCK: 8vsb (ss=59 snq=72 seq=100)
> PROGRAM: 3: 29.1 WUTV-HD
> 
> But maybe the numbers aren't comparable between the two utilties.

I would not count on the numbers being comparable.   The numbers between
my 5550 and my actual hdtv differ quite a bit, the hdtv fails to work
at about 80% or below, and the 5500 fails at around 65-70, and checking
the same signal the 5500 gives numbers that are 10-15 % lower.   I would
expect the HDHR to be different from either of the 2.

My biggest issue with antennas was I had a bad cable and a bad splitter,
both had been used outside for a while and apparently got water damage.

                           Roger