[mythtv-users] Indoor HD antenna question

Barry Martin barry3martin at gmail.com
Fri Apr 13 22:42:27 UTC 2018


Leo and Ashu:


One of the problems with digital TV is too much signal can be as bad as 
too little signal: both conditions will cause the signal to drop out.  
With borderline conditions (back-and-forth with too much, too little) 
the tuner will pixelate; with too much or too little the screen will 
turn blue or otherwise blank.  With Analog/NTSC the screen went 'snowy'.

This is why sometimes amplified antennae work and sometimes they don't.  
Then there's the length and type of coax, splitters -- and number (2-way 
is 3 dB and 4-way is 6 dB)....

Leo: if the too-much signal is your issue they do make attenuators.  Can 
be the variable type or the fixed (3 dB, 6 dB, etc.) type.  Sort of 
getting into a different issue from Ashu's.

Ashu:

>>> FIrst - my apologies - i was out of town for the whole week and couldn't reply back. So let me start off by saying that when I put the antenna directly in my TV - i get all the OTA channels (except CBS - channel 2)

Just to drive ya nutz <g>....   The Good News is _any_ antenna will pick 
up _any_ signal.  Antennae are basically anything that picks up a 
signal.  They start differentiating themselves with selectivity.  The 
old 'rabbit ears' antenna was designed to received the old Channel 2 
through Channel 13 VHF TV Band _but_ they will also pick up the UHF 
band, just not as efficiently.

Channel 2 - Chicago is WBBM:
https://en.wikipedia.org/wiki/WBBM-TV  ...OK, over in sidebar off to the 
right is what I'm talking about:

Channels <https://en.wikipedia.org/wiki/Channel_%28broadcasting%29>

	Digital <https://en.wikipedia.org/wiki/Digital_terrestrial_television>: 
12 (VHF <https://en.wikipedia.org/wiki/Very_high_frequency>)
Virtual <https://en.wikipedia.org/wiki/Virtual_channel>: 2 (PSIP 
<https://en.wikipedia.org/wiki/Program_and_System_Information_Protocol>)
Subchannels <https://en.wikipedia.org/wiki/Digital_subchannel> 	

  * *.1:* 1080i <https://en.wikipedia.org/wiki/1080i> 16:9
    <https://en.wikipedia.org/wiki/16:9> CBS2-HD
  * *.2:* 480i <https://en.wikipedia.org/wiki/480i> 4:3
    <https://en.wikipedia.org/wiki/4:3> Decades

Translators <https://en.wikipedia.org/wiki/Broadcast_relay_station> 	26 
(UHF <https://en.wikipedia.org/wiki/Ultra_high_frequency>) Chicago
WMEU-CD <https://en.wikipedia.org/wiki/WMEU-CD> 32.3 and 32.4 (UHF)/ 
48.3 and 48.4 (PSIP) Chicago


(I wonder how that's going to upload: as I write this it was imported as 
a nice chart.)

WBBM says they're "Channel 2" because from the Olde Dayz of NTSC 
(analog) they were Channel 2 -- at the very bottom of the VHF band. Now 
with ATSC (digital) they're at the top of the VHF band.  WTTW used to be 
analog at Channel 11 so where WBBM is now is one click higher.   The 
problem in not receiving might be because they (WBBM) are in the VHF 
band.  Most of the digital stations moved to the UHF band (Chs 14 to 83 
on the old analog sets).  [There's a technical error in the digital 
interpretation of that statement -- I'm trying not to confuse you any 
more than you possibly are.]

Most "digital TV antennas" are designed to receive the UHF band and and 
essentially ignore the VHF band.  This might be why your test 
connection  to your TV did not pick up WBBM.  Could also because the 
antenna was pointed in the wrong direction, there's a skyscraper in the 
way, there's a metal support beam in the signal path, etc., etc.  You 
might be able to get around with moving your present antenna, using a 
coupler to add a rabbit ear antenna to your present antenna, or if the 
coupler creates problems you probably need to get a UVSJ like I talked 
about in a previous message.

OK, back to that chart from  WBBM.  (Actually it's a pretty good example 
of a few other things!)

Subchannels section.  They're all the same main channel, just 
different.  I sort of think of it as the SCA signal In FM but most 
people go 'huh?'.  Sloppier example but workable would be the left and 
right channels in FM Stereo.  The left channel is Channel 2.1 and the 
right channel is Channel 2.2.  (Oh there are so many things technically 
wrong!!)

I'm going to go on to the Translators part.  For whatever reason WBBM 
has their main signal at Digital Channel 12 (VHF) but they are also 
transmitting at Digital Channel 26, which is a UHF frequency. You might 
be able to receive them at RF 26 but not RF 12.

Not trying to confuse the issue but we have a similar translator issue 
here in the Quad Cities.  (Yes, I'm 180 miles west of you: Davenport, 
Bettendorf, Iowa; Rock Island and Moline in Illinois.) WHBF is Channel 4 
and is transmitting on VHF Channel 4 at the Bettendorf IA antenna farm.  
They have problems getting that signal into Rock Island (which is 
'funny' because their studios are in Rock Island) and so have a second 
transmitter at Channel (RF) 47.  We don't quite have those billion-story 
skyscrapers <g> but the reception issues have the same effect.

Here at the house I pick up Ch 4 with no problems -- the transmitter is 
about 2 miles away.  I can also usually pick up Ch 47 which transmits 
about 4 miles away (lower power, directional).  The 'fun' part is some 
TVs will see two 4.1's, 4.2, 4.3, and 4.4, some display as 4.1 (etc.) 
and 47.1 (etc.), and other TV combine: I have "4.1" but it could be 
picking up 47.1.  (Good news: in the Backend my HVR-1600, HVR-2500 and 
HVR-950Q kept the two separate as 4.x and 47.x.)

Back to WBBM, I'm also seeing where it appears both of WBBM's channels 
are being simulcast on WMEU's 32.3 and 32.4.  I'm not quite sure what 
station 48.3 and 48.4 are -- WMEU might have a translator.



Somewhere it was stated you have a PVR-150 and other responses said it 
was an analog tuner.  Won't work because it doesn't know what to do with 
digital signals.  Hauppauge's HVR-950Q is a pretty good digital tuner.  
I'd probably pick up a few, plug them into a powered USB hub, and plug 
the hub into a rear panel port.

I mention I'm using HVR-1600 and HVR-2500.  The 1600 is PCI and has a 
single tuner.  The 2250 is PCIe and has dual tuners (two tuners in one 
board).  I don't recall what available slots are on your motherboard.  
I'm not sure if these would be a good option: they were really good when 
I purchased but that was years ago.  Tuner sensitivities have improved 
since then.  Go with the advice of the others.

Barry




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