[mythtv-users] Question about Channel frequency tables...

Brian Wood beww at beww.org
Tue Apr 13 01:07:56 UTC 2010


On Monday 12 April 2010 06:48:14 pm Steven Dennis wrote:
> Hello all.  New to Mythtv, Linux, and the United States TV industry so
> I've been swimming in water much too deep.  I'm having a little
> trouble understanding the channel frequency tables that mythtv allows
> you to chose from.  I would like to understand the difference between
> the following:
> us-bcast (OTA broadcasts)
> us-cable-hrc
> us-cable-irc
> What are the frequency ranges on each of these?

http://www.csgnetwork.com/tvfreqtable.html

There are also HRC and IRC cable frequency assignments, if you are tuning a 
cable system and they are using one of those schemes you will have to adjust 
accordingly. This only matters if you are tuning cable TV channels (analog or 
digital), and usually only with a couple of channels (4 and 5 often).

The origin of HRC/IRC is obscure, and complicated as it involves marketing and 
technical issues. Google around if you're interested.

Essentially if you are receiving from an antenna  you need to select 
"broadcast", if using a cable system, wither STD, HRC or IRC cable channel 
frequencies.


> Do these include digital as well as analogue?

There should be no analog through the air, but you may encounter it from a 
cable TV wire, and also from devices like STBs, DVD players etc. putting out 
analog channel 2/3/4 to drive a TV set.

> 
> Second
> If I am in the US do I need to worry about any digital modulation besides
>  ATSC?

Not with signals from an antenna, if you connect to a cable TV wire you will 
encounter QAM, and probably some analog NTSC. QAM is often encrypted, NTSC 
rarely is these days (actually NTSC channels can be "scrambled", but not 
really encrypted).

Welcome to the Wonderful World of the FCC-Regulated Country, and MythTV. I 
much prefer the latter.



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