[mythtv] [mythtv-commits] Ticket #2060: US cable frequency tables incorrect
Michael T. Dean
mtdean at thirdcontact.com
Fri Jul 21 19:29:53 UTC 2006
On 07/21/2006 02:06 PM, Daniel Kristjansson wrote:
>The variability in published tables on this is absolutely maddening.
>The FCC offsets you explained probably explains some of it and the
>bttv 62.5kHz limitation explains some of it (at least in the software
>I've looked at), but the rest of the variability seems unexplainable..
>
Yeah. As far as the "specifications" go, the FCC "Numerical designation
of television channels" (47CFR73.603) is available (for free) at
http://frwebgate.access.gpo.gov/cgi-bin/get-cfr.cgi?TITLE=47&PART=73&SECTION=603&TYPE=TEXT
and gives the channel number for each frequency band. All our
ntsc_bcast frequencies are 1.25MHz higher than the lower boundary of the
band, so I'd say we can write them off as correct.
Myth's ntsc_bcast table, however, gives frequencies for channels 70-83,
but the FCC list doesn't because that frequency range (806-960MHz) was
reallocated for mobile radio services in 1970 under 35FR11179 (I
couldn't find it online, but the reallocation is referenced in
http://www.fcc.gov/omd/history/radio/documents/short_history.pdf ). It
probably doesn't hurt to leave them in there, but let me know if you
want to clean them out.
For cable (standard, HRC, and IRC), the EIA/CEA-542-A "Cable Television
Channel Identification Plan," has been in use for US cable TV since
1997, and is available from
http://global.ihs.com/doc_detail.cfm?currency_code=USD&customer_id=2125464C5C0A&shopping_cart_id=282528372E4A40344E5A3D302C0A&country_code=US&lang_code=ENGL&item_s_key=00160646&item_key_date=060321&input_doc_number=EIA%2D542&input_doc_title=
. If you'd like, I can buy a copy (it's only $30--not one of those
$10,000 ones :). I tried to see (using a Google search) if any of the
"usual suspects" (ivtv, V4L, etc. projects) mentioned having a copy, but
didn't see anything.
I would guess that the DVB guys working on ATSC have it since they
actually use "EIA-542" in their frequency table filenames... So, if you
have some contacts there, you might be able to get them to verify our
list or guarantee theirs or...
Mike
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