[mythtv] [mythtv-commits] Ticket #2060: US cable frequency tables incorrect

[Michael T. Dean]

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