Questions about DTV core channels

[thathoustonradiogeek]

After NTSC broadcasts are discontinued in February 2009, how many channels will remain?

I keep reading that they will be either 2-51 or 7-51.

Reference link (old, from circa 1998) :
http://www.fcc.gov/Speeches/Furchtgott_Roth/Statements/sthfr804.html

My questions are:

1-Will they be renumbered 1-50 or 1-45?

2-Supposing that channels 2-6 are reassigned to other services, what would a TV station which has both signals on out of core channels (example: WKMG Orlando ATV ch 6/DTV ch 58) do? Move to a third channel vacated by another station after the switch is over? (Most logically.)

3-This is more of wishful speculation: If the FCC decides to reassign the frequencies of channels 2-6 then the 12 MHz from 76-88 (ch 5 & 6) could be used for LPFM, thus putting an end to big broadcasters argument that LPFM will causes interference. Yes, I know. I didn't call it "wishful" for nothing. :

Thanks in advance.

 

[Julius Leonard Marx]

My wishful thinking: Assign channels four and five to an expanded FM band.

 

[thathoustonradiogeek]

After NTSC broadcasts are discontinued in February 2009,
...

I can't seem to find the "modify Post" link

Anyway I have another question:

4-Can 2 different full power DTV stations operate on adjacent channels without interfering with each other?

Edit: So, topic starters can't be edited? hmmmmmm

 

[pabsungenis]

Whether "full power" or not is debatable, but we do have DTV stations in the Philadelphia market operating on adjacent channels, WUVP-DT 66 and WCAU-DT 67. Those two, however, have antennas in different locations (Waterford Works, NJ and Roxborough, PA) which might cut down on interference.

The final assignments after switchover once again have WCAU-DT on the first adjacent of another channel: WYBE-DT (at 34 and 35, respectively). Those anntennae are closer to each other, but still not in the same location.

I would imagine the error correction of ATSC would cut down on adjacent channel interference, but I'm not certain it could rule it out entirely if one transmitter or the other isn't properly tuned.

 

[w9wi]

After NTSC broadcasts are discontinued in February 2009, how many channels will remain?

I keep reading that they will be either 2-51 or 7-51.

http://www.fcc.gov/oet/faqs/dtvfaqs.html
You're interested in the 13th question, "Question: What are the channel assignments for digital television?"

The answer is 2-51.

My questions are:

1-Will they be renumbered 1-50 or 1-45?

They will not be renumbered - they will remain 2-51. However, as a viewer you will see the station's old analog channel number. For example, here in Nashville the CW is on CW58, WNAB-TV. WNAB's analog assignment is channel 58; their DTV is on channel 23. WNAB will not change digital frequency when the transition happens in a year - their digital signal will remain on channel 23. However, to watch WNAB you will continue to punch "58" on your remote. Your TV will maintain a lookup table that says to tune to channel 23 when the user presses 58.

Of course this applies only to OTA reception. If you have cable or satellite then it's up to the cable/satellite operator.

2-Supposing that channels 2-6 are reassigned to other services, what would a TV station which has both signals on out of core channels (example: WKMG Orlando ATV ch 6/DTV ch 58) do? Move to a third channel vacated by another station after the switch is over? (Most logically.)

Since channels 2-6 will remain "inside core" the specific example doesn't happen, but there are other examples. Situations where both the station's analog and DTV channels are above 51. One example is WGBO in Joliet, Ill. whose analog assignment is 66 and interim DTV is 53.

And your presumption is correct. WGBO will take over the channel 38 assignment being abandoned by the analog signal of WCPX Chicago. WCPX's digital signal will remain on its current channel 43.

Stations that *don't* have an outside-core problem are also being allowed to negotiate for channels abandoned by other stations. And actually, WKMG is an example of this. Rather than return their DTV operation to channel 6 after transition, WKMG has negotiated to use the channel 26 assignment being abandoned by WVEN in Daytona Beach. (WVEN-DT will remain on channel 49)

3-This is more of wishful speculation: If the FCC decides to reassign the frequencies of channels 2-6 then the 12 MHz from 76-88 (ch 5 & 6) could be used for LPFM, thus putting an end to big broadcasters argument that LPFM will causes interference. Yes, I know. I didn't call it "wishful" for nothing. :

I think this is very unlikely to happen, and in any case listeners are unlikely to go out of their way to buy new radios just to get LPFMs.

Personally I think the FCC should allow digital radio operation in all low-band VHF channels 2-6, as a secondary service to DTV. In most parts of the country there are no DTV stations on these channels, and nowhere (except Butte, Montana) is more than one of these channels in use. The channels could be used for HD Radio in full-digital mode, at least as an alternative to hybrid mode on AM frequencies. (where about all it's accomplishing is the generation of interference)

4-Can 2 different full power DTV stations operate on adjacent channels without interfering with each other?

Yes, if they're close enough together. (so that their signal strengths are similar at most receiving points)

The FCC did try to avoid this, but they didn't always succeed.

 

[thathoustonradiogeek]

Thank You for your replies.

The way I see it then, the reassignment of ch 2-6 is just at the "toying with" stage at the FCC.

I guess then that WKMG's moving to a 3rd channel is a form of "insurance" should the reassignment ever happen.

I hope that, when and if it does happen, there will be smarter people leading the Commission.
(place praying/hoping icon here).

 

[pabsungenis]

No, WKMG's moving is an example of self-preservation. While 2-13 are remaining "in core," VHF is bad for ATSC television, and 2-6 is VERY bad for ATSC. Those channels are much more subject to noise and weaker signals, and the smart engineers talked their management into switching to UHF.

 

[w9wi]

The way I see it then, the reassignment of ch 2-6 is just at the "toying with" stage at the FCC.

Depends on who you think they're toying with reassigning it to . I think the only three services that have any interest in that spectrum are TV broadcasters, would-be LPFM/microcaster/community radio broadcasters, and hams. There has been no formal proposal before the FCC to reassign it to anyone except TV broadcasters, and I think there'd be serious opposition to any move to reassign it to anyone else with the possible exception of "regular" non-commercial broadcasters. (who have not expressed interest)

I would be very surprised if in ten years there's anything there except TV stations.

I guess then that WKMG's moving to a 3rd channel is a form of "insurance" should the reassignment ever happen.

I don't think WKMG was worried about channel 6 getting reassigned.

There have been well-publicized problems in Chicago with noise (power lines etc. & lightning) and interference (inadequately-shielded computers, "skip" of other TV stations, etc.) making reception of WBBM-DT difficult. WBBM drew DTV channel 3. These problems are FAR worse at low-band VHF than at channels 7 and up. The FCC made special provisions for stations that wanted to leave channels 2-6 to do so, and WKMG took them up on it. (as did WBBM, which negotiated an agreement to use channel 11 for their permanent DTV facility)

Probably the other major-market low-band DTV assignment is channel 2 in Cleveland. I haven't heard much about that one one way or the other. I've heard reports that channel 3 has actually worked pretty well in Roanoke, Va...

I hope that, when and if it does happen, there will be smarter people leading the Commission.
(place praying/hoping icon here).

Couldn't get much worse

The Commission is far more political in the last five years or so than it was in the 35-year period I've been following it. Though the problems are not 100% the FCC's own fault: when the Commission decides the science simply doesn't justify the rules the industry wants, the industry goes to Congress & gets them to order the FCC to ignore science & enact the rules anyway.

 

[azumanga]

when the Commission decides the science simply doesn't justify the rules the industry wants, the industry goes to Congress & gets them to order the FCC to ignore science & enact the rules anyway.

And eventually, reality comes and shoots the industry in the foot -- take a look at AM radio and IBOC, for instance. The stations wanted to use IBOC at night, as well as during the day (which already caused enough trouble), and look what happened.