Cable Carriage of Local Stations on Channel Numbers Other than Their OTA Numbers

[Joey1986]

For example, on my Time Warner system in L.A., KCET (PBS) is carried on channel 6, even though over the air, it's 28. How does this work?

 

[w9wi]

For example, on my Time Warner system in L.A., KCET (PBS) is carried on channel 6, even though over the air, it's 28. How does this work?

The cable system can buy "frequency converters" which will convert any OTA station from its broadcast channel to any other channel.

Actually, most larger cable systems receive a fiber feed directly from the TV station and have their own modulators determining what channel the station will show up on on cable. The system may choose any channel they want.*

And since the OTA signals went digital in June, often an OTA station isn't really transmitting on the channel you think it's transmitting on. KCET is actually a bit unusual in that it actually is transmitted on the same channel you punch in to view it. KNBC is a more common case -- you may know them as "channel 4", and you may punch in "04" to watch them, either on cable or OTA, but they're actually broadcast on channel 36...

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In the early days of cable, many systems offered only 12 channels, 2-13. UHF stations like KCET 28 could not be carried on their OTA channel numbers, because cable channel numbers above 13 simply did not exist -- the cable system's hardware would not transmit such channels. In Madison, Wis. where I was in the 1970s and 1980s, channels 15 NBC, 21 PBS, and 27 ABC were on cable on channels 5, 11, and 7 respectively. People in Madison are used to tuning to channel 5 to watch NBC; today there's no technical reason cable couldn't carry NBC-15 on channel 15, but it would confuse the heck out of viewers who've been tuning to 5 for decades...

Carrying a VHF station on its OTA channel number could lead to "ingress" interference.** The OTA signal leaks into the cable and interferes with the cable signal on the same frequency.*** You get a pretty nasty "ghost". Now that the OTA signals are digital, instead of the ghost, the cable signal appears to be much weaker than it really is -- much "snowier".

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* within guidelines established by the FCC which, to somewhat oversimplify, suggest OTA stations must be carried on their OTA channel or some other mutually-agreeable channel.

** For channels 2-6 this pretty much ceased to be a problem when OTA signals went digital in June. Few stations are using OTA channels below 7 - KNBC may call itself "channel 4" but it's actually broadcast on 36 and thus cannot interfere with a signal on cable channel 4. KCBS is on 43 and KTLA on 31.

*** For this reason, it's my understanding it's illegal for a cable system in Canada to carry a station on a channel used by an OTA signal in the same area.

 

[azumanga]

Carrying a VHF station on its OTA channel number could lead to "ingress" interference.** The OTA signal leaks into the cable and interferes with the cable signal on the same frequency.*** You get a pretty nasty "ghost". Now that the OTA signals are digital, instead of the ghost, the cable signal appears to be much weaker than it really is -- much "snowier".

The Largo area of Pinellas County, FL is served by Bright House's south county system, which carries WTSP channel 10 on channel 10. Largo is roughly 15 miles away from WTSP's Holiday transmitter to the north. Living in that area and getting the south county line-up, I've very rarely gotten a clear picture on channel 10, because of co-channel interference. It's this reason that the north county system, which includes areas surrounding Largo on all sides, carries WTSP on channel 12, instead of 10.

*** For this reason, it's my understanding it's illegal for a cable system in Canada to carry a station on a channel used by an OTA signal in the same area.

I don't know if such a law does exist, or if it's enforceable -- Videotron's systems in Montreal and Quebec City have most, if not all, of 2-13 occupied, though in most cases, the channel position is occupied by an American channel or a "throw-away" -- for instance, Montreal's Videotron analog system as WETK on cable 6 (the OTA channel for CBMT), and "TV Achats" (a shopping channel) on cable 10 (where CFTM is over the air).

In 2001, while vacationing in Ottawa, the Rogers system had American channels on the channel positions as the local OTA channels -- for instance, Rochester's WOKR (WHAM) was on channel 13, where CJOH broadcasted over the air. Of course, due to the questionable cable wiring where I stayed at, many of the upper cable channels were snowy or untunable, and WOKR had CJOH bleeding in.

 

[DToTheJ]

Two words: Fort Myers.

 

[JayR]

Two words: Fort Myers.

You beat me to it.

Cable channel 11 would always experience OTA signal leakage from WINK TV's former analog channel 11.

Getting back on topic...

The stations started identifying themselves exclusively by their cable channel placement numbers around early-to-mid-90s.

 

[Gregg]

Re: Cable Carriage of Local Stations on Channel Numbers Other than Their OTA Num

>>>*** For this reason, it's my understanding it's illegal for a cable system in Canada to carry a station on a channel used by an OTA signal in the same area.<<<

I think w9wi meant that it's not permitted for a Canadian TV station to be carried on cable on its over-the-air channel within its home community. Not that no programming can be carried on a channel that's being used by a local TV station.

For instance, in Toronto, CBLT 5 is I believe carried on Channel 6 and CFTO 9 is carried on 8. Other programming is carried on cable channels 5 and 9. But CHCH 11, a station from Hamilton, 40 km away, IS carried on cable in Toronto on 11. I guess that's far enough away not to cause interference. However, in Hamilton, CHCH is NOT carried on Channel 11.

A friend of mine was living in Syracuse some years ago and I was surprised to see that his cable system at the time had all the over-the-air channels one channel higher than they broadcast. So channels 3, 5 and 9 showed up on 4, 6 and 10 on his cable system.

But I think today's cable systems can better protect against ghosts so the Syracuse cable system back in the 90s rearranged the channels, with the VHF stations being seen on their over-the-air channel position. Of course, with all analog TV signals now turned off, the problem no longer exists in the U.S.





Gregg
[email protected]

 

[fybush]

Re: Cable Carriage of Local Stations on Channel Numbers Other than Their OTA Num

Of course, with all analog TV signals now turned off, the problem no longer exists in the U.S.

Tell that to my upstairs TV sets, which get terrible ingress from WHEC-DT 10 and WHAM-DT 13 (on RF 10 and 13, respectively) that manifests itself as snowy pictures on the analog cable feeds of WHEC and WHAM (on 10 and 13, respectively).

It's better than it was in the analog-against-analog days, and the ingress issue on WROC-TV 8 is gone completely, since WROC-DT is on RF 45, but the problem most certainly continues to exist in some areas.

 

[recto101]

For example, on my Time Warner system in L.A., KCET (PBS) is carried on channel 6, even though over the air, it's 28. How does this work?

Look in San Francisco KNTV (NBC) is on Channel 11 on Dish, Directv and on DTV but on Comcast its on channel 3

 

[radiorob2.0]

The cable system serving Richmond, Kentucky placed the OTA on the corresponding cable channel. This was the case until the late 80's when they added the new independent and for a moment replaced Cincinnati with Louisville.

Lexington 18, 27, 36 and 46
Cincinnati 5, 9, 12, 19
Louisville 32 & 41

When WDKY was placed on Channel 12 when they signed on and Channel 19 was removed.

Around 1990, the Lexington stations requested the larger cable systems in the area to align their channels:

2-27
8-18
10-36
12-46

WDKY didn't request alignment until a few years later. In the last few years, Channel 27 moved to Channel 9 due to low band inference on some sets.

 

[stationless listener]

Re: Cable Carriage of Local Stations on Channel Numbers Other than Their OTA Num

I'm not a technician or anything of that type but looking at my locals: 2, 4, 5, 7, 9, 11, 13, 21, 25, 31, 41, 47, 63 and 68 are on their respective positions in the cable lineup.

48 is on 91
50 is on 165
54 is on 98
66 is on 96

I don't get WSAH, WNYN or WPXO.

The only channels where there's an issue with PQ are 9 and 25, IMO. Then again, I mostly watch for sports, so I can't vouch for the PQ of the rest.

 

[w9wi]

Re: Cable Carriage of Local Stations on Channel Numbers Other than Their OTA Num

>>>*** For this reason, it's my understanding it's illegal for a cable system in Canada to carry a station on a channel used by an OTA signal in the same area.<<<

I think w9wi meant that it's not permitted for a Canadian TV station to be carried on cable on its over-the-air channel within its home community. Not that no programming can be carried on a channel that's being used by a local TV station.

What I meant was that it's not permitted for any station that's required to be carried to be carried on a channel that has an OTA signal.

IOW, yes, if you're a cable system in Toronto you can't carry CBLT 5 on cable channel 5. Nor can you carry it on cable channel 9. (because of CFTO) You could carry WKBW on channel 5 or 9, because it's not a required signal.

But I think today's cable systems can better protect against ghosts so the Syracuse cable system back in the 90s rearranged the channels, with the VHF stations being seen on their over-the-air channel position. Of course, with all analog TV signals now turned off, the problem no longer exists in the U.S.

Up until the very end of analog OTA, we had SERIOUS ingress problems in Nashville. (where VHF stations have been carried on their OTA channel positions for as long as I've been here, nearly 20 years)

Today the problem is a lot less, but it still exists with several people asking me why channels 5 and 8 are so snowy... channel 10 as well -- that's where my station's OTA digital signal is, though luckily our cable position is 4 so we're wiping out one of the educational access channels instead of ourselves...

 

[charlestondxman]

Well, in my area, around Charleston, the TV stations are all carried on the big local cable systems (Comcast and Knology) on different channels. NBC 2 (used to be ABC) is on 3, FOX 24 is on 6, ABC 4 (was NBC) is on 8, and CBS 5 is on 9. ETV 7 (PBS) is on 11, and My (36) is on 13. It's been that way as long as I can remember, as it's like that in the metro area.

ESPN, TNT, the Weather Channel, and a local channel get lots of interference from local stations on older TV sets, but newer sets don't cause these troubles.

Farther away from Charleston and on satellite, the stations are carried on their respective channel numbers.

 

[mjlarochelle]

There isn't a station in Canada that is carried locally on cable on the same cable position as the OTA channel - however, one doesn't have to go far out of the originating community to find it in the same position. In Belleville, CJOH Ottawa is carried on Cable 6, and it broadcasts on Channel 6 from a rebraodcast transmitter just southeast of the city near Deseronto. CHCH Hamilton is carried on Cable 12 in Hamilton, but it is on Cable 11 almost everywhere else.

One of the quirks of this has come out with TVO and Global. In virtually every community in Ontario, they are carried on Cable 2 and 3, respectively. But in Barrie, Global can't use Cable 3 because CKVR broadcasts locally on Channel 3; they use Cable 13 instead. There are also a few places where TVO is not on Cable 2.

 

[azumanga]

One of the quirks of this has come out with TVO and Global. In virtually every community in Ontario, they are carried on Cable 2 and 3, respectively. But in Barrie, Global can't use Cable 3 because CKVR broadcasts locally on Channel 3; they use Cable 13 instead. There are also a few places where TVO is not on Cable 2.

However, in Windsor, TVO is seen on cable 2 -- and was subject to interference from WJBK across the river. The Cogeco system (and is predecessors) had WJBK on cable 7 instead, but it was hard to watch in some areas, due to WXYZ.

 

[BRNout]

It seems like the cable systems with the oldest hardware are most susceptible to the issue of interference. The systems with newer hardware are less prone to signal leakage and only tend to see this kind of issue in the areas closest to the local stations' transmitters. Even there, my understanding is that traps can be installed to deal with the issue. Of course now, with all stations having gone digital, such interference is even more unusual.

Most cable systems in places I've lived over the past 10 or so years have offered VHF locals on their original channel numbers and we've rarely had an issue. On the other hand, I sure do recall having cable in the late 80's and 90's where the interference was a real issue. In a couple of cases, the cable system dealt with it (likely after receiving thousands of complaints) by moving the station in question by one channel and replacing it with something like a community bulletin board.

 

[fybush]

It seems like the cable systems with the oldest hardware are most susceptible to the issue of interference. The systems with newer hardware are less prone to signal leakage and only tend to see this kind of issue in the areas closest to the local stations' transmitters. Even there, my understanding is that traps can be installed to deal with the issue. Of course now, with all stations having gone digital, such interference is even more unusual.

A lot depends on the geography of the market. Here in Rochester, we have a worst-case scenario: all of the city's TV transmitters are on short towers right in the middle of a very populated area, less than a mile from downtown. "Traps" aren't going to do any good on a cable-ready TV when the TV itself is literally being bathed in RF from a 316 kW VHF signal that's 4000 horizontal feet away and maybe 250 vertical feet up.

Similar situations (urban tower, low antenna height, dense population) exist in other places, too - Washington DC comes to mind immediately, as does Seattle.

In other markets with dense population near the towers, there's at least the advantage of considerable tower height to get the worst of the RF near field above the market - Boston, for instance, has several hundred thousand people within a couple of miles of the towers, but at least they're thousand-foot towers. Same deal in Cleveland and San Francisco. (That said, I still had nasty ingress problems in the nineties when I lived in Waltham, Mass., six or seven miles from the towers; much of that was probably attributable to an ancient and very poorly-maintained TCI cable system.)

And as you move south and west into Zone II, the towers get much taller and generally more distant from the population center, making ingress even less of an issue.

 

[Neel]

that's what charter cable in the LA area does and now it makes sense. Without a cable box, KTLA 5 is on channel 6. I always wondered why they did this, but it's probably the signal issue.

It seems like the cable systems with the oldest hardware are most susceptible to the issue of interference. The systems with newer hardware are less prone to signal leakage and only tend to see this kind of issue in the areas closest to the local stations' transmitters. Even there, my understanding is that traps can be installed to deal with the issue. Of course now, with all stations having gone digital, such interference is even more unusual.

Most cable systems in places I've lived over the past 10 or so years have offered VHF locals on their original channel numbers and we've rarely had an issue. On the other hand, I sure do recall having cable in the late 80's and 90's where the interference was a real issue. In a couple of cases, the cable system dealt with it (likely after receiving thousands of complaints) by moving the station in question by one channel and replacing it with something like a community bulletin board.

 

[KML0224]

Soon after the analog shutoff this past June, WFSB-DT (CBS) of Hartford was moved from analog channel 2 to analog channel 3 (we only have color bars on channel 2 now). Despite their old analog transmitter being up on Avon Mountain, I still would get occasional ingress from over-the-air 3 when tuning to analog cable 3. No such problems today!

Likewise, WTNH-DT (ABC) of New Haven was channel 8 for analog. It's been on cable channel 8 here in New Britain for seemingly forever (back to the 1980s). We're far enough from their Hamden transmitter, so it was never a problem.

 

[ohdxer]

When I was growing up in Columbus, Ohio back in the 1970's and early 1980's, we had Coaxial Cable for cable tv service in our neighborhood. WLWC/WCMH 4 was on cable channel 5, WTVN/WSYX 6 was on cable channel 7, WBNS 10 was on cable channel 11. I can't recall what channel WOSU 34 was on though.

 

[searadiofreak]

Two words: Fort Myers.

You beat me to it.

Cable channel 11 would always experience OTA signal leakage from WINK TV's former analog channel 11.

Getting back on topic...

The stations started identifying themselves exclusively by their cable channel placement numbers around early-to-mid-90s.

Not everywhere! Out west, most stations are still imaged with their OTA channel number, despite their cable position. I would say 90%.
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