How is the transmitter system in the US structured?

[Sammi Brie]

We Americans are lucky in that we still have abundant localism in television, but even here it feels worse than it did in 1994. Too much corporate for my tastes.

Even Canada and Australia are...well, less than local.

 

[azumanga]

The idea of having say ITV on channel 8 in Liverpool and channel 6 in London would seem crazy to most Brits- because ITV is synonymous with channel 3- indeed we often say ' did you catch such-and-such-a-show on three last night?' meaning ITV.

Of course, with the arrival of BBC 3 and BBC 4, are you still understood when you say "3" or "4"? (I imagine "4" would always mean Channel 4, but has any confusion occurred between ITV (on 3) and BBC 3?)

Even Canada and Australia are...well, less than local.

These days, they now seem to follow the UK model -- everyone gets the same schedule, with the only variances being news and commercials.

 

[BMR]

What does it mean, then, when I see something like
BBC1 on C28 in Brougher Mountain?

I take it that was a technical document you were looking at?

C28 refers to the broadcasting frequency- which is 527.25mhz for the video and 533.25 audio, which actually corresponds to BBC2 analogue Brougher Mountain.

This is purely for the technical bods- with any vaguely modern (post 1990) TV these frequencies were hidden from the viewer by the auto set up in the TV set.* Digital Converter boxes hide this stuff even deeper, but some have a technical menu where you can view frequencies.

If you talk to the average viewer in Northern Ireland, and ask them "what is on channel 28?", they would proberbly reply "E4"- which is on number 28 on your converter box just as it is everywhere else in the UK. If they were still on analogue, they might say "channel 28?! We only get four channels!". Almost nobody would connect channel 28 and BBC2.


------------------------------

I can see how this dual meaning of the word "channel" would be very confusing for someone from overseas. Just consider whether what you are reading is a technical document for technicians (or geeks!) or a site for the general public.


* indeed it is so well hidden in many later analogue sets so as to make them useless for DXing and other anoraky pastimes.

 

[BMR]

The idea of having say ITV on channel 8 in Liverpool and channel 6 in London would seem crazy to most Brits- because ITV is synonymous with channel 3- indeed we often say ' did you catch such-and-such-a-show on three last night?' meaning ITV.

Of course, with the arrival of BBC 3 and BBC 4, are you still understood when you say "3" or "4"? (I imagine "4" would always mean Channel 4, but has any confusion occurred between ITV (on 3) and BBC 3?)

I can certainly see the potential for confusion, and ITV haven't helped matters either by launching a separate channel called ITV3! But ITV and channel 3 are so closely wedded in Brit's minds, it seems to be OK at the moment.

 

[w9wi]

In the UK, the transmitter network was built by what was effectively a government department, not the TV stations themselves. and was/is designed to give near-as-possible universal coverage of four analogue services. So you get all your analogue services from the same transmitter wherever you are, and that same transmitter network is now being converted to give near universal provision for the umpteen digital channels*

Do you have a similar system in the US? Do you get all the stations from the same transmitter, or do you have to rotate the aerial to get each of the networks? Have things changed with the introduction of digital?

Here, the transmitter network was built by the stations themselves. Largely for regulatory reasons. "Localism" has always been an important goal in U.S. broadcasting (at least for the government) and that's been a higher priority than universal coverage. Indeed, the government was quite slow in the 1950s to authorize relay transmitters, fearing they would make it economically impossible to develop local stations in smaller cities. (they finally gave up that battle when hundreds of relays were built without government authorization, and state governments threatened to block federal attempts to shut down the unauthorized transmitters...)

Federal regulations do encourage stations to locate their transmitters for a given area in proximity to each other. Local planning regulations have probably had more to do with that; it's MUCH easier to get a mast ("tower", over here) approved if it's near other existing masts. So yes, in most places you don't have to rotate your aerial ("antenna") to receive all the networks.

However, there's nothing to *force* stations to co-locate their transmitters. Here in Nashville, channels 2 and 8 transmit from a site ~8km south of the city center. Channel 4 transmits from ~8km west. Channels 5, 17, 28, 30, and 58 transmit from ~8km northwest. And two minor stations transmit from ~20km east. Rotators are rare but the installation of three receiving antennas on a single mast are fairly common. (actually, in the city most over-the-air viewers use indoor "rabbit ears" antennas.)

In some cases, in smaller cities especially, one or more of the major channels is actually authorized to serve some other city -- and thus, the transmitter must be located elsewhere. For example, Wausau, Wisconsin, where the ABC and CBS stations are authorized to serve Wausau and transmit from a mountain just outside the city. The NBC station, however, is authorized to serve Rhinelander about 100km to the north. The NBC transmitter is located between the two cities.

For the most part, things have not changed with digital. In the vast majority of cases, especially with the most commonly watched stations, the digital transmitter is located at the same site as the old analog transmitter. (in many cases, after an interim operation on a different frequency, stations are transmitting their digital signal **on the same frequency** as their old analog signal -- and thus can use their old analog transmitting antennas.)

In a few cases, due to changes in the regulations with digital, stations whose analog transmitters had to be at some distance from the city's other transmitters have been able to move to co-site with the other stations. However, this usually involves minor stations that almost nobody watches!

 

[w9wi]

A few fundamental regulatory differences between U.S. and U.K. broadcasting that I think may explain differences in the layout of our transmitter networks:

1. A U.S. broadcasting license conveys authority for only one transmitter. You can take out licenses for additional low-power relay transmitters, and/or for additional main transmitters which can be used to relay your one main transmitter. However, you will compete with other applicants for these frequencies.

2. Until very recently, a single firm could not control two or more main transmitters with overlapping coverage. Especially for TV. (the rules were relaxed for radio before they were relaxed for TV)

3. A single firm cannot control enough main transmitters to provide nationwide coverage. The rules are a LOT more lax today than they were for most of the post-WW2 period, but you still can't control enough stations to provide anywhere near national coverage. For MANY years, a given firm could only control seven main transmitters - obviously nowhere near enough to cover the entire U.S..

4. A licensee cannot delegate legal responsibility for its transmitter. I suppose it would be possible for a station to lease its transmitter from someone else. But it would be the station (not the lessor) that would be responsible to the government for the legal operation of that transmitter -- for keeping it on frequency, etc..

 

[w9wi]

Are you guys in the UK using DVB-T or one of the other systems? Over here we're using what is basically a horribly convoluted and hacked-up version of the proprietary Digicipher II.

I imagine we'd be on DVB-T right now, had the FCC's brains not been firmly planted in their wallets. ;o)

There really isn't a huge difference between DVB-T and the ATSC system in the U.S., beyond two elements:

- PSIP, the "metadata" system which appears to me to be far more capable under ATSC than under DVB.

- 8VSB modulation. The way the data is impressed onto the RF carrier is VERY different in the U.S.. To VASTLY oversimplify, the U.S. system is said to provide better coverage per watt of transmitted power; the COFDM system used by DVB-T is said to work better with indoor antennas.

 

[bpatrick]

All this is beginning to make sense, if I put myself into the
mind of a resident of the UK. But even our networks have,
in recent years, put more pressure on affiliates to carry all
network shows at the recommended time; they haven't been
totally successful (as we know, for example, from those stations
that carry "Young And The Restless" in late afternoon instead of
midday), but you don't see as many shows on delay as you once
did. And it sure isn't affecting localism, not when practically every
network affiliate (including Fox) is doing as much as 44 hours a week
of local news. Although I think a time could come when the
U.S. networks go to cable, in the meantime, affiliates try to get as
much time for themselves as they can (time they can sell to advertisers,
you know) and aren't going to give the networks as much control over
their schedules as you're saying is the case in the UK, Canada, or Australia.

 

[Darth_vader]

Also W9, remember that DVB-xyz systems have the option of using either MPEG 1 layer 2 audio tracks (similar to MP3) *or* AC3, whereas ATSC/DC2 are limited *only* to AC3.

Especially for DVB-S if received on a computer using some type of satellite receiver expansion kit, this makes it easy to listen to satellite audio transmisisons if they are in MPEG format. Even easier yet to save the audio stream directly to a file on your hard drive, then all you'd have to do is load them into your Winamp or whatever and you're set.

Many--but not all--of the MP3-capable devices and CD players will also happily play back MP2 files, provided you give them an MP3 extension. In fact, this is how I'd do it with the Muzak streams on Echostar 7--Set PVid to record it off the satellite, come back several hours later and have a nice, big several-hundred-megabytes file of continuous MP2 music waiting for me on my desktop. At that point I'd simply rename it as "filename.mp3", record it to a CD, drop it into my I-River and strap a pair of earphones firmly upon my cranium. (Then when Echostar decided to switch to Nagravision 3 a few years later Muzak decided to follow suit, and now you can't get any of that stuff free to air anymore, without having to do a little bit of work to get at it! But that's another story.)

With an AC3 stream, you have to convert between formats in order to really do anything useful with it, and even then it doesn't always seem to want to work right. (At least from my experiences with it, which haven't all been particularly pleasant....)

I don't have any specifics on hand right now (will try to look it up later, I am on a long-distance dialup line right now) but I think DVB-T works the same way, does it?

 

[alg2468]

An example of a TV station whose analog transmitter had to be located at a distance from its main coverage area due to interference was WLNE, the ABC affiliate on channel 6 for the Providence, RI area. The station had to locate its transmitter in Tiverton, RI, about 17 miles southeast of Providence due to close co-channel spacing with other channel 6's in Portland, ME (WCSH) and Schenectady, NY (WRGB) and adjacent channel spacing with channel 5 (WCVB) in Boston, MA. When WLNE's digital signal was chosen - on channel 49 - the digital transmitter could be located with several other Providence area stations in Rehoboth, MA, about 5 miles east of Providence.

 

[BMR]

[ Here in Nashville, channels 2 and 8 transmit from a site ~8km south of the city center. Channel 4 transmits from ~8km west. Channels 5, 17, 28, 30, and 58 transmit from ~8km northwest. And two minor stations transmit from ~20km east. Rotators are rare but the installation of three receiving antennas on a single mast are fairly common. (actually, in the city most over-the-air viewers use indoor "rabbit ears" antennas.)

That's another difference between the two systems. In the UK, many TV transmitters are away from the main city centres. For instance in Derby we get local radio from Drum Hill, 2 miles (3 km) north of the city centre. But the TV transmitters are many miles away.

Most Derbians either get their TV from Sutton Coldfield, 27 miles away (43 km), or Waltham which is even further- 31 miles or 50 km. That means good rooftop aerials are essential. Quite a few people use cable, although my street was built 8 years ago and still doesn't have it.

 

[w9wi]

That's another difference between the two systems. In the UK, many TV transmitters are away from the main city centres. For instance in Derby we get local radio from Drum Hill, 2 miles (3 km) north of the city centre. But the TV transmitters are many miles away.

Most Derbians either get their TV from Sutton Coldfield, 27 miles away (43 km), or Waltham which is even further- 31 miles or 50 km. That means good rooftop aerials are essential. Quite a few people use cable, although my street was built 8 years ago and still doesn't have it.

It's not at all unheard-of for American stations to operate transmitters outside the city. It would have been legally possible under the analog rules to be as far as 58km from the furthest border of the city served, though I can't think offhand of any transmitters quite that far away. The transmitters serving Sacramento, California are about 20km out from the city center; Mobile, Alabama and Pensacola, Florida are served by a common set of transmitters -- the cities are about 80km apart. There are plenty of other examples.

Availability of cable is nearly universal in urban and suburban areas, and quite common in rural areas. Generally, only the most rural locations are unable to get cable. (and of course they have access to satellite services)

Rooftop aerials are becoming scarce around here. Most people consider them unsightly and will subscribe to cable if indoor aerials don't deliver adequate reception. Some communities have attempted to *prohibit* rooftop antennas, though federal law greatly limits the ability of local governments (and property deed restrictions) to do so. It's difficult to buy an outdoor antenna locally -- you generally have to order them online/by telephone -- and install them yourself, most of the installers have retired.

*Radio* transmitters are all over the place. Many of the largest FM transmitters are co-located with the major TV stations -- but many aren't. Of the 32 FM stations in the Nashville radio market, only *ten* are actually licensed to serve Nashville. The rest theoretically serve other cities -- Lebanon, Murfreesboro, Gallatin, Pegram, even one town in Kentucky. In fact, they target Nashville, but they're required by the government to provide a "70dBu signal" across the city they're actually licensed to serve. 101.1, the station authorized to Russellville, Kentucky, cannot transmit from the TV-2 tower south of Nashville because they couldn't deliver enough signal across Russellville from there. (even though nearly all the station's listeners are in Nashville)

It's been difficult to share AM (MW) sites here. (not that it doesn't happen, but it's relatively rare) Most stations with more than trivial nighttime power must use directional antennas to avoid interference. Many sites are even directional during the day. While you *can* share a site among multiple directional transmitters, it's difficult and not very common. IIRC, there are only two shared sites (with only four transmitters) here in Nashville, among 21 MW frequencies in the area.

 

[BMR]

Availability of cable is nearly universal in urban and suburban areas, and quite common in rural areas. Generally, only the most rural locations are unable to get cable. (and of course they have access to satellite services)

That's another area where the UK system falls down. Cable in the UK never really took off, and just as it was finally warming up in the 1990s, along came Sky Satellite TV who went very agressively after subscribers.

There has been no new cable build in ages. Near me, the town of Burton-upon-Trent (pop 60,000) has no cable TV, and Sky dishes are every where. I think there are even odd corners of London with no cable telly!

 

[w9wi]

That's another area where the UK system falls down. Cable in the UK never really took off, and just as it was finally warming up in the 1990s, along came Sky Satellite TV who went very agressively after subscribers.

There has been no new cable build in ages. Near me, the town of Burton-upon-Trent (pop 60,000) has no cable TV, and Sky dishes are every where. I think there are even odd corners of London with no cable telly!

I would imagine the timing of Sky had everything to do with that.

The infrastructure costs of a cable plant are astronomical. In theory we're supposed to have cable competition in the U.S. (the ability for more than one cable operator to operate in the same city) but in practice it's been pretty rare. (telephone companies are now beginning to light up competing systems over fiber, but I suppose that's because they're seeing their landline phone business drying up & figure providing television is the only way to keep those poles bringing in money)

If satellite TV had launched in the U.S. within say, five years of the first cable operators, I'd bet cable would be a lot rarer here as well. But cable got launched at almost the same time as TV itself, and satellite simply wasn't technologically possible until cable had a 30-year head start.

The dishes have been a bit of a local political punching bag as well, with a number of communities and, especially, housing developments trying to ban them as well, for aesthetic reasons. The same federal regulations that prohibit a ban on regular aerials also prohibit a ban on dishes.

 

[mjlarochelle]

Canada used to have a US-style system, except where CBC was concerned - CBC itself owned a large number of stations from the beginning, but there were always affiliates of that network and CTV. Back in the 1970s, there was an excellent system and Canadians were served well from coast-to-coast.

The problem was, localism wasn't as much of a priority for Canadian regulators as it was for American regulators. The big priority for Canadian regulators was "Canadian content" regulations. The CRTC didn't have the guts to say "no" to broadcasters wanting to acquire as many stations as they could or to open rebroadcast transmitters in far-flung locations.

 

[vchimpanzee]

These now reside in the UHF spectrum, as lof-VHF was abandoned for digital TV broadcasting.

If only.

 

[BMR]

Above people have told me how rare over-the-air is getting, and how most people use satellite or cable. Cable is obviously local. How do satellite viewers get their 'correct' affiliates? Surely they don't broadcast them all on direct-to-home satellite?

 

[tripinva]

They're locked out by ZIP code.

- Trip

 

[BMR]

They're locked out by ZIP code.

- Trip

So they are all broadcast (thats a *lot* of affilates!), but you can only view your local one? Or can you choose?

 

[fybush]

They're locked out by ZIP code.

- Trip

So they are all broadcast (thats a *lot* of affilates!), but you can only view your local one? Or can you choose?

They're all broadcast, but on narrow spot beams, so transponder frequencies can be reused many times across the country. You can only (legally) get the affiliates that are "local" to your area. That's determined by Nielsen's Designated Market Areas (DMA), and each zip code is in one and only one DMA.