# How does TV broadcasting work on a tech level?



## dpeters11 (May 30, 2007)

This is why I'm asking:

Our local FOX station lost power due to a blown transformer during Hell's Kitchen Thursday. They had a slide up that they were having technical difficulties, but a friend said that they still aired commercials.

They are reairing it on Saturday, but in SD only. They say they don't have the equipment to show it in HD. But they air things in HD all the time on the normal schedule including Hell's Kitchen.

So my questions are, how can a station lose power and not be able to air programming, but commercials play, and how can a station have the equipment to air all the normal programming in HD but can't do a reair in HD?


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## Davenlr (Sep 16, 2006)

Fox network sends its programs in a special format via satellite to affiliates, which allows them room to add one subchannel in SD. The local station can switch to the network feed for the HD programming, and back to their own feed in SD, but currently cannot air bottom third graphics over network HD programming (have to switch to the SD feed to slide a weather warning for example). They can air recorded HD material from sources for program distribution centers, but have no way to record the FOX network HD feed for rebroadcast in HD. Its just the way FOX chose to distribute their prime time programming. Until they come up with the hardware/software for the affiliates to manipulate their proprietary distribution method, there isnt any current broadcast equipment to do what you want them to do. 

As for how the commercials run, if the power knocked out the network feed, it probably didnt knock out the control room, which was on backup power, so they could air locally generated material, but not network feeds. Perhaps their receiving site is away from their control center, and only the receiving site lost power. Surprising they dont have it on backup power though.


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## Nighthawk68 (Oct 14, 2004)

I am not 100% sure on this, but I heard something about this a while back. The 1st run primetime shows from FOX, CBS, NBC & ABC come in HD from the network and go thru a type of repeater, but the re-runs are archived at the station and thus goes thru the stations equipment, not that repeater (not sure if thats the correct term).

This happens here in northern Michigan alot, all primetime or 1st run shows, AM, afternoon (some) & PM are HD, but everything else is only SD. Like Two and half men on our CBS station at 7:30 is SD, even though the guide says HD.
As it was explained to me, the station itself hasn't gone HD, only digital. Local news is only SD and 4:3 ratio. They also havn't figured out how to overlay weather warnings with HD, and HD broadcasts will switch to SD in the middle with a weather warning. VERY annoying.

Hopefully someone else with more knowledge here can chime in further.

Ed


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## dpeters11 (May 30, 2007)

Thanks. The local Fox does do their local news in HD, so that added to my confusion, but this makes some sense.


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## BattleZone (Nov 13, 2007)

It's a simple question of money.

The equipment alone to convert a station to HD is in the neighborhood of $3-10 million or more. Then many other things have to be upgraded, such as feeds from various sources (analogous to upgrading your computer from dial-up to a cable modem). And then there's the problem of dealing with decades of archive material. And don't forget one of the other BIG costs: training everyone to use the new equipment properly.

It's a lot more complicated than most folks realize, because ALL of that equipment has to work seamlessly with the stations automation system (almost nothing at a TV station is done live; it is all programmed in advance on a rigid schedule).

So, because the expense is so high, many local stations around the country simply don't have the budget to go HD at the station. They just had to pay to change to digital broadcasting, but can still use their analog SD equipment for everything internal to the station. And, most stations can "pass-through" the live HD broadcasts from the network, but their own archiving equipment is still SD-only.

These stations may need years to save the necessary funds to afford the transition to HD for local content. It ain't cheap.


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## dpeters11 (May 30, 2007)

BattleZone said:


> These stations may need years to save the necessary funds to afford the transition to HD for local content. It ain't cheap.


That's for sure. Like I mentioned in my last post, our Fox is HD for local news. But it wasn't until earlier this year that our local CBS could pass 5.1 audio. You got HD video, but audio was 2.0 stereo.


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## Nighthawk68 (Oct 14, 2004)

Our ABC, CBS, NBC & FOX are 2.0 audio, PBS is 5.1 and has the most HD content of all our locals. ABC, NBC & FOX were originally 5.1 audio, but switched to 2.0 with no explanation.


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## Stewart Vernon (Jan 7, 2005)

I forget now for sure which ones... but some of our local stations have the ability to archive, and thus can show delayed OR syndicated HD programming.

Other local stations didn't have the money to invest in that... so they can show live broadcasts from the network feeds in HD... but not syndicated or delayed stuff.

A really good example is our local CW station and local ABC station. Our local ABC station can do syndicated and delayed stuff in HD... and they do their local news in HD.

Our CW station carries the CW programming in HD... BUT at 10pm they run a special version of the "ABC11 10pm news" provided by the ABC station, which shoots in HD... but the CW station can't use that and has to broadcast it in SD instead.


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