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Anyone have any idea how many transponders are not being used currently? Seems like all the talk about adding more channels won't lead up to much if they don't have transponders to send it out with. From what I've read they get about 8 regular channels per transponder, but only 1 or or maybe 2 HD channels. Is this correct? I guess they could eliminate some pay per view channels???


This shows the transponder usage for 101:
http://www.dbsforums.com/dbs/DTV101.htm


101-24 is HD PPV (nothing else on the transponder)



What else was on transponder 24 before HDPPV started, or do they remap all the channels frequently?
 

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kwerner,

Quote:
Anyone have any idea how many transponders are not being used currently?
There are probably 1.5 - 2.0 transponders available right now, enough for two to six HDTV channels. However, more capacity will free up at 101 later this year, when DirecTV completes its two new uplink centers. That will enable them to move more locals to spots and/or use more spots with fewer transponders per spot. Then, in December, DirecTV will launch its DirecTV-7S satellite, which will enable them to move the locals currently on 119 CONUS to spot beams, thus freeing up several additional transponders.


In all, thanks to these new uplink centers, and the DirecTV-7S satellite, they should have five to six new transponders available for HDTV by January or February of next year, sufficient for up to twelve 1080p/24 movie channels (like HBO), or six 1080i video/sports channels, or eighteen 720p/24 movie channels, or some combination thereof. If DirecTV were to swap out all 180,000+ existing HDTV receivers with models supporting 8PSK, they could significantly increase their HDTV channel capacity.

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From what I've read they get about 8 regular channels per transponder, but only 1 or or maybe 2 HD channels. Is this correct? I guess they could eliminate some pay per view channels???
DirecTV has ~550 locals distributed across 38 spot beam transponders. That's about 14 or so NTSC channels per transponder. The remaining 248 channels are spread across 26 CONUS transponders, for an average loading of 9 to 10 channels per transponder. DirecTV is in the process of moving to new encoding equipment, which allows them to fit each local channel in as little as 2Mbps (up to 15 per transponder), with only minimal degradation in quality.


DirecTV can fit one to three HDTV channels per transponder, depending on the channel's ATSC format (720p24, 720p60, 1080i/30, 1080p/24 etc) and whether it shows primarily film-sourced or HD video sourced content. HDTV channels with live sports and video obviously require more bandwidth than filtered 24fps movie channels.


Thus far, DirecTV has been able to fit two 1080p/24 HDTV movie channels (HBO) per transponder, and one 1080i HDTV video channel (Hdnet) per transponder. That said, HBO and Showtime currently reside at different orbital locations, and DirecTV tried Hdnet on a transponder with another HDTV channel, but some viewers here complained. Any excess transponder space is occupied by SD channels.

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I guess they could eliminate some pay per view channels???
DirecTV is more likely to add than eliminate some PPV channels, as this is where they make a good portion of their revenue.
 

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There are probably 1.5 - 2.0 transponders available right now, enough for two to six HDTV channels.


It sounds as if two channels HBO-HD and Showtime-HD can fit in 1.5 transponders because of it's format?


However, more capacity will free up at 101 later this year, when DirecTV completes its two new uplink centers.


Do you have a date on that or more like mid or later summer for the uplink centers? And how can a new uplink center open up more TS space? When you say uplink center, do you mean Satellite?


1080p/24 movie channels (like HBO),


Are the movie HD channels really 1080p/24? If so, my receiver is probably converting it to 1080i. Would it not be better to transmit 1080i/24 to save bandwidth?


DirecTV tried Hdnet on a transponder with another HDTV channel, but some viewers here complained.


That was very big for DirecTV to switch that back knowing how valuable bandwidth is. I remember when that was going on and yes, HDNet just did not have that HD look that we should expect.
 

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Is there any information about whether the new HD stations will all be on the 110 or 101 satellites and whether HBO-HD and HDNET would move to 110?


Also, do all of those music stations get much use by a substantial number of customers to justify the transponder space they are taking up?
 

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Quote:
It sounds as if two channels HBO-HD and Showtime-HD can fit in 1.5 transponders because of it's format?
I suspect they could fit three HBO-HDTV type channels. DirecTV gets in the range of 31.5Mbps - 33Mbps per transponder with QPSK 6/7 FEC--I don't know the exact figure, because DirecTV doesn't use DVB, and thus the standard ratio for R-S doesn't apply---while HBO HDTV is flagged at 14.2Mbps, although it typically uses less. Hdnet uses more; it was originally announced at 18.2 Mbps, but some people have suggested it may be using 19.4 Mbps.

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Do you have a date on that or more like mid or later summer for the uplink centers? And how can a new uplink center open up more TS space? When you say uplink center, do you mean Satellite?
No, I mean uplink centers, as in ground stations. From any given region in the United States, DirecTV can only transmit a certain number of frequencies to a given satellite in space. This limits the number of local channels they can uplink to the spot beams, and thus impacts their spot beam configuration. This is the reason why some locals are still on the CONUS (national) beam at 101, rather than on spots. They address this issue to some degree by building additional uplink centers in different parts of the country, so they can send more frequencies to the satellite for delivery on spots. This increases locals capacity and gives more versatility in how they can configure the spots.


I don't have dates when they will be up and running, but it is my understanding that they will be completed sometime this year.

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Are the movie HD channels really 1080p/24? If so, my receiver is probably converting it to 1080i. Would it not be better to transmit 1080i/24 to save bandwidth?
1080p/24 is what people on this forum are reporting, based on the repeat flags they've observed when looking at the MPEG-2 bit stream. I don't have any specific information in this regard, aside from what forum members are saying they have observed. I'm not sure why HBO isn't using 1080i/24, which is also an ATSC format.
 

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Quote:
Are the movie HD channels really 1080p/24?
Depends on how you look at it. The MPEG-2 syntax for

these streams is [email protected] with inverse telecine

(repeat_first_field, top_field_first and progressive_frame

flags used). However, if you were to decode each MPEG-2

frame, you would see a sequence of progressive frames

at 23.976 fps which would be exactly the same thing you

would get from a [email protected] bitstream.


The only difference, is that the 1080i with flags stream

can handle cadence breaks in the 3:2 telecine sequence

because it can just signal the odd cadence with the

appropriate flags (the rule is, the flags add up to

29.97 fps but the number of MPEG-2 frames can be

anywhere from 24.976 to 29.97 fps).


So 1080i is a more flexible system and since most displays

today are 1080i, it makes the most sense. When 1080p

displays become more commonplace, then actual 1080p

coding would be preferred. But to make for good [email protected]

coding, the telecine should be "perfect" (no cadence

breaks). Or better yet, there's no telecine at all

(for instance, direct from a 24p digital camera).


Ron
 

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Quote:
Originally posted by bfdtv


No, I mean uplink centers, as in ground stations.

I don't have dates when they will be up and running, but it is my understanding that they will be completed sometime this year.

Do you have a link to this info? I wasn't aware they were building any new uplink centers?
 

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Quote:
Originally posted by dr1394
Or better yet, there's no telecine at all

(for instance, direct from a 24p digital camera).


Ron
All? (there may be one or 2 shows left that are 1080i) are produced soley in 1080/24p. Either by telecine running at 24p or from 24p HD video cameras. The 3/2 is the final process in the air master. Both Sony HDCAM and Panasonic HDD5 have 3/2 adders built in. It a simple process to add 3/2. They work from timecode which identifies the A film frame. This is of course subject to error if the timecode is wrong.


DVD encoders can use the timecode or field averaging to remove 3/2. ATSC encoders presently do not read timecode.
 

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Thanks for all the techno info.


I must add that I am really unclear why they aren't making the 8PSK move. It will only get more expensive to achieve this later and making the move is absolutely essential to remaining remotely competitive in HDTV.


Mark
 

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It's not so much the cadence breaks that prevent them from using 1080/24p (there aren't any cadence breaks in a film), but the 60 Hz material.


Plus, the source material may not be in an actual 24 fps format. The encoder is heuristically identifying the progressive frames.
 

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I should say it's the 60 Hz material that makes them _think_ they should not use 1080/24p, because they think it would be bad to switch modes. I.e. switch to 1080/24p at the start of a film, switch to 1080i or 480p or 720p at the end.


I personally think that would be great, and I wish they would do it.
 

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Do you have a link to this info? I wasn't aware they were building any new uplink centers?
I don't have a link, but perhaps you could find one with a search. They're being built in Winchester, Virginia and Oakdale, Minnesota. The primary purpose is to support DirecTV-7S, launching in December. The existing teleport facilities reside in Castle Rock, Colorado and Long Beach, California. At any given facility, they can obviously uplink no more Ku frequencies than they are authorized to downlink (i.e. no more than 32 from Castle Rock to 101, 11 to 119, 3 to 110, etc).


From Castle Rock, DirecTV is uplinking 24 transponders worth of national channels, plus 8 transponders of locals to the satellites at 101. They are sending another 32 transponders worth of locals to 101 from Marina Del Ray (corrected). So right now, they can use no more than 40 of the 54(?) transponders on DirecTV-4S for spot beams. By uplinking from another ground station, they could move the remaining locals on the 101 CONUS beam to spots.


Obviously, sending a spot beam satellite like DirecTV-7S with 54 transponders to 119 would be pointless if they only had one ground station, and thus could only uplink local channels on 11 frequencies. Actually, they could uplink even less, because DirecTV will be using 8 of those 11 transponders for national programming, so that means they could only uplink three frequencies worth of locals to the 54 transponder DirecTV-7S spot beam satellite if they relied on a single ground station. Obviously, that would be inadequate for the 50+ local markets they intend to deliver from this slot.
 

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What are the economics of all this including the value of the frequencies themselves? I keep wondering at what point it would be appropriate and maybe cheaper in the long term for DirecTV to introduce a new receiver capable of higher powered decoding algorithms such that they could better utilize the available frequencies.


Yeah, the ultimate cost of any equipment swaps isn't cheap, but then neither is the infrastructure they're building up now. And there ultimately is a limited total bandwidth available, especially since DirecTV satellite dishes only get two full satellites if transponders at most (the SatC signals from a handful of transponders being injected over other transponder space DirecTV doesn't own at 119).
 

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Quote:
Originally posted by bfdtv
They're being built in Winchester, Virginia and Oakdale, Minnesota. The primary purpose is to support DirecTV-7S, launching in December.
I find this bizarre. I would think the path loss between a northern ground station and an equatorial satellite would be significantly greater than if the ground station were further south. I would think since they're transmitting 24/7, having to use, say 25% more power would be a big concern. (I pulled 25% out of the air, but it doesn't seem unreasonable.) But I guess it isn't if they're building it!


Oh, and seeing all this technical information from people who clearly know what they're talking about is refreshing. bfdtv, if your name stands for what I think it stands for, I love it!
 

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The economics of all this are complicated. But having the additional uplink facilities made sense regardless. Why? Because it allows for the maximal amount of spot-beamed locals as the ground frequencies can now be re-used 4x, instead of just 2x.


As for a different modulation scheme and compression method, there are a couple of issues:


(1) Is it even remotely realistic to change encoding schemes? This means switching from MPEG-2 (DirecTV's scheme is slightly odd, but basically MPEG-2) to MPEG-4. It is not really realistic to do now and given that they get the HD channels in MPEG-2, they'd have to be transcoded. In fact, it's possible some SD channels are coming in digitally already, too.


The magic that allows them to real-time-encode hundreds of channels as they currently do would cost a fortune to swap out.


The only thing here that makes sense is to make sure that if they do build a "new technology" set-top, the decoder would optimally decode MPEG-2 and MPEG-4 and -- in theory -- any codec that could be defined in firmware to allow them to switch encoding schemes someday.


(2) Should they switch modulation schemes from today's QPSK to 8PSK? Well, the jump to 8PSK would allow for about a 30-50% increase in total bandwidth per transponder. That's a good thing. Alas, there are zero compatible 8PSK DirecTV receivers out there. The expense of switching to 8PSK modulation is far less than switching to MPEG-4.


(3) Do they use a new scheme for just HD or for both HD and SD? What Dish did was to implement 8PSK for HD only and thereby set up a very realistic path to 2 HD channels per transponder and a hypothetical path to 3 HD channels per transponder. DirecTV could do this, too, but would have to swap out all existing HD receivers or -- like Dish -- phase in new offerings that could only be obtained with the new receiver architecture.


The expense for swapping the HD receivers out is $100 million -- and rising. The penalty for not doing it is an abandonment of a position in the HD race within about 3 years. No amount of uplink centers or spot beams will solve their problems. The only alternative is more frequencies at different orbital locations or different frequency bands (like the Ka band, which is not currently useable with small dishes).


This means new satellites and new dishes, which is pricey.


Mark
 

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Quote:
The expense for swapping the HD receivers out is $100 million -- and rising. The penalty for not doing it is an abandonment of a position in the HD race within about 3 years. No amount of uplink centers or spot beams will solve their problems. The only alternative is more frequencies at different orbital locations or different frequency bands (like the Ka band, which is not currently useable with small dishes).
DirecTV could always lease Ku-FSS capacity from PanAmSat. I suppose DirecTV will work the math, and determine whether it is more feasible to a) do a HDTV receiver swap out, b) lease Ku-FSS space from PanAmSat, and move to a new, even larger dish with four or more LNBs, or c) not aggressively pursue carriage of future HDTV channels. The need will of course depend on whether HDTV continues to gain momentum.


When they introduce a HDTV DirecTivo (perhaps a model with a smaller HD and single satellite tuner to cut costs?) late this year or early next, that would seem like a good time to do a receiver swap out for 8PSK, if they were going to do such a thing. I don't think you'd have many customer complaints.
 

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It seems to me that it would be feasible to transmit local stations from some sort of ground-based digital transmitter, located near each city, within several dozen miles of the viewer.


They could send out the signals from a tower or other tall structure, and it could be received by the viewers, directly. The "senders" of these local TV signals could even employ local people, pay local taxes, and buy local goods. Even the electricity to run them could be purchased locally.


And, without satellite bandwidth to deal with, they could use as much bandwidth as needed, to create a truly "watchable" picture. Maybe even digital sound, too!


Anyone who was too far away from one of these "ground-based spot beams" could get their TV from one of the major cities, via satellite.

This could free up many, many, transponders for other services.


Oh, well! Maybe there will be this kind of technology in the future ;) .
 

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"It seems to me that it would be feasible to transmit local stations from some sort of ground-based digital transmitter, located near each city, within several dozen miles of the viewer.


They could send out the signals from a tower or other tall structure, and it could be received by the viewers, directly. The "senders" of these local TV signals could even employ local people, pay local taxes, and buy local goods. Even the electricity to run them could be purchased locally. "




Yep! Called local TV stations, Ken. What a great concept. I believe the planet used something like that back in the 20th or 21st century. In the 21st century I recall they were all forced to switch from analog to digital and the cost bankrupted all the stations because the TV sets being sold were not required to have digital tuners immediately and few people couldn't watch. With few people watching, the stations couldn't make a profit selling advertising and they just went under. Cable and sat networks were far more prolific being distributed by fiber cable and satellite band that most people had these and few watched these local broadcast stations. The networks feeding these locals quickly recovered by becoming another cable/satellite network and as I recall, CBS led the way by distributing all their channels regular and Hidef via Echostar.

:)
 

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Quote:
Originally posted by bfdtv
I don't have a link, but perhaps you could find one with a search. They're being built in Winchester, Virginia and Oakdale, Minnesota. The primary purpose is to support DirecTV-7S, launching in December. The existing teleport facilities reside in Castle Rock, Colorado and Long Beach, California. At any given facility, they can obviously uplink no more Ku frequencies than they are authorized to downlink (i.e. no more than 32 from Castle Rock to 101, 11 to 119, 3 to 110, etc).


From Castle Rock, DirecTV is uplinking 24 transponders worth of national channels, plus 8 transponders of locals to the satellites at 101. They are sending another 32 transponders worth of locals to 101 from Long Beach. So right now, they can use no more than 40 of the 54(?) transponders on DirecTV-4S for spot beams. By uplinking from another ground station, they could move the remaining locals on the 101 CONUS beam to spots.

OakDale Minn? Remember USSB? I wonnder if it's that plant? BTW, there are actually two uplink centers in So California. I have been lucky to tour both. :) Long Beach is for DirecTV Latin america. Los Angeles (Marina del Rey to be exact) has another large facility. I think it's even bigger than Castle Rock. This shares with Castle Rock and can be a backup. This plant is featured in this month"s Broadcast Engineering. www.broadcastengineering.com The emphasis of the artical is about handlingn local sations.
 
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