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Wireless Networking Communications Networking Television The Internet IT

L.A. TV Stations Free Up Some Spectrum For Wireless Broadband 80

alphadogg (971356) writes An effort to free up some of the airwaves used by TV broadcasts and make them available for wireless broadband took a big step forward this week in the U.S. Two TV stations in Los Angeles, KLCS and KCET, have agreed to share a single frequency to deliver their programming freeing up a channel that can be auctioned off to wireless carriers next year. The change, which the Federal Communications Commission calls "repackaging," is possible because digital TV broadcasts don't need the full 6MHz of broadcast spectrum that was used for analog TV.
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L.A. TV Stations Free Up Some Spectrum For Wireless Broadband

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  • So two stations that were previously using 6 MHz bandwidth each, will now share one channel, presumably using 3 MHz each.... and so each will have a 50% drop in picture quality. How is this a good thing for the consumer?

    • by mmell ( 832646 )
      An incentive to buy cable or satellite access?

      *ducks*

      • by Ken_g6 ( 775014 )

        I don't have cable or satellite, but I heard their picture quality is way worse than broadcast usually has been. This could just be evening the score.

        • Of course its' worse. The cable companies get their feed from an antenna. So they recompress that rather than the original source.

    • by crow ( 16139 )

      Possibly, but more likely they're dropping their subchannels that were ignored by everyone anyway.

      Most broadcasters use their physical channel for one HD logical channel and several SD streams. For example, 4.1 might be HD CBS, 4.2 might be the same thing in SD, and 4.3 might be continuous weather. If they drop the SD channels, they can probably fit in both HD channels with little degradation.

      • I have heard that two 720p channels can coexist on one carrier. I haven't heard of anyone doing this with 1080i or 1080p, and I don't know if the 720p channels were running 30 or 60 FPS.

        • Channels don't exist on a carrier. The data stream exists on the carrier, the (MPEG2) transport stream is encoded in the data stream, and as many audio and video streams of whatever resolution you want are multiplexed into that transport stream. Only practicality limits you to two 720p60 MPEG2 video streams in a single 6MHz 8VSB band, as the compression levels needed to push further down than that on typical content starts to become very noticeable.
          • Channels don't exist on a carrier.

            Unhelpful pedantics. My point, as you correctly gathered, os one of there being or not/being sufficient bandwidth to do the job.

        • by TheSync ( 5291 )

          I have heard that two 720p channels can coexist on one carrier.

          Not two "good quality" 720p channels! MPEG-2 encoder technology (of the highest quality pro encoders) continues to get better, but we're not quite able to fit two good 720p's into 19 Mbps. Give it a year or two.

          Of course you can jam in as many video channels as you want if you don't mind it looking like crap in high-motion scenes (like sports for instance).

      • Continuous weather is low-motion, low-bandwidth- and usually SD. The main subchannel still has plenty of bandwidth left in that case.

        Are stations really still airing SD on a subchannel?

    • So two stations that were previously using 6 MHz bandwidth each, will now share one channel, presumably using 3 MHz each.... and so each will have a 50% drop in picture quality. How is this a good thing for the consumer?

      You have no idea how "Digital" works do you?

      • by davidwr ( 791652 )

        So two stations that were previously using 6 MHz bandwidth each, will now share one channel, presumably using 3 MHz each.... and so each will have a 50% drop in picture quality. How is this a good thing for the consumer?

        You have no idea how "Digital" works do you?

        If by "quality" the original poster meant "maximum picture quality" i.e. the combination of resolution and ability to change the image over time, he is correct. If by "quality" he meant things like noise/static, then for practical purposes you are correct.

        A 6MHz channel can support 1 HD channel plus some leftover room, a 50/50 split of that channel cannot.

        • No. Charliemopps was referring to the fact that you do not subdivide your spectrum. Subchannels are separated logically, not physically. Two video streams on a 6MHz channel is two video streams on a single 6MHz channel, not two video streams each with their own 3MHz channel.
          • Two video streams on a 6MHz channel is two video streams on a single 6MHz channel, not two video streams each with their own 3MHz channel.

            That's not relevant.

            What is relevant is that you can't squeeze blood out of a turnip.

            If you are logically splitting the bandwidth with another broadcaster and you are broadcasting a show that uses 50% of the bandwidth, that only leaves 50% for the other broadcaster. If you want to broadcast a show that requires more bandwidth, such as a typical HD (1080p) television show, it can't do it unless the other broadcaster isn't trying to use more than the remaining bandwidth during that time period.

            Assuming you c

            • Assuming you can't get the other broadcaster to cooperate, you can't broadcast with the same "quality" (as defined by resolution and frequency-of-scene-changes) as you could if you controlled the entire 6MHz channel.

              There is only one broadcaster. There is only one MPEG2 transport stream, now containing both programs. They must cooperate, as they are sharing one piece of transmission gear. It's not like a cellular network where two different entities are sharing time slices of a common spectrum. Also, I'm not aware of any broadcaster that uses 1080p.

              • by davidwr ( 791652 )

                I should have said 1080i, not 1080p. My point was, if both television programs (as seen by the viewer) take up so much bandwidth that there is not enough room for the other program to be at "maximum quality," then the other program will not be at "maximum quality" and the earlier editor's claim that channel-sharing (typically) results in a lower maximum-quality show (as displayed on the customer's screen) is true.

                Also, of course the two companies must cooperate in a technical sense. I should have clarifie

    • by Anonymous Coward

      That is not the case. A single 6MHz band can carry multiple "subchannels", practically up to about 5. Most broadcasters are wasting most of their bandwidth, since few transmit more than two subchannels (Ion and PBS being major exceptions). Both of these stations can put a Hi-Def subchannel into that stream, with no problems or loss of quality.

    • So two stations that were previously using 6 MHz bandwidth each, will now share one channel, presumably using 3 MHz each.... and so each will have a 50% drop in picture quality. How is this a good thing for the consumer?

      Answer: Because NOTHING you've said has a shred of truth. You might try looking-up KCET and KLCS before ignorantly spouting off next time...

      KLCS has been operating on a waiver... They've never been broadcasting any HD channels, but just 4 SD channels. KCET has one HD 720p channel, and 3 S

      • Wish I had a mod point for you today.

        I'm very unhappy with the state of PBS in Los Angeles.

        For the second biggest TV market in the US, it has a miserable selection of mediocre PBS stations, and very little original content (unlike say WGBH or KQED) but it seems like KOCE is slowly stepping up its game...

        • I certainly don't need the mod points, but it's damn sad to see the ass-backwards moderation on this story.

          This factually incorrect nonsense is +5:
          * http://slashdot.org/comments.p... [slashdot.org]

          While my correction actually got modded down:
          * http://slashdot.org/comments.p... [slashdot.org]

          Similarly with this thread, I'm clearly the only one who has provided information specific to the situation, and my comments get ignored, while generalized rants with terrible info are +5.

          It's a crushing disappointment to see just what /. has turned

          • Indeed. Slashdot is a nebulous ghost of what it once was. The insightful and informative community seems to have departed for elsewhere, leaving us with trolls, juveniles and politically motivated archive-oriented moderators.

      • Before KCET dropped their PBS affiliation (an idiotic move, but that's another topic)

        What are they affiliated with now? Konami Computer Entertainment Tokyo?

    • by kb7oeb ( 543726 )

      So two stations that were previously using 6 MHz bandwidth each, will now share one channel, presumably using 3 MHz each.... and so each will have a 50% drop in picture quality. How is this a good thing for the consumer?

      They are sharing 19MB data stream, it means dropping PQ or Sub channels or both

    • by antdude ( 79039 )

      I care not about these two stations. They're not good as the old days like in the (19)80s. I used to watch Bob Ross's paintings, This Old House, Sesame Street, Nature, NOVA, National Geographic, Wild America, 3-2-1 Contact, Reading Rainbow, Square One Television (Mathnet!), The Voyage of the Mimi, etc. These days, pretty much NOTHING! :(

      Does anyone remember the very old colored animal shows (filmed in 1970s?)? IIRC, each episode was like 30 minutes, different topics, and the ending credits showed a jeep dr

  • In my area, many of our OTA network stations share a channel (due to financial issues, not to free up spectrum). Fox/ABC, CBS/CW, NBC/myTV.

    I think most programs have no issues with 12+ Mbps, which usually leaves room for a SD sub-channel. However, shoving two HD programs into a 6 MHz channel leaves each ~9 Mbps. Sports programs suffer significant blocking and pixelation on fast action and pans. Live shows such as America's Got Talent also block and pixelate. Studio shows fare better.

    I believe the probl

    • Generally studio shows fare better because they're only 24fps with frame duplication. There's simply much less data to send.

The aim of science is to seek the simplest explanations of complex facts. Seek simplicity and distrust it. -- Whitehead.

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