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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Apparently you and I lived through completely diffent 1970s.
The only thing superior about analog TV was figiting with the horizontal hold to un-twist scrambled naughty broadcast signals at 1 in the morning.
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They also use considerably higher frequencies. (Score:5, Interesting)
Well, everyone except Joe Sixpack; but he's just an ignorant dolt anyhow (an insensitive clod?).
Modern UHF vs. classical UHF (Score:3, Informative)
Modern digital television is on even higher frequencies.[than analog UHF]
Not true. Digital television frequencies are basically the same as the analog ones, with some channels either no longer used or no longer used except under special circumstances (e.g. grandfathered stations, low-power stations, etc.).
In practice, most US digital TV stations are UHF stations between channels 14 and 69.
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Modern UHF vs. classical UHF (Score:1)
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But you're right - I've pulled in 20 or 30 stations with a piece of 8 to 10 foot long wire from my first floor place. Just insert it into the center pin where the cable F connector would normally go.
And those of us in Urban environments tend to get better service that way anyhow.
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Lower frequencies cast a much longer shadow behind obstacles, where higher frequencies will fill-in the area more immediately behind the obstacle. People might be most familiar with AM radio fading out when driving under a bridge, while FM radio does not.
The flip side of that, which you're talking about, is that lower frequencies will lose less of their power over long distances, diffracting around the cur
Re:Of course they don't need the full spectrum (Score:4, Informative)
Analog power was measured as peak power while digital power is measured as average power. If you measured analog power in RMS, that 100 kW would become about 25 kW (less than the 45 kW ceiling). A similar difference arises between 316 kW becoming about 80 kW (less than the 160 kW ceiling). On UHF, the power difference is 5000 kW for analog versus about 1250 kW for digital, slightly more than the 1000 kW ceiling, but only by about 1 dB.
On top of that, about 50 dB SNR was needed for a clear picture with an analog signal, while a digital signal requires only 16 dB for a perfect decode. So the difference in required SNR is more than 30 dB, but the power change, even if it actually was 5000 kW to 1000 kW, is only 7 dB.
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I meant "average" and not "RMS" in my second sentence. Wish I could edit...
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That's the frustrating thing about digital broadcasts. With analog you have a gradual variation in quality and can tweak your antenna to get it as good as you can. With digital if your reception is on the edge you get a perfect picture/sound most of the time but occasionally (how occasional depends on how marginal the reception is and what interference sources you have arround) multi-second breakups when impulse interference causes the error correction to fail and the whole system has to re-sync.
A perfect p
Signal strength button (Score:2)
With analog you have a gradual variation in quality and can tweak your antenna to get it as good as you can. With digital if your reception is on the edge you get [...] multi-second breakups
Better receivers, such as the box I bought in the coupon era, have a button on the remote that pops up a signal strength meter. I don't know whether that just means raw level of the signal or the actual SNR, but it has helped me aim the antenna to minimize signal dropouts.
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Yeah, going to echo the sentiments of the poster below, and suggest you don't remember analogue TV. Every bit of noise meant a visual artifact on the screen(or audio). Whereas digital can use an ECC to fix erroneous data.
The big problem is there is a threshold of quality for which a signal simply doesn't work at all. Which means these are the stations that had a constant unwanted background buzz and flickering static for you before.
Seconded! (Score:3)
Digital gets a little twitchy, you see a still frame (or nothing). Sound becomes silent. It's hard for your brain to actually filter out a blank screen and no audio.
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Yeah, and I'm saying that those issues kick in under much more extreme conditions than analogue ones.
Not in my personal experience. (Score:2)
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Digital gets a little twitchy, you see a still frame (or nothing). Sound becomes silent. It's hard for your brain to actually filter out a blank screen and no audio.
That's just the extreme tipping point. Before reaching that point you can pick up a very crusty signal and still enjoy a perfect picture and audio while the error correction is working its ass off behind the scenes.
With analogue signal as bad, you might already be losing color information, and luxuries like NICAM sound are a distant dream.
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At the end of the day, all I know is that stations which once were viewable (some even perfect) under analog are no longer viewable under digital.
That sounds like other changes were made at the same time, independent of the digital transition. Their new transmitters are cheap shit. They dropped to a lower transmit power. They moved to a different antenna or frequency that results in increased interference.
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Why can't you just go up on your roof and mount a VHF/UHF antenna?
Renting (Score:2)
Why can't you just go up on your roof and mount a VHF/UHF antenna?
It could be technically the landlord's roof, not mmell's.
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As long as mmell doesn't share the roof with other tennants, he has the right to mount an antenna up there.
Law of the land since 1996:
http://www.fcc.gov/guides/over... [fcc.gov]
Multi-family units (Score:2)
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That doesn't preclude installing an antenna, it just reduces your options. Multi-floor apartment balconies and/or windows usually get pretty good TV reception. If previous occupants had DBS dishes mounted, you can stick an antenna on that J-channel. And landlords are usually reasonable. You can always ask for permission to install an antenna, explaining the non-destructive mounting option (chimney straps, non-penetrating root mo
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The problem with that theory is what is known of as "impulse interference". When some large and sudden electrical event (distant lightening strikes, switching of large loads, that sort of thing) happens it can create electromagnetic radiation that is very limited in the time domain but very widespread in the frequency domain.
With an analog transmission you get a very brief flicker but stuff almost immediately returns to normal. With compressed and error-corrected digital transmissions either nothing happens
Digital would be less "twitchy", but... (Score:2)
Digital becoming twitchy isn't just because of transitioning to digital. It's also because they lowered the transmitter power. [wikipedia.org]
So if you were watching
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Analog power was measured as peak power while digital power is measured as average power. If you measured analog power in average, that 100 kW would become about 25 kW (less than the 45 kW ceiling). A similar difference arises between 316 kW becoming about 80 kW (less than the 160 kW ceiling). On UHF, the power difference is 5000 kW for analog versus about 1250 kW for digital, slightly more than the 1000 kW ceiling, but only by about 1 dB.
On top of that, about 50 dB SNR was needed for a clear picture with a
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The problem is that a 6MHz channel only allows ~18Mbps of usable bandwidth using 8VSB (current ATSC standard OTA encoding) which isn't a lot if you're using MPEG2 for 1080i/720p @30fps, cutting it down to ~9Mbps means you're getting worse than DVD bandwidth for what's supposed to be an HD signal.
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I'm somewhat confused. Each ATSC channel is a fixed 6 MHz wide spectrum. They can either do one HD channel or four SD channels (I think but I cannot find solid technical info on TV broadcast except very general info that is aggregates of what everyone else posted, or very esoteric technical specific). I can get MPEG2 is high bandwidth and not that great compared to H264 but MPEG2 continues on because that's the way it is (like DVDs).
I was talking with someone who gave additional reason to cut cord from Co
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I was talking with someone who gave additional reason to cut cord from Comcast is HD from OTA is far superior than on cable which is highly compressed to transmit all those channels down the coax.
I long suspected Cox cable re-compressed our local stations, but then found out all the stations are sharing 2 HD stations per transmitter, some with an extra SD subchannel. So even over the air, all my locals are less than 9 Mbps. Cox has the dirty work done for them already, and just sends out the same signal.
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I'm somewhat confused. Each ATSC channel is a fixed 6 MHz wide spectrum. They can either do one HD channel or four SD channels
There's no explicit maximum, or at least none that you could ever reasonably reach. It all comes down to how much you compress the data. You can run dozens of HD channels on a single multiplex if they look like shit, or are primarily static images.
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Umm, tvfool.com has had that info forever.
I linked to the FCC's DTV transition plan in my journal about OTA TV in 2007:
http://slashdot.org/journal/18... [slashdot.org]
Specifically:
"FCC DTV tentative frequency assigments"
http://hraunfoss.fcc. [fcc.gov]
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78s and 45s are still better than digital.
Old 78s and 45s were never better than digital, in any fashion. They added weight and ceremony to listening to music, because of the care needed in using them. They added distortions that people like to call "warmth". Both of these are form, and run in direct violation to their primary function as a storage medium.
Sharing channel == worse picture quality (Score:2, Insightful)
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?
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*ducks*
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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.
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Of course its' worse. The cable companies get their feed from an antenna. So they recompress that rather than the original source.
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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.
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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.
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Unhelpful pedantics. My point, as you correctly gathered, os one of there being or not/being sufficient bandwidth to do the job.
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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).
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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?
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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?
You have no idea how "Digital" works do you?
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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?
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.
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That's not relevant (Score:1)
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
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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.
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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
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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.
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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
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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...
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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
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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.
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Actually, wavelength at 800Mhz is only about 1ft (~30cm), so that's practical to hide. Hell, you could disguise it as a chimney or some other roof penetration.
My plan would be to mount them on telephone poles wherever available. There, they could just use business-class cable/DSL/FIOS service as the backhaul. Maybe that possibility would enco
The other KCET (Score:2)
Before KCET dropped their PBS affiliation (an idiotic move, but that's another topic)
What are they affiliated with now? Konami Computer Entertainment Tokyo?
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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?
They are sharing 19MB data stream, it means dropping PQ or Sub channels or both
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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
Quality Loss Depends (Score:1)
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
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