World's Tallest Free-Standing Broadcast Tower Completed 65
dtmos writes "The world's tallest free-standing broadcast tower has been completed, in Tokyo (video). Rising to 634.0 metres (2,080 ft), it is the second-tallest structure in the world, after the Burj Khalifa. Completion was delayed two months due to the effects of the 2011 Japanese earthquake and tsunami."
So ugly (Score:2, Informative)
I know it needs to be strong enough for earthquakes but the design looks a bit dated.
Re:An impressive project (Score:5, Informative)
Very impressive, though I can't help thinking its a vanity project and broadcasting from a number of smaller towers would be cheaper. I suppose that probably goes for all the world's ultra tall buildings though
It replaced the Tokyo Tower (a smaller tower), specifically because the surrounding buildings were getting quite tall and causing problems.
You say a bunch of smaller towers would be cheaper, but I hear the real estate in Tokyo is just a tad expensive.
Re:So ugly (Score:5, Informative)
From wikipedia:
Earthquake resistance
The tower has state-of-the-art seismic proofing, including a central shaft made of reinforced concrete. The main internal pillar is attached to the outer tower structure 125 meters (410 ft) above ground. From there until 375 meters (1,230 ft) the pillar is attached to the tower frame with oil dampers, which act as cushions during an earthquake. According to the designers, the dampers can absorb 50 percent of the energy from an earthquake.
So no, it's not dated. Ugly, true, but not dated.
Re:An impressive project (Score:5, Informative)
You need to understand how the broadcast television system works in Japan. There are ~8-10 total networks with terrestrial broadcast stations throughout the entire country, several run by the NHK (government-run television system). In Tokyo, you can get about 7 of them. Most other stations are only available via cable or satellite, and the number of local channels even via cable in Japan is extremely low compared to the US.
That said, in Japan space on the ground is often at more of a premium than materials to build with. If they can create one large broadcast tower to service all of Tokyo, they will - in the overall scheme - probably save billions and billions of yen. This was the idea behind the Tokyo Tower (the big red Eiffel tower looking thing) but that was created so long ago that it is now outdated and needs an upgrade to reach everyone.
I find the architecture to be pretty cool in this Sky Tree, though it really sticks out. I think the guys over at Tokyo Yakei (Tokyo Night Windows) got the best shots of it so far(even though it's earlier on in the construction): Tokyo Sky Tree at Night [tokyoyakei.jp]
Re:what's it for (Score:4, Informative)
It broadcasts
DTV (national channels)
(7 channels, broadcast power of 10kw, 1 wide area Kanto (sort of the center of the main island), 1 nation wide, 4 Kanto Area)
Expected to reach 14 million households
DTV (Tokyo channels)
(1 channel, broadcast power 3kw)
FM stations (2, broadcast power of 10kw)
81.3, 82.5
"Multimedia broadcast" (Not sure, maybe cellular television?)
1 station at 25kw, effective radiated power up to 105kw
And a few special purpose taxiTV stations are moving to the sky tree, they play advertisements and entertainment in the taxi.
Re:An impressive project (Score:3, Informative)
It turns out you actually can use several smaller towers instead of one big one for broadcasting. In digital TV, it's trivially easy - several fully independent stations pump out their signal on various UHF frequencies, but they all use the same PSIP - the "virtual" channel number encoded into the stream so the blissfully ignorant can "keep on watching channel three like I always did, bohygawd." Consumer decoder boxes are clever enough to only offer the one with the lowest bit error rate (=best signal). I have no idea how you license this, and if I did have some idea under 47CFR, it wouldn't apply in Tokyo, so whatever...
Analog audio broadcasting is slightly more complicated, and this is where it gets good. With AM, you can phase lock the carriers (and as a result, the modulation) to GPS. Sub-nanosecond phase accuracy is more than good enough at 1700 kilocycles. Vaisala will sell you such a rig off-the-shelf. It's kind of a neat way to get around licensing, too: each station can be configured as a legal, license-free Part 15 device, and yet with a handful of them you can cover a decent-sized town. FM is a lot more expensive, but it works the same way. You just write a bigger check.
Re:An impressive project (Score:2, Informative)
That said, in Japan space on the ground is often at more of a premium than materials to build with.
Not disagreeing with you, but I wanted to point out to people who don't live in Japan that space in *Tokyo* (and other large cities) is at a premium. I live out in the boonies and land is actually quite cheap (compared to Europe, for instance). In addition to a reducing population, people are moving in droves to the big cities (especially Tokyo) looking for work.
There are a lot of people who have the idea that Japan is crammed wall to wall with people, but it actually has a lower population density than England. Even Tokyo, which has a very high population density, is not as crowded as a lot of people think. It has a little over twice the population density of the greater New York metropolitan area, but it is more or less evenly distributed. Manhattan, for instance has a population density of 27,000+ people per km2 while Shibuya (the most crowded area of Tokyo I could think of) has a population density of only 13,000 people per km2.