Broadband from World's Tallest Building 195
StarPie writes "The Chicago Tribune is reporting that Sprint Broadband will be broadcasting DSL from the top of the Sears Tower in Chicago. The range is said to be 33 miles -- a lot better than wire DSL. All you need is line of sight from the Sears Tower." I've spent the last couple minutes straining my eyes but try as I might, I can't see it. I'm stuck with 128kbits.
What about the upload? (Score:1)
Not the world's tallest building. (Score:5)
Since 1998, the Petronas Twin Towers in Kuala Lumpur, Malaysia have been the world's tallest building [about.com] (not including tower structures like broardcast towers) - 1,483 feet vs 1,450.
How will this work? (Score:1)
Line of Sight (Score:2)
eudas
Line of site ? (Score:1)
I don't put a lot of faith in this if it's line-of-site visibility
It's part of a roll-out to skip the last mile. (Score:3)
Broadband on the water (Score:1)
My experience w/ wireless microwave internet (Score:3)
Anyway, it was more like $150 a month or something and was still line of site, and I think it's 2GHZ. All I can say is, it sucks. A lot. I think we get about 80% uptime with it and the latency is horrible, dare I say it, even worse than a modem. We're talking anywhere from 30 to 300ms ping time to the first hop on the other side, usually in the mid 100's.
The thing was though, the through put was still like 80K/sec or so, so as long as I wasn't streaming anything or playing games it was OK, say for like the web, except for that 80% uptime thing. Think about that, it doesn't sound too bad, but that means 1 in 5 times that I sit down to use the internet that the route is down.
It was also tedious to program over the link since our webserver was co-located on the other side and with the link going down so much I spent lots of time banging on my keyboard waiting for my cursor to move again, only to see like 5 extra lines deleted in vi or something.
We're getting a T1 now. I'm going to be very happy. :)
PS: About the streaming thing, I stream video with real server to work from my house with DSL, and the best I can get is using the 56.6K setting, and usually that gets all out of sync so I actually use 33.6K. How's that for "High Speed?"
Re:What about mobile? (Score:1)
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Just one man beneath the sky,
Re:No you are still wrong (Score:2)
Its only by a quirk in the architectural definition of what is part of the building and what is not which makes some people think the Petronas Tower is taller. The decorative spire on the top of the Petronas tower, which is defined as being part of the building, rises above the roof of the Sears Tower, but it's merely decorative. However the Sears Tower's antennas which have a functional purpose for the building, including for the use mentioned in this article, but are not considered architecturally to be part of the building, top the Petronas Tower's spire.
So there you have it. A useless piece of ornamentation hardly makes Petronas taller than the full functional height of the Sears Tower.
Re:Not the world's tallest building. (Score:5)
The four categories are:
Re:Not the world's tallest building. (Score:5)
If it is anything like their PCS network (Score:3)
Sorry, I will never ever ever buy a Sprint product or service every again. 'Crystal clear calling' my ass.
-josh
What about security? (Score:2)
I know that there are a lot of good encryption techniques out there, and that they're widely adopted, but I still like the idea of having the privacy of a wire line, which not every freak-with-an-antenna can pick up.
-Scott
Re:Not the world's tallest building. (Score:1)
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Re:NtWTB - This has been argued (Score:3)
This has been argued actually; note there is only 33 feet difference between the two. Those measurements, if memory serves me right, do not include the antenna tower on top of Sears Tower, yet include the pinnacle* of Petronas. The logic here by the official raters is that the antenna tower can be easily removed, while the pinnacle is a permanent feature of the Petronas towers. Granted, I do not quite see the logic here; if you have a better explaination, please chime in.
If you include both the pinnacle and the antenna tower, Sears Tower beats Pentronas by a foot or so, and the same holds true if neither the antenna tower or pinnacle is counted. Note I am recalling all this from memory, so I might have something incorrect.
Still, the link you provide is intresting. Looks like something (two somethings, actually) may shortly beat Petronas.
* A pinnacle is a fancy top piece for a building, typically with a large point on top of it. The concept dates back to at least Medival times.
Available now in AZ (Score:3)
Re:My experience w/ wireless microwave internet (Score:1)
Re:Line of Sight (Score:2)
He was actually being funny for once...
Hopefully better than Sprint PCS... (Score:1)
I'd be screwed without AT&T. (Hear that, RCN?)
Just to set thing straight (Score:1)
The Petronas Towers were previously the world's tallest building, but only because of a decorative spire on top of both of the towers, the Empire State building is the tallest including the antenna, the Sears Tower is the tallest in the other two categories (highest occupied floor and highest to the top of the roof). You can read all about it here [chipublib.org].
Re:Available now in AZ (Score:1)
Re:What about security? (Score:1)
The real story... (Score:1)
__
This is the acid test for MMDS data (Score:5)
Note that "line of sight" for MMDS is much better than optical; it means "not over the horizon". Since Chicago is basically flatland, hills aren't the problem they would be in, say, New England. Which is why this Chicago rollout is so important; it could give the technology a real boost. MMDS operates around 2.5 GHz. It is not subject to significant rain fade, and passes easily enough through trees. (Contrast this to LMDS at 29 GHz, which has a typical reliable range of around 2 miles, because of rain fade, though it goes much farther on dry days.)
Each market has one MMDS licensee. This was the FCC's last pre-auction lottery, nicknamed "wireless cable". It was intended for pay-TV broadcast distribution. A bunch of shady operators took fees to enter people into the license lottery ca. 1993. The MMDS companies who bought up the licenses from the lottery winners discovered that there wasn't much of a market, so they went bankrupt or sold out to Sprint and Worldcom (who between them have most of the country's population covered by their licenses, but are just starting to offer service). Now it's viewed as a DSL alternative. Some other operators are also in business; Oxford Telecom, for instance, does MMDS data in Portland, Maine.
This is mostly two-way radio, something the FCC authorized a couple of years ago. (Early systems were dial-up return.) I don't really think there's enough bandwidth there to replace DSL or cable modems in urban areas, but it's a good alternative for people who are out of range of those services. Alas, with only one license per city (spectrum being a scarce resource), it's not totally competitive.
Re:Hopefully better than Sprint PCS... (Score:1)
Line of sight is line of sight, but dont give up.. (Score:4)
For example, where I'm located there is a ring of mountains directly in front of a satellite (Telstar IV). There is no line of site. Yet, I can get decent reception in some parts of town because the mountains form a knife edge and the resulting diffraction pattern alters the signal strengths in some spots.
In other places I have turned dish antenna at ninety degrees to the normal signal path because the reflections off a group of office buildings were stronger.
The only practical way to know is to get the guy with the field strength meter to come and see. Remember, higher is usually better, so now maybe there's a reason to get that apartment on the top of the building.
Re:Just to set thing straight (Score:2)
Once again, I'm finding life more and more like a monty python skit.
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minusthink [Code poet or super hero? (you decide)]
Wait a sec... (Score:3)
You can't beam DSL! Don't they even know what it stands for? It's a Digital Subscriber Line!
I'm having visions of streams of thousands of cables shooting out of the top of the Sears tower...
A tourist attraction? (Score:1)
Re:Available now in AZ (Score:1)
I live in Las Vegas where it isn't available yet. Worst part is that Sprint owns the FCC license for MMDS in my area so I'm screwed. Well not exactly screwed. I have a cable modem and DSL is available and Ricochet2 (128Kbps) is "comming soon" to LV.
Re:What about mobile? (Score:1)
It's Not DSL (Score:1)
Re:This is the acid test for MMDS data (Score:1)
Re:wrong (Score:1)
Re:Not the world's tallest building. (Score:1)
This is because the Sears tower replaced one of the two antennas on top of the building recently. The two antennas used to be the same height, but now the west antenna is taller the east one and it is higer than the one on the World Trade center.
Incidently, here in Chicago, we call the spires on the Petronas towers "cheatsticks". :-)
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Re:Not the world's tallest building. (Score:3)
Cool! (Score:1)
Re:Not the world's tallest building. (Score:3)
Mr. AC
Re:Not the world's tallest building. (Score:1)
Just like the airport. O'Hare [berkeley.edu] used to be the 'busiest' until Atlanta's Hartsfield surpassed it in number of flights. That doesn't stop Chicago from still claiming it is the busiest, as long as you measure number of people who pass though each year instead of number of flights in and out. (although I thought Alanta passed Chicago for that too now).
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Can't see it (Score:1)
Re:What about security? (Score:1)
Its the difference between having your box hacked by a script kiddie, as opposed to someone breaking in and stealing it.
Its also a pretty serious vandal that would go around ripping up DSL lines....both in equipment and intent. The air equivalent would be someone broadcasting a tone in the DSL frequency range to interfere with transfers.
-Scott
Re:Not the world's tallest building. (Score:1)
this is gonna be great (Score:1)
Should be about another 18 months right?
yeah baby.
http://www.hyperpoem.net
It's not DSL. It's MMDS. (Score:5)
It's not DSL. It's MMDS -- Multichannel Multipoint Distribution Service.
Sprint Broadband [sprintbroadband.com] is one of the largest customers of Hybrid Networks Inc. [hybrid.com]
In fact, there's even an interesting little press release [hybrid.com] on Hybrid's site regarding the whole deal in Chicago.
This isn't very new to me, as the majority of my work and home bandwidth is provided by a local ISP that has been deploying these systems since the Fall of 1998. As an individual subscriber I've pulled traffic nearing the 8Mbit/sec mark. Yep, that's something a little more than the equivalent of five T-1's.
MMDS has a lot of advantages over your typical "unlicensed" wireless gear operating in the 900MHz and 2.4GHz spectrum... namely the fact that MMDS is licensed [fcc.gov] by the FCC [fcc.gov] (in the US).
Businesses that build their existance and survival on the fragile structure of "unlicensed" wireless often don't spend the time to properly research what it is that they are getting into... a mess. The first "provider" in an area to deploy "unlicensed" equipment has great success... and then the second "provider" comes along... and things start to slow down a little... and then another provider comes along perhaps... and things start to break (more)...
And then an Amateur Radio Operator/ham comes along and decides to start using the spectrum for Amateur TV, and the FCC comes in and shuts the "providers" down as they are infringing on the rightful license of said ham to use the 2.4GHz spectrum. *poof* :)
Another thing to consider, and one of the other reasons I like my MMDS provider... They don't have that interestingly restrictive TOS [slashdot.org] that Sprint Broadband has.
no one agree with you (Score:1)
what is a real asian country? someone tell me? i bet you are someone who has never left your country thinking its the greatest country in the world. well... too bad.
malaysia is not a third world country, and it consists of around 20% chinese (migrated from china), 10% indian (migrated from india), 69% malays (migrated from arab), and 2% natives of the land. their skin colors range from white, yellow, brown, to black.
their factory workers have cell phones. and they have one of the widest selections of food in the world. i was there for almost 18 years and i have to tell you that you are horribly wrong if you think you don't need to leave your country. america is not that great after i discovered asia. we have tech. they have tech. we have little in terms of spirituality. they do. we have such boring food. they'll blow you away with their food, and our food. travel. open your eyes. america is what they want you to believe it is. but there are better, more balanced worlds out there.
:: transmission terminated
Realities of microwave t/r and a factoid on twoway (Score:5)
Clouds, though, shouldn't realy be a problem unless they're VERY thick. The wavelength of a 2.2 GHz wave (I'm assuming 2.2 GHz because I know 2.4 is occupied, and it's the same drek in a different package) is:
c / freq == 300Mm/s / 2.2GHz ==
The wavelength is 13 cm or so. That's mighty small (when you consider that AM 1000 is 300m and FM 100.0 is 3m), but they can pass through anything short of a heavy rainfall or a blizzard. (I have a DBS system and can receive in virtually all conditions. Idiot involvement, though, seems to screw everything up royally.)
The short wavelength dictates the LOS and the power of the frequency will determine the range.
I have to commend Sprint's good timing, since a lot of DSL'rs got screwed when northpoint Comms. went bankrupt.
And now, for the coup de grace that'll get me jacked on wireless broadband: It's two-way. According to this marketdroid page [sprintbroadband.com], it's completely free of the telephone grid.
However, for you QUAKErs, your ping time may be slightly slower than it would be on a comparable hard-wired connection. This appears (from what little data that's available) to be (at least in part) a party-line system.
According to the site (use zip 60625 if asked) [sprintbroadband.com], the max d/l is 5 Mbps, and they project 'typical' to be in the
They have an upload cap of 256 kbps.
A few things worth keeping in mind:
1. It's running on RF frequencies, which means that, depending on your paranoia level, you may not want it since quality receivers are available that can receive above 2GHz. And it's not protected by the anti-cell-scanner bills (not like anyone interested in cracking t
2. IP Masquerade is probably the best way to go. They seem to be MScentric [sprintbroadband.com]. (They are intending to charge an additional ten bucks a month per extra rig online. I didn't know IP's were that rare
Ruling The World, One Moron At A Time(tm)
"As Kosher As A Bacon-Cheeseburger"(tmp)
Re:Just to set thing straight (Score:2)
'Mine is bigger than yours!'
'Is not!'
'Is so!'
'Wait, let's solve this objectively... do you measure from the pubic bone or from the base of the scrotum?'
'We need a Council on Large Genitals to come up with a standard!'
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According to Guinness... (Score:1)
Re:Line of site ? (Score:3)
Its uses a fixed dish that connects to an external modem made by a company called Hybrid. The reciever and transmitter are combined and the unit works for the most part like any standard cable modem.
On average you can expect in a fully subscribed market around t1 speeds down and isdn speeds up.
The technology from the tower to the fixed wireless antenna at a subscriberes home is RF based cloud cover and rain fade do not have nearly the affect on RF as it does on satellite based systems, the only time weather really has much affect at all is when there is very heavy ice build up and even then its minimal.
Re:Perhaps, but... (Score:1)
Broadband will bring about the apocalypse! (Score:1)
Sprint is clearly symbolic for the four horsemen! We must prepare our souls for the war, before it is upon us. The plaque has hit already, and the pestilence is taking a new form... Slashdot Trolls and Crapflooders!
Run! Run far away! Very, very far away!
But don't tell my ex-boyfriend... he's a motherfucking asshole.
Re:If it is anything like their PCS network (Score:2)
try 1000+ pings to your gateway b/c they are daisychaining racks then telling you that it is not them that is causing the problem it is you!
CN is an antenna, Petronas is a rip-off. (Score:2)
2.) IMO, the Petronas Towers is essentially ripping-off the Sears Tower in the World's Tallest category. The Sears Tower has more occupied floors and the heighets occupied floor. As can be seen from a side-by-side to-scale comparison here [historychannel.com], the only reason the Petronas Tower is considered tallier is that the antenna on top is considered to be part of the art-deco cap, while the antennae on the Sears Tower aren't.
So, now we have proof that architecs (sp?) smoke crack! :)
Re:This is the acid test for MMDS data (Score:1)
Some answers... (Score:4)
Ow (Score:1)
As long as I am rolling on a stream of consciousness, reminds me of a story, back in the day microwave station operators in the artic used to stand in front of their dishes to warm up. Maybe true, I don't know. Anyone can corraborate?
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Re:wrong (Score:1)
Re:Available now in AZ (Score:2)
Trollicious (Score:1)
Re:Broadband on the water (Score:1)
Re:wrong (Score:1)
Re:Trollicious (Score:1)
Re:Just to set thing straight (Score:1)
Re:Trollicious (Score:1)
Re:Ow (Score:1)
Oddly, many of their friends have long since died of cancer. I met these two at a HAM radio/Boy Scout thing many years ago. Couldn't tell ya if they're still around. But just knowing what the WLW tower and the VOA antenna were capable of causing (as in, your stove being hot when turned off, the ability to hear the broadcast on your fence, etc...), I have no reason NOT to believe them.
Re:Not the world's tallest building. (Score:2)
Ya really, Taco, haven't you seen Entrapment [imdb.com]?
Re:This is the acid test for MMDS data (Score:1)
Think about what you just said. :)
Line of Sight means there must be a more or less unobstructed path from you to the tower. The tower is one point, your antenna is another point, you have to be able to draw a straight line between the two withint intersecting any non-vaporous objects. No trees, no buildings, no Goodyear Blimps, no nothing.
LOS changes in definition at some manufacturer's whim... but when it comes to the Hybrid equipment that Sprint Broadband is working with [hybrid.com], and when doing RF-return, the above definition certainly sticks.
The world of RF is complex, and often things aren't as simple as pointing your antennas at each other... Just ask any RF engineer about water. Or hills. And the fun beast known affectionately as "multipath".
Go do some research and reading on Multichannel Multipoint Distribution System (MMDS), QAM64, QPSK, and all kinds of other fun acronyms. And for some more information regarding MMDS peek at this comment, below [slashdot.org].
Re:What about mobile? (Score:2)
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Re:Not the world's tallest building. (Score:1)
| Cunning Pike... Good Guy...
Max Range? (Score:2)
If you are in an apartment building on a upper floor, you may have a clear shot at the transmitter from more than 33 miles. This is because the horizon is a 5 to ten miles away from the apartment window, and this adds to the horizon distance as seen from the sky scaper.
Not accounting for trees, hills, and intervening objects, etc.
The way I originally submitted it... (Score:3)
I don't think Taco realized the flamefest he was starting by deleting that little word in parentheses. Anyway, I do live in line-of-sight to the Sears Tower, but I'm a tad out of reach of the Petronas Towers, so I guess I'll have to live with the shame of getting broadband from the second banana in the skyscraper world.
Re:Not the world's tallest building. (Score:2)
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Re:Not Semantics (Score:2)
You're forgetting an equally important category: (Score:2)
This accolade goes to a strip mall in Minneapolis, by towering acting architect Benjamin Johnson, locally known as "The Big Johnson Building".
There's another category for "highest architect", but the winning building fell down less than 2 weeks after official completion.
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Dude, they do offer it in Vegas (Score:2)
Chris Cothrun
Curator of Chaos
Re:It's not DSL. It's MMDS. (Score:2)
Yeah, we have 902-928 Mhz and several slices in the 2.4 Ghz area.
The thing that most people don't know is that their cordless phones and cell phones are often transmitting in plain FM on a public amateur radio band 902-928. They even have secondary allocation, so if I interfere with someone's oh-so-important cell phone call with my 1500 watts, they can't do anything about it, as long as I didn't do it "intentionally", but that is kinda a hard thing to prove.
I don't do that type of thing of course, just pointing out the possibilities.
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Re:What about security? (Score:2)
Uh no.
ELF Extremely Low Frequency 3 - 30 Hz 100,000 - 10,000 km
SLF Super Low Frequency 30 - 300 Hz 10,000 - 1,000 km
ULF Ultra Low Frequency 300 - 3000 Hz 1,000 - 100 km
VLF Very Low Frequency 3 - 30 kHz 100 - 10 km
LF Low Frequency 30 - 300 kHz 10 - 1 km
MF Medium Frequency 300 - 3000 kHz 1 km - 100 m
HF High Frequency 3 - 30 MHz 100 - 10 m
VHF Very High Frequency 30 - 300 MHz 10 - 1 m
UHF Ultra High Frequency 300 - 3000 MHz 1 m - 10 cm
SHF Super High Frequency 3 - 30 GHz 10 - 1 cm
EHF Extremely High Frequency 30 - 300 GHz 1 cm - 1 mm
And if it is some sort of marketing BS that made up "XHF", shame on you for perverting science with marketspeak.
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Re:Not the world's tallest building. (Score:2)
Surely Mount Everest is the World's tallest free standing "structure" (in height above sea level). The CN tower only wins if you discount non manmade things.
PCM (Score:2)
Look for your latency elsewhere.
KFG
Though I would agree with you.. (Score:2)
It is entirely possible to use the modulation techniques of DSL over RF.... you simply modulate a different carrier. I know we've looked at using DSL chipsets to do wireless before.. I believe the spectrum required or something was just not feasible..
Clarify? (Score:2)
Most wireless is either MMDS, or 2.4Ghz ISM band stuff (I know there is some 2.4Ghz ISM stuff going on in central IL, http://www.illicom.net)
I might be out of my league here... (Score:2)
You certainly cannot go through 'lots of trees'. 2.4 scatters like mad.. it doesn't penetrate worth crap.
Is it just the power levels this operates at that make it work through obstacles?
I think line-of-sight still means unobstructed view, though perhaps the odd tree or something will be okay.. but if you are underground, behind a hill, or something, you're probably out of luck.
Re:I might be out of my league here... (Score:2)
MMDS occupies regulated spectrum and thus can operate at much higher power and is able to penetrate obstructions like trees.
Re:I might be out of my league here... (Score:2)
Multipath's a different story. Different radios survive it differently. Cisco, for instance, is quite vocal about how their OFDM radios for MMDS are multipath resistant (they work okay even if the signal is bounced off of a few buildings). Some others aren't. I don't know what radio Spring is using here but I suspect it's one of the newer, more multipath-resistant ones. That, btw, is what vendors are talking about when they say they support non-line-of-sight. Hills are a different story -- that's no path!
Want speed? (Score:2)
At the time I ordered and had installed Cox@Home (I know, I know - it sucks, but I can't get DSL where I am at, last I checked), I firewalled it, as recommended by just about every sane individual on the planet.
When I had it installed, due to a couple of reasons I had to set up the firewall on a Windows 95 box. This box was also my GF's box, so I was a little nervous running both user apps and a firewall, but at the time I didn't have a choice.
The firewall I chose was ZoneAlarm - simple to install, admin, and best of all, free. Today I would probably choose Tiny, but that wasn't available then (and I only recently learned about it). I searched for some kind of NAT solution (the box runs 95, not 98), but came up empty handed, so I opted for a proxy server: AnalogX's Proxy. This solution worked well for quite some time, and I never had many problems (occasionally the Win95 box would freak, and I would have to reboot), except for one thing - it seemed "slow", compared to my GF's box. All the apps on my GF's box ran through the firewall, while my box ran through the proxy, then the firewall. It was all still faster than a modem, to be sure, so I lived with it, figuring that I would be using a regular firewall later, and besides, what more should I expect from a free solution...?
I always intended to set up a "real" firewall at a later point. I had thought about a Linksys router/NAT box, or possibly building it myself. Things dragged on, then recently I gained the oppourtunity to do what I wanted. I chose to build a box - to get the experience, number one, and because it was overall cheaper, plus I could expand it (unlike the Linksys router).
I chose Freesco (which is based off of LRP), because it is easy to admin, has remote admin capability (telnet and web), good documentation, and support for a ton of NICs. After getting it setup, and running it, I found out a very good thing:
Your speed is only as good as your routing software (or hardware, as the case may be)!
I guess I should've known this - it is a good lesson to learn. The majority of people don't have to worry about this on a cable modem or DSL: they only run one machine, or a wide open network (the latter can be a risky situation, IMO). I run (or attempt to) a secure home network, so having the routing capability is a must.
The speed improvement is incredible - I don't have hard numbers - but I know web page loads, mail downloads, everything is faster - much faster. So, if you are having speed issues (or you think you are), look into changing your routing/firewall software or hardware system - you may be surprised.
Now, if I could only get rid of this upload cap (can anybody point me in a good direction - heck, I would even be willing to try to spoof being the BOOTP server for the cable modem, if it would work)...
Worldcom [worldcom.com] - Generation Duh!
Re:Not the world's tallest building. (Score:2)
Re:Available now in AZ (Score:2)
Re:The way I originally submitted it... (Score:2)
Re:CN is an antenna, Petronas is a rip-off. (Score:2)
Re:Who cares the chinese will win (Score:2)
Re:Not the world's tallest building. (Score:2)
Re:Not the world's tallest structure (Score:2)
Re:Not the world's tallest building. (Score:2)
If Oshkosh gets to be the "busiest" airport for one week, then can I temporarily build the "tallest man-made structure" by tying a long cable to a big rocket and firing it upward? Granted, it doesn't last long, but for a few brief seconds I've got the tallest "free standing" structure. It's made of one cable and a rocket, and it won't last more than a few seconds, but still...
I don't consider the caveats put on the Sears Tower by Chicago to be "cheating". The spire of the tower in Toronto is just for show, as is the decrative structure at the top of the one in Malasyia. The Sears Tower actually has real, honest to goodness EMPLOYEES using those floors all the way up to the top. The reason the observation deck isn't at the top is because the top actually has offices in it.
The Sears Tower has the highest floors that are actually USED by people for something.
Re:Not Semantics (Score:2)
Re:no one agree with you (Score:2)
Re:Not the world's tallest building. (Score:2)
Double-ended explanation. (Score:2)
So... AFA the units: Sorry to have offended you. Perhaps you can clarify if the SI unit is "cycle".
And AFA the XHF notation:
The way I've experienced the radio spectrum, and according to my ARRL Handbook, you can split the RF into three discrete parts. Note that the top and of each range overlap in characteristics at times with the bottom of the range of the next type; ex. a 60 MHz transmission is more likely to act like a VHF wave and duct tropospherically rather than get ionospheric bounce.
Less than 60 MHz: These are long waves. These waves bounce off the ionosphere, which is between 50 and 650 clicks up. Some of the layers only work during daylight hours, and these higher levels bounce the higher frequencies. (You can listen to the BBS arounf 17500 kHz during the day and have to settle for somewhere in the 6000 kHz range at night.)
Antennas are LARGE. From wire dipoles meters long to huge yagis and quads, the antennas need to be very large for any reasonable gain.
60 - 1000 MHz: These can be 'ducted' in the troposhpere, which extends from where you are now to about cruising altitude, 10 clicks up. Ducting is pretty tough and pretty tricky unless you're either damn lucky or damn skilled. It's a really funky process.. these signals are weird that way. You can miss a friend's call from across town, but you can hear people from thousands of miles away on a lark. These signals, though, can be directed (useful in moonbounce communications) or broadcast in a spherical pattern (look at your TV or radio).
Antennas for these frequencies are considerably smaller. Any kind of antenna can work, with the exception of bullhorn antennas (used for microwave work.. read on). Huge dishes, yagis, quads, hell, walkie-talkies use rubber-ducks!
Above 1 GHz: These freqs are increasingly limited to LOS. You can get some propagation on the lower end, but the higher you go in freq, the smaller the stuff that conflicts with the signal. (Above 10 GHz, water vapor and O2 can affect the signal!)
Bouncing off airplanes is possible, and done by some to, ex. communicate over a mountain.
Directionality becomes important here. This increases the beam's focus, and you don't accidentally fry yourself with microwaves. That's why dishes and bullhorns are used with these signals.
OK? Lather, rinse, repeat, chill!
Ruling The World, One Moron At A Time(tm)
"As Kosher As A Bacon-Cheeseburger"(tmp)
Translation of sig (Score:2)
We saw, we conquered, we came.
Cute.
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Re:I might be out of my league here... (Score:2)
Yes, I was referring to ISM band devices, and yes, I know that MMDS occupies licensed spectrum.
The whole spectrum, though, is regulated. The 2.4Ghz ISM band is also regulated. There are rules one must follow.