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No Wi-Fi Around Huge Radio Telescope
JG0LD writes "Students at a tiny Appalachian public school can't use Wi-Fi because any such network can throw the radio equivalent of a monkey wrench into a gigantic super-sensitive radio telescope just up the road. GBT's extraordinary sensitivity means that it's very susceptible to human-generated radio interference, according to site interference protection engineer Carla Beaudet. 'If there was no dirt between us and the transmitter, a typical access point ... would have to be on the order of 1,000,000 km [more than 620,000 miles, or about two and a half times the distance from the Earth to the Moon] distant to not interfere. Fortunately, we have mountains around us which provide lots of attenuation, so we're not seeing everything from everywhere,' she said. A standard Wi-Fi access point would wipe out a significant range of usable frequencies for the observatory. 'It simply ruins the spectrum for observations from 2400-2483.5MHz and from 5725-5875MHz for observational purposes,' wrote Beaudet."
The National Radio Quiet Zone has been there since 1958. It's not like it was just discovered yesterday. People living in this zone have always had to live without radio transmitters. Not having 802.11 is just another of the services they cannot use, like wireless garage-door openers and cell phones.
This is also a huge problem for spaceborne radiometers that observe the Earth's surface (example paper). A radiometer is essentially a very sensitive receiver, and there are portions of the UHF and microwave spectrum reserved specifically for scientific research so that terrestrial stations don't interfere with the measurements. Unfortunately, interference may occur from transmitters directly in the band, from adjacent channels, or inadvertent harmonics from poorly-filtered transmitters. Pinpointing and correcting these sources is a logistical nightmare, especially when you have to deal with every individual country's RF regulators.
"here is a technological solution to the problem in the pipeline -802.11ad, a next-gen wireless standard that uses 60GHz frequencies to send and receive information, instead of the usual 2.4GHz and 5GHz bands. At 60GHz, according to Beaudet, radio energy essentially just bounces off the atmosphere -meaning that the frequency is useless to the Green Bank Telescope in the first place. Signals to and from 802.11ad access points, then, would have no effect on the work taking place at the GBT, allowing for the best of both worlds. Unfortunately, 802.11ad is very much a technology of the future, not of the present -experts at an Interop New York panel last year predicted that devices using the standard wouldn't hit the market until 2014."
NSF plans to cut the funding for the National Radio Astronomy Observatory at Green Bank. So I guess the kids will soon have WiFi and cell phones. This is a good thing, right?
Bluetooth will cause the exact same problem... A real solution here might be using infrared though.
There is also no issue today.
Cat5 wires to every computer. Its not that big of a deal.
Sig Battery depleted. Reverting to safe mode.
If conditions are right, I can have a contact with someone on CW running 5 watts, on the other side of the globe.
Such is the sensitivity of tuned circuits. For untuned interference, like your cell phone trying to interfere with your TV, rejection is great. But when you're specifically tuned to receive a frequency, you've got such a high sensitivity to that specific frequency, (and very high rejection of any other frequencies) that a cricket fart of a signal a long ways away can sound like a lightning strike on your house, if it's on the same frequency you're straining to hear.
They're a little better off than my CW example, being on a high frequency that's mainly line-of-sight, for which surrounding mountains would be a pretty effective shield, but still their receivers are just incredibly sensitive at their design frequencies. They just can't have anything anywhere near them or you will be all they can hear. It'd be like trying to listen to someone talking to you from a table at the other end of the restaurant, while you are seated right next to a table full of loud party animals. You'd have no chance.
I work for the Department of Redundancy Department.
Just let FedEx handle all your data transfer needs.
High latency, High bandwitdh. But given the road, fedex is a little slow. IPoAC would be better. http://en.wikipedia.org/wiki/IP_over_Avian_Carriers
So some kids can't get Wi Fi. A vast majority of people around the world grew up without WiFi and of those most who went to school did so without WiFi.
[best Walter Brennan voice]
Yup sonny, I can remember back in the day having to use Wires!! Wires for pete sake. Imagine that!
Went by the name of CatFive, for some crazy reason. You had to plug them into the wall.
If you lost your wire you couldn't do anything. Had 8 wires in them, but only used 4 of them.
Durndest thing you ever did see.
Sig Battery depleted. Reverting to safe mode.
When Greenbank was built this "high tech modern society" stuffe didn't exist. It's been there for about 50 years. People can choose not to live there. It was remote initially. People moved in.
The article doesn't explain why the tablet computers must have a network connection to be used to read digital textbooks. Is there any reason why the digital textbooks can't be loaded from a hardwired connection and then used when the tablets are offline?
The article also doesn't explain why every student in the entire school must have simultaneous internet access in order to take the online standardized tests. It should be possible to set a computer lab with enough computers to allow every student in a single grade to take the online standardized tests.
The article mentions that there is a highly restricted NSA facility near the school. I'm sure that the NSA knows how to limit signal leakage and radio frequency interference. Perhaps the NSA facility can find a solution to this problem that doesn't require a wireless network.
The summary is restating the obvious but the actual article is about how the school district and state are moving to use ebooks and online testing so this school needs a lot of additional networking gear to keep everything wired only. They also mention how 802.11ad would work since it's signal range is too high to get through the atmosphere so the observatory doesn't care about it, but 802.11ad isn't readily available yet.
This is why the proposal to build a radio telescope array on the far side of the Moon has been around for so long. Having the moon between us and it is one helluva lot of dirt for blocking stray signals. Plus no atmosphere to get in the way. All you have to worry about then is reflection of Earthly signals off of other bodies in the solar system.
Too bad about the expense...
This is the second post I've seen in as many days on Green Bank, and no mention of the fact that the NSF is planning on closing the facility to save money. Green Bank is the largest movable radio telescope in the world. If you feel--like I do--that this would be a detriment to the nation, please sign the petition or, even better, write your Congressperson.
If they really need to use the frequencies that a technologically developed society uses all the time, then they should build their instruments in a remote enough location that regular use of technology would not be likely to interfere with them, instead of building it near enough to a town or city that a school could reasonably pose a threat just by using wifi.
Well now, aren't we the social experts all of a sudden? The National Radio Astronomy Quiet Zone, aka the NRAQZ, was setup in the 1950's as someone has already pointed out, and it is a natural bowl with 3 to 5 miles of real estate that is shielded from a lot of earthy interference because of the surrounding hills.
In 1950, there may have been some daytime AM radio in the area, which is not much of a problem because they don't listen to much below 300 mhz, 300 times the frequency of a Ma & Pa radio station. Its (the ma & pa radio) still there too.
Interesting side effect was that distant tv stations were forced to either be low band vhf, or if high band, more limited in power output. WTDV, on channel 5, about 80 Mhz, built their original facility on Fisher Hill, which was actually about 2 miles inside this designated areas borders, and was put there by the FCC's rules & regs when it was built in the later 50's because it was the highest point, and could not be moved more than 2 or 3 miles from where it a was at without being short-spaced to some other station. But was allowed to use the full 100kw sync tip peak power that any low band vhf can us as a maximum ERP.
WBOY, 17 miles north in Clarksburg and assigned to channel 12, was not allowed the high band vhf's max power of 330 kw ERP. but was limited to 100kw because of the slightly above 200Mhz frequency.
So, in the run up to the digital conversion, they wanted to recover all the low band stuff for use by Law Enforcement & because their assignment program was written by an idiot that wasn't aware of the NRAQZ, and proceeded to assign both stations new channels in the 56-58 range. That's in the high middle of the 700Mhz range. So I called the enforcement/compliance officer at Green Bank and asked him how much noise I could make on channel 58. 58 don't mean nothing so I had to translate to the actual frequency, which he plugged into his program and which said that the maximum power I (WDTV, I was the C.E. at the time) could send from 270 degrees true to Green Bank was 4.78 watts. Anything more than that he would have us shut down. I said send me a letter to that effect, and he did.
So I went to the NAB a couple months later and had a ball going around to the various transmitter makers showing that letter and asking for bids on a 4.78 watt transmitter. IOW, I had a ball poking fun at the commishes obvious stupidity.
Eventually, along with some heavy duty prompting by our Washington legal people, they saw fit to let us stay on our low band frequency. Quite a few of the tv broadcasters in the more mountainous areas have also stayed on our original channels.
As for de-funding or de-protecting the area from interference from the broadcasters, no way. 90% of what we know about the radio universe around us, came from Green Back, and to a certain extent, Aricebo. But while Aricebo can hear farther, it isn't nearly so steerable, nor as sharply focused as Green Bank's big dish. The new dish they built to replace the 300 meter that fell from rust & corrosion way back when, is performing at a level the old dish only dreamed about. It can move faster too in the event of a gamma ray burst, it can slew and be looking at the source of that burst in just a couple minutes. That facility is IMO a national treasure. FWIW, you have to take the bus into the place is your car has spark plugs. So everything that moves in that valley moves in a diesel bus, or by muscle powered bicycles.
Like Paul Harvey would say, and that's the rest of the story.
Cheers, Gene
iPads don't have USB ports
Of course it does, and both genders at that.
or any sort of removable storage whatsoever
Come again?
There is not any living quarters other than what may be a dorm for interns doing research, that I know of "inside the bowl", but Davis (I think that's the name) is only 2 or 3 miles away, south on the blacktop, and there are farms all around it.
I don't live there obviously, but have been down to play tourist a couple times. At my age now, 78 & diabetic, the walking would get me down quickly as the hip joints are about shot, and the better half has COPD, so I expect we have been there for the last time. We stopped for a sandwich & cup in that town (maybe 300 on Saturday night) the last time, and with the relative quiet on the car radio, you got the impression you were transported back to a simpler, slower time, and one that I, after all the years in broadcasting, could easily enjoy the contrast. People there seem to actually talk to each other! The hills there aren't quite as 'in your face' as they are locally. Here, you leave by the same road that got you into this little cul-de-sac, or you rappel from tree to tree just to get to the top of the hill 100 yards away from my front deck.
Cheers, Gene
They allowed development with the understanding that no wireless devices be used. The people that developed knew, and know, full well what they are allowed and not allowed to do there.
I'm a radio astronomer who frequently uses the Parkes radio telescope in Australia, and I really wish we had an exclusion zone around it like the one around Green Bank. It's not really something you can put in place retrospectively, though: you need to write the exclusion zone into law when you build the telescope, and fight to keep it from then on. At least we've been smart enough to put an exclusion zone in place around the new ASKAP telescope in Western Australia.
I've got to say, though, that
90% of what we know about the radio universe around us, came from Green Back, and to a certain extent, Aricebo.
is a bit of an exaggeration. Even just in the US, you've got the VLA, which is arguably a more important radio instrument than Green Bank; and then you've got Effelsberg, Lovell, LOFAR and the WSRT in Europe, the GMRT in India, Parkes and the ATCA in Australia ... None of them are quite as good as Green Bank at what it does - broad frequency coverage and excellent point-source sensitivity - but each of them has something that it can do better than any other instrument in the world. Parkes, for example, is good at high-time-resolution surveys - it's found more radio pulsars than every other telescope put together.
So I went to the NAB a couple months later and had a ball going around to the various transmitter makers showing that letter and asking for bids on a 4.78 watt transmitter.
Kewl. QRP commercial television station. Do you QSL?
Not that I know of. Used to be fun back in the late 40's when you could pick up a Miami FL station running an Indian Head test pattern at 3 in the afternoon in rural Iowa. :)
I think a lot of the "mountain area" VHF TV stations haven't been forced to digital is because, at least in Oregon, they are translators put up by a group of local residents so they could get ANY TV. Those groups are long gone and nobody has much money to buy new equipment, so the residents got their legislators to exempt them. I think.
Nice story. Thanks.
Humm, quote parent doesm't quote it all, come on /., get with it!
Actually, translator rules are under a different section in 47CFR, and I believe they can stay by getting one of those digital to analog boxes they gave out coupons for back in 2008 so we didn't force everyone to buy a new tv when the old one was still working. We are doing it too, putting the converted to analog signal on one of the low uhf channels, but it doesn't get very far on 10 watts, I am 16 miles away and I can see its on the air is about the best I can say about it. West of the river, I think the translator power limit is lower, but some of that stuff is pretty bad technically, so trying to get a digital signal thru them undamaged can be pretty frustrating. Power is measured differently too, for digital its average, the old analog rules were peak, so 100kw sync tip peak, took 26.3kw (IIRC) peak out of the tx, which actually measures 16.7 as heat in the dummy load. the 26.3kw to 100kw was the 4 bay antenna gain. That same power amplifier, when linearity corrected for the digital signal, can make about 4 or 5kw of usable digital power since it has to operate nominally 12 db below its peak ability in order to have room for the peaks of the digital signal. Which still generates 35kw worth of hot water or hot air, whatever the cooling method used.
Most of those translators are owned & licensed to the parent tv station they carry. Maintenance too is generally by the tv station engineering staff. Cost is justified by the additional eyeballs in the ratings. :)