Square Kilometre Array is so sensitive, its datacenter needs two Faraday cages to stop RF leaks Work on the datacenter that serves the Square Kilometre Array’s (SKA’s) site in Western Australia is all but complete, including the installation of two Faraday cages to ensure the equipment inside does not leak radio waves that could harm the operation of the giant radio telescope. The SKA is an international project that is …
Or is one inside the other to maximize the effectiveness?
What are they going to do about people showing up on site with phones, watches, and other electronic devices on their person? What about cars, especially EVs? They'd need a fence surrounding it a mile away on all sides otherwise lookie-loos showing up to take pictures are going to be a problem.
Phones, watches, other electronic devices? I expect there will be a ban on bringing powered-on electronics to the site (unless suitably shielded). I'm not sure that EVs are going to be worse than spark-ignited engines (petrol), but compression-ignition (diesel) should be better. I think the main defence against lookie-loos is the "800km from Perth" - that 500 miles is not uninhabited, but there isn't a lot there either.
My new car has electronic keys which only have to be within about 20m of the car to work. (There are articles on the Register about stealing cars by intercepting comms between the electronic key and the car even when the keys are in a house.) I bought a couple of Faraday pouches, one for each key, but the car will not lock if even one key, in a pouch, is in the car. This sort of thing must be a nightmare for such sensitive equipment. I just wonder whether building the support facilities underground would have been cost-effective.
Looking forward to the discoveries.
> I expect there will be a ban on bringing powered-on electronics to the site
The few people who will make that boring trip all know about that. It's a little like "don't wear your manure-covered wellies in the operating room", usually hospital staff doesn't need to be told.
"I'm not sure that EVs are going to be worse than spark-ignited engines (petrol), but compression-ignition (diesel) should be better. "
Even newer diesel vehicles are loaded with electrocrap these days. I need to look if EV's can be put in "airplane mode". I don't have one yet but plan on buying one if the roof holds together and the creek don't rise.
Spark ignited engines are not as big an issue as they were when they had a distributor. With all of the electronics in cars, there's a need to minimize noise radiating from the ignition system so the car doesn't score own goals.
Chances are your phone won't work because there won't be a cell tower for a few hundred kM, so fairly quickly the battery will go flat.
ANYONE walking onto an astronomy site is going to be lynched if they have a Sat Phone..... Bloody LEO com-sats screwing up observations and all that :-)
Given that any modern vehicle leaks and radiates absolute floods of data I think that even a modern diesel should be kept away from it.
An old one, no problem, but all newer cars have been obliged to fit mobile data transmitters and disabling that tends to be buried several menu layers deep (if available at all). In addition, a lot of them now have radar which is apparently so powerful that it picks up mosquitos from a mile away (the only reason I can see for the apparant random slwoing down of my car when adaptive cruise control is on).
They should go and talk to the Dutch about bicycles..
The problem is that the high voltage ignition systems, specifically the spark plugs generate large amounts of RF over a large frequency range. I used to pick it up on AM radios tuned between stations. Not sure how much leaks out from the spark plugs due to them being surrounded by metal but the lead to the spark gap, the return path though the metal block and ceramic insulator(?) probably radiate a fair amount. I believe the first radio transmitters used spark gaps to generate the RF.
The ignition noise on petrol engine.s is mostly radiated by the high voltage leads.
The spark plug gap typically breaks down at 15 20kV depending on the gap size and Air-Fuel ratio of the mixture in the cylinder. The arc usually burns at approx. 2 kV for 1.5ms during which time it draws as much current as it needs. The rate of drop from 20kV to 2kV and the rise of current from 0 to whatever is what determines the bandwidth of the EM waves generated. With copper wire leads, the dv/dt and di/dt are HUGE and so is the bandwidth. Modern ignition leads are carbon impregnated fibre with a substantial resistance which limits the both of these, massively reducing the bandwidth.
It won't fully eliminate the rf emissions so spark ignition engines would not welcome anywhere near the antennas.
The first radio transmitters were indeed spark based as electronic oscillators were yet to be invented.
Although EM waves had been predicted by James Clerk Maxwell, it was Heinrich Hertz who discovered them when he discharged Leydon Jar (capacitor) across a Riess Spiral & saw a spark jump across the gap of a separate nearby one
" With copper wire leads, the dv/dt and di/dt are HUGE and so is the bandwidth."
... was. Non-resisting wires and/or spark plugs ceased to exist in 70s when AM radios were replaced with FM. Also wires are shielded, not plain wires.
5k ohms is more or less standard since then.
Some RF of course still leaks, but different magnitude of what it was in the old times.
They will be made to leave them in the mailbox outside
I wasn't talking about people who work there or research there. I'm talking about "tourists" who stop by for a look. Yes I'm sure it is way out in the middle of nowhere, but so is Area 51 but that hasn't stopped people from trying to get close and AFAIK SKA isn't patrolled by men with machine guns.
All you need is ONE conspiracy theory about "what's really going on there" and suddenly visitors are a real problem! Based on finding out there's a massive "medbed" conspiracy theory I had never heard of until last weekend, I've decided there is nothing so stupid that it won't get a lot of people to believe it. I thought Qanon was crazy but that's got nothing on medbed. I think they might be stupider than flat earthers.
"What are they going to do about people showing up on site with phones, watches, and other electronic devices on their person? "
I think that keeping people from showing up at random will be the first line of defense. A locked gate at the end of a long road and sign written in nasty. It won't take long before word gets out that you can't get anywhere near to see anything, so don't bother.
"The SKA’s designers chose Murchison because it is remote and almost devoid of human activity"
You know, if they had changed the requirement by only one teensy-tiny little letter ...
"remote and almost devoid of humane activity"
... they could have put it in the middle of Canberra.
Yup, seems the regular transmissions from services like Starlink can be filtered out, as they are predictable signals, but these same systems apparently constantly leak other RF frequencies, from things like the on board electronics, and these are less predictable so harder to deal with.
Seems there are no regulations currently on leaking other RF signals for satellites, so no requirement to add shielding, or a Faraday cage etc, to block these errant signals, as that would add weight and cost, so companies like Starlink simple don't bother.
> the regular transmissions from services like Starlink can be filtered out
...but you'll be also filtering all wanted information on the affected frequencies (+ side bands and harmonics). It's like trying to capture the sound of a worm slithering right in front of a rock concert's loudspeaker wall*: The music might be mostly predictable, but it definitely create a lot of problems...
* And it's not even the scale. It would be more like the sound of paint drying next to a Saturn rocket launch...
They need to stop the pesky French from running their trains there too
Almost a Faraday Cage -->
“People effectively go through airlocks,” Diamond said. “The inner door will not open until the outer door is closed. And they make Star-Trek-like noises as they open and close.”
It doesn't say whether it's the doors making the noises or the people supplying the sound effects. Knowing techies, it's about evens which it is.
I've been there. 250km from the nearest town. 'Remote' is an understatement. Closest mobile phone tower is more than 150km away, but the site only investigates relatively low frequencies under 2.4GHz. Starlink et al are far more of a problem than watches and other RFI locally. Here are some photos I took there back in 2018. They were still working on the Faraday cages back then. One of the engineers who was involved in the construction noted how amazed he was how RFI could escape from the cages with even a very minor flaw in the welds. They spent a lot of time meticulously testing all the potential escape vectors to ensure it was 100% sealed. Yes, it's HOT. Yes, there are LOTS of flies...
https://photos.app.goo.gl/ZxBkEVM8Mr7PLNNX6
