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Quiet Cellular Antenna Tech To Boost S. African SKA Bid
slash-sa writes "Two South Africans have given their home country a boost with its Square Kilometre Array (SKA) bid by inventing cellular antenna technology which reduces 'noisy' emissions from cellular base stations in the area. They reduced emissions by using an antenna based on phased-array principles, providing omnidirectional coverage but also blocking the RF transmissions along a single direction (that would correspond with the bearing of the SKA core site). The antenna has been tested and performs extremely well. Trialling measurements have shown that the RF signal levels at the proposed SKA core site can be reduced significantly, while at the same time, much of the original GSM coverage can be retained."
science still gets some funding. Amongst all the cuts we've seen in the past years, this is excellent news!
Imperium et libertas
Autocracy and freedom
Australia would be welcome to do something like this... I'm a South African EE student at the moment, I'm working towards an SKA related project, and whether or not South Africa is chosen ultimately, we have our own radio telescope plans, so this would be useful anyway.
The SKA is about international collaboration, AFAIK. It's good for countries to share inventions.
One thing I know, and that is that I am ignorant...
Apparently one of the big advantages the Australians have in the bid is that their site already has significantly less RF interference because of it's relative remoteness and much lower surrounding population density. However, that remoteness is a downside too, as it makes construction and supply costs much more expensive. This technology could really improve South Africa's chances, because apart from RF interference, they seem to have a stronger bid. The Karoo, being less remote, reduces costs for building, communication infrastructure, supply etc. Also, South African labour costs are cheaper. If this technology can reduce RF interference to comparable level with the Australian site, it'll be great. Sure the Australians could use it, but my understanding is that there's so little RF interference at their site as to already be barely above the detectable threshold of the proposed SKA equipment. (Citation, drunken conversation two weeks ago with one of the people working on the S.A. bid)
Getting the antenna deployed is another matter. For example ICASA has serious corporate governance problems.
I live in South Africa and I regularly pick up high power WLANs in my neighbourhood. And I suspect many of them are used to carry CCTV signals or to bypass the expensive telecoms operators. The public is sympathetic to these cause. So compliance with government regulations will not be very high.
However, that remoteness is a downside too, as it makes construction and supply costs much more expensive.
This is actually one of the real forte's of Australia's construction force. Our many remote mining and gas projects which create a local town to sustain the business have basically trained a contract workforce and vendor supply chain easily capable of building massive projects in the middle of no where.
Though this is a double edged sword. The last gas plant I worked in recently had massive troubles finding qualified welders to work during their maintenance shutdown due to the amount of work going on around the country sucking up local resources.
Every cell phone tower in the US has access to extremely high precision time signals via GPS (and indeed, most of them function as secondary GPS locators by effectively forwarding that signal plus tower location data for phone "GPS" which isn't). Every cell phone tower is basically a big antenna. Every cell phone tower has excellent signal connectivity (usually fiber, sometimes microwave) to a communications network that can carry the signals they receive at any particular frequency, convolved with a universal time reference frequency synchronized by means of the aforementioned GPS, to a large processing station. Hence it is absolutely bone-simple to turn the entire network of existing cell phone towers into one great big radiotelescope.
/., but so be it.
The cost of doing so is almost certainly going to be a tiny fraction of the cost of building an actual devoted function radiotelescope. I had a student estimate the cost per tower to be in the ballpark of $1000 US for a local computer and sundry electronics, probably less purchased in bulk. One could very likely get the tower owners to donate at least the access to the radio signals (basically costs them nothing), a place to site electronics (ditto), and with luck even a channel and some bandwidth to permit the upload of x-hours of recorded phase locked signal in off-peak bursts as part of their "public service" requirement.
The additional benefit is that one ends up with a radiotelescope that spans a continent -- an aperture several thousand kilometers across, with hundreds of thousands to millions of towers contributing. The resolution would thus be orders of magnitude greater than any of these toys that they are trying to fund and the sensitivity (proportional to N^2) would be MANY orders of magnitude greater as well. In fact, one could probably build arrays that spanned continents and turn the entire surface area of the earth into one big radiofrequency "eye" that can be turned not just anywhere but everywhere 24x7 -- the towers basically record a high resolution hologram of the night sky and one can "look" in any direction you like within any single dataset by simply adjusting the phases of the recorded signals appropriately in the decoding. That is, one doesn't have to devote the towers to looking in some particular direction, one can look in all directions at once and choose what to actually look at in detail in the step where the signals are decoded and recombined with appropriate phase delays.
This will never get funded, of course -- it isn't "big science" in any visible way. Or rather, perhaps it already has been funded, because it is one of the few ways I can think of that one could provide an ABM defense with a universal direction "eye" with sufficient resolution to locate an incoming warhead, and (by using the entire array as a phase-locked TRANSMISSION array) one might even be able to deliver a megawatt or so of power of microwave energy directly onto the missile itself and burn it out. Of course, if this is true then I guess I'll soon have somebody knocking on my door for publishing this on
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Even when the experts all agree, they may well be mistaken. --- Bertrand Russell.