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more on the cringely-wireless discussionRuss commented: Isn't that around the time his child died from SIDS? It might explain his absense. He had an article about in April. Insanely tragic.This is quite possible, and what happened with his child was horrible indeed. Whether this was the reason or not, Cringely clearly knows what he's talking about and his other comments on tech are usually on the mark, so I am more skeptical of the skepticism than anything else. Also, what he did has been replicated in other places, the first guy that did it in Egypt did it way earlier than him. Also my friend Chris said this in an email (btw, Chris, when are you getting a weblog? :-)): Technically it is totally feasible. Actually we have set up a 2+km wireless link between two distant buildings belonging to the University. By using the appropriate high-gain directional antennas (say a 17dBi parabolic antenna) you can support links up to 3-5 km long. A University in Spain has set up a link which is even longer (something like 12km).Heh, I like the idea of using it to cook food. A sort of microwave oven for the masses! Seriously, though, at Trinity, we've been setting up an experimental ad hoc network called DAWN throughout the campus, using basically the same technology but using less power (and so less range). Now that I think about it, there is also a broadband wireless service here in Ireland with a 2Km range. So I'm wondering if the people that objected to it were objecting to something specific about the technology, like using a certain type of transmitter... in any case the result is certainly feasible. So even if the specific technology might have seemed strange, the result is not. Categories: technologyPosted by diego on January 16 2003 at 7:46 AM Comments (please see the comments & trackback policy).
I was expected to be published, so here are some points I should make: 1. A wireless link is actually called a "microwave link". The spectrum that the several flavors of IEEE802.11 operate is the same that is used by microwave ovens. So the only thing that prevents oneself being cooked from the emmited radiation is the signal's power. FCC and EU have set up a limit of 200mW for any such link (compare that with the 500W of your microwave oven). 2. In order to create a long distance link you can either 1) use an ominidirectional antenna (radiating in a 360 degree window) with a high input signal (beyond those 200mW we refered to before). This means that you are breaking the law, and exposing your neighbors to high radiation levels. Also, it is highly uneconomical since you need a very powerful amplifier for the output signal, even if you try to cover relatively short distances, not to mention the fact that it might be unhealthy as well. As an alternative you can 2) use a highly directional antenna (for instance a parabolic antenna, like those used for satelite TV), and focus the signal directly to your target. This way, using the same low power signal you can create these long distance point to point links. Now, as a testament to how long such a link can be, check: http://www.gaips.upv.es/Castellano/Enlace35.htm which contains a description of how the Universidad Politecnica de Valencia in Spain managed to create a 35km link using 802.11! However, with regard to the radiation issue, one has to bare in mind that our mobile phones (operating at 0.9 and 1.8GHz) dissipate 2.0W. A wireless link, which operates at 2.4GHz, has a signal which is even weaker. Let's not be overly excited at the issue... After all, there are so many forms of electromagnetic radiation, emitting from power lines, phones, wireless devices, and yet people are still healthy. Posted by: Chris at January 16, 2003 9:03 AMI was expected to be published, so here are some points I should make: 1. A wireless link is actually called a "microwave link". The spectrum that the several flavors of IEEE802.11 operate is the same that is used by microwave ovens. So the only thing that prevents oneself being cooked from the emmited radiation is the signal's power. FCC and EU have set up a limit of 200mW for any such link (compare that with the 500W of your microwave oven). 2. In order to create a long distance link you can either 1) use an ominidirectional antenna (radiating in a 360 degree window) with a high input signal (beyond those 200mW we refered to before). This means that you are breaking the law, and exposing your neighbors to high radiation levels. Also, it is highly uneconomical since you need a very powerful amplifier for the output signal, even if you try to cover relatively short distances, not to mention the fact that it might be unhealthy as well. As an alternative you can 2) use a highly directional antenna (for instance a parabolic antenna, like those used for satelite TV), and focus the signal directly to your target. This way, using the same low power signal you can create these long distance point to point links. Now, as a testament to how long such a link can be, check: http://www.gaips.upv.es/Castellano/Enlace35.htm which contains a description of how the Universidad Politecnica de Valencia in Spain managed to create a 35km link using 802.11! However, with regard to the radiation issue, one has to bare in mind that our mobile phones (operating at 0.9 and 1.8GHz) dissipate 2.0W. A wireless link, which operates at 2.4GHz, has a signal which is even weaker. Let's not be overly excited at the issue... After all, there are so many forms of electromagnetic radiation, emitting from power lines, phones, wireless devices, and yet people are still healthy. Posted by: Chris at January 16, 2003 9:03 AMCopyright © Diego Doval 2002-2007.
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