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Australia's Outback Could Get Web Via TV Antenna
disco_tracy writes "Australia began switching off its analog TV signals in June and the transition to digital-only transmission is expected to be complete by the end of 2013, five years before the roll out finishes for the NBN. The leftover analog spectrum could be used to deliver Internet to people living in remote areas. Unlike 3G networks, which lose download speed with more users, the analog signal would provide a consistent speed no matter how many users there were."
Unlike 3G networks, which lose download speed with more users, the analog signal would provide a consistent speed no matter how many users there were.
Gentlemen, I think we've found our solution. With 4G, we need to first convert the digital signal to analog before transmission. Network congestion will be a thing of the past!
I don't have time for a full writeup, but read for some reasonable info. This is intended for areas where the user density is very low, so low that the users are at significantly different angles from the base station, and multiple steered beams can be sent to different users at the same time. They can get about a 6x gain in capacity that way.
The "reuse of analog" simply means that existing VHF antennas at the user end will work. This is useful, because in remote areas, people already have big towers with fixed antennas pointing in the right direction. The base station antennas change drastically, the modulation scheme changes, the user interface boxes are new. Only the user end antennas remain. But that's the item that's a pain to replace in the field.
The guy behind this is a serious RF guy, worth listening to. He can probably make this work.
(Disclaimer, I work for a broadcaster in Australia, so take this with a grain of salt)
OK for starters the bit about "consistent speed no matter how many users there were" is complete garbage, with ANY radio based system data system.
Secondly, if you start using the TV spectrum for data in both directions, you start putting a really strong signal OUT your TV antenna, which despite being on a different frequency to the actual TV channels, it is close enough to swamp the (really weak by several orders of magnitude) TV signal on the next band with the (extremely strong in comparison) outgoing signal.
So you can forget about watching TV while you're using the internet.
The decision to sell the TV bandwidth rather than just keep it for the public use (eg. super HD TV, or super multichanneling or whatever is in the future) is completely about $$$$ and greed by the Federal Govt so they can sell the bandwidth to the highest bidder.
Grrr.
I'm a perfectionist but I'm trying to cut back.
The ability to transmit VHF (TV) into the hinterlands had as much to do with multi-kilowatt signals as it did with frequency. Pump 60 Kw into a 2.4 GHz wifi transmitter with a good directional antenna placed on a high tower and I'll bet the punters in the outback can find a working hotspot -- probably one in China at that power.
Learning HOW to think is more important than learning WHAT to think.
There is no such thing is digital. When you go to smallest elements (atoms, electrons, ...) you enter realm of quantum physics. There is no clearly defined "is" and "is not" - there are only continuous probabilities.
There is no such thing as continuous probabilities. Once all probabilities are determined you enter the realm of all knowledge. Having all knowledge clearly enables one to know what "is" and what "is not".
Never happened. True story.
I suspect the GP was engaging in a bit of hyperbole with the "China" reference, but reception of Chinese VHF TV signals in Australia is in fact possible on rare occasions via the ionosphere. The propagation modes usually involve simple refraction from the E layer or F layer, although occasionally more exotic types of propagation, such as trans-equatorial propagation ("TEP"), occur. However, these all fall into the category of anomalous propagation, occurring for a few hours per month or year and, while interesting phenomena in their own right, aren't suitable on which to base one's daily Internet service.
It is also true that ionospheric propagation of 2.4 GHz signals is unknown. However...
There are propagation modes that favor the higher frequencies over the lower ones. Tropospheric propagation, for example, is much more effective at 2.4 GHz than it is at VHF, and can occur at all parts of the sunspot cycle, since it depends on weather conditions instead of the ionosphere. For example, Table 2.1 in this article shows propagation from California to Hawaii on 2304, 3456, and even 5760 MHz via a well-known tropospheric duct. (See also this discussion on the relevance to trans-Australia propagation.) Paths in excess of 6000 km (Western Australia to Reunion Island, off the east coast of Africa) have been reported. But again, this is anomalous propagation, unsuitable for daily Internet service.
The GP has a point about transmitted power. VHF TV broadcast stations have effective radiated powers ("ERPs", defined as their transmitted powers multiplied by their antenna gains) measured in the hundreds of thousands to millions of watts, as well as high antenna sites (on towers), so it's a bit unfair to compare VHF TV reception ranges to those of 2.4 GHz Wi-Fi systems.
The main advantage of the proposed system is that the users, in remote sheep stations, won't have to replace their existing VHF TV antennas, which would otherwise be a significant financial investment (and that the system would be point-to-point, rather than point-to-multipoint, which enables frequency reuse without loss of bandwidth). Were this not the case, it would be clear to most RF system designers that a microwave system would be superior to the VHF system. Not only is more bandwidth typically available (remember, there are no competing services in the outback), but a 2.4-GHz antenna the same physical size (strictly speaking, having the same effective area) as the VHF TV antenna would have substantially more gain: The gain of a parabolic dish goes up as the square of the operating frequency. Operating an antenna at 2.4 GHz instead of, say, 60 MHz (in the VHF TV band) would result in a gain increase of 1600, or 32 dB. If it had 18 dB of gain at VHF (a pretty decent TV antenna), it would now be 50 dB at 2.4 GHz. (This is why point-to-point microwave systems were used before they were overtaken in the bandwidth race by optical fiber.) This additional 32 dB of gain would greatly increase the range of the 2.4 GHz system over the VHF system, and would be available all the time -- making for a suitable Internet connection. In fact,
I mean, how it is *remotely possible* that an article with only 1 technical fact (TV frequencies can be used for long-distance communication relatively cheaply), and a bunch of complete *bullshit* (High Speed Internet a "basic human right", Internet as an analog signal, no decrease in speed with increase in users), make it through the editorial screening for the "News For Nerds" site, but I *know* that other articles with much greater merit get completely ignored?
No, I'm not new here, but man, it's like they just don't give a shit about *pretending* to give a shit about doing their job anymore.
So how does this allow the subscriber to send data? Does everyone have to have a megawatt transmitter in their home?