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#1
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Another BPL?
There's an article in today's Washington Post
http://preview.tinyurl.com/6ego68 that describes a technology that's under development to provide Internet access using spectrum in the TV channel range. Apparently this scheme checks for a signal before it uses a specific frequency and switches to a different one if it detects that the frequency is in use. I wonder how this will work and play with amateur radio. I remember when TV channel 2 was established in my home town, effectively shutting down six meter ham operation because the TV signal was so weak that even a correctly-operating six-meter rig would create serious TVI for the fringe reception of channel 2. Decades have passed and this new technology surely is much less sensitive to adjacent signals than the TVs of my childhood, but the analogy persists. 73, Steve KB9X |
#2
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Another BPL?
On Jul 24, 1:41 pm, Steve Bonine wrote:
There's an article in today's Washington Post http://preview.tinyurl.com/6ego68 that describes a technology that's under development to provide Internet access using spectrum in the TV channel range. Apparently this scheme checks for a signal before it uses a specific frequency and switches to a different one if it detects that the frequency is in use. I wonder how this will work and play with amateur radio. Interesting story but a lot of information you need to determine how much of a problem this would be is missing. As it sits, the use of "unused" spectrum space in the current TV broadcast band seems to be a non-issue to us. Seems that they are at least trying to live within the part 15 rules and are working to detect when other users pop up on the spectrum and they are working in a band that will be open for new use in Feb 09. As long as they keep part 15 power levels, don't try and connect directly to long unshielded wires hung up high and stay out of the ham radio allocations what can we say? However if they are demonstrating something to the FCC, it would seem that they are looking for some kind of operational waver or rules change. Worth keeping an eye on. |
#3
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Another BPL?
On Thu, 24 Jul 2008 14:41:36 -0400, Steve Bonine wrote:
There's an article in today's Washington Post http://preview.tinyurl.com/6ego68 that describes a technology that's under development to provide Interne t access using spectrum in the TV channel range. Apparently this scheme checks for a signal before it uses a specific frequency and switches to a different one if it detects that the frequency is in use. I wonder how this will work and play with amateur radio. I remember when TV channel 2 was established in my home town, effectively shutting down six meter ham operation because the TV signal was so weak that eve n a correctly-operating six-meter rig would create serious TVI for the fringe reception of channel 2. Decades have passed and this new technology surely is much less sensitive to adjacent signals than the TVs of my childhood, but the analogy persists. I'm not too worried about interference to/from amateur radio. Users aren't going to recognize overload problems as coming from ham gear .. The things are simply going to intermittently stop operating and they're going to blame it on an outage of the ISP's base station. It won't play your voice out their speakers the way it does with an analog TV set. And they're never going to get FCC approved unless they know how to confine their emissions to the TV channel they determined was unused. They're no t going to spill over into ham bands. (at least not the legal ones. The illegal ones will spill even if the FC C never approves this technology.) I'm a lot more worried about it as a TV engineer and semi-rural over-the-air TV viewer. In early tests these things weren't very good at determining whether a channel was unused. I can see that becoming a big problem in semi-rural areas like this, where people might be using roofto p antennas to get TV but the Internet devices will probably be on makeshift indoor aerials. On the other hand, I'm not holding my breath waiting for someone to build a base station out here. The technology may well never come to places rural enough to be in TV fringe reception. |
#4
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Another BPL?
On Fri, 25 Jul 2008 05:23:27 -0400, Doug Smith W9WI wrote:
I'm a lot more worried about it as a TV engineer and semi-rural over-the-air TV viewer. In early tests these things weren't very good at determining whether a channel was unused. I can see that becoming a bi g problem in semi-rural areas like this, where people might be using roof to p antennas to get TV but the Internet devices will probably be on makeshi ft indoor aerials. (which may end up being the vector by which this stuff bothers ham radio -- it will interfere with TV reception and the viewers will blame us...) |
#5
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Another BPL?
In article ,
Doug Smith W9WI wrote: I'm a lot more worried about it as a TV engineer and semi-rural over-the-air TV viewer. In early tests these things weren't very good at determining whether a channel was unused. I can see that becoming a big problem in semi-rural areas like this, where people might be using rooftop antennas to get TV but the Internet devices will probably be on makeshift indoor aerials. According to an article in Moble Radio Technology magazine recently, there's another issue in some areas (about ten major metro areas) where various public safety agencies have already been authorized to use the white space in the channel 14-20 range for various types of public safety communication. Some of these applications (e.g. video surveillance cameras) are designed to be "indetectable" while in operation... which makes things problematic for the proposed free-white-space-detection devices. The police would be unamused by having their stakeout-surveillance video feed stomped upon by web-browsing passersby! The quick solution to this is to forbid the use of free-white-space devices in this frequency range, in those cities where public safety operations have already been authorized. This won't necessarily solve the problem, if (for example) a user of such a device brings it from a "wide open" city into a city with restrictions, and doesn't realize that s/he has to change the device's mode to stay legal. The pro-audio industry is also up in arms over these whitespace proposals, as they've been depending for years on Part 15 (or similar) wireless microphones which operate in the unused TV channel frequencies. Having to face competition for these frequencies from a whole bunch of non-coordinated new "find a 'free' frequency and camp on it" devices could cause problems for them, to say the least! -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#6
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Another BPL?
Doug Smith W9WI wrote:
On Thu, 24 Jul 2008 14:41:36 -0400, Steve Bonine wrote: There's an article in today's Washington Post http://preview.tinyurl.com/6ego68 I had to chuckle at the part where she holds the camera on herself at arms length. High budget reportage. I also was in awe of the publc safety aspect touted by the one engineer. First responders, yada yada. Of course they could use it. The manager who is talking about having a product out in less than a year, after tehy know what the "rules" are. Finally the last guy in the red shirt who basically says that what they have doesn't work. Golly, if it doesn't have to work, I could have something on the market in a week or so evil grin I'm not too worried about interference to/from amateur radio. This isn't too likely to interfere with Amateur radio. Of course, I don't think it is too likely to work either. Given the nature of UHF, the system will have to look at the possible occupation of a frequency at both the broadcast site and receiver site. Picket fencing can be an issue. Let's take a look at a potential experience. The home system (digital signal source) and receiver system (laptop) look around for a clear space. Say they find one. I am guessing that there is some sort of Pre-communication going on on some dedicated frequency. So they find a clear frequency. They start exchanging packets. Now the laptop moves and a picketed signal shows up, or say the local church starts it's Saturday evening service. So now the home system and the receiver system have to search around for a new frequency. Maybe they find one, and maybe they don't. Immediate thoughts come to mind: These systems have to be in some kind of communication to begin with. I suppose that the laptop could just start transmitting on different frequencies, hoping to hit the home system, but that would be a long process. Talk about a system ripe for interference. There could be a new game in town, the opposite of Wardriving. If all it takes is another signal on the same frequency to start a search for a clear one, some social misfits might just have fun with a sweep generator. Keep the system hopping, and it will never settle on a frequency. snippage I'm a lot more worried about it as a TV engineer and semi-rural over-the-air TV viewer. In early tests these things weren't very good at determining whether a channel was unused. I can see that becoming a big problem in semi-rural areas like this, where people might be using rooftop antennas to get TV but the Internet devices will probably be on makeshift indoor aerials. Is is possible that this is another setup put together by digital engineers as opposed to RF engineers? So I agree with Steve that it is likely to be another BPL. This one might get a little further before failure though, as I think ARRL's efforts went a long way toward getting BPL marginalized. Obviously we won't be spending our money on a problem that won't directly affect Hams. But it has th esame problems, likely interference, lack of robustness, and probably won't help th epeople touted as the beneficiaries. Just my .$0.02 - 73 de Mike N3LI - |
#7
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Another BPL?
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#8
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Another BPL?
On Fri, 25 Jul 2008 16:08:32 -0400, Dave Platt wrote:
The quick solution to this is to forbid the use of free-white-space devices in this frequency range, in those cities where public safety operations have already been authorized. This won't necessarily solve the problem, if (for example) a user of such a device brings it from a "wide open" city into a city with restrictions, and doesn't realize that s/he has to change the device's mode to stay legal. They'll probably have to ban them from T-band altogether. But see below. The pro-audio industry is also up in arms over these whitespace proposals, as they've been depending for years on Part 15 (or similar) wireless microphones which operate in the unused TV channel frequencies .. Having to face competition for these frequencies from a whole bunch of non-coordinated new "find a 'free' frequency and camp on it" devices could cause problems for them, to say the least! One proposal I saw would require wireless-microphone users to transmit a "beacon" signal at some predetermined location within the TV channel. Th e white-space devices would monitor for this beacon. (both the DTV and analog TV standards essentially already have beacons) So I suppose you could have the public-safety organizations also transmit the beacons. Yes, sometimes I get the impression the pro-audio folks are more upset about this than the broadcasters. |
#9
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Another BPL?
On Sat, 26 Jul 2008 02:00:41 -0400, Phil Kane wrote:
These are one type of systems that our company designs for public-safety clients. Many agencies are asking the FCC to reassign unused commercial channels in the T-Band for Public Safety use. We're in the thick of that. What we are trying to do also is to get the FCC to expand the radius around the authorized cities as urban growth moves outward. I think the problem you're going to have (with both of those projects) is that the compression of the TV band is going to make unused channels in T-band less common. And especially in the areas outside the existing radius where you'd like to expand it. I think the argument you'll get is that 24MHz above channel 51 has alread y been set aside for public-safety, should it really need more below channe l 21? |
#10
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Another BPL?
On Fri, 25 Jul 2008 17:06:30 -0400, Michael Coslo wrote:
Is is possible that this is another setup put together by digital engineers as opposed to RF engineers? Like BPL and IBOC I'd suggest it wasn't engineers who came up with this idea... |
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