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Comment 100 kW ERP is commonplace - My laser pointer... (Score 1) 75

ERP is Effective Radiated Power. In the direction of maximum beam of my laser pointer, I get a spot on the order of 1 " in diameter 200' away. This means that most of the 5 milliwatts the laser puts out is contained in a spot of on the order of one square inch. This intensity is brought about by the columnation or directivity of the laser itself. It's a puny 5 milliwatt transmitter with a high gain antenna. In order to get the same intensity from an isotropic antenna (one that spews equally in all directions) rather than a directive one, I'd need to increase the power by the ratio of 4*PI*(200 feet*12 inches/foot) ^2. That's how many square inches are in a sphere with radius 200'. That's almost 80 dB (a hundred million times) change of directivity. BTW directivity is the same as antenna gain if the antenna is well matched and not lossy. 80 dB above 7 dBm ( 5 mW) is +87 dBm or +57 dBW That's HALF A MILLION watts! But this is not "cooking power". Energy is conserved, it's still only a 5 milliwatt, Class III laser and this ERP number is only a measure of what transmit power would be necessary if there weren't any antenna gain. All this alarm about ERP is about not understanding what the terms mean. ERP is transmitter power + antenna gain, not real power. The actual transmitter is something like 24 watts, roughly the same as one segment antenna of a cell site. The system has high ERP because it's at millimeter where the antenna has a lot of gain. This whole thread is alarm about nothing...

Comment *Freespace* wireless isn't so bad, (Score 1) 190

In spite of all the bad press *freespace* wireless isn't as terrible as you think. See and in particular slide 16. The problem is that we live in a world with anything but freespace paths (truly laser light line-of-sight). The difference can be a factor of a million to 1 (60 dB)in throughput over common paths. Your cell phone could talk to another one 2000 miles away if you had free space but sometimes you can't get to a tower 2 miles away. Thus, this really is a problem Shannon's equation can apply to. Wireless for 3g,4g,5g only works when the paths are *really* short - like a few tens of meters. See the rest of the paper.

Comment Re:Too high - need groundpowered drone - possible (Score 1) 99

what if ur in a city and the to of the buildings are already several hundred meters high? then if a thing is tethered to the ground it might bump into buildings.

Start at the building tops - cell sites already do. The issue is to get very close to LOS to the user base so that that data vs. energy is maximized. Take a look at COST231/Hata or similar real-world RF pathloss models. Anything other than LOS is a killer and can't be afforded. The present flooding model for cellular architecture is inherently broken. Montana|Idaho|etc never will get full coverage highspeed data, the present approach doesn't scale. Going too far/high doesn't work either. Satellite distribution (from Iridium to geosynchronous and beyond) doesn't work either. Has to server too many users/needs to much devoted energy/user. Has to be lots of points of presence, LOS and close to end users.

Comment Too high - need groundpowered drone - possible (Score 1) 99

I think he is on to something but the path lengths are too long. Presuming the market will stand for nothing less than mobility and at least 4G class data rates, physics requires that radio paths be shorter than he conjectures. Here's why: Mobility means the user device must be powered from batteries and fit in your pocket. It must contain its own antenna. Thus there is a maximum local_storage/delivered_bit ratio available. It costs battery power to deliver a bit of information. Non-line-of-sight paths are entirely too wasteful - witness a cellphone "handy-talky" that can communicate 2000 miles in truly free space not making it into a cell site only 2 miles away in real world conditions. Wireless goes as inverse-square so that's a million-to-one loss, 60 dB. Given one has to use truly LOS (as in laser light), the question of radio path length is answered by looking at the aperture of the antenna in the user's device. It can be thought of as a "bucket" that catches whatever falls on it. The size of the bucket is roughly the physical size of the device. While as frequency goes up (shorter wavelength) antenna gain goes up, so does path loss. The device can only catch as much flux as is falling on it. This is like solar panels - sunlight is about 1 kW/m^2 on earth- try as you might you won't get more energy per unit capture area. If one does the link analysis and applies Shannon's equation, the ONLY solution that works requires paths of, perhaps, a few hundred meters. For this reason, the drones need to be quite low and there need to be more of them. It turns out that this is possible if they are tethered and powered from the ground. gives an example of a way to do this while also allowing the (heavy) network hardware to stay on the ground. Demo coming soon. n6gn

Comment Re:It's like you're not even trying. (Score 2) 79

I agree. Got to a WebSDR like and automate the process. You can get a large amount of OTA signals to examine, in the correct ratios, styles and weightings. This requires you to decide whether or not the signal under test is CW or not but that's part of your algorithm anyway. n6gn

Comment Re:How the system will work. (Score 1) 120

I note that the OPERA report (Open PLC European Research Alliance, Document OP_WP1_D5_v0.9.doc) indicated a lot less than 200 Mbps of information capacity on typical European systems.A better guess seems to be 20Mbps on a good day. Thus, with your estimations, more like 50 kbps per home with conventional BPL/PLC techniques (below 80 MHz) seems likely. All the more reason to move it to microwave-over-powerline. n6gn

Comment Re:A slight order of magnitude problem (Score 1) 120

Don't confuse the user connection with the 'backhaul' which is the over-power-line part. However, also don't confuse 200 Mbps on a lab bench with a lot less than that over a single hop on real lines having excess noise, attenuation. The 200 Mbps hardware may only need 20 MHz of spectrum in the 4-80 MHz region to support that raw rate but after a few links are chained together throughput will likely be a LOT lower than that. Now aggregate 1000 homes onto that backhaul and you may scarcely have enough performance. Fortunately, the smart-meter requirements for average data rate and latency are probably very small so it might all work fine - except for the ingress/egress radiation problems from the line which could be a show stopper. Too bad they don't move it all up to microwave-over-power-line and avoid the interference problem at the same time they get 10X or more capacity improvement. disclaimer: I resemble the above remark. n6gn

Comment Bi-di satellite comms is bad physics (Score 1) 337

Consider 77 satellites, each catching [100 watts] of solar power that you perfectly turn into useful, information carrying RF, and then perfectly overlay so that the entire surface of the earth is covered. That sets available flux at ground level, You can't use more gain and not lose coverage area (location independent access). Now add users with omni-directional antennas. User antennas must not only be small but generally omni-directional - they have to see all the sky and can't be high gain beams constantly pointed (too big, too expensive). The associated antenna aperture determines captured power. Because of system noise temperature (antenna sees terra firma no matter what NF the equipment has, S/N ratio is determined, thus due Shannon capacity of link is set. Guess what, it's not much to write home about if you plug in reasonable numbers. A few users on each satellite can get a little bit but all users can't use it all (or much) of the time. And we haven't even talked about backhaul, real-world efficiences etc. This problem is akin to the problem of getting 3G or 4G mobile networks to work everywhere. They don't and won't unless the paths are shortened greatly and the density of points-of-presence (cell sites) is greatly increased. n6gn

The Proton Just Got Smaller 289

inflame writes "A new paper published in Nature has said that the proton may be smaller than we previously thought. The article states 'The difference is so infinitesimal that it might defy belief that anyone, even physicists, would care. But the new measurements could mean that there is a gap in existing theories of quantum mechanics. "It's a very serious discrepancy," says Ingo Sick, a physicist at the University of Basel in Switzerland, who has tried to reconcile the finding with four decades of previous measurements. "There is really something seriously wrong someplace."' Would this indicate new physics if proven?"

4G iPhone Misplacer Invited To Germany For Beer 164

eldavojohn writes "You may recall the hapless engineer who left a fairly sensitive iPhone at a bar recently. Well, in a PR stunt, Lufthansa has invited him to visit Germany on their dime after citing his latest Facebook status, 'I underestimated how good German beer is' as well as his obvious passion for German beer and culture. It's not clear if Gray Powell has decided to 'pick up where he last left off' (as the letter puts it). I know what my decision would be."

Comment Build an on-channel active repeater (Score 1) 214 This is essentially what one does with after market cellphone amplifiers, but the link offers more detail of the theory and what it takes to operate them properly. These amplifiers are bi-directional, both uplink and downlink are supported but in opposite directions. Use two isolated antennas and make the one pointed at the cell site (particularly) as directional as possible. I suggest a $50/$75 3' parabolic 'grid' reflector for PCS/850 MHz respectively. The ones offered for WiFi (2.4 GHz) actually work very well on PCS but not at 850 MHz and offer ~24 dBi gain. If you are really cheap, build corner reflectors

Comment Because you're buying service, not just hardware.. (Score 1) 727

We hear with our brains as much as with our ears. Simply buying hardware to compensate for the roll-off is NOT the solution. Hearing is tremendously adaptive and interactive. When you buy HAs from a reputable source you are actually buying a lot of visits for measurement/modification to allow you to adapt to the augmentation as well as possible. This is unique to each individual. This easily adds up to MANY (10-20/year) office visits over the life of the device(s). I too used to think that simply measuring the roll-off and applying compensation was a solution. It emphatically is NOT. Before you all attribute the cost of the hardware to greed, take a look at the service and also look around and find evidence of overly-fat audiologists. I don't find them around where I live... n6gn

Man Fined $1.5 Million For Leaked Mario Game 287

An anonymous reader writes "A Queensland man will have to pay Nintendo $1.5 million in damages after illegally copying and uploading one of its recent games to the internet ahead of its release, the gaming giant says. Nintendo said the loss was caused when James Burt made New Super Mario Bros Wii available for illegal download a week ahead of its official Australian release in November of last year. Nintendo applied for and was granted a search order by the Federal Court, forcing Burt to disclose the whereabouts of all his computers, disks and electronic storage devices in November. He was also ordered to allow access, including passwords, to his social networking sites, email accounts and websites."

Comment Re:EXPOSURE: 1 hour of cellphone=lifetime with WiF (Score 1) 474

Most modern phones and PDAs run no more than 400 mW maximum (+26 dBm). However, that is not a typical level. Most systems utilize power control as part of the protocol. CDMA, for example, updates the channel power ~800 times per second. It is a goal of the system to use no more power from the handset than necessary to achieve parity among users sharing a system. Average transmit power may be sub-microwatt ( It's true some may spend more time with their phone at their ear than warming food but peak exposure from 'good' microwave ovens, never mind leaky ones, may dwarf that of communication's RF. n6gn

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