I have had many discussions with my co-workers regarding their wi-fi usage. For myself, I use wired networks as much as I can, leaving wi-fi as my fall back in case I have no other option. My co-workers think I am old fashioned, but when it comes to network speed, 100 Mbps Cat5e wire beats wi-fi hands down, especially when there are lots of folks trying to use their wi-fi gear all at the same time. I guess they never heard of QRM and how to avoid it.
There are small white dots in the upper left and upper right corners of the original. The look like they could have been thumb-tack holes very close to the corners. And no, those spots are not his monitor.
The sequence of photo edits is funny, but I think the guy was serious about asking for help with removing those small white spots. It's too bad there were so many clowns who do not remember their own newbie days to actually stop and help him. Just because they are Photoshop jockeys now does not mean they were born able to edit pictures flawlessly.
I think these folks really do have something to hide. For example, do you recall the county in Ohio in 2004 that came up with something like 4 thousand more votes than there were voters? Or how about the places where the number of votes a candidate received at the end of the day was negative?
I think at least part of the problem we see here stems from the fact these machines are all built using the Windows platform and with Microsoft tools. The Microsoft EULA requires that Microsoft's code remain secret. Since that includes both the OS, and the EXCEL spreadsheet software being used underneath the application code, even if the companies DO release THEIR application's source code, there remains a huge amount of proprietary code that cannot be checked unless Microsoft suddenly opens up their proprietary products for inspection.
I am running Ubuntu right now, and I like it. If you used BitTorrent to download 7.10, you may have received a few chunks from my machine, because I downloaded Ubuntu 7.10 as soon as it came out, and I have had my machine seeding it ever since, except for the few hours it took Sunday evening for me to update my own machine from Ubuntu 7.04 to Ubuntu 7.10. I now work one block from the Blue Cube, for a start-up in the solar power field. I am an analog and RF design engineer and a computer network wrangler. You can reach me directly by email to rgetsla {at} yahoo [dot] com.
I used to work at SLAC, and I got to know something about how the whole machine worked and what we (as a member of the team who made it work) were doing. You are 100% correct about beer and bubble chambers. At one time SLAC had a huge bubble chamber filled with liquid hydrogen (as I recall, I could be wrong). They also had a huge cloud chamber, and even a very large spark chamber, and giant solenoid magnets around those chambers, to make charged particles leave curved tracks. Back then, they photographed each pulse of the accelerator as seen in the bubble chamber, the cloud chamber, or the spark chamber (something like 5 to 10 pulses per second) on black and white movie film. They then had teams of people studying those films, frame by frame, looking for "interesting events". I'm sure the folks doing this visual analysis rapidly developed eye strain. I'm also sure the development of the particle detector (as represented by SLD) was a great improvement, both because the experimental machinery could run faster, and because computers could do the data analysis much faster and more accurately than people.
Although I am no longer working for SLAC, I always thought SLAC was a great place to work. There was so much history there that I could see and touch, and I sometimes got to talk with the people who were there when exciting discoveries were made. SLAC was where quarks were first observed in the form of three small (but hard) pits in the middle of a large squishy thing called a proton. They made this discovery by studying the scattering of some high speed electrons shot into a tank of liquid hydrogen. They then shot the same high speed electron beam into a tank of liquid deuterium. Deuterium has one proton and one neutron in its nucleus. To derive what the neutron looked like, they subtracted out what the scattering effect was from liquid hydrogen (which has only a proton in it's nucleus) and from that concluded that neutrons also were large squishy things with three hard pits in the middle, just like protons.
SLAC and the team that performed this high speed electron scattering experiment won a Nobel Prize for their work.
SLAC is also where the quark theory was tested in one of the first storage rings called SPEAR, earning SLAC another Nobel Prize. The Tau particle was found there, too, although the tau had been recorded but not recognized in other places. The discovery of the tau earned SLAC their third Nobel Prize.
While I worked there, my email and newsgroup signature line was, "Nobel Prizes R Us!"
The Stanford Linear Accelerator Center, or SLAC, generates and accelerates electron and positron beams (and when needed, polarized or spin oriented beams) for colliding beam and fixed target experiments. SLAC has literally hundreds of dipole, quadrapole, and sextupole electromagnets placed along their accelerator, beam lines, and storage rings, all for focusing and directing their charged particle beams. If the center of mass of colliding electron and positron beams is high enough (at a collision energy called a "resonance") new particles will be created from the combined beam energies. During the 1990's, SLAC accelerated electrons and positrons to approximately 49 Giga Electron Volts (or GeV) each with their accelerator. After the two beams drifted in evacuated beam lines away from the accelerator, they were directed such that the electron beam and the positron beam approached an interaction point in the center of a large particle detector called SLD, from opposite sides. In the detector, the two beams would collide, creating new chargeless particles called Z-Zero or Z-Naught particles, with a collision energy of about 95.5 GeV. The Z-Zero, before it decays, is about one half as heavy as a silver atom, but quickly decays into a lot of smaller fragments, some charged and others not charged. The mass of that Z-Zero particle represents the direct conversion of the accelerator's energy into matter.
In the diagram shown in the link above, look for the e- and e+ labels. Those represent the electron (e-) and positron (e+) beams entering the SLD detector from opposite sides. In the center of the SLD detector is a small cylindrical piece called a Vertex Detector. The center of the vertex detector (a silicon CCD device about the size of a soft drink can with several million pixels in three concentric layers) is where SLAC's electrons actually collided with positrons. The parts of the detector around the Vertex detector are like the layers of an onion. Each layer gathers a different kind of data about the collisions that took place inside the vertex detector at the interaction point. There are a lot of very sophisticated electronics in the layers of all particle detectors, but all of the electronics have one purpose, to gather information about the decay fragments coming from the electron/positron collisions so the events that took place during and immediately after the collision can be reconstructed and analyzed with very sophisticated computers.
Beginning in 1998, SLAC began an experiment called the asymmetric B-meson factory, or "B Factory" for short. In the B Factory, the electron beams run at a little over 9 GeV beam energy, while the positron beams run at only about 3 GeV. Both colliding beams run at very high currents, on the order of two amperes in the electron storage ring, and three amperes in the positron storage ring. The collision of these two high current beams produces millions of B mesons, each with a residual momentum (due to the asymmetric beam energies) that makes it possible for the particle physicists to study more effectively how those B mesons decayed.
Here is a link to more information about "Storage Rings" and their electromagnets:
And here are links to three of SLAC's web pages, where you can learn more about colliding beam physics. BaBar is name of the particle detector used to study their decaying B Mesons, and PEP-II is the storage ring collider used to make those B Mesons.
I agree SRI was important to the development of Silicon Valley, but SRI was not alone. I suggest you consider the Stanford Linear Accelerator Center, too. Stanford broke ground for the construction of a two mile long linear accelerator in the early 1960's. The engineers and physicists at SLAC were early adopters and developers of many technologies including semiconductors of all kinds.
Do you remember the Homebrew Computer Club? Do you know where they met every Wednesday evening? Clue: it was on the SLAC campus.
Where did Jobs and Wozniac learn the details of what would become their most infamous (and illegal product), the "blue boxes" they made and sold to finance the Apple I? Clue: it was on the SLAC campus and open to anyone who walked in.
Final question: There were TWO garage partnerships formed at Stanford, and both partnerships brought Stanford lots of fame and money. Who were the other partners beside Hewlett and Packard? Clue: they invented and built the first klystron, which was used to power a microwave driven linear accelerator located in the basement of the Physics building on the Stanford campus. That success of that linear accelerator lead directly to the decision to build the 2 mile long microwave powered accelerator at SLAC.
I think an argument can be made that SLAC was also a significant factor in making Silicon Valley world famous. SLAC had a policy of buying local whenever they could do so, and several companies came into being specifically to sell equipment (mostly electronic) to the physicists of SLAC.
A large percentage of the membership of the Homebrew Computer Club worked at SLAC, which is why the club met there. Very soon after Intel announced the 8080, SLAC engineers were designing them into the specialized controllers needed to make the 2 mile electron accelerator work, because without a distributed control system, controlling the accelerator was nearly impossible.
I think you jumped over a few historical facts when you mentioned the Interstate Highways were unfair competition to the railroads. When the Interstate Highways were designed in the early 1950's and built in the late 50's and early 60's, they were paid for by.... long pause so you can think....
The Department of Defense.
Of course the railroads could not compete with the Interstate Highways. But why would the DOD build the Interstate Highways? Well, to understand that, you needed to look at the first Interstate Highways built, and notice they were all very flat, and that NOTHING crossed over them, not even power lines. These new highways were built with several hundred feet of separation between the opposite direction traffic lanes. And they were incredibly straight. The few curves these highways had were all very gradual.
Any ideas yet why DOD paid for building the Interstate Highways? Here's a hint -- the Strategic Air Command.
During the late 50's and early 60's, the Strategic Air Command was a very large part of our national defense, with many long range bombers in the air at any one time. But, an enemy might attack our airfields, in particular, those with 10,000 foot runways. Such an attack could prevent many of our long range bombers from taking off, and prevent the bombers already in the air from refueling before they flew to their targets over the North Pole.
AH HA!
Our Interstate Highways were built to be used as runways -- runways for our bombers to use for refueling. By covering the countryside with runways, there was no way a potential adversary could prevent our long range bombers from refueling so they could reach their targets. But technology eventually obsoleted the Strategic Air Command as our primary defense, and we no longer needed those runways all over the countryside.
At about the same time as the Interstate Highway system was being built, a nationwide broadband network was being built by AT&T. This nationwide network, consisting of microwave relay stations and coaxial cable repeaters, carried long distance telephone calls and network television programs. About 1/2 of the capacity of this broadband network was leased to the Federal Government. The Federal Government provided guaranteed traffic for this nationwide network, insuring it would be built. Here are two links to some of the history and technical details of AT&T's broadband network.
The AT&T "Long Lines" network was built with no central control point, specifically so it would survive a nuclear war. But eventually, the AT&T microwave and coaxial cable network approached saturation, and more bandwidth was needed. Worse, many of the consulates and embassies belonging to our adversaries now had arrays of microwave antennas on their roofs.
Here is are two links to what some of the government traffic passing through the AT&T microwave and coaxial cable physical network was:
In the 1990's, AT&T sold off their microwave and coaxial cable physical network because by then AT&T had deployed a fiber mesh network with far higher bandwidth. This fiber network also offered significantly better security than the microwave network did because intercepting message traffic on a fiber network without being detected is quite difficult. AT&T's conversion to an all fiber network made those consulate and embassy roof microwave antennas largely obsolete for gathering electronic intelligence.
I am part of a start-up company, and before we got very far into building our business, we had many long discussions about our computers. It seems all of us had Windows machines, but we all felt like Microsoft didn't care about us, other than their forcing WGA on us, and making us prove we are not pirates. That atmosphere of suspicion did it, and we are now in the process of switching our entire operation over to Ubuntu Linux 7.04. Ubuntu looks and feels enough like XP that most of our people have found the transition to Ubuntu almost painless. There were, and are, a few rough spots, but on the whole, we are glad we have decided to dump MS.
The most painful part of our transition (which is still in progress) involves Open Office. While OO is close to MS Office, it is enough different that the folks making the transition are complaining about features that do not work EXACTLY the way MS implemented them. But, after some initial grumbling, they get down to work with OO, and after a while, the grumbling seems to have quieted down.
My guess is the real problem involves people learning new habits. After they are past the steepest part of the learning curve, their pain subsides, and their real work gets done, just like before.
But there is a really big plus in our conversion to Linux; we don't have to deal with the likes of Microsoft when we want to add new software or hardware, trying to convince them that we aren't pirates. There is nothing equivalent to WGA in Linux. And we probably will not be forced to "upgrade" just because someone snaps their fingers and says, "I think it's time we collected some more money from our customers."
In my part of the world (Silly-con Valley) the folks making the most noise about how bad municipal WiFi is for everyone happen to be the local CATV monopoly, Comcast. Comcast is aggressively trying to stop municipal WiFi every way they can. Although our incumbent telephone company, AT&T is not exactly warm to the idea of metropolitan area WiFi, they seem to understand that they might become the "wire" backbone to the WiFi "last mile", so AT&T isn't as aggressively fighting the idea of metro WiFi.
We do have a private municipal WiFi system recently deployed in Mountain View, by Google. And more private WiFi systems may be coming. These new systems might be privately owned like Google's, or they might be municipally owned. Most of them are still in the planning stages, and many of them probably could best be described as in the "drawn on a paper napkin at Denny's" stage.
We have a local phone company (they used to be PacBell, until PacBell was bought out by SBC. SBC then renamed themselves "AT&T", but the people running that renamed company are still SBC in how they treat customers). AT&T refuses to provide DSL here with anything like the kind of speed that DSL service has in other parts of the world, despite proof that the technologies involved work. So most of us muddle along with 1.5 megabits down and 384 Kbits up (or we pay a significant premium for 6 megabit down by 768 K up) because "they" think that if we had a 20 Megabit fully symmetrical system (see the post way above this post about a neighborhood fiber system to see what is possible and how much it might cost) we might actually be free to be content producers instead of only being content consumers.
The business model SBC/AT&T seems to be pushing (Comcast pushes this same model) is that the Internet is really just "The Great Shopping Mall", and anyone with a DSL or Cable modem is really just looking for ways to do all of our shopping from home. If "they" could make their service to us even more asymmetrical than it is now, trust me, they would. They know clicking on a link, or responding to a "roll-over", followed by typing a credit card number and a shipping address requires only a few bytes per second in the up direction, but just look at how the same folks put on the speed (but limited to only two or three seconds)in the down direction so "they" can deliver some nice jpeg or gif (or whatever other format) picture to us of a product.
Municipal WiFi stands to break this asymmetrical model, and I think THAT is what is so threatening about it. Imagine what might happen if people could Source information as rapidly as they can Consume it? People might produce and distribute their own music and videos and they might even host their own websites! HORRORS!
I think the quantity compared here should be "Percentage Bandwidth" rather than simple "bandwidth". At 800 MHz, modulation of plus or minus 10 MHz (meaning you are using the space from 790 MHz to 810 MHz) represents a larger percentage bandwidth than the same plus or minus 10 MHz centered at 1900 MHz (meaning you are using the space from 1890 MHz to 1910 MHz). If you compare the two, the 800 MHz center frequency with plus or minus 10 MHz for modulation means you are occupying more than twice the percentage bandwidth as you would with a 1900 MHz center frequency and the same plus or minus 10 MHz for modulation.
You make an interesting technical argument, but there are a few details I think you missed. The 2.4 GHz and the 5.6 GHz bands are license free ISM bands. They allow ANY device to operate, within reason, provided the device conforms to certain power radiation limits and stays within the ISM band limits. There are many different kinds of RF devices operating in ISM bands including (but not limited to) diathermy machines, induction heaters, cordless telephones, and microwave ovens.
There is a physical chemistry reason why certain frequencies were designated for the ISM bands; they happen to be frequencies that are not as useful as other (similar) frequencies for communication purposes because those frequencies represent electrical resonances in commonly occurring atmospheric gas molecules. These resonances cause excessive path loss in what would otherwise be usable free space paths. Water is one molecule that causes excessive path loss, but only at certain frequencies. The fact some of the ISM bands coincide with water molecule resonances is not an accident. Ever wonder why your microwave oven operates at 2.4 GHz in the ISM band and not some other frequency? The radio frequency energy absorbed by all those water molecules has to go somewhere....and the conversion of RF energy into molecular vibration (heat) is a good candidate for the cause of the excessive path loss at 2.4 GHz compared to path losses at 2.3 GHz or 2.5GHz.
The cellular companies all operate on licensed frequencies for which they have paid "Big Bucks" to the Federal Government and they need to make a return on their "Investment" for their shareholders. BTW, the fees the cellular companies pay to the FCC have been used by Congress to balance the Federal budget. There is a long story here that I won't go into now about spectrum use, but suffice it to say, the creation of the Cellular telephone" bands was not the first time, nor the last time, that Congress has "auctioned" off parts of the RF spectrum to the highest bidder, spectrum previously used for other purposes.
The cellular phone companies routinely disable features built into the hardware and software in many of the newer cell phones because they hope to force their customers into paying exorbitant prices for "enabling" those features, even if these are features that actually have almost no inherent cost. SMS is one example. SMS stands for "Short Message Service" and is actually the use of a very small portion of the bit rate available to cell phone users. SMS bits are like "space available" seats on airliners, they are used to fill otherwise partly empty data packets, so SMS should cost users almost nothing, but SMS users pay a higher price for SMS bits than they do for voice data bits when they talk.
I think the reason for this is consumer ignorance. Kids frequently "texting" each other have no idea how SMS works, nor do they know how much bandwidth they are NOT using when they send SMS messages to each other. SMS does not even have guaranteed delivery, unlike some other wireless messaging protocols. But don't forget that a corporation is legally obligated to make as much money as possible for its stockholders.
The infrastructure cost of an ad hoc 802.11x mesh network is "unfair competition" as far as the cellular operators are concerned because 802.11x access point costs only a few hundred dollars each. Site rent for them is also low because they usually are located on top of streetlight poles. But the cellular phone operators must pay rent for their sites on the order of $1500 each per month, on top of hardware investments in the many thousands of dollars. This "overhead" cost for the cellular operators must come from somewhere, or they will go out of business.
There is an old saying, "You can lead a horse to water, but you can't make him drink." which applies here. You can spoon feed folks like Sparky all manner of facts and lead them to all of the sources, but they will continue to insist that you are wrong and they are right. It's sad, but there are some people with closed minds who take what they hear from right-wing talk radio and from Fox TV as Gospel TRUTH, and NOTHING you can say or do will convince them to even look at the facts for themselves.
I once had a friend who said, "Thinking makes my head hurt!" and that was why my friend always took the opinions of "experts" over his own. He was far more comfortable repeating the opinions of others than he was in drawing his own conclusions, no matter what the subject. I have since met many people like my friend. These people seem to trust the opinions of authority figures over everything else, and they regularly will toss their own conclusions onto the scrap heap as worthless.
For those who are more open minded, consider the following:
Watch the videos of the three WTC buildings collapsing, and use a stop watch to measure how long it took for each building to collapse. Then compare those videos with videos of other controlled building demolitions. I think you will see many similarities. Then go to any beginning physics text book and read about gravity and falling objects. Using the equations you will find in that book, you can calculate how long a free fall would take for a demolished building, given the height of the building, and you can draw your own conclusions. I think you will find that comparing your measured collapse times with your calculated free fall times, all three of the WTC buildings collapsed at almost free-fall speed. I have not seen any other logical explanations for such rapid collapses other than that the vertical steel beams were severed by explosive charges into short pieces as the buildings were collapsing. The upper parts of the WTC buildings met with almost no resistance as the buildings collapsed. If there had been any resistance from the lower parts of the buildings, their collapse would have taken longer because the lower parts would have absorbed energy from the falling upper parts, slowing the fall of the upper parts.
Placing the explosive charges to make a controlled demolition takes a fair amount of time, usually several days, and it requires an accurate knowledge of the building structure, so all of the explosive charges required can be properly placed. Then the explosive charges must be set off in sequence by a remote control system to cause the buildings to collapse the way you see them collapse in those videos. Building 7 looks like a "classic" demolition, because the outer walls fell inward after the center of the building collapsed, and are lying on top of the pile of rubble from the core of the building, limiting the amount of rubble outside of the building's footprint. WTC 7 does not look like a demolition planned and executed in an hour or two.
One inconvenient fact is the energy released into the pile of rubble from each building is more than can be accounted for by converting the potential energy in the mass of the WTC buildings into kinetic energy as they collapsed. The excess energy must have come from somewhere. I think the excess energy came from the explosives used to sever all of those steel columns and beams, and went into the pools of molten metal in the basements of the WTC buildings. But if those beams and columns had been severed by explosives, wouldn't that have been evident in the rubble pile? Well of course it would, but the entire area around the WTC site was immediately declared a crime scene and the scrap metal was hauled away to steel mills on the other side of the world as quickly as possible, so forensic analysis of most of it could not be done. Why was there such a rush to recycle that steel? And why would anyone want to block photographers and other investigators from the WTC site, and even go so far as to
I have been wondering just how long it would be before someone realized that the annual tithe they pay to the folks in Redmond made little sense when the purpose was for students to learn how to use a spreadsheet or a word processor. There are plenty of lower cost or even no cost (as in free beer) versions of these old warhorses. If the basics of page layout and print formatting are the subject at hand, then using MS Word or Office is not the most economical way to go.
What this really does do, though, is break the lock step routine that has been going on for a while -- the schools teach MS specifics because Business uses MS, while Business says they use MS because that's what new hires know, so the new hires won't waste a lot of time having to learn new tricks.
I hope to see more of this, because for too long MS has been "locking" students into their way of thinking and of doing things. Bravo for the folks with enough courage to stand up to the MS juggernaut!
First, you need to know what the 19.3 megabit DTV "Transport Stream" looks like. The "Broadcast Flag" is a small collection of bits embedded in "Transport Stream." DTV equipment will be required to watch (or listen) for those bits and take the appropriate action.
But suppose you know where those bits are, and what they mean, too. Why couldn't you simply flip the ones you don't like and then record or whatever? All you would need is a serial to parallel converter to turn the serial stream into a 16 bit parallel bus (for example) and them suck those bits into a DSP, where you do a little bit bashing. Then run them into a parallel to serial conervter to reconstruct the transport stream as seen by your digital disk recorder? If you have a commercially made unit, it will be looking for the flag bits, so it will know what it can or cannot do, but your freshly set bits tell it that this program is OK to record and play as long as you like.
I think such a device is likely to appear as a small plastic box with 2 firewire ports and a wall-wart, selling for $20 in a year or two.
Remember Macrovision on VHS? Do you know how easy that was to defeat? All you had to do was to make your VCR run with fixed video gain instead of AGC all the time. A little hardware hacking was all that was needed. This shouldn't be much worse. But don't try bit bashing after the compressed video is expanded. The data rate there is likely to be upwards of a gigabit, and most folks don't know how to make PCBs to handle stuff going that fast. This is precisely why the DRM folks want the interconnects to be 1 gigabit or faster. But remember, the "broadcast flag" must be readable in the 19.3 megabit transport stream.
Thanks for saying what I am sure many of us are thinking, and Thank You to Elena for one of the best photo-journalism stories I have seen/read anywhere.
I agree, Elena's bike trip through Chernobyl is one hell of a photo-essay. While I am not able to do this, probably someone here can, namely, set up an account somewhere so we can chip in to help pay for the bandwidth we used from her hosting site.
As I skimmed each of the 26 chapters, I also saved them to disk, so I can look them over again, taking more more time on each, without taking up any more of her limited bandwidth.
BTM, her English is a whole lot better than my Russian.
I agree! How would anyone know if SCO were to steal some source code from Linux and then claim the stealibng was the other way around? SCO has kept their code secret, so only an insider at SCo could possibly blow the whistle, and I don't think that's likely to happen.
As I broadcast engineer, I think I need to burst your bubble. The amount of "processing" done before the audio even makes it into the stereo encoder is obscene, and then there are the low pass filters that knock off anything above 15 Khz because the 19 KHz stereo pilot tone must be protected, and the L-R (stereo difference) information is put on a double sideband-suppressed carrier signal centered at 38 KHz. I'm sorry, but you cannot convince me that there is "relatively high quality music out there today on radio...." And this is not taking into account stuff like the composite clipping done to make an FM station sound even LOUDER than they otherwise would or the DSPs used to add "punch" to the sound. Dynamic range??? Frequency response??? Distortion (both IM and harmonic)??? Only the Chief Engineer cares, and he/she does what the GM wants, and that is a modulation monitor with it's meters quivering at 100% all the time.
If you care about classic jazz, there are some seriously good radio stations (they tend to be non-commercial, like KCSM-FM91, San Mateo, live in the San Francisco Bay Area and streaming on the web) but if you are talking about Commercial radio, especially radio intended to be listened to in cars or through small speakers, you are way off base.
As for the P2P networks, I agree. They offer a tremendous opportunity to anyone with some creativity and a little technical knowledge.
I think the global economic down turn has had more of an effect on music sales (all formats) than the RIAA is willing to admit. Right now, I am underemployed, with 2 part-time jobs totalling less than 20 hrs/week, which does not leave me with enough money to buy anything much, so I only look for used CDs of music I have wanted for a while. If a CD costs more than $5, I'll pass. Perhaps I will be able to buy that CD next year, if I can find more work and George the Lesser hasn't made even more of a mess of the economy by then.
The best discussion I have seen or heard about file swapping and the price of CDs was on radio last year when Janis Ian was on On-Line Tonight with David Lawrence. OLT probably has a recording of that interview available. Their URL is http://www.online-tonight.com/
If OLT doesn't have it, they should, because Janis is both a singer and a song writer, and she knows more about the music industry then most of the folks posting their ignorance here. You can also visit Janis's web site at http://www.janisian.com/ and read her thoughts about file swapping, etc. there.
Not long ago I remember reading about a "directed energy weapon" intended for military use in non-lethal "crowd control." This crowd control device is actually a very short wavelength, high power microwave beam radiated from an antenna on the roof of a vehicle. It is supposed to produce a buring pain in the skin of those in the beam, but is supposed to be a non-lethal because, while it feels like a burn (and perhaps the microwave beam could cause REAL burns) the pain induced supposedly can be stopped simply by getting out of the beam. My recollection is that this military microwave device operates at something like 70 GHz with several kilowatts of power (which is why this thing is mounted on a vehicle -- the vehicle provides the electrical power required to generate the microwave beam.) If anyone else remembers this, please post a URL or two where the details can be found.
So, what is the difference between this microwave beam weapon and a microwave beam rocket launcher except where the high power microwave beam happens to be aimed? I suspect that if one happened to be hit by scattered microwave energy from the microwave rocket launcher, that expereince could be downright painful, or even worse, depending on how much scattered microwave energy one happened to intercept.
As for the idea of microwave power beams coming down to earth from orbiting satellites; I cannot imagine a more efficient or militarily desirable "Death Ray." Think about a solar powered satellite dumping a few thousand megawatts of microwave power (at 100 GHz or so) onto a 100 foot by 100 foot area somewhere on the surface of the earth. Such a beam would probably be lethal to anything living it hits, and there would be no residual ionizing radiation, no radioactive fallout, or toxic chemical pollution left after the microwave beam "Death Ray" was shut off.
There must folks in the Pentagon rubbing their hands in glee, because I doubt that there are many weapons able to kill people by the hundreds or even by the thousands in a matter of seconds that leave no hazardous residues after their use.
I suggest that high power microwave beams like these be kept in places where they can do no harm, preferably, in laboratories.
I designed and installed a true "Broadband" network some 3 miles in length for the Stanford Linear Accelerator Center. This network used RF carriers, and your description of 10broad36 is almost correct. Look into IEEE 802.7 or MAP/TOP networks for more information. The network I designed was a "mid-split" bi-directional network, with 5 to 115 Megahertz signals flowing one way in the cable while 150 to 450 Megahertz signals flowed the other way, through the same cable.
SLAC's Broadband network had 5 data independant data streamsflowing in it, each totally isolated from the others, together with some 30 video signals. This was similar to, but not quite the same as, the Cable TV networks most people have bringing television into their homes. The main difference is that SLAC's Broadband network provided for a lot more "up-stream" bandwidth than a cable TV system would ever think of providing. Remember, the model for Cable TV is that you are only supposed to be a consumer, so you can only receive signals, so signals only flow toward you, and not away from you.
This asymmetry persists because most people want fast downloads, but rarely do they ask about their upload speed. If more people did their own web hosting, I am sure this asymmetry would change, but I am also sure there would be loud howls of protest from many of the existing content providers, because they would rather not have any more competition.
The term "Broadband" is now used interchangeably with high speed (as in gigabit data rates). I think this is due to a fast baseband system's ability to "time multiplex" many independant signals, apparently carrying them all at once. A true "Broadband" system uses "frequency multiplexing", and can also carry many independant signals, all at once, hence the confusion.
The Dense Wave Division Multiplexing (DWDM) scheme found in most fiber backbone networks is a close relative to the frequency multiplexing schemes used in Broadband cable networks, because different lasers are used to produce lightwave carriers in the fiber cable, each on a different light wavelength (or frequency.) These lightwave carriers are completely independant of each other as they all pass through the fiber, effectively multiplying the capacity of a single fiber many times over.
The last I heard, well over 100 seperate lightwave signals, each carrying a 10 gigabit (or faster) data stream, could be put into the same fiber, and that all those signals could then be transported hundreds of kilometers, without demodulating and remodulating any of them.
You have described an NTSC analog TV front end. The problem is that the transmission system the FCC picked for use here in the United States is 8 level VSB. The "comb filter" you described is used to seperate the luninance component of the picture from the chromanance component. The DTV signal is a much different animal involving a digital data "transport stream" of 19.3 megabits per second. Within the transport stream are many kinds of data packets, each serving a different purpose. Some packets are Dolby digital 5.1 audio. Others are MPEG-2 compressed video with something like 18 different video formats. High defintion TV accounts for only a few of those video formats. The DTV system is able to "multicast" several strandard definition video streams (with their accompanying audio streams). To sort these streams requires some meta-data packets, which tell your DTV receiver which audio stream goes with a particular video stream. There are other uses for meta-data as well, such as conditional access (subscription programming) where only certain receivers are allowed to decode and display a program stream.
The big problem as I understand it is that the 8-VSB system we have is quite prone to damage from multipath, or ghosting, which makes it very difficult to impossible for a DTV receiver to stay "in sync" with the transmitter. Recovering the transport stream intact, in the presence of multipath requires what is called an "adaptive equalizer" and that is a very complex digital device. I met someone who worked for a company designing demodulator chips for DTV receivers. The European Coded Orthoganal Frequency Division Multiplexing (or COFDM) transmission system requires something like 1.5 million transistors in the demodulator chip. Our 8 level Vestigial Side Band (or 8-VSB) system required 8.5 million transistors, and they weren't really happy with the performance of that chip. Understand that we are talking about demodulators that are as large and complex or larger and more complex than most Pentium class microprocessors. These are non-trivial designs, yet without them, DTV is not usable.
Recall that I said 19.3 megabits per second for the "transport stream" but that is not what you will see at the antenna. At the antenna you will see an almost 30 megabit per second stream because there is forward error correction added into the transport stream. There is 1 FEC bit for every 2 data bits. There also is a "sync" interval that consists of relatively wide pulses, used to make clock acquisition and tuning a little easier. If you were to look at a DTV signal with a spectrum analyzer, you would see a rectangular shaped block a little less than 6 MegaHertz wide, with a small "spike" near the lower frequency edge of the top of the block. That is the "pilot" signal, also used to ease tuning in a receiver.
There probably are several of these signals present at the antenna input of your TV set now, if you use a regular TV antenna. If you use a CATV system to get your TV programing, then all bets are off, because the Cable folks decided that their digital transmission scheme would Quadrature Amplitude Modulation, or QAM. They use either 16-
I worked for a major research facility and after 7 years there, became unemployed (for reasons that are a long story not relevant here.) I soon realized that I had to find a way to change my own perspective. I did several things:
1) I looked for a group of similarly situated people. Here in Silicon (Silly Con?) Valley, there is a no cost organization for unemployed professional and technical people called Promatch. Promatch is a chapter of Experience Unlimited, and costs you nothing but a few hours eac week. Look for Experience Unlimited in your area. The Promatch URL: www.promatch.org.
2) I went back to school on a one class per term basis. In particular, I went to a community college. In this area, one of the best is DeAnza College in Cupertino. Can you imagine a router lab featuring 24 live Cisco routers(something like 8 different models) I couldn't until I saw them, and what really blew me away was that they were all donated. These were not old, out of date junk, but new and pretty much the stuff you see in the "Real World."
And again, I met a lot more people I would not have met any other way. As I said before, having a contact inside a company can be priceless.
3) I am 60, and as an engineer, I know that I probably will not land another full time job, so I decided to get a business license and try doing some consulting. I am currently working on 3 projects.
The first project is a biofeedbeck device. We now have one patent applied for, and another patent we are investigating. Both patents will have my name on them. Eventually this could become a viable company (and an income.)
The second project is a electrical power monitor for small businesses. This power monitor would be on a company's LAN and appear as an internal web site, where it would provide a running plot of power consumption over the past 24 hour and give an estimate their power bill. If they have "time of use" billing, this energy usage plot could be worth BIG BUCKS.
My third project involves a chemical vapor deposition system, to coat teflon tubing (inside and outside) with an anti-coagulant layer a few molecules thick. My job will be designing and building some high power (kilowatt level) RF equipment in a high volume manufacturing environment.
I also have a part-time job working one morning per week on a mountaint top just south of San Francisco, maintaining a 60 kilowatt UHF television transmitter. This is my only steady income.
You need to get into circulation to make new contacts. BTW, drop that shotgun resume. Every resume you write should be customized for the specific job you want, with a custom cover letter. This is where your contacts will come in handy, because most jobs are not advertised. I think you can do better hunting with a rifle instead of using a shotgun.
Back in the dawn of time, using the web was like visiting a library. There was a lot of information available, if you knew how to look for it. Then came the likes of doubleclick, and the library was suddenly turned into a shopping mall. The problem now is, how do I get where I want to go, which is still the library? It appears that I now must pass through through the mall every time I want to visit the library.
What is wrong with this picture?
Maybe some folks need to look at one of the more successful commercial websites; a website that is actually making money! 3 guesses who it is and how they do it.
Can't guess -- OK, I'll tell you -- it's Google. No pop-ups. No pop-unders. No animation. No pictures of products, even. Just sponsored links located on the right margin of a search result page, and notice that the sponsored links are put into colored boxes labelled as to what they are. But look again at those ads. They are related rather closely to the subject of the search you asked Google to do. This is how Google makes sure that their advertising is seen by people wanting to look at it. Not a bad approach, if you ask me. In fact, I have clicked on some of Google's ad links simply because they were exactly what I wanted!
Gosh! When did linking a search to tasteful ad links for related products turn into rocket science?
The real problem here is that there are some people who think the only way to make a buck in advertising is to annoy people. You don't need to be very old to have seen (and heard) a TV ad for a brand of laundry detergent that used a jingle with the words, "Ring around the collar!" This particular television ad is an example of a class of advertising called irritant advertising, and unfortunately, irritant advertising does work. Irritant advertising is not the only kind of advertising that works, but it is fairly easy to make.
So how does Google do it? Google's ads are not irritating and they don't beat anyone over the head, yet they are making money (or at least they were, the last time I heard about them on CNET radio.)
Perhaps now is the time to rethink the purpose of the world wide web. Is the web still a way of finding and sharing information, or has it become only a medium for aggressive advertising? If the web is now nothing but an advertising medium, I would like to know who tore down the library?
Slashdot Mirror
I have had many discussions with my co-workers regarding their wi-fi usage. For myself, I use wired networks as much as I can, leaving wi-fi as my fall back in case I have no other option. My co-workers think I am old fashioned, but when it comes to network speed, 100 Mbps Cat5e wire beats wi-fi hands down, especially when there are lots of folks trying to use their wi-fi gear all at the same time. I guess they never heard of QRM and how to avoid it.
In one word -- GREED!
There are small white dots in the upper left and upper right corners of the original. The look like they could have been thumb-tack holes very close to the corners. And no, those spots are not his monitor.
The sequence of photo edits is funny, but I think the guy was serious about asking for help with removing those small white spots. It's too bad there were so many clowns who do not remember their own newbie days to actually stop and help him. Just because they are Photoshop jockeys now does not mean they were born able to edit pictures flawlessly.
I think these folks really do have something to hide. For example, do you recall the county in Ohio in 2004 that came up with something like 4 thousand more votes than there were voters? Or how about the places where the number of votes a candidate received at the end of the day was negative?
I think at least part of the problem we see here stems from the fact these machines are all built using the Windows platform and with Microsoft tools. The Microsoft EULA requires that Microsoft's code remain secret. Since that includes both the OS, and the EXCEL spreadsheet software being used underneath the application code, even if the companies DO release THEIR application's source code, there remains a huge amount of proprietary code that cannot be checked unless Microsoft suddenly opens up their proprietary products for inspection.
I am running Ubuntu right now, and I like it. If you used BitTorrent to download 7.10, you may have received a few chunks from my machine, because I downloaded Ubuntu 7.10 as soon as it came out, and I have had my machine seeding it ever since, except for the few hours it took Sunday evening for me to update my own machine from Ubuntu 7.04 to Ubuntu 7.10. I now work one block from the Blue Cube, for a start-up in the solar power field. I am an analog and RF design engineer and a computer network wrangler. You can reach me directly by email to rgetsla {at} yahoo [dot] com.
Thank you for your kind remarks.
I used to work at SLAC, and I got to know something about how the whole machine worked and what we (as a member of the team who made it work) were doing. You are 100% correct about beer and bubble chambers. At one time SLAC had a huge bubble chamber filled with liquid hydrogen (as I recall, I could be wrong). They also had a huge cloud chamber, and even a very large spark chamber, and giant solenoid magnets around those chambers, to make charged particles leave curved tracks. Back then, they photographed each pulse of the accelerator as seen in the bubble chamber, the cloud chamber, or the spark chamber (something like 5 to 10 pulses per second) on black and white movie film. They then had teams of people studying those films, frame by frame, looking for "interesting events". I'm sure the folks doing this visual analysis rapidly developed eye strain. I'm also sure the development of the particle detector (as represented by SLD) was a great improvement, both because the experimental machinery could run faster, and because computers could do the data analysis much faster and more accurately than people.
Although I am no longer working for SLAC, I always thought SLAC was a great place to work. There was so much history there that I could see and touch, and I sometimes got to talk with the people who were there when exciting discoveries were made. SLAC was where quarks were first observed in the form of three small (but hard) pits in the middle of a large squishy thing called a proton. They made this discovery by studying the scattering of some high speed electrons shot into a tank of liquid hydrogen. They then shot the same high speed electron beam into a tank of liquid deuterium. Deuterium has one proton and one neutron in its nucleus. To derive what the neutron looked like, they subtracted out what the scattering effect was from liquid hydrogen (which has only a proton in it's nucleus) and from that concluded that neutrons also were large squishy things with three hard pits in the middle, just like protons.
SLAC and the team that performed this high speed electron scattering experiment won a Nobel Prize for their work.
SLAC is also where the quark theory was tested in one of the first storage rings called SPEAR, earning SLAC another Nobel Prize. The Tau particle was found there, too, although the tau had been recorded but not recognized in other places. The discovery of the tau earned SLAC their third Nobel Prize.
While I worked there, my email and newsgroup signature line was, "Nobel Prizes R Us!"
The Stanford Linear Accelerator Center, or SLAC, generates and accelerates electron and positron beams (and when needed, polarized or spin oriented beams) for colliding beam and fixed target experiments. SLAC has literally hundreds of dipole, quadrapole, and sextupole electromagnets placed along their accelerator, beam lines, and storage rings, all for focusing and directing their charged particle beams. If the center of mass of colliding electron and positron beams is high enough (at a collision energy called a "resonance") new particles will be created from the combined beam energies. During the 1990's, SLAC accelerated electrons and positrons to approximately 49 Giga Electron Volts (or GeV) each with their accelerator. After the two beams drifted in evacuated beam lines away from the accelerator, they were directed such that the electron beam and the positron beam approached an interaction point in the center of a large particle detector called SLD, from opposite sides. In the detector, the two beams would collide, creating new chargeless particles called Z-Zero or Z-Naught particles, with a collision energy of about 95.5 GeV. The Z-Zero, before it decays, is about one half as heavy as a silver atom, but quickly decays into a lot of smaller fragments, some charged and others not charged. The mass of that Z-Zero particle represents the direct conversion of the accelerator's energy into matter.
http://www2.slac.stanford.edu/vvc/detectors/sld.html
In the diagram shown in the link above, look for the e- and e+ labels. Those represent the electron (e-) and positron (e+) beams entering the SLD detector from opposite sides. In the center of the SLD detector is a small cylindrical piece called a Vertex Detector. The center of the vertex detector (a silicon CCD device about the size of a soft drink can with several million pixels in three concentric layers) is where SLAC's electrons actually collided with positrons. The parts of the detector around the Vertex detector are like the layers of an onion. Each layer gathers a different kind of data about the collisions that took place inside the vertex detector at the interaction point. There are a lot of very sophisticated electronics in the layers of all particle detectors, but all of the electronics have one purpose, to gather information about the decay fragments coming from the electron/positron collisions so the events that took place during and immediately after the collision can be reconstructed and analyzed with very sophisticated computers.
Beginning in 1998, SLAC began an experiment called the asymmetric B-meson factory, or "B Factory" for short. In the B Factory, the electron beams run at a little over 9 GeV beam energy, while the positron beams run at only about 3 GeV. Both colliding beams run at very high currents, on the order of two amperes in the electron storage ring, and three amperes in the positron storage ring. The collision of these two high current beams produces millions of B mesons, each with a residual momentum (due to the asymmetric beam energies) that makes it possible for the particle physicists to study more effectively how those B mesons decayed.
Here is a link to more information about "Storage Rings" and their electromagnets:
http://en.wikipedia.org/wiki/Storage_ring
And here are links to three of SLAC's web pages, where you can learn more about colliding beam physics. BaBar is name of the particle detector used to study their decaying B Mesons, and PEP-II is the storage ring collider used to make those B Mesons.
The PEP-II storage ring collider is at: http://www.slac.stanford.edu/grp/ad/ADPEPII/ADPEPII.html
The BaBar detector is at: http://www-public.slac.stanford.edu/babar/
And SLAC's main web page (the first web page in t
I agree SRI was important to the development of Silicon Valley, but SRI was not alone. I suggest you consider the Stanford Linear Accelerator Center, too. Stanford broke ground for the construction of a two mile long linear accelerator in the early 1960's. The engineers and physicists at SLAC were early adopters and developers of many technologies including semiconductors of all kinds.
Do you remember the Homebrew Computer Club? Do you know where they met every Wednesday evening? Clue: it was on the SLAC campus.
Where did Jobs and Wozniac learn the details of what would become their most infamous (and illegal product), the "blue boxes" they made and sold to finance the Apple I? Clue: it was on the SLAC campus and open to anyone who walked in.
Final question: There were TWO garage partnerships formed at Stanford, and both partnerships brought Stanford lots of fame and money. Who were the other partners beside Hewlett and Packard? Clue: they invented and built the first klystron, which was used to power a microwave driven linear accelerator located in the basement of the Physics building on the Stanford campus. That success of that linear accelerator lead directly to the decision to build the 2 mile long microwave powered accelerator at SLAC.
I think an argument can be made that SLAC was also a significant factor in making Silicon Valley world famous. SLAC had a policy of buying local whenever they could do so, and several companies came into being specifically to sell equipment (mostly electronic) to the physicists of SLAC.
A large percentage of the membership of the Homebrew Computer Club worked at SLAC, which is why the club met there. Very soon after Intel announced the 8080, SLAC engineers were designing them into the specialized controllers needed to make the 2 mile electron accelerator work, because without a distributed control system, controlling the accelerator was nearly impossible.
I think you jumped over a few historical facts when you mentioned the Interstate Highways were unfair competition to the railroads. When the Interstate Highways were designed in the early 1950's and built in the late 50's and early 60's, they were paid for by .... long pause so you can think ....
The Department of Defense.
Of course the railroads could not compete with the Interstate Highways. But why would the DOD build the Interstate Highways? Well, to understand that, you needed to look at the first Interstate Highways built, and notice they were all very flat, and that NOTHING crossed over them, not even power lines. These new highways were built with several hundred feet of separation between the opposite direction traffic lanes. And they were incredibly straight. The few curves these highways had were all very gradual.
Any ideas yet why DOD paid for building the Interstate Highways? Here's a hint -- the Strategic Air Command.
During the late 50's and early 60's, the Strategic Air Command was a very large part of our national defense, with many long range bombers in the air at any one time. But, an enemy might attack our airfields, in particular, those with 10,000 foot runways. Such an attack could prevent many of our long range bombers from taking off, and prevent the bombers already in the air from refueling before they flew to their targets over the North Pole.
AH HA!
Our Interstate Highways were built to be used as runways -- runways for our bombers to use for refueling. By covering the countryside with runways, there was no way a potential adversary could prevent our long range bombers from refueling so they could reach their targets. But technology eventually obsoleted the Strategic Air Command as our primary defense, and we no longer needed those runways all over the countryside.
At about the same time as the Interstate Highway system was being built, a nationwide broadband network was being built by AT&T. This nationwide network, consisting of microwave relay stations and coaxial cable repeaters, carried long distance telephone calls and network television programs. About 1/2 of the capacity of this broadband network was leased to the Federal Government. The Federal Government provided guaranteed traffic for this nationwide network, insuring it would be built. Here are two links to some of the history and technical details of AT&T's broadband network.
http://www.corp.att.com/history/nethistory/milesto nes.html
http://long-lines.net/
The AT&T "Long Lines" network was built with no central control point, specifically so it would survive a nuclear war. But eventually, the AT&T microwave and coaxial cable network approached saturation, and more bandwidth was needed. Worse, many of the consulates and embassies belonging to our adversaries now had arrays of microwave antennas on their roofs.
Here is are two links to what some of the government traffic passing through the AT&T microwave and coaxial cable physical network was:
http://www.albany.edu/ltl/using/history.html
http://www.inetdaemon.com/tutorials/internet/histo ry.shtml
In the 1990's, AT&T sold off their microwave and coaxial cable physical network because by then AT&T had deployed a fiber mesh network with far higher bandwidth. This fiber network also offered significantly better security than the microwave network did because intercepting message traffic on a fiber network without being detected is quite difficult. AT&T's conversion to an all fiber network made those consulate and embassy roof microwave antennas largely obsolete for gathering electronic intelligence.
About our trans-oceanic te
I am part of a start-up company, and before we got very far into building our business, we had many long discussions about our computers. It seems all of us had Windows machines, but we all felt like Microsoft didn't care about us, other than their forcing WGA on us, and making us prove we are not pirates. That atmosphere of suspicion did it, and we are now in the process of switching our entire operation over to Ubuntu Linux 7.04. Ubuntu looks and feels enough like XP that most of our people have found the transition to Ubuntu almost painless. There were, and are, a few rough spots, but on the whole, we are glad we have decided to dump MS.
The most painful part of our transition (which is still in progress) involves Open Office. While OO is close to MS Office, it is enough different that the folks making the transition are complaining about features that do not work EXACTLY the way MS implemented them. But, after some initial grumbling, they get down to work with OO, and after a while, the grumbling seems to have quieted down.
My guess is the real problem involves people learning new habits. After they are past the steepest part of the learning curve, their pain subsides, and their real work gets done, just like before.
But there is a really big plus in our conversion to Linux; we don't have to deal with the likes of Microsoft when we want to add new software or hardware, trying to convince them that we aren't pirates. There is nothing equivalent to WGA in Linux. And we probably will not be forced to "upgrade" just because someone snaps their fingers and says, "I think it's time we collected some more money from our customers."
In my part of the world (Silly-con Valley) the folks making the most noise about how bad municipal WiFi is for everyone happen to be the local CATV monopoly, Comcast. Comcast is aggressively trying to stop municipal WiFi every way they can. Although our incumbent telephone company, AT&T is not exactly warm to the idea of metropolitan area WiFi, they seem to understand that they might become the "wire" backbone to the WiFi "last mile", so AT&T isn't as aggressively fighting the idea of metro WiFi.
We do have a private municipal WiFi system recently deployed in Mountain View, by Google. And more private WiFi systems may be coming. These new systems might be privately owned like Google's, or they might be municipally owned. Most of them are still in the planning stages, and many of them probably could best be described as in the "drawn on a paper napkin at Denny's" stage.
We have a local phone company (they used to be PacBell, until PacBell was bought out by SBC. SBC then renamed themselves "AT&T", but the people running that renamed company are still SBC in how they treat customers). AT&T refuses to provide DSL here with anything like the kind of speed that DSL service has in other parts of the world, despite proof that the technologies involved work. So most of us muddle along with 1.5 megabits down and 384 Kbits up (or we pay a significant premium for 6 megabit down by 768 K up) because "they" think that if we had a 20 Megabit fully symmetrical system (see the post way above this post about a neighborhood fiber system to see what is possible and how much it might cost) we might actually be free to be content producers instead of only being content consumers.
The business model SBC/AT&T seems to be pushing (Comcast pushes this same model) is that the Internet is really just "The Great Shopping Mall", and anyone with a DSL or Cable modem is really just looking for ways to do all of our shopping from home. If "they" could make their service to us even more asymmetrical than it is now, trust me, they would. They know clicking on a link, or responding to a "roll-over", followed by typing a credit card number and a shipping address requires only a few bytes per second in the up direction, but just look at how the same folks put on the speed (but limited to only two or three seconds)in the down direction so "they" can deliver some nice jpeg or gif (or whatever other format) picture to us of a product.
Municipal WiFi stands to break this asymmetrical model, and I think THAT is what is so threatening about it. Imagine what might happen if people could Source information as rapidly as they can Consume it? People might produce and distribute their own music and videos and they might even host their own websites! HORRORS!
I think the quantity compared here should be "Percentage Bandwidth" rather than simple "bandwidth". At 800 MHz, modulation of plus or minus 10 MHz (meaning you are using the space from 790 MHz to 810 MHz) represents a larger percentage bandwidth than the same plus or minus 10 MHz centered at 1900 MHz (meaning you are using the space from 1890 MHz to 1910 MHz). If you compare the two, the 800 MHz center frequency with plus or minus 10 MHz for modulation means you are occupying more than twice the percentage bandwidth as you would with a 1900 MHz center frequency and the same plus or minus 10 MHz for modulation.
You make an interesting technical argument, but there are a few details I think you missed. The 2.4 GHz and the 5.6 GHz bands are license free ISM bands. They allow ANY device to operate, within reason, provided the device conforms to certain power radiation limits and stays within the ISM band limits. There are many different kinds of RF devices operating in ISM bands including (but not limited to) diathermy machines, induction heaters, cordless telephones, and microwave ovens.
There is a physical chemistry reason why certain frequencies were designated for the ISM bands; they happen to be frequencies that are not as useful as other (similar) frequencies for communication purposes because those frequencies represent electrical resonances in commonly occurring atmospheric gas molecules. These resonances cause excessive path loss in what would otherwise be usable free space paths. Water is one molecule that causes excessive path loss, but only at certain frequencies. The fact some of the ISM bands coincide with water molecule resonances is not an accident. Ever wonder why your microwave oven operates at 2.4 GHz in the ISM band and not some other frequency? The radio frequency energy absorbed by all those water molecules has to go somewhere....and the conversion of RF energy into molecular vibration (heat) is a good candidate for the cause of the excessive path loss at 2.4 GHz compared to path losses at 2.3 GHz or 2.5GHz.
The cellular companies all operate on licensed frequencies for which they have paid "Big Bucks" to the Federal Government and they need to make a return on their "Investment" for their shareholders. BTW, the fees the cellular companies pay to the FCC have been used by Congress to balance the Federal budget. There is a long story here that I won't go into now about spectrum use, but suffice it to say, the creation of the Cellular telephone" bands was not the first time, nor the last time, that Congress has "auctioned" off parts of the RF spectrum to the highest bidder, spectrum previously used for other purposes.
The cellular phone companies routinely disable features built into the hardware and software in many of the newer cell phones because they hope to force their customers into paying exorbitant prices for "enabling" those features, even if these are features that actually have almost no inherent cost. SMS is one example. SMS stands for "Short Message Service" and is actually the use of a very small portion of the bit rate available to cell phone users. SMS bits are like "space available" seats on airliners, they are used to fill otherwise partly empty data packets, so SMS should cost users almost nothing, but SMS users pay a higher price for SMS bits than they do for voice data bits when they talk.
I think the reason for this is consumer ignorance. Kids frequently "texting" each other have no idea how SMS works, nor do they know how much bandwidth they are NOT using when they send SMS messages to each other. SMS does not even have guaranteed delivery, unlike some other wireless messaging protocols. But don't forget that a corporation is legally obligated to make as much money as possible for its stockholders.
The infrastructure cost of an ad hoc 802.11x mesh network is "unfair competition" as far as the cellular operators are concerned because 802.11x access point costs only a few hundred dollars each. Site rent for them is also low because they usually are located on top of streetlight poles. But the cellular phone operators must pay rent for their sites on the order of $1500 each per month, on top of hardware investments in the many thousands of dollars. This "overhead" cost for the cellular operators must come from somewhere, or they will go out of business.
There is an old saying, "You can lead a horse to water, but you can't make him drink." which applies here. You can spoon feed folks like Sparky all manner of facts and lead them to all of the sources, but they will continue to insist that you are wrong and they are right. It's sad, but there are some people with closed minds who take what they hear from right-wing talk radio and from Fox TV as Gospel TRUTH, and NOTHING you can say or do will convince them to even look at the facts for themselves.
I once had a friend who said, "Thinking makes my head hurt!" and that was why my friend always took the opinions of "experts" over his own. He was far more comfortable repeating the opinions of others than he was in drawing his own conclusions, no matter what the subject. I have since met many people like my friend. These people seem to trust the opinions of authority figures over everything else, and they regularly will toss their own conclusions onto the scrap heap as worthless.
For those who are more open minded, consider the following:
Watch the videos of the three WTC buildings collapsing, and use a stop watch to measure how long it took for each building to collapse. Then compare those videos with videos of other controlled building demolitions. I think you will see many similarities. Then go to any beginning physics text book and read about gravity and falling objects. Using the equations you will find in that book, you can calculate how long a free fall would take for a demolished building, given the height of the building, and you can draw your own conclusions. I think you will find that comparing your measured collapse times with your calculated free fall times, all three of the WTC buildings collapsed at almost free-fall speed. I have not seen any other logical explanations for such rapid collapses other than that the vertical steel beams were severed by explosive charges into short pieces as the buildings were collapsing. The upper parts of the WTC buildings met with almost no resistance as the buildings collapsed. If there had been any resistance from the lower parts of the buildings, their collapse would have taken longer because the lower parts would have absorbed energy from the falling upper parts, slowing the fall of the upper parts.
Placing the explosive charges to make a controlled demolition takes a fair amount of time, usually several days, and it requires an accurate knowledge of the building structure, so all of the explosive charges required can be properly placed. Then the explosive charges must be set off in sequence by a remote control system to cause the buildings to collapse the way you see them collapse in those videos. Building 7 looks like a "classic" demolition, because the outer walls fell inward after the center of the building collapsed, and are lying on top of the pile of rubble from the core of the building, limiting the amount of rubble outside of the building's footprint. WTC 7 does not look like a demolition planned and executed in an hour or two.
One inconvenient fact is the energy released into the pile of rubble from each building is more than can be accounted for by converting the potential energy in the mass of the WTC buildings into kinetic energy as they collapsed. The excess energy must have come from somewhere. I think the excess energy came from the explosives used to sever all of those steel columns and beams, and went into the pools of molten metal in the basements of the WTC buildings. But if those beams and columns had been severed by explosives, wouldn't that have been evident in the rubble pile? Well of course it would, but the entire area around the WTC site was immediately declared a crime scene and the scrap metal was hauled away to steel mills on the other side of the world as quickly as possible, so forensic analysis of most of it could not be done. Why was there such a rush to recycle that steel? And why would anyone want to block photographers and other investigators from the WTC site, and even go so far as to
I have been wondering just how long it would be before someone realized that the annual tithe they pay to the folks in Redmond made little sense when the purpose was for students to learn how to use a spreadsheet or a word processor. There are plenty of lower cost or even no cost (as in free beer) versions of these old warhorses. If the basics of page layout and print formatting are the subject at hand, then using MS Word or Office is not the most economical way to go.
What this really does do, though, is break the lock step routine that has been going on for a while -- the schools teach MS specifics because Business uses MS, while Business says they use MS because that's what new hires know, so the new hires won't waste a lot of time having to learn new tricks.
I hope to see more of this, because for too long MS has been "locking" students into their way of thinking and of doing things. Bravo for the folks with enough courage to stand up to the MS juggernaut!
First, you need to know what the 19.3 megabit DTV "Transport Stream" looks like. The "Broadcast Flag" is a small collection of bits embedded in "Transport Stream." DTV equipment will be required to watch (or listen) for those bits and take the appropriate action.
But suppose you know where those bits are, and what they mean, too. Why couldn't you simply flip the ones you don't like and then record or whatever? All you would need is a serial to parallel converter to turn the serial stream into a 16 bit parallel bus (for example) and them suck those bits into a DSP, where you do a little bit bashing. Then run them into a parallel to serial conervter to reconstruct the transport stream as seen by your digital disk recorder? If you have a commercially made unit, it will be looking for the flag bits, so it will know what it can or cannot do, but your freshly set bits tell it that this program is OK to record and play as long as you like.
I think such a device is likely to appear as a small plastic box with 2 firewire ports and a wall-wart, selling for $20 in a year or two.
Remember Macrovision on VHS? Do you know how easy that was to defeat? All you had to do was to make your VCR run with fixed video gain instead of AGC all the time. A little hardware hacking was all that was needed. This shouldn't be much worse. But don't try bit bashing after the compressed video is expanded. The data rate there is likely to be upwards of a gigabit, and most folks don't know how to make PCBs to handle stuff going that fast. This is precisely why the DRM folks want the interconnects to be 1 gigabit or faster. But remember, the "broadcast flag" must be readable in the 19.3 megabit transport stream.
Well Said!
Thanks for saying what I am sure many of us are thinking, and Thank You to Elena for one of the best photo-journalism stories I have seen/read anywhere.
I agree, Elena's bike trip through Chernobyl is one hell of a photo-essay. While I am not able to do this, probably someone here can, namely, set up an account somewhere so we can chip in to help pay for the bandwidth we used from her hosting site.
As I skimmed each of the 26 chapters, I also saved them to disk, so I can look them over again, taking more more time on each, without taking up any more of her limited bandwidth.
BTM, her English is a whole lot better than my Russian.
Kudos and a big Thank You to Elena!
Bob
I agree! How would anyone know if SCO were to steal some source code from Linux and then claim the stealibng was the other way around? SCO has kept their code secret, so only an insider at SCo could possibly blow the whistle, and I don't think that's likely to happen.
As I broadcast engineer, I think I need to burst your bubble. The amount of "processing" done before the audio even makes it into the stereo encoder is obscene, and then there are the low pass filters that knock off anything above 15 Khz because the 19 KHz stereo pilot tone must be protected, and the L-R (stereo difference) information is put on a double sideband-suppressed carrier signal centered at 38 KHz. I'm sorry, but you cannot convince me that there is "relatively high quality music out there today on radio...." And this is not taking into account stuff like the composite clipping done to make an FM station sound even LOUDER than they otherwise would or the DSPs used to add "punch" to the sound. Dynamic range??? Frequency response??? Distortion (both IM and harmonic)??? Only the Chief Engineer cares, and he/she does what the GM wants, and that is a modulation monitor with it's meters quivering at 100% all the time.
If you care about classic jazz, there are some seriously good radio stations (they tend to be non-commercial, like KCSM-FM91, San Mateo, live in the San Francisco Bay Area and streaming on the web) but if you are talking about Commercial radio, especially radio intended to be listened to in cars or through small speakers, you are way off base.
As for the P2P networks, I agree. They offer a tremendous opportunity to anyone with some creativity and a little technical knowledge.
I think the global economic down turn has had more of an effect on music sales (all formats) than the RIAA is willing to admit. Right now, I am underemployed, with 2 part-time jobs totalling less than 20 hrs/week, which does not leave me with enough money to buy anything much, so I only look for used CDs of music I have wanted for a while. If a CD costs more than $5, I'll pass. Perhaps I will be able to buy that CD next year, if I can find more work and George the Lesser hasn't made even more of a mess of the economy by then.
The best discussion I have seen or heard about file swapping and the price of CDs was on radio last year when Janis Ian was on On-Line Tonight with David Lawrence. OLT probably has a recording of that interview available. Their URL is http://www.online-tonight.com/
If OLT doesn't have it, they should, because Janis is both a singer and a song writer, and she knows more about the music industry then most of the folks posting their ignorance here. You can also visit Janis's web site at http://www.janisian.com/ and read her thoughts about file swapping, etc. there.
Not long ago I remember reading about a "directed energy weapon" intended for military use in non-lethal "crowd control." This crowd control device is actually a very short wavelength, high power microwave beam radiated from an antenna on the roof of a vehicle. It is supposed to produce a buring pain in the skin of those in the beam, but is supposed to be a non-lethal because, while it feels like a burn (and perhaps the microwave beam could cause REAL burns) the pain induced supposedly can be stopped simply by getting out of the beam. My recollection is that this military microwave device operates at something like 70 GHz with several kilowatts of power (which is why this thing is mounted on a vehicle -- the vehicle provides the electrical power required to generate the microwave beam.) If anyone else remembers this, please post a URL or two where the details can be found.
So, what is the difference between this microwave beam weapon and a microwave beam rocket launcher except where the high power microwave beam happens to be aimed? I suspect that if one happened to be hit by scattered microwave energy from the microwave rocket launcher, that expereince could be downright painful, or even worse, depending on how much scattered microwave energy one happened to intercept.
As for the idea of microwave power beams coming down to earth from orbiting satellites; I cannot imagine a more efficient or militarily desirable "Death Ray." Think about a solar powered satellite dumping a few thousand megawatts of microwave power (at 100 GHz or so) onto a 100 foot by 100 foot area somewhere on the surface of the earth. Such a beam would probably be lethal to anything living it hits, and there would be no residual ionizing radiation, no radioactive fallout, or toxic chemical pollution left after the microwave beam "Death Ray" was shut off.
There must folks in the Pentagon rubbing their hands in glee, because I doubt that there are many weapons able to kill people by the hundreds or even by the thousands in a matter of seconds that leave no hazardous residues after their use.
I suggest that high power microwave beams like these be kept in places where they can do no harm, preferably, in laboratories.
I designed and installed a true "Broadband" network some 3 miles in length for the Stanford Linear Accelerator Center. This network used RF carriers, and your description of 10broad36 is almost correct. Look into IEEE 802.7 or MAP/TOP networks for more information. The network I designed was a "mid-split" bi-directional network, with 5 to 115 Megahertz signals flowing one way in the cable while 150 to 450 Megahertz signals flowed the other way, through the same cable.
SLAC's Broadband network had 5 data independant data streamsflowing in it, each totally isolated from the others, together with some 30 video signals. This was similar to, but not quite the same as, the Cable TV networks most people have bringing television into their homes. The main difference is that SLAC's Broadband network provided for a lot more "up-stream" bandwidth than a cable TV system would ever think of providing. Remember, the model for Cable TV is that you are only supposed to be a consumer, so you can only receive signals, so signals only flow toward you, and not away from you.
This asymmetry persists because most people want fast downloads, but rarely do they ask about their upload speed. If more people did their own web hosting, I am sure this asymmetry would change, but I am also sure there would be loud howls of protest from many of the existing content providers, because they would rather not have any more competition.
The term "Broadband" is now used interchangeably with high speed (as in gigabit data rates). I think this is due to a fast baseband system's ability to "time multiplex" many independant signals, apparently carrying them all at once. A true "Broadband" system uses "frequency multiplexing", and can also carry many independant signals, all at once, hence the confusion.
The Dense Wave Division Multiplexing (DWDM) scheme found in most fiber backbone networks is a close relative to the frequency multiplexing schemes used in Broadband cable networks, because different lasers are used to produce lightwave carriers in the fiber cable, each on a different light wavelength (or frequency.) These lightwave carriers are completely independant of each other as they all pass through the fiber, effectively multiplying the capacity of a single fiber many times over.
The last I heard, well over 100 seperate lightwave signals, each carrying a 10 gigabit (or faster) data stream, could be put into the same fiber, and that all those signals could then be transported hundreds of kilometers, without demodulating and remodulating any of them.
You have described an NTSC analog TV front end. The problem is that the transmission system the FCC picked for use here in the United States is 8 level VSB. The "comb filter" you described is used to seperate the luninance component of the picture from the chromanance component. The DTV signal is a much different animal involving a digital data "transport stream" of 19.3 megabits per second. Within the transport stream are many kinds of data packets, each serving a different purpose. Some packets are Dolby digital 5.1 audio. Others are MPEG-2 compressed video with something like 18 different video formats. High defintion TV accounts for only a few of those video formats. The DTV system is able to "multicast" several strandard definition video streams (with their accompanying audio streams). To sort these streams requires some meta-data packets, which tell your DTV receiver which audio stream goes with a particular video stream. There are other uses for meta-data as well, such as conditional access (subscription programming) where only certain receivers are allowed to decode and display a program stream.
The big problem as I understand it is that the 8-VSB system we have is quite prone to damage from multipath, or ghosting, which makes it very difficult to impossible for a DTV receiver to stay "in sync" with the transmitter. Recovering the transport stream intact, in the presence of multipath requires what is called an "adaptive equalizer" and that is a very complex digital device. I met someone who worked for a company designing demodulator chips for DTV receivers. The European Coded Orthoganal Frequency Division Multiplexing (or COFDM) transmission system requires something like 1.5 million transistors in the demodulator chip. Our 8 level Vestigial Side Band (or 8-VSB) system required 8.5 million transistors, and they weren't really happy with the performance of that chip. Understand that we are talking about demodulators that are as large and complex or larger and more complex than most Pentium class microprocessors. These are non-trivial designs, yet without them, DTV is not usable.
Recall that I said 19.3 megabits per second for the "transport stream" but that is not what you will see at the antenna. At the antenna you will see an almost 30 megabit per second stream because there is forward error correction added into the transport stream. There is 1 FEC bit for every 2 data bits. There also is a "sync" interval that consists of relatively wide pulses, used to make clock acquisition and tuning a little easier. If you were to look at a DTV signal with a spectrum analyzer, you would see a rectangular shaped block a little less than 6 MegaHertz wide, with a small "spike" near the lower frequency edge of the top of the block. That is the "pilot" signal, also used to ease tuning in a receiver.
There probably are several of these signals present at the antenna input of your TV set now, if you use a regular TV antenna. If you use a CATV system to get your TV programing, then all bets are off, because the Cable folks decided that their digital transmission scheme would Quadrature Amplitude Modulation, or QAM. They use either 16-
I worked for a major research facility and after 7 years there, became unemployed (for reasons that are a long story not relevant here.) I soon realized that I had to find a way to change my own perspective. I did several things:
1) I looked for a group of similarly situated people. Here in Silicon (Silly Con?) Valley, there is a no cost organization for unemployed professional and technical people called Promatch. Promatch is a chapter of Experience Unlimited, and costs you nothing but a few hours eac week. Look for Experience Unlimited in your area. The Promatch URL: www.promatch.org.
2) I went back to school on a one class per term basis. In particular, I went to a community college. In this area, one of the best is DeAnza College in Cupertino. Can you imagine a router lab featuring 24 live Cisco routers(something like 8 different models) I couldn't until I saw them, and what really blew me away was that they were all donated. These were not old, out of date junk, but new and pretty much the stuff you see in the "Real World."
And again, I met a lot more people I would not have met any other way. As I said before, having a contact inside a company can be priceless.
3) I am 60, and as an engineer, I know that I probably will not land another full time job, so I decided to get a business license and try doing some consulting. I am currently working on 3 projects.
The first project is a biofeedbeck device. We now have one patent applied for, and another patent we are investigating. Both patents will have my name on them. Eventually this could become a viable company (and an income.)
The second project is a electrical power monitor for small businesses. This power monitor would be on a company's LAN and appear as an internal web site, where it would provide a running plot of power consumption over the past 24 hour and give an estimate their power bill. If they have "time of use" billing, this energy usage plot could be worth BIG BUCKS.
My third project involves a chemical vapor deposition system, to coat teflon tubing (inside and outside) with an anti-coagulant layer a few molecules thick. My job will be designing and building some high power (kilowatt level) RF equipment in a high volume manufacturing environment.
I also have a part-time job working one morning per week on a mountaint top just south of San Francisco, maintaining a 60 kilowatt UHF television transmitter. This is my only steady income.
You need to get into circulation to make new contacts. BTW, drop that shotgun resume. Every resume you write should be customized for the specific job you want, with a custom cover letter. This is where your contacts will come in handy, because most jobs are not advertised. I think you can do better hunting with a rifle instead of using a shotgun.
Back in the dawn of time, using the web was like visiting a library. There was a lot of information available, if you knew how to look for it. Then came the likes of doubleclick, and the library was suddenly turned into a shopping mall. The problem now is, how do I get where I want to go, which is still the library? It appears that I now must pass through through the mall every time I want to visit the library.
What is wrong with this picture?
Maybe some folks need to look at one of the more successful commercial websites; a website that is actually making money! 3 guesses who it is and how they do it.
Can't guess -- OK, I'll tell you -- it's Google. No pop-ups. No pop-unders. No animation. No pictures of products, even. Just sponsored links located on the right margin of a search result page, and notice that the sponsored links are put into colored boxes labelled as to what they are. But look again at those ads. They are related rather closely to the subject of the search you asked Google to do. This is how Google makes sure that their advertising is seen by people wanting to look at it. Not a bad approach, if you ask me. In fact, I have clicked on some of Google's ad links simply because they were exactly what I wanted!
Gosh! When did linking a search to tasteful ad links for related products turn into rocket science?
The real problem here is that there are some people who think the only way to make a buck in advertising is to annoy people. You don't need to be very old to have seen (and heard) a TV ad for a brand of laundry detergent that used a jingle with the words, "Ring around the collar!" This particular television ad is an example of a class of advertising called irritant advertising, and unfortunately, irritant advertising does work. Irritant advertising is not the only kind of advertising that works, but it is fairly easy to make.
So how does Google do it? Google's ads are not irritating and they don't beat anyone over the head, yet they are making money (or at least they were, the last time I heard about them on CNET radio.)
Perhaps now is the time to rethink the purpose of the world wide web. Is the web still a way of finding and sharing information, or has it become only a medium for aggressive advertising? If the web is now nothing but an advertising medium, I would like to know who tore down the library?