The original IEEE plan for 802.15.3 was to make it backwards compatible with 802.15.1 (i.e., Bluetooth). However, the IP agreement between the Bluetooth SIG and the IEEE specifically limits the use of Bluetooth IP to 15.1, and the Bluetooth SIG was unwilling to allow its use in other IEEE standards. Ergo, no backwards compatibility.
I really can't blame the IEEE in this case; they tried.
The difficulty is that those who voted for Nader gave Bush the 2000 election, by splitting the anti-Bush vote. If Nader had not run, it is likely that the majority of Nader voters would have voted for Gore, rather than Bush, handing Gore the election. Note that this is not the fault of those who voted for Nader, who, as ubikkibu notes, thought they were doing The Right Thing(tm) by voting for the candidate they preferred. Rather, the fault is due to the plurality voting system, in which to get a result most in accordance with his desires a voter is sometimes best served by voting for someone other than the candidate he prefers--in this case, "whatever half-assed corporate whore the Democrats put up," instead of Nader. In 2000, a vote for Nader was a vote for Bush, which was likely not the intent of the voter (again, as ubikkibu notes). (And it works both ways--in 1992 Perot probably took enough votes from Bush I for Clinton to win.)
Other voting systems exist that are much more fair to the wishes of the electorate; one that receives high marks in this regard is the Condorcet system, in which the voter states his preferences pairwise among the listed candidates. The drawback of this method is its complexity, which may be a problem in a country in which the "butterfly ballot" is beyond the capabilities of the voter.
From perusing the SensorML site, SensorML seems geared for satellite-based geosensing and other applications for which significant computing resources are available. I'm interested in small wireless sensor networks, which have very limited computing resources (usually just an 8-bit 8051 or HC08-based MCU, running at 4 to 8 MHz, with about 5k ROM and 1k RAM available). SensorML seems to have a lot of optional fields that could perhaps be eliminated for a "stripped down" version suitable for these types of sensors but, while I'm not an expert in the field, it's always been my understanding that XML=bloat. Can anyone comment on the feasibility of SensorML for small embedded applications?
I found the article's comment about the need for the NSF to motivate standards in wireless sensor networks to be strange, since the IEEE 802.15.4 standard is due to be published any day now (the final draft is alread for sale at the IEEE online store). The IEEE 802.15.4 standard is designed for low cost, very low power consumption wireless sensor networks; it has a raw over-the-air data rate of 250 kb/s, operates in the unlicensed 2.4 GHz ISM band, and can support peer-to-peer multihop (so-called "mesh") networks with device duty cycles below 3 ppm.
The IEEE 802.15.4 standard is being used by the ZigBee Alliance, an organization of more than 50 large and small companies, to establish networking and application profile interoperability standards, much like Wi-fi has done with IEEE 802.11. The ZigBee Alliance will have a session open to the public at its next meeting, in Berlin June 3.
Interesting that UC Riverside would put out a press release on April 2, 2003, announcing a "new physical phenomenon" published by their researchers in the April 15, 2002 issue of Applied Physics Letters--perhaps the phenomenon also involves some form of time dialation?
Also, anybody cannot just be held without council.
Now if we are talking about US citizens on US soil, with out a warranty and right to council, then you would be entirely correct, such behavior would be entirely unconstitutional.
Tell that to Jose Padilla, a U.S. citizen arrested in Chicago, now rotting in a South Carolina naval brig without trial or counsel. (The DoJ is appealing a federal judge's order that he receive counsel; see here and here.) He is being held based solely on the word of the President that he is a terrorist; no public trial has been held and no evidence against him has been presented. This precedent is dangerous; the next person to be so treated could be you!
The best math book I read while getting my degree, and the most unique math book I've ever seen, was/is "A Pathway into Number Theory," by R. P. Burn (Cambridge: Cambridge University Press, 1982, ISBN 0521241189).
Burn covers the main points of an introduction to number theory with what I can only describe as a combined experimentalist/Socratic approach--the book has no prose text in the conventional sense, and no formal proofs. Rather, the book is a series of questions that build upon each other, starting with the simple (e.g., "What is the relation between each number in table 1.1 and the number below it?") and building to the powerful (e.g., the fundamental theorem of arithmetic). Burns works through special cases of fundamental results, then leads the reader to speculate on the underlying principle, then helps him prove that it is true in general.
In the introduction he states that the book was put together "by keeping a record of how I actually resolved the blocks which I encountered as I read a number of standard texts. Time and again, it was the exploration of special cases which illuminated the generalities for me. This collection of explorations was then organised into a sequence in such a way that the 'pathway' would climb towards the standard theorems which occur here as problems for the student at the end of each section." It was a marvelous way to learn.
I am an electrical engineer, and Amroarer is correct. The issue here is one of received power, not angular resolution, and a large but sparse distributed array would be of little help.
Also, keep in mind the problem of acquisition: Since (like all oscillators) Pioneer's oscillators drift slightly over time, there is an uncertainty about *exactly* what frequency one should attempt to receive. To overcome this, and achieve the maximum possible sensitivity, NASA can operate most deep space probes in so-called "synchronous mode," meaning that NASA transmits a carrier of known frequency to Pioneer, to which Pioneer locks (instead of its own oscillator) and uses to transmit back to Earth. I believe NASA has been using this mode to contact Pioneer 10 for the last few years. If the proposed amateur group were trying to improve over existing DSN performance, somebody would have to transmit that signal as well.
An equally fundamental problem, I think, is due to the skin effect.
IIRC, the rate of attenuation of an electromagnetic wave in a conductor is
sqrt(2/wus),
where
w = 2*pi*f = frequency of the wave, in radians u = permeability of the conductor, maybe 4*pi*10^(-7) Henry/m for copper s = conductivity of the conductor, maybe 6*10^7 mhos/m,
meaning that 1/e or about 37% of the wave decays in this distance into the conductor.
If my numbers are right, f = 5.2*10^14 Hz for yellow light, and the skin depth in copper for yellow light is then 2.8*10^(-9) m, or 2.8 nm.
Since the wavelength is 570 nm but the skin depth is only 2.8 nm, it seems that a copper antenna would instead act more like a mirror, reflecting the radiated energy rather than absorbing it.
Clearly no one on this thread works for a manufacturer doing international business from the U.S. (or recalls the export restrictions on encryption a few years back--since relaxed). The U.S. government does quite a good job of imposing morality on business, through its export control classification number (ECCN) system, run by the Bureau of Industry and Security at the Department of Commerce.
This organization has its roots in the old Atomic Energy Commission rules on limiting the export of nuclear materials in the 1940s, but has been greatly expanded, starting in the 1980s, then explosively in the last few years. Every item exported, from software to plastic, must be classified prior to shipment, and there are quite lengthy and detailed descriptions involved. (The sections most relevant to the average/. reader are Category 3-electronics, Category 4-computers, Category 5 (Part 1)-telecommunications, Category 5 (Part 2)-information security, and Supplement No. 2, general technology and software notes, all in section 774.) The rules are in place ostensibly to keep the unwashed heathen overseas from access to U.S. technology that can be turned against the U.S., or technology that they can use to protect themselves against the U.S. Technologists should be aware that the rules were "clarified" a year or two back to include "technology" export, not just the export of physical objects, and that simply discussing a "controlled" technology with someone inside the U.S. that has citizenship from a "banned nation" list makes one subject to fines and/or imprisonment. (This policy works because, as everyone knows, the U.S. is the source of all useful technology;).)
I bring this up to show that moral obligations (at least in the form of obligations that protect U.S. interests) are already placed on businesses, and that the mechanisms are already in place to control whatever export the federal government desires to control.
I realize having Bill even reply to a Slashdot missive is far, far out into fantasyland, but here's what I've always been interested in.
Bill went from being a (perhaps upper-) middle-class Harvard student to the richest person on the planet in the space of fifteen years or so. That *had* to involve a large lifestyle change. While I'm not at all interested in his present personal affairs, I am interested in how he handled the transition from college drop-out to industry icon. I'd like to ask:
-How did you handle the transition from handling your own personal affairs (going down to the dealer to by a car, buying your own Pepsi and Fritos at the grocery, etc.) to having assistants and minions perform all these functions for you? When did this transition occur? At the time, did you view the transition positively or negatively (i.e., as one of the benefits of success, or one of the banes)?
-When was the last time you drove yourself to work on public roads, or flew on a commercial airline flight? When the transition to limousines and personal aircraft occurred, what was the rationalization (e.g., more time available for work, increased prestige, etc.) for their use?
-When did you first feel the need for 24x7 personal security? How did having people around you constantly affect your lifestyle? (Personally, I'd find it pretty creepy to have people monitoring me all the time--but even more creepy to realize that they were needed.)
-You were single a relatively long time, then married a woman who worked at your office. As the richest bachelor on the continent, I can imagine that the competition among the single women at MS for your attentions must have made Machiavelli look like a Sunday-school teacher. Were you aware of this? If so, how did you address the resulting problems with office politics? Did you suffer from the insecurity, so common among the wealthy and powerful, that everyone that meets you is more interested in your money and power than in you?
Just post the above in the "unavailable for comment" file....
The feet are very involved in the control of balance, as the designers of the Millennium Bridge (a walking bridge over the Thames in London) found out. The feet are much more sensitive to horizontal movement, in fact, than they are to vertical movement. People respond subconsciously to lateral movement of the foot with a restoring force: If a foot is moved a trivial amount to the right, say, the body makes an unconscious movement to return to its original position by pushing the foot to the right (to move the body back to the left). (The evolutionary importance of this fast reaction to slipping is clear.) Since this restoring force is in the same direction as the original movement, amplification can result. As any engineer can tell you, a source of amplification can be a source of oscillation if a resonant structure is available; if the body is on a suspension bridge, a natural resonance of the bridge can be excited. Further, once the bridge begins to sway laterally, people find it most comfortable to walk in phase with the swaying, in a manner that also amplifies the swaying.
The Millennium Bridge was completely stable under conventional dynamic analysis; with a small number people walking on it, or with a large number of people merely standing on it, it was also stable. However, with a large number of people (80,000-100,000) walking on it, as happened on opening day, "unexpected movements occurred." resulting in its temporary closure until modifications (in the form of resonance damping) were made. As described by the designers,
Chance footfall correlation, combined with the synchronisation that occurs naturally within a crowd, may cause the bridge to start to sway horizontally. If the sway is perceptible, a further effect can start to take hold. It becomes more comfortable for the pedestrians to walk in synchronization with the swaying of the bridge. The pedestrians find this makes their interaction with the movement of the bridge more predictable and helps them maintain their lateral balance. This instinctive behaviour ensures that the footfall forces are applied at the resonant frequency of the bridge and with a phase such as to increase the motion of the bridge. As the amplitude of the motion increases, the lateral force imparted by individuals increases, as does the degree of correlation between individuals.
Additional information on the phenomenon of synchronous lateral excitation of bridges is available here.
-Multiple simultaneous beams. The maximum number of possible beams is equal to the number of radiating elements in the array. The Pringles can, of course, has only one main lobe (beam).
-Near-instantaneous beam switching from one direction to another or, said another way, the ability to track very quickly, since the beamsteering is done electrically, rather than mechanically, as the Pringles can does.
The big question I've not seen answered is, how do they handle the Wi-Fi beacons? A beacon serves multiple purposes--synchronizing the network nodes and advertising the presence of the network to prospective new network members being two of them. If the beamforming is used to reach long distances, the beam is very narrow; new nodes won't be able to detect the network since it's unlikely they'll be in the beam. Conversely, if a wide beam is used to enable new nodes to join, range to existing LAN members will suffer.
I wonder if it's significant that, in the Wired article, the tests were performed starting close to the AP, then walking away from it. It would be interesting to try the reverse...
AFAIK no draft standards are available for purchase. 802, like most standards organizations, works hard to limit draft distribution outside the organization (and to stop companies that advertise "compliance" to a draft). Drafts are, by definition, unapproved by the organization. Since they change often, they can cause confusion; also, it is felt that interested persons can best improve the draft by becoming active in the standards organization itself. After all, anyone can attend a meeting; at the 802.11/.15/.18/.19 meetings a Wi-Fi LAN and server is installed, over which attendees can download draft standards to their laptops 'til their hearts are content.
The next meeting is November 10-15 in Kauai, Hawaii; the one following that is January 12-17, 2003 in Ft. Lauderdale, Florida.
The IEEE 802 standards that form the basis of the Wi-Fi Alliance (IEEE 802.11,.11a,.11b, etc.) are available for FREE download from the getieee web site, six months after they are published in pdf by the IEEE Standards Association.
Arthur C. Clarke described a "golden reef," in which several species of coral were genetically engineered to extract gold from sea water, in his book "Imperial Earth," published in 1976. In a rather detailed passage, he describes his corals as being up to ten per cent gold, but states that the gold extraction feature weakened the health of the coral, so that they suffered from parasitism and disease and required regular gardening and maintenance to remain viable.
The Mho is the old, "unofficial" unit of conductance. The Siemen, the formal unit of conductance designed to replace the mho, is a derived SI unit of conductance, established some time back.
The main reason for discussing conductivity, as the AC suggests, is in cases where the resistance is very low, such as in describing the electrical conductivity of liquid solutions or soils. It is also used when analyzing parallel (not series) circuits, wherein, also as the AC suggests, 1/R1 + 1/R2 = 1/Rtot, but it's much easier to calculate S1 + S2 = Stot.
Be careful! The witness must certify not only that he *read* the disclosing material, but also that he *understood* it. If the invention is sufficiently technical, an ordinary off-the-street Notary Public will not suffice.
This is one of the reasons Edwin Armstrong lost control of the regenerative amplifier patent he filed as a teenager back in the 1910s, when challenged by that pinnacle of morality, Lee DeForest.
(Disclaimer: IANAL, but I do have several issued patents and dozens more pending at the USPTO.)
To me this is a case of operating within one's rights, to the detriment of one's business. Baseball has done this in spades for as long as I can remember, and it's finally beginning to affect the business.
I have had season tickets to a major league baseball team for the past ten years, meaning that during that time I have seen over 750 games (I've had to miss a few due to business trips, etc.). The basic attitude of the team and MLB in general, seems to be that fans are obligated to attend, regardless of how they are treated.
Probably the best example of this is the stadium's "security" policy regarding material one may bring to the games. I would like to bring in things like a score book, media guide, binoculars, sunscreen, pencils, etc., but they won't allow a bag larger than 8-1/2" x 11" (21.5 cm x 28 cm) into the stadium--even if you let them search the bag, or even empty it out at the feet of the inspector. The bag itself is not permitted, for some reason. However, they *will* allow women's purses and infants' diaper bags of any size, and they don't perform body searches or use metal detectors--whatever is in your pockets or under your clothes is yours to keep.
What they *think* they are accomplishing by this I cannot imagine, but I can say what they *are* accomplishing: As a result of this policy I can always tell a new, prospective fan, going to a game for the first time--I pass him walking back out to the parking lot as I am walking in, carrying the bag or knapsack he quite reasonably expected to be able to take to the game. Or I pass him at the inspector's station at the stadium entrance, presenting rational but useless arguments and expressions of surprise and disbelief to the bored workers there. As a business, the team has the right to set up rules for all those who enter, but the team shouldn't complain when no one bothers to come any more, and new fans prove difficult to attract. It's always been a puzzle to me how baseball owners could have business acumen sufficient to amass personal fortunes, yet run major league baseball as if they were the stupidest form of life on the planet.
This kind of behavior is rampant in MLB and, barring an unforeseen turnaround, may soon enable baseball to reach the popularity of those other major sports of the 1950's--boxing and horse racing.
Wi-Fi (IEEE 802.11b) is a direct sequence spread spectrum system--not a frequency-hopping system. The signal is spread, then placed on a fixed channel--one of the 14 available. As mentioned above, however, only 11 are legal to use in the U.S. and, of these, only three don't overlap.
The confusion probably arises from the original 1 Mb/s IEEE 802.11 WLAN standard, which actually had three physical layers--Direct sequence spread spectrum (on the same channels as Wi-Fi), frequency hop spread spectrum (on 79 channels between 2402 and 2480 MHz in the U.S.), and infrared (IR).
The value in using Channel 1 for a direct sequence system is entirely due to the law of unintended consequences--most WLAN software does a simple channel scan from the bottom to the top of the band, and T-mobile wants to be discovered first. Had the software designers realized the built-in marketing advantage they were giving to Channel 1, and the ensuing free-for-all that would result, they might have randomized the search, to give all channels equal access.
Interesting how much economic effect can result from a computer language syntax feature like "ChanNum++".
Option (b) allows IP holders to erect a "toll booth" on 802 protocols only if the standards body agrees (by a passing vote of the standard) that the value of the IP is worth it. If 802 doesn't agree (at either the Task Group, Working Group, or Sponsor levels), the IP holder is left in the cold, and an alternate technical choice is made. This is a motivator for the IP holder to be "reasonable": The market force of a successful IEEE standard (e.g., 802.11b) is considerable. If your IP is not included in the standard, in order for you to get any money from anyone for it you have to think it's of such tremendous value that people will pay to use it in some (closed) competitive standard of yours, rather than use some open IEEE standard that does not use it. It is therefore nearly always in your best interest to be "reasonable," and get your IP into the standard under some terms 802 can accept (and vote for).
Note that the standards marketplace is a competitive one; any standard that is too expensive to use in the judgement of the market--including IEEE standards--is replaced by one having a cost/benefit ratio the market prefers.
The point of patent disclosure is not just to disclose patents that you yourself have invented; the point is to recognize any that you know, from anywhere. Many (perhaps even most) times the IP is from some third party that has no idea the subject is even under consideration. A textbook case is the use of turbocodes in wireless channel coding--these are of great technical value, but variations of these have been patented by many, many people around the world, most of whom have never even heard of your little standards group. Even within a single large corporation, this is often impossible--most large corporations have 500-1000 patents assigned to them each year (each with perhaps a dozen or more claims); it's impossible for any single individual to know what's in each of them--or to form a legally binding opinion regarding their relevance to your standards proposal. The best one can do is to disclose IP "of which you are aware."
The IEEE Standards Association, home to the 802 family (Ethernet, Wi-Fi, etc.) and legions of others, has a more enlightened IP policy, IMHO, as described in their bylaws and operations manual. From the bylaws:
IEEE standards may include the known use of patent(s), including patent applications, provided the IEEE receives assurance from the patent holder or applicant with respect to patents essential for compliance with both mandatory and optional portions of the standard. This assurance shall be provided without coercion and prior to approval of the standard (or reaffirmation when a patent becomes known after initial approval of the standard). This assurance shall be a letter that is in the form of either
a)
A general disclaimer to the effect that the patentee will not enforce any of its present or future patent(s) whose use would be required to implement the proposed IEEE standard against any person or entity using the patent(s) to comply with the standard or
b)
A statement that a license will be made available without compensation or under reasonable rates, with reasonable terms and conditions that are demonstrably free of any unfair discrimination.
This assurance shall apply, at a minimum, from the date of the standard's approval to the date of the standard's withdrawal and is irrevocable during that period.
This seems to provide a good compromise; patented technology may get into a standard, but only after disclosure and subsequent approval of the standard by the organization. In addition, while I can't speak for the IEEE-SA as a whole, 802 voters vote as individuals--there are no "corporate votes." Individual consultants have the same voting power as a corporate VP: While the VP may spend corporate $$ to have a collection of subordinates attend enough meetings to become eligible voters, members of the EFF, or any other collection of people, could also attend and vote. While the 802 process isn't perfect, and abuses have been known to occur, this aspect of the IEEE standards process also works to get the best technical standard produced.
There are many other research programs, both academic and industrial, on wireless ad hoc networks, going back at least to the 1978 DARPA-sponsored Distributed Sensor Nets Workshop at Carnegie-Mellon University. Most of the work has been funded by DARPA, by the low-power wireless integrated microsensors (LWIM) project of the mid-1990s and now by the SensIT project. (Their projects page lists more than 25 academic research programs on these networks, complete with links.)
The University of California at Los Angeles, often working in collaboration with the Rockwell Science Center, has had a Wireless Integrated Network Sensors (WINS) project since 1993. UCLA also supports the similar-but-different "Smart Dust" program, which also employs ultra-low-power networking, but uses optical communication between network nodes.
Professor Anantha Chandrakasan at the Massachusetts Institute of Technology is the Principal Investigator of the uAMPS (microAMPS) project.
On the commercial side, these networks are being developed by Ember, graviton, Wherenet, and Motorola, just to name a few.
The ZigBee industry consortium is the marketing and compliance arm of the IEEE 802.15.4 draft standard, in a relationship similar to that between WECA (with the "Wi-Fi" brand) and IEEE 802.11b. This draft standard for ultra-low-power, ultra-low-cost wireless networking, now under development, should be finished this winter.
1. Implement the suggestions of those who have posted before me. Their comments are insightful, and greatly strengthen your letter.
2. (style) In the "Open Source Software" paragraph, it should read, "Software engineers like me," not "like myself."
3. (substance) The example of GPS as a digital device without a protection scheme is not a good one. GPS, developed by the military, has plenty of encryption, both in the physical layer and above. I haven't read the bill, and so don't know what its definition of "digital device" is, but perhaps a better example would be a digital watch or clock. This paragraph could perhaps be strengthened by opening with a quote of the bill's definition of "digital device" (assuming it has one), then pointing out that, as you suggest, unintended devices may be affected.
- While antennas for microwave astronomy could, of course, resemble the familiar parabolic dishes found on earth (although other types are possible), their size would be limited less by design problems caused by the effects of gravitational stress (as they are on Earth) than by material shipment and construction costs. However, antennas for the lower frequencies of radio astronomy, e.g., 1-10 MHz, could be markedly different from those found on earth. Since, for equivalent performance, the dimensions of an antenna are proportional to the radio wavelength being received, a 1 MHz (300 m wavelength) antenna, for example, requires a million (a thousand squared) times the physical area as the equivalent antenna at 1 GHz (30 cm wavelength). Thus, land costs are the largest problem on earth for low frequency antennas (along with other impracticalities). This problem is effectively eliminated on the moon, freeing the antenna engineer to study other possibilities.
Also note that, while the 1 MHz antenna is larger than the 1 GHz antenna, the tolerance on the placement of its physical components is looser by the same proportion: While a very fine mesh reflector for the 1 GHz antenna must have wires, say, every 3 cm or so, +/- 1 cm, the equivalent specification on the 1 MHz antenna would be wires every 30 m +/- 10 m. This may be significantly easier to build by robotic devices. (For practical reasons one probably wouldn't use a reflector-type antenna at 1 MHz, but the principle holds regardless of the antenna type.)
- There is a second, equally important problem to doing low-frequency (30 MHz) radio astronomy on Earth, besides the man-made interference. It's the ionosphere. The same refractive layer(s) in the atmosphere that enable worldwide shortwave communication also shield the surface of Earth from external radio sources; signals that do reach the surface are greatly attenuated, and have significant phase and angular (i.e., apparent location) distortion. Since the moon has only a trivial (most would say substantially nonexistent) atmosphere, the ion density in it is much, much lower; this leads to refraction of radio signals only at much lower frequencies, something on the order of 100 kHz or less, IIRC.
Slashdot Mirror
The original IEEE plan for 802.15.3 was to make it backwards compatible with 802.15.1 (i.e., Bluetooth). However, the IP agreement between the Bluetooth SIG and the IEEE specifically limits the use of Bluetooth IP to 15.1, and the Bluetooth SIG was unwilling to allow its use in other IEEE standards. Ergo, no backwards compatibility.
I really can't blame the IEEE in this case; they tried.
The difficulty is that those who voted for Nader gave Bush the 2000 election, by splitting the anti-Bush vote. If Nader had not run, it is likely that the majority of Nader voters would have voted for Gore, rather than Bush, handing Gore the election. Note that this is not the fault of those who voted for Nader, who, as ubikkibu notes, thought they were doing The Right Thing(tm) by voting for the candidate they preferred. Rather, the fault is due to the plurality voting system, in which to get a result most in accordance with his desires a voter is sometimes best served by voting for someone other than the candidate he prefers--in this case, "whatever half-assed corporate whore the Democrats put up," instead of Nader. In 2000, a vote for Nader was a vote for Bush, which was likely not the intent of the voter (again, as ubikkibu notes). (And it works both ways--in 1992 Perot probably took enough votes from Bush I for Clinton to win.)
Other voting systems exist that are much more fair to the wishes of the electorate; one that receives high marks in this regard is the Condorcet system, in which the voter states his preferences pairwise among the listed candidates. The drawback of this method is its complexity, which may be a problem in a country in which the "butterfly ballot" is beyond the capabilities of the voter.
From perusing the SensorML site, SensorML seems geared for satellite-based geosensing and other applications for which significant computing resources are available. I'm interested in small wireless sensor networks, which have very limited computing resources (usually just an 8-bit 8051 or HC08-based MCU, running at 4 to 8 MHz, with about 5k ROM and 1k RAM available). SensorML seems to have a lot of optional fields that could perhaps be eliminated for a "stripped down" version suitable for these types of sensors but, while I'm not an expert in the field, it's always been my understanding that XML=bloat. Can anyone comment on the feasibility of SensorML for small embedded applications?
I found the article's comment about the need for the NSF to motivate standards in wireless sensor networks to be strange, since the IEEE 802.15.4 standard is due to be published any day now (the final draft is alread for sale at the IEEE online store). The IEEE 802.15.4 standard is designed for low cost, very low power consumption wireless sensor networks; it has a raw over-the-air data rate of 250 kb/s, operates in the unlicensed 2.4 GHz ISM band, and can support peer-to-peer multihop (so-called "mesh") networks with device duty cycles below 3 ppm.
The IEEE 802.15.4 standard is being used by the ZigBee Alliance, an organization of more than 50 large and small companies, to establish networking and application profile interoperability standards, much like Wi-fi has done with IEEE 802.11. The ZigBee Alliance will have a session open to the public at its next meeting, in Berlin June 3.
The IEEE 1451.5 wireless sensor standard, which will standardize sensor discovery and data formatting, is at an earlier stage of development; proposals are now being presented.
With all this activity, it's not clear to me just what the NSF is expecting to standardize.
Interesting that UC Riverside would put out a press release on April 2, 2003, announcing a "new physical phenomenon" published by their researchers in the April 15, 2002 issue of Applied Physics Letters--perhaps the phenomenon also involves some form of time dialation?
Tell that to Jose Padilla, a U.S. citizen arrested in Chicago, now rotting in a South Carolina naval brig without trial or counsel. (The DoJ is appealing a federal judge's order that he receive counsel; see here and here.) He is being held based solely on the word of the President that he is a terrorist; no public trial has been held and no evidence against him has been presented. This precedent is dangerous; the next person to be so treated could be you!
The best math book I read while getting my degree, and the most unique math book I've ever seen, was/is "A Pathway into Number Theory," by R. P. Burn (Cambridge: Cambridge University Press, 1982, ISBN 0521241189).
Burn covers the main points of an introduction to number theory with what I can only describe as a combined experimentalist/Socratic approach--the book has no prose text in the conventional sense, and no formal proofs. Rather, the book is a series of questions that build upon each other, starting with the simple (e.g., "What is the relation between each number in table 1.1 and the number below it?") and building to the powerful (e.g., the fundamental theorem of arithmetic). Burns works through special cases of fundamental results, then leads the reader to speculate on the underlying principle, then helps him prove that it is true in general.
In the introduction he states that the book was put together "by keeping a record of how I actually resolved the blocks which I encountered as I read a number of standard texts. Time and again, it was the exploration of special cases which illuminated the generalities for me. This collection of explorations was then organised into a sequence in such a way that the 'pathway' would climb towards the standard theorems which occur here as problems for the student at the end of each section." It was a marvelous way to learn.
It's still in print.
I am an electrical engineer, and Amroarer is correct. The issue here is one of received power, not angular resolution, and a large but sparse distributed array would be of little help.
Also, keep in mind the problem of acquisition: Since (like all oscillators) Pioneer's oscillators drift slightly over time, there is an uncertainty about *exactly* what frequency one should attempt to receive. To overcome this, and achieve the maximum possible sensitivity, NASA can operate most deep space probes in so-called "synchronous mode," meaning that NASA transmits a carrier of known frequency to Pioneer, to which Pioneer locks (instead of its own oscillator) and uses to transmit back to Earth. I believe NASA has been using this mode to contact Pioneer 10 for the last few years. If the proposed amateur group were trying to improve over existing DSN performance, somebody would have to transmit that signal as well.
An equally fundamental problem, I think, is due to the skin effect.
IIRC, the rate of attenuation of an electromagnetic wave in a conductor is
sqrt(2/wus),
where
w = 2*pi*f = frequency of the wave, in radians
u = permeability of the conductor, maybe 4*pi*10^(-7) Henry/m for copper
s = conductivity of the conductor, maybe 6*10^7 mhos/m,
meaning that 1/e or about 37% of the wave decays in this distance into the conductor.
If my numbers are right, f = 5.2*10^14 Hz for yellow light, and the skin depth in copper for yellow light is then 2.8*10^(-9) m, or 2.8 nm.
Since the wavelength is 570 nm but the skin depth is only 2.8 nm, it seems that a copper antenna would instead act more like a mirror, reflecting the radiated energy rather than absorbing it.
Clearly no one on this thread works for a manufacturer doing international business from the U.S. (or recalls the export restrictions on encryption a few years back--since relaxed). The U.S. government does quite a good job of imposing morality on business, through its export control classification number (ECCN) system, run by the Bureau of Industry and Security at the Department of Commerce.
This organization has its roots in the old Atomic Energy Commission rules on limiting the export of nuclear materials in the 1940s, but has been greatly expanded, starting in the 1980s, then explosively in the last few years. Every item exported, from software to plastic, must be classified prior to shipment, and there are quite lengthy and detailed descriptions involved. (The sections most relevant to the average /. reader are Category 3-electronics, Category 4-computers, Category 5 (Part 1)-telecommunications, Category 5 (Part 2)-information security, and Supplement No. 2, general technology and software notes, all in section 774.) The rules are in place ostensibly to keep the unwashed heathen overseas from access to U.S. technology that can be turned against the U.S., or technology that they can use to protect themselves against the U.S. Technologists should be aware that the rules were "clarified" a year or two back to include "technology" export, not just the export of physical objects, and that simply discussing a "controlled" technology with someone inside the U.S. that has citizenship from a "banned nation" list makes one subject to fines and/or imprisonment. (This policy works because, as everyone knows, the U.S. is the source of all useful technology ;).)
I bring this up to show that moral obligations (at least in the form of obligations that protect U.S. interests) are already placed on businesses, and that the mechanisms are already in place to control whatever export the federal government desires to control.
I realize having Bill even reply to a Slashdot missive is far, far out into fantasyland, but here's what I've always been interested in.
Bill went from being a (perhaps upper-) middle-class Harvard student to the richest person on the planet in the space of fifteen years or so. That *had* to involve a large lifestyle change. While I'm not at all interested in his present personal affairs, I am interested in how he handled the transition from college drop-out to industry icon. I'd like to ask:
-How did you handle the transition from handling your own personal affairs (going down to the dealer to by a car, buying your own Pepsi and Fritos at the grocery, etc.) to having assistants and minions perform all these functions for you? When did this transition occur? At the time, did you view the transition positively or negatively (i.e., as one of the benefits of success, or one of the banes)?
-When was the last time you drove yourself to work on public roads, or flew on a commercial airline flight? When the transition to limousines and personal aircraft occurred, what was the rationalization (e.g., more time available for work, increased prestige, etc.) for their use?
-When did you first feel the need for 24x7 personal security? How did having people around you constantly affect your lifestyle? (Personally, I'd find it pretty creepy to have people monitoring me all the time--but even more creepy to realize that they were needed.)
-You were single a relatively long time, then married a woman who worked at your office. As the richest bachelor on the continent, I can imagine that the competition among the single women at MS for your attentions must have made Machiavelli look like a Sunday-school teacher. Were you aware of this? If so, how did you address the resulting problems with office politics? Did you suffer from the insecurity, so common among the wealthy and powerful, that everyone that meets you is more interested in your money and power than in you?
Just post the above in the "unavailable for comment" file....
The feet are very involved in the control of balance, as the designers of the Millennium Bridge (a walking bridge over the Thames in London) found out. The feet are much more sensitive to horizontal movement, in fact, than they are to vertical movement. People respond subconsciously to lateral movement of the foot with a restoring force: If a foot is moved a trivial amount to the right, say, the body makes an unconscious movement to return to its original position by pushing the foot to the right (to move the body back to the left). (The evolutionary importance of this fast reaction to slipping is clear.) Since this restoring force is in the same direction as the original movement, amplification can result. As any engineer can tell you, a source of amplification can be a source of oscillation if a resonant structure is available; if the body is on a suspension bridge, a natural resonance of the bridge can be excited. Further, once the bridge begins to sway laterally, people find it most comfortable to walk in phase with the swaying, in a manner that also amplifies the swaying.
The Millennium Bridge was completely stable under conventional dynamic analysis; with a small number people walking on it, or with a large number of people merely standing on it, it was also stable. However, with a large number of people (80,000-100,000) walking on it, as happened on opening day, "unexpected movements occurred." resulting in its temporary closure until modifications (in the form of resonance damping) were made. As described by the designers,
Additional information on the phenomenon of synchronous lateral excitation of bridges is available here.
The advantages of a phased array AP are two:
-Multiple simultaneous beams. The maximum number of possible beams is equal to the number of radiating elements in the array. The Pringles can, of course, has only one main lobe (beam).
-Near-instantaneous beam switching from one direction to another or, said another way, the ability to track very quickly, since the beamsteering is done electrically, rather than mechanically, as the Pringles can does.
The big question I've not seen answered is, how do they handle the Wi-Fi beacons? A beacon serves multiple purposes--synchronizing the network nodes and advertising the presence of the network to prospective new network members being two of them. If the beamforming is used to reach long distances, the beam is very narrow; new nodes won't be able to detect the network since it's unlikely they'll be in the beam. Conversely, if a wide beam is used to enable new nodes to join, range to existing LAN members will suffer.
I wonder if it's significant that, in the Wired article, the tests were performed starting close to the AP, then walking away from it. It would be interesting to try the reverse...
AFAIK no draft standards are available for purchase. 802, like most standards organizations, works hard to limit draft distribution outside the organization (and to stop companies that advertise "compliance" to a draft). Drafts are, by definition, unapproved by the organization. Since they change often, they can cause confusion; also, it is felt that interested persons can best improve the draft by becoming active in the standards organization itself. After all, anyone can attend a meeting; at the 802.11/.15/.18/.19 meetings a Wi-Fi LAN and server is installed, over which attendees can download draft standards to their laptops 'til their hearts are content.
The next meeting is November 10-15 in Kauai, Hawaii; the one following that is January 12-17, 2003 in Ft. Lauderdale, Florida.
The IEEE 802 standards that form the basis of the Wi-Fi Alliance (IEEE 802.11, .11a, .11b, etc.) are available for FREE download from the getieee web site, six months after they are published in pdf by the IEEE Standards Association.
Arthur C. Clarke described a "golden reef," in which several species of coral were genetically engineered to extract gold from sea water, in his book "Imperial Earth," published in 1976. In a rather detailed passage, he describes his corals as being up to ten per cent gold, but states that the gold extraction feature weakened the health of the coral, so that they suffered from parasitism and disease and required regular gardening and maintenance to remain viable.
The Mho is the old, "unofficial" unit of conductance. The Siemen, the formal unit of conductance designed to replace the mho, is a derived SI unit of conductance, established some time back.
The main reason for discussing conductivity, as the AC suggests, is in cases where the resistance is very low, such as in describing the electrical conductivity of liquid solutions or soils. It is also used when analyzing parallel (not series) circuits, wherein, also as the AC suggests, 1/R1 + 1/R2 = 1/Rtot, but it's much easier to calculate S1 + S2 = Stot.
Be careful! The witness must certify not only that he *read* the disclosing material, but also that he *understood* it. If the invention is sufficiently technical, an ordinary off-the-street Notary Public will not suffice.
This is one of the reasons Edwin Armstrong lost control of the regenerative amplifier patent he filed as a teenager back in the 1910s, when challenged by that pinnacle of morality, Lee DeForest.
(Disclaimer: IANAL, but I do have several issued patents and dozens more pending at the USPTO.)
To me this is a case of operating within one's rights, to the detriment of one's business. Baseball has done this in spades for as long as I can remember, and it's finally beginning to affect the business.
I have had season tickets to a major league baseball team for the past ten years, meaning that during that time I have seen over 750 games (I've had to miss a few due to business trips, etc.). The basic attitude of the team and MLB in general, seems to be that fans are obligated to attend, regardless of how they are treated.
Probably the best example of this is the stadium's "security" policy regarding material one may bring to the games. I would like to bring in things like a score book, media guide, binoculars, sunscreen, pencils, etc., but they won't allow a bag larger than 8-1/2" x 11" (21.5 cm x 28 cm) into the stadium--even if you let them search the bag, or even empty it out at the feet of the inspector. The bag itself is not permitted, for some reason. However, they *will* allow women's purses and infants' diaper bags of any size, and they don't perform body searches or use metal detectors--whatever is in your pockets or under your clothes is yours to keep.
What they *think* they are accomplishing by this I cannot imagine, but I can say what they *are* accomplishing: As a result of this policy I can always tell a new, prospective fan, going to a game for the first time--I pass him walking back out to the parking lot as I am walking in, carrying the bag or knapsack he quite reasonably expected to be able to take to the game. Or I pass him at the inspector's station at the stadium entrance, presenting rational but useless arguments and expressions of surprise and disbelief to the bored workers there. As a business, the team has the right to set up rules for all those who enter, but the team shouldn't complain when no one bothers to come any more, and new fans prove difficult to attract. It's always been a puzzle to me how baseball owners could have business acumen sufficient to amass personal fortunes, yet run major league baseball as if they were the stupidest form of life on the planet.
This kind of behavior is rampant in MLB and, barring an unforeseen turnaround, may soon enable baseball to reach the popularity of those other major sports of the 1950's--boxing and horse racing.
Wi-Fi (IEEE 802.11b) is a direct sequence spread spectrum system--not a frequency-hopping system. The signal is spread, then placed on a fixed channel--one of the 14 available. As mentioned above, however, only 11 are legal to use in the U.S. and, of these, only three don't overlap.
The confusion probably arises from the original 1 Mb/s IEEE 802.11 WLAN standard, which actually had three physical layers--Direct sequence spread spectrum (on the same channels as Wi-Fi), frequency hop spread spectrum (on 79 channels between 2402 and 2480 MHz in the U.S.), and infrared (IR).
The value in using Channel 1 for a direct sequence system is entirely due to the law of unintended consequences--most WLAN software does a simple channel scan from the bottom to the top of the band, and T-mobile wants to be discovered first. Had the software designers realized the built-in marketing advantage they were giving to Channel 1, and the ensuing free-for-all that would result, they might have randomized the search, to give all channels equal access.
Interesting how much economic effect can result from a computer language syntax feature like "ChanNum++".
Option (b) allows IP holders to erect a "toll booth" on 802 protocols only if the standards body agrees (by a passing vote of the standard) that the value of the IP is worth it. If 802 doesn't agree (at either the Task Group, Working Group, or Sponsor levels), the IP holder is left in the cold, and an alternate technical choice is made. This is a motivator for the IP holder to be "reasonable": The market force of a successful IEEE standard (e.g., 802.11b) is considerable. If your IP is not included in the standard, in order for you to get any money from anyone for it you have to think it's of such tremendous value that people will pay to use it in some (closed) competitive standard of yours, rather than use some open IEEE standard that does not use it. It is therefore nearly always in your best interest to be "reasonable," and get your IP into the standard under some terms 802 can accept (and vote for).
Note that the standards marketplace is a competitive one; any standard that is too expensive to use in the judgement of the market--including IEEE standards--is replaced by one having a cost/benefit ratio the market prefers.
The point of patent disclosure is not just to disclose patents that you yourself have invented; the point is to recognize any that you know, from anywhere. Many (perhaps even most) times the IP is from some third party that has no idea the subject is even under consideration. A textbook case is the use of turbocodes in wireless channel coding--these are of great technical value, but variations of these have been patented by many, many people around the world, most of whom have never even heard of your little standards group. Even within a single large corporation, this is often impossible--most large corporations have 500-1000 patents assigned to them each year (each with perhaps a dozen or more claims); it's impossible for any single individual to know what's in each of them--or to form a legally binding opinion regarding their relevance to your standards proposal. The best one can do is to disclose IP "of which you are aware."
The IEEE Standards Association, home to the 802 family (Ethernet, Wi-Fi, etc.) and legions of others, has a more enlightened IP policy, IMHO, as described in their bylaws and operations manual. From the bylaws:
This seems to provide a good compromise; patented technology may get into a standard, but only after disclosure and subsequent approval of the standard by the organization. In addition, while I can't speak for the IEEE-SA as a whole, 802 voters vote as individuals--there are no "corporate votes." Individual consultants have the same voting power as a corporate VP: While the VP may spend corporate $$ to have a collection of subordinates attend enough meetings to become eligible voters, members of the EFF, or any other collection of people, could also attend and vote. While the 802 process isn't perfect, and abuses have been known to occur, this aspect of the IEEE standards process also works to get the best technical standard produced.
There are many other research programs, both academic and industrial, on wireless ad hoc networks, going back at least to the 1978 DARPA-sponsored Distributed Sensor Nets Workshop at Carnegie-Mellon University. Most of the work has been funded by DARPA, by the low-power wireless integrated microsensors (LWIM) project of the mid-1990s and now by the SensIT project. (Their projects page lists more than 25 academic research programs on these networks, complete with links.)
The University of California at Los Angeles, often working in collaboration with the Rockwell Science Center, has had a Wireless Integrated Network Sensors (WINS) project since 1993. UCLA also supports the similar-but-different "Smart Dust" program, which also employs ultra-low-power networking, but uses optical communication between network nodes.
Professor Anantha Chandrakasan at the Massachusetts Institute of Technology is the Principal Investigator of the uAMPS (microAMPS) project.
On the commercial side, these networks are being developed by Ember, graviton, Wherenet, and Motorola, just to name a few.
The ZigBee industry consortium is the marketing and compliance arm of the IEEE 802.15.4 draft standard, in a relationship similar to that between WECA (with the "Wi-Fi" brand) and IEEE 802.11b. This draft standard for ultra-low-power, ultra-low-cost wireless networking, now under development, should be finished this winter.
Three comments:
1. Implement the suggestions of those who have posted before me. Their comments are insightful, and greatly strengthen your letter.
2. (style) In the "Open Source Software" paragraph, it should read, "Software engineers like me," not "like myself."
3. (substance) The example of GPS as a digital device without a protection scheme is not a good one. GPS, developed by the military, has plenty of encryption, both in the physical layer and above. I haven't read the bill, and so don't know what its definition of "digital device" is, but perhaps a better example would be a digital watch or clock. This paragraph could perhaps be strengthened by opening with a quote of the bill's definition of "digital device" (assuming it has one), then pointing out that, as you suggest, unintended devices may be affected.
An excellent first draft, BTW.
Two points:
- While antennas for microwave astronomy could, of course, resemble the familiar parabolic dishes found on earth (although other types are possible), their size would be limited less by design problems caused by the effects of gravitational stress (as they are on Earth) than by material shipment and construction costs. However, antennas for the lower frequencies of radio astronomy, e.g., 1-10 MHz, could be markedly different from those found on earth. Since, for equivalent performance, the dimensions of an antenna are proportional to the radio wavelength being received, a 1 MHz (300 m wavelength) antenna, for example, requires a million (a thousand squared) times the physical area as the equivalent antenna at 1 GHz (30 cm wavelength). Thus, land costs are the largest problem on earth for low frequency antennas (along with other impracticalities). This problem is effectively eliminated on the moon, freeing the antenna engineer to study other possibilities.
Also note that, while the 1 MHz antenna is larger than the 1 GHz antenna, the tolerance on the placement of its physical components is looser by the same proportion: While a very fine mesh reflector for the 1 GHz antenna must have wires, say, every 3 cm or so, +/- 1 cm, the equivalent specification on the 1 MHz antenna would be wires every 30 m +/- 10 m. This may be significantly easier to build by robotic devices. (For practical reasons one probably wouldn't use a reflector-type antenna at 1 MHz, but the principle holds regardless of the antenna type.)
- There is a second, equally important problem to doing low-frequency (30 MHz) radio astronomy on Earth, besides the man-made interference. It's the ionosphere. The same refractive layer(s) in the atmosphere that enable worldwide shortwave communication also shield the surface of Earth from external radio sources; signals that do reach the surface are greatly attenuated, and have significant phase and angular (i.e., apparent location) distortion. Since the moon has only a trivial (most would say substantially nonexistent) atmosphere, the ion density in it is much, much lower; this leads to refraction of radio signals only at much lower frequencies, something on the order of 100 kHz or less, IIRC.