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Geez, you couldn't even type "aviation radio heterodyne" into Google to see what I was talking about. Everything I've posted comes up on the first page!

• Advanced Aviation Technology Ltd. makes a device for this purpose, their sales pitch (section 3) describes the problem. (How nice of them.)

• Salon posted an article about the problem on March 28th. Same example -- Tenerife airport.

Not going to bother bashing lawyers here -- this is Slashdot, feelings on that subject are well known.

• 
  "Let me run the numbers for you on interference."

• "...For now, UWB communications devices will be restricted to intentional operation only between 3.1 and 10.6 GHz; through-wall imaging and surveillance systems restricted between 1.99 and 10.6 GHz (and used only for law enforcement, fire and rescue, and other designated organizations) and automotive radars restricted to frequencies above 24.075 GHz."

  Further, maximum output -- anywhere in the spectrum -- must be under limits set by part 15 (for now). That's -41.25 dBm/MHz.

Much of this has to do with CS researchers forcing the conference publishers to allow distribution of papers via personal webpages. Once you have that, the rest follows.

But in fairness, Nature is only $160/year ($100 students), which covers 52 issues. Of course, you have to put up with advertising and pay a subscription...

Last month, Wired ran an article about the new construction at the South Pole. It makes no mention of this fiber.
As an Engineer for one of the Telephone Companies, I can tell you that fiber is stronger than you think. I had a pole get hit, knocking the cables the ground- a few 18 wheelers drove over the cables, partially crushing a copper cable. But, the two fiber cables were uninjured (part of their sheathing was shorn away, though).
Still, running fiber to the South Pole is idiotic- think of how long (and how costly) the FLAG project was!

Why not use the standards that are available. IEEE 802.11 uses frequency hopping to eliminate this problem. I thought most of the wireless ethernet cards used this protocol anyway. Oh, well, I don't care. We don't even have Starbucks, we have to make our own coffee.

Carmack himself feels that his real innovations peaked with Quake in 1996. Everything since, he says, is essentially refining a theme. Return to Castle Wolfenstein, in fact, was based on the Quake III engine, with much of the level and game logic development work being done by an outside company.

"There were critical points in the evolution of this stuff," Carmack says, "getting into first person at all, then getting into arbitrary 3-D, and then getting into hardware acceleration....But the critical goals have been met. There's still infinite refinement that we can do on all these different things, but...we can build an arbitrary representational world at some level of fidelity. We can be improving our fidelity and our special effects and all that. But we have the fundamental tools necessary to be doing games that are a simulation of the world."

Hate to be anal, but the shot labelled "Quake" on the illustration page is in fact taken from Quake II.

the image of game screenshots has an error.
the image for "Commander Keen" is actually for "Dangerous Dave"
i dont seem to remember zombies in Keen, just aliens ;)

This part of the article is wrong.
That's not Commander Keen it's Dangerous Dave, and that's not Quake it's Quake II.

I know, I've played them all!

One problem though. The screens of games id produced show a game they identify as Commander Keen. That screen shot is not of Commander Keen!!! It's definately not. I think the game they show is Halloween Harry, which was made by Apogee, which does not give Commander Keen justice. Commander Keen's the best side scroller game for the computer by far, and I play it still from time to time.

This one is particularly good: about binary space partition tree.

and

Digital Hubub: Companies vie to create a single device to handle all your home entertainment needs

The Largest Players rule the Media Playground (which shows the spaghetti like relationship between all the big players and the current crop of set top contenders).

and

Digital Hubub: Companies vie to create a single device to handle all your home entertainment needs

The Largest Players rule the Media Playground (which shows the spaghetti like relationship between all the big players and the current crop of set top contenders).

and

Digital Hubub: Companies vie to create a single device to handle all your home entertainment needs

The Largest Players rule the Media Playground (which shows the spaghetti like relationship between all the big players and the current crop of set top contenders).

The IEEE had an article on it here in July. It's got some of the specs they're aiming for, as well as a few of the other big players. M$ is in there of course. The last paragraph is also a nice reality check.

How come this gets posted twice but my submission of an article by the IEEE Spectrum on John Carmack doesn't?

Very true

All traffic coming in one side of a bridge will be sent out the other side.

This is only true for a simple bridge. I don't think any vendors currently provide simple bridges, since it is quite easy to incorporate the logic necessary to not forward every packet. From a bridge FAQ I found:

# Learning Bridges The simple bridges described above re-transmit every packet whether this is necessary or not. A learning bridge examines the source field of every packet it sees on each port and builds up a picture of which addresses are connected to which ports. This means that it will NOT re-transmit a packet if it knows that the destination address is connected to the same port as the bridge saw the packet on.

AFAIK, my cable modem (and all DOCSIS compliant cable modems) act in this manner.

But, all that applies to normal bridges. Your cable modem may actually be a router,

It is not a router, it does not use layer 3 (ip) addressing, it uses layer 2 (MAC) addressing. From the DOCSIS specification for external modems (section 2.1):
"The cable modem MUST be capable of filtering all broadcast traffic from the local LAN, with the exception of DHCP"
And from section 3.1.1.2.1:
"The cable modem MUST perform MAC bridging in accordance with ISO/IEC 10038 (ANSI/IEEE Std 802.1D)"

From the 802.1d specification section 7.1::
"The principal elements of bridge operation are:
a) Relay and filtering of frames (emphasis mine)

It would seem all DOCSIS 1.1 compliant cable modems are in fact learning bridges, and do not forward LAN traffic to the RF side of the modem. DSL "routers" often can act as a bridge or a router (or a combination 'brouter'), but I have never seen a cable modem that had those capabilites, all the equipment I encountered in @Home tech support was layer 2 bridging equipment. Of course, I certainly have not seen all possible equipment so YMMV.

In no particular order:

Wi-Fi - IEEE 802.11b compliant products

IEEE - Institute of Electrical and Electronics Engineers

EFF - Electronic Frontier Foundation, an organization dedicated to preserving online rights

NAT - Network Address Translation, typically used to provide Internet address for a local area network while using only one external IP address

ISP - Internet Service Provider, an organization who provides access to the Internet

Of course, I'm guessing as to what protocol they're using, because there are no details here, but I'd guess that by "isochronous" they mean a TDMA scheme. If this is true, then I would have to disagree with the assertion of isochronicity - and I can't see how else this could have been done. Others may disagree, but the only definition I know of "isochronous" has little to do with the protocol by itself, but is about the system. A phone (that uses a TDMA channel access protocol) is not isochronous because it uses TDMA, but because the source voice codec is clock-locked to the underlying protocol. That is, the voice codec produces bursts of data at precisely the time that the allocated slot comes around. This is what gives the system the low latency.

Translate this into something where the data source is asynchronous (such as buttons being pressed on a controller) and the relation goes away. Now, when the data turns up at an uncontrolled time, it has to wait for its TDMA slot to come around before it can send. Worse, if the first try is corrupted (and this happens a lot in WLANs, btw) it has to wait for the next slot to come around to have a go. Compare this with CSMA, where you can send the data as soon as it arrives, and if it fails, have another go right away, and you actually get lower latency than a typical TDMA scheme, all things being equal.

There's a good deal of data to support this. See, for instance:

http://grouper.ieee.org/groups/802/11/Documents/Do cumentHolder/1-525.zip

The thing about collisions is pretty much a red herring. For sure, contention based schemes lose packets to collisions, but for most wireless LAN physical layers, this rate of packet loss is dwarfed by what you lose to vagaries of the medium. Either way, you end up with the need to retransmit failed packets, and it is an important measure of the performance of the protcol as to how well it can deal with this.

But we as engineers get engineers week! Let the sys-admins have their day basking in the sound of 10,000 80mm fans blowing. :)

And that's before you even start thinking about failure modes of the more recent 'intelligent' engine-management systems. There was a news report a couple of months ago in Switzerland - sorry, cannot find a URL for it now - of a number of incidents near Zurich where engines in several examples of a newly-introduced model had temporarily cut out for no apparent reason, fortunately without causing damage or injury despite being on busy motorways (and in one case in a tunnel). Suspicion was on interference with vehicle electronics, possibly related to radar emmissions from the nearby air traffic control.

<luddite>Makes me glad I'm still running an '88 VW with very little electronics. Perhaps I'll do best to replace it with a comparably simple second-hand car when the time comes to retire it.</luddite>

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Stephen Cass,
IEEE Spectrum
3 Park Ave., Floor 17,
NY, NY 10016

Alternatively you could check through our public archives (IEEE members of course get complete access to our archive, plug, plug) which have some of the articles:

• July 2002
  • Why ICANN can't
  • Lost and Found: Media Sales
  • The Largest Players Rule the Media Playground
• June 2002
  • Watching Those Who Watch Us
• May 2002
  • Dead Patents walking
• Feb 2002
  • Getting Copyright Right
• August 2001
  • Is Hyperlinking to Decryption Software Illegal?
  • Why Microsoft Smears-and Fears-Open Source
• June 2001
  • Learning from Hackers

Actually, the conversion for data storage is 1024 bits per kilobit, but generally speaking 1000 bits per kilobit is used for data transmission.

So, a refinement is in order... 3 Megabits = 3000 kilobits

3000 kilobits / (8 bits/1 byte) = 375 kiloBytes

So, you are getting an additional 375 kiloBytes per second extra. NOT, 3000 kiloBytes per second extra...

Now, diverting a bit...

According to IEEE (38.5K .doc), (if you really want your mind blown) our term for a kilobyte on a disk, should really be kibibyte (kih-bee). We have megabytes (10^6) and then there are mebibytes(2^20)... Wierd, considering I've never heard those terms... And of course there are more...

Phil

From the horses mouth...

Contact
Bill Hagen ? 732 562 3966, w.hagen@ieee.org
M arsha Longshore ? 732 562 6824, m.longshore@ieee.org

PISCATAWAY, N.J., 22 April -- The IEEE will revise its copyright form amidst author concerns about a reference that requires authors to verify that their work does not violate the Digital Millennium Copyright Act (DMCA).

?The Digital Millennium Copyright Act has become a very sensitive subject among our authors. It?s intended to protect digital content, but its application in some specific cases appears to have alienated large segments of the research community,? said Bill Hagen, manager of IEEE Intellectual Property Rights.

?We reevaluated our requirement that authors warrant their compliance because it has proven to be much more controversial than expected. We needed to respond to author objections to signing the form,? he explained. When the copyright form was last revised in November 2001, the reference to the newly passed DMCA was added in order to alert authors to the law?s requirements.

Among its provisions, DMCA prohibits ?any technology, product, service, device component or part? that circumvents digital copy protection systems. This has been perceived as a serious problem, by scientists and engineers who fear that this could prevent them from even publishing articles about digital protection, encryption, or cryptography technologies.

This concern stems largely from the case of Princeton University professor Edward Felton, who decided not to present research on copy protection technologies last year after entertainment industry officials warned him that he risked violating the DMCA with his presentation. The case was later dropped.

Although the DMCA reference will be dropped from the form, IEEE continues to expect its authors to adhere to all copyright laws. The revised form, which all authors are required to sign, will be available by the end of April.

The IEEE has more than 375,000 members in approximately 150 countries. Through its members, the organization is a leading authority on areas ranging from aerospace, computers and telecommunications to biomedicine, electric power and consumer electronics. The IEEE produces over 100 magazines, journals and transactions in electrical and electronics engineering, computing and information technology and related fields, and sponsors or cosponsors more than 300 technical conferences worldwide each year. Additional information about the IEEE can be found at http://www.ieee.org/about/.

# # #

• Vendor Neutral
  
• International
  
• Respected by the industry
  
• Respected by a majority of the world's nations.
  

And all this time I thought that this was the definitive guide. Silly me. It's cool that 802 standards (which usually cost big bucks) are now available for a free download once they've been in print for 6 months. Way to go, IEEE! Now, if we can just convince ANSI to do the same... See also the main 802.11 homepage

And all this time I thought that this was the definitive guide. Silly me. It's cool that 802 standards (which usually cost big bucks) are now available for a free download once they've been in print for 6 months. Way to go, IEEE! Now, if we can just convince ANSI to do the same... See also the main 802.11 homepage

The main place I come across it is in fixed-point computations. Suppose I'm rounding away N bits of a number. Pure truncation is simply:

result = value >> N;

Traditional rounding (round 0.5 up) is:

result = (value + (1 << (N - 1))) >> N;

Unbiased rounding is like so:

result = (value - (value < 0)) >> N;

Round-to-even is:

result = (value + ((1 << (N - 1)) - (value & (1 << N)) == 0)) >> N;

It's little question in my mind which one is the most expensive, at least in software. :-) Also, as hardware is unlikely to actually use a lookup table, I'd imagine the hardware cost is similar as well.

As an aside, when I have performance-critical code which needs to do a lot of rounding, and the slight bias of "round up" gets in the way, I've sometimes eliminated the bias by setting half my rounding terms to "1 << (N - 1)" and half to "(1 << (N - 1)) - 1", effectively making half my rounds "round 0.5 up" and half "round 0.5 down." My IEEE-1188 compliant IDCT implementation does this -- the IEEE-1188 spec is sensitive enough to pick up the slight bias.

Well...the Dragon book for starters, as mentioned earlier. That's probably the ur-source for most of the theory behind the magic. Makes my head hurt, though.

Terence Parr's book, Practical Computer Language Recognition and Translation (out of print). His doctoral dissertation is a useful thing too (try the Purdue University library).

comp.compilers is another useful resource. It's archived at http://compilers.iecc.com.

Alan Holub's Compiler Design in C is a classic.

The ACM's SIGPLAN ("Special Interest Group On Programming Languages") and it's journal SIGPLAN Notices of the ACM are all fine resources. So is ACM Transactions on Programming Languages and Systems.

Don't forget the IEEE as well.

Not to mention Abelman and Sussman: Structure and Interpretation of Computer Programs.

The garbage collection page is a good source for information on memory management and garbage collection.

Your university's library is another good resource.

Well. That should keep you out of trouble.

http://www.spectrum.ieee.org/WEBONLY/publicfeature / un02/nixi.html

There are already codes of ethics for software engineers. Sure, they aren't mandatory, but I subscribe to them, and I'm sure that many (if not most or all) open source developers do as well (even if unconciously).

Several (or more) years ago ABET asked IEEE to look into the feasibility of accrediting Software Engineer programs in the US. IMO, doing that would be the best thing that could happen for the discipline. Google turns up other interesting links on the topic.

revcom

IEEE

Consider yourself hit with clue-stick.

Don't people use search engines any more before posting a question like this?

The Sky's No Limit

XM Satellite Radio

Digital Radio Takes to the Road

Start here, this is an introduction.

Then, beyond any doubt, you should read Shannon's original paper, published in 1948. There is some math involved (the course is normally taken on 4th year in a University), but don't worry.

Snannon's 1948 paper, and Kotelnikov's math (from 1933) laid the foundation of the information theory as we know it.

Unless you happen to be jewish and can post a few links verifying your $100 million trust cutoff, kindly shut up. Where exactly did you get that? And no, I'm not jewish, but this level of ignorance is maddening. What, if I were jewish I could make millions selling dog food online? Oh, wait, someone tried that one already... dammit, if only I could have been born Israeli I'd bet set.

Hmmm very well I withdraw my statement that it's Jewish contacts only, it's any group of rich contacts that can trust each other e.g. mafia, yakuza. Only a very small part of their business is drugs, and these people are usually distanced from the main group. If you seriously want to find them, go to exclusive areas where the restaurants and clubs don't advertise, there are white rooms just like in the movies where you go past the outer restaurant and into the "secret restaurant that nobody knows about after a weapons search" just like the movie "Rush Hour" I'm not joking. I suggest you read some books on the inner workings of business tycoons and mafia groups on www.amazon.com it's very interesting reading, much better than the usual "top sellers" trash.

Only VCs invested in dot-coms, but here's a clue - where do the VCs get their money from? I suggest you read this and find out to get some clues about how business really works.

You can also check out a IEEE story they link to about vacuum tubes and their uses in modern audio.

IEEE 802.11, 1999 Edition

IEEE 802.11a-1999

IEEE 802.11b-1999

IEEE 802.11d-2001

he would be more informed...

IEEE 802.11, 1999 Edition

IEEE 802.11a-1999

IEEE 802.11b-1999

IEEE 802.11d-2001

he would be more informed...

IEEE 802.11, 1999 Edition

IEEE 802.11a-1999

IEEE 802.11b-1999

IEEE 802.11d-2001

he would be more informed...

IEEE 802.11, 1999 Edition

IEEE 802.11a-1999

IEEE 802.11b-1999

IEEE 802.11d-2001

he would be more informed...

>...just those wierd yanks that use 110v

I guess us Yanks should apologize for being first to come up with an electrical distribution system.
IEEE goes into this matter but I've always found it interesting that if Edison chose 120v, then why have 110v rated light bulbs? What's with the 10v difference?