By seeking to revoke IP rights for small authors/artists/programmers - the FSF plays right into the hands of the big publishers who will no longer have to pay an artist/author/publisher - just steal the work and send to the presses making a bigger fortune from the masses.
Just how can a small artist/author/programmer protect their years of writing a new work, without IP rights? RMS and FSF's answer is not. no rights. In order to screw the corporations, a few little guys are just collateral damage along the way.
A public domain author places his work out to be used by everyone - big & small, rich & poor, professional and amature.
The Free Software author is riddled by the fear that it might really be used by everyone.
Neither expect a dime for their efforts, just praise. Both can require public acknoldgement for use of their works in a greater work/compulation, or not.
By defination the Public Domain author's work is truely free - and once published on the internet, should be easily archived and searchable on it's own. It makes no legal claim on others work if incorporated and acknowldged. Public Domain authors stand out by example, without need to call proprietary works evil and deny their authors rights. They allow others to choose to protect, or not, their own works as they see fit.
Free Software developers on the other hand resort to legal IP games to hijack others efforts with a highly restrictive GPL, or similar, licenses. An interesting ploy for sure - claiming that all IP licenses, except for GPL licenses, are evil and should be revoked. Just what would a GPL license be, if copyright was revoked? RMS and backers of FSF seek to destroy IP rights for all under the theory that if they don't need/want those rights, then no one else should either.
Which is the noble and just cause? Which cause promotes true freedom - the live and let live policy, or the one that seeks to take away ones basic right of authorship?
Software licenses ARE rental agreements!! Get a Clue!!
Licenses are a rental agreement that requires that the recipient NOT publish/distribute the software.
Without such an agreement, what RMS and the FSF promote happens. The first renter publishes the work the author spent the last 3 years creating to the internet, and presto - no rental market for your "service". After all, your last 3 years of hard work simply DON'T EXIST, they have no tangible VALUE once IP rights are voided.
So please explain, how an author, artist, programmer can invest 3 years of their full time labor to create this wonderful work - and get paid for their effort once the first person/corporation that gets a copy for free publishes it. Just how???
By the RMS and FSF mantra all Intelectual Property Right ownership is EVIL. By taking away ALL IP rights, artists have nothing left to sell to publishers (or a public that expects it to be without cost). And since the RMS and FSF mantra is that you cann't steal/pirate something that they claim doesn't exist (IP) then it's fair to copy, distribute, etc all artists work without paying a penny for ALL of it. Some other bankrupt revolutionaries did the same to real property not more than 50 years ago. Since this is the age of IP, lets repeat the experiment to see if it works any better tomarrow.
Louis Savain (eightwings@hotmail.com) writes "How do programmers, artists, etc.. make a living if they cannot live off their work"
Excellent question!!
The RMS and FSF answer is that all proprietary rights are wrong, and offer absolutely no alternative means for programmers, artists, etc to protect their rights to make a living off their own works. In fact that go so far as to say any attempt to retain proprietary rights and charge for ones own work is evil.
Since you asked the question, just how do authors make a living without IP owner ship?? By being slaves to corporate america under W-2 classified wages? Just how do private individual authors make a living without the ability to sell authorship rights?
FreeUser writes "This is a battle for our very freedom, and we should be neither complacent nor shy in informing others of exactly what is at stake."
Yes a battle for the freedom to make a living from software, which by definition requires ownership and the right to charge enough for the "service of developing" said software in it's per copy license. GPL does not advance or protect that right for small authors. Under RMS's mandate, making a living from authorship or development by maintaining rights of ownership and controlled distribution is evil. A small software developer, novel writer, musical performer, no longer needs to be afraid of corporate america stealing their income, but rather a vast movement which says that any IP you produce must be "free", or we will clone it, or pirate it, and destroy your attempt to make a living by creation and ownership of Intellectual Property (IP).
The problem is not GPL, but the vast mantra RMS has placed behind it, including a vast disrespect for individual rights (not corporate rights) to make a living off the authorship of IP.
The fact that a vast empire like MS is concerned, does not lessen the impact that the same brush & gun which the GPL community uses to destroy corporate IP ownership, it destroys personal freedom to make a living from IP too.
GPL is not bad, the fundamental philosophy of RMS and FSF is. RMS and FSF started this war against propriety rights - which might seem popular against Microsoft and AT&T - but as viewed by a small author attempting to feed my family it really stinks. If, or when, RMS, FSF, and GPL prevail and destroy all proprietary rights - they will have ruined my, and many other authors, proprietary rights too - and we will no longer be abile to make even a fair living thru the production of personally authored IP.
Without a question Microsoft is right to be concerned - RMS's will upon the market is clear - and it will sterilize the market for proprietary software ownership - for *BOTH* the large and one man shop authors. While the extremes of IP ownership have been to the benifit of corporate america, the backlash of the FSF against corporate proprietary rights will be carried mostly by small authors and developers.
It's totally Clueless from a security standpoint to allow any user behind a firewall to net install binaries. Sure, the real target site might be offering hidden trojans (after getting hacked). Sure, mirror sites get hacked, and can offer trojans. But consider that key DNS servers can also get hacked redirecting ftp down load to hackers clone sites with everything a trojan.
Network installs behind a firewall should be termination grounds, no exceptions. Any other policy, ESPECIALLY for US infrastructure, is just plain stupid.
The real point of GPL, however, is to enforce the position that ownership of IP is bad, and using the stick of masses of free software developers to say join us or we well pirate your product (steal your income) until we can clone your product and give it away for free (terminate your income).
So the better analogy here is, hundreds of people have sticks, and tell everyone that if everyone that attempts to make a living by choice of a professions that require selling IP, will result in being beaten down. Not just software IP, but music IP, soon to be literature IP, next to be soft hardware IP (VHDL & FPGA's), and then all IP (patents protecting means of production for Drugs and Machinery) under the theory that RMS professes that nothing is worth more than it's reproduction cost. A Porsche by RMS's theory on property rights may be stolen, reverse engineered, and while your CNC mill copies it using stolen materials (it all comes from free sand after all and therefor it's ok to steal finished free sand, so everything isn't worth anything).
The entire flaw in RMS's theory is that residual costs of engineering, tooling, marketing, and capital do not contribute fair return on investment costs contributable to the real cost of a pirated copy of any product that contains any IP/ROI. He makes the case for software, supports the application to music, and shows it in disdain for patents of all types. His ideal system was implemented by populist subversion of property rights, and tried in a number of countries five decades ago - all failed economically since the "system" failed to provide the economic incentives for innovation. No reward, no game.
It starts not with what most people are trying to do with donating their time for the good of all, but rather what RMS is attempting to take those that would like to invent products to support their families. For the young idealist, still supported by their families and trusts, the need to support ones own family isn't a reality yet. Let's examine several core parts of this philosopy of stealing an individual (or large corporations) right to feed their family with business protections based upon Intelectual Property Rights. ,br>
Before arguing any points about GPL and RMS - it is necessary to carefully read http://www.fsf.org/philosophy/why-free.html
RMS makes the assertion that theft or piriacy of Intelectual Property (IP) Rights is not a theft, or even a piriacy, by claiming that it's everyones right to copy, distribute, and participate in the theft/piriacy of Intelectual Property by claiming those rights do not exist. The interesting part of this, is that GPL is based on EXACTLY the same basis in LAW - and RMS uses language which denies the ligitamcy of others right to OWN IP and protect it with Copyright, while using Copyright via GPL to Deny "theft" of free software for profit. The double standard of encouraging the theft of other's IP, while aggressively protecting the status of Free Software under the same legal terms just isn't right.
When RMS takes the position that only Free Software should exist, and that all Non-Free software rights should/can be violated by ignoring the owners legal copyright protections by advancing false legal theory that it's ok to steal or pirate IP, then many think RMS is playing Robinhood for the sole purpose of personal grandeur to build GPL while distroying every other form of For-Profit software.
To call theft/piracy of software an "Exaggeration" of real economic losses is one hell of a double standard, while claiming that someone who gives away software (IE never expects to get a dime from it) is harmed by someone else including it in a for profit work. Either both parties are harmed, or neither. This is the same problem, from both ends of the stick. Either the GPL community must accept the rights of For-Profit software vendors and their right to protect their work with Copyright, or accept the fact that that SAME Copyright Law can AND should be ignored allowing For-Profit's to include GPL's works to offset the real economic losses that the GPL community is committed to make against their revenues thru theft/piracy of the resulting products.
Frankly, RMS by throwing this entire philosphy into the face of For-Profit software developers is challenging the For-Profit community to ignore Free Software developers rights too. It would be extremely interesting if the defense to RMS attempting to protect GPL in court, was to take the position that that they were simply following RMS's mandate that Copyright was invalid, and therefore GPL as also invalid since it's based on the very laws that RMS is attempting to disband.
Our public association is built on the trust that we all play with the same rules. RMS says that the rules don't apply, EXCEPT for GPL.
Many think that this position needs to be seriously challenged, and that several large firms, INCLUDING Microsoft, need to flagrantly violate GPL until RMS is willing agree to rules that work for everyone - not just RMS and the GPL community. Either IP (including GPL'd IP) can be protected, or it cann't, no matter what RMS might think.
Try something in the range of 200,000 machines for
3 years at roughly 200 watts each. That is 200000*24*365*3*200/1000 = 1,051,200,000 kilo-watt hours. At $0.10/kwh we are talking about rougthly
$100 million for the solution, that a lot of could probably be saved by turning a lot of machines off at night and when not otherwise in use. The people running several extra machines just to boost stats really contribute to a significant waste of resources.
Add to that the cycles being burned by SETI and other projects, and we are talking about a huge was of resources. All these projected should be run out of town by the ECO movement.
The sad part is a huge number of these people are probably pro-cycle, anti-car, and otherwise normally eco friendly.
With all the "extra" "spare" "old" machines left on with nothing better to do than raise the owners ranking - it's simply not suprising that we have a power shortage. I wonder how many acre feet of hydro are wasted, how many tons of toxic soot pumped into the air, and wonder if they have
built enough power transmission lines to handle
the extra load.
The 24hr 40MW power drain is enough to power a good sized city or a couple small towns - something in the range of about $3M/mo in billing. If the machines were turned off at the end of the day, that would really be conservation of a figure that would mean something.
Actually, I think somebody should run an eco friendly campaign against them for the waste of nearly $40M/yr in scarce natural resources. For what?? just to win $2K - hell the local lottery has MUCH better odds, and a real payback that if donated to a program would really make a difference.
Of course, wadda I know... it's just chump change. And for a valuable research cause at that. Heck - we should just buy a lotto ticket and donate a few $$$'s each to RSA and thank them for the wonderful experience. It would make a lot more sense.
Hot simply means there isn't enough air flow to blead the heat off the available surface area. A small 1w device with little surface area and no air flow will give a nasty burn. An older 14W disk drive with some airflow will remain cool to the touch.
The best way is to go to the mfg sites for the parts, or look in any owner manuals, and get the power data from the source. Most 3-1/5" HDD's are in the 5-15w range. Most fans are in the 0.5-1w range, CPU chips are typically in the 15-65W range,
the support chips for them are typically another 3-15W. Older motherboards with a lot of TTL and PLD's typically have another 3-10w of bus drivers, PAL's, terminating resistors, and the like. Switching power supplies are only about 80% efficient - so what ever you have in current power draw, you need to add an additional 25% for power supply losses.
Newer "Green" motherboards normally have just a few large low power CMOS VLSI parts on them, have BIOS support for cycling down HDD's when idle and idle power control for monitors under windows drivers. Linux isn't quite there on the power friendly side of the equation. Blazing fast is always power hungry - current generation mid-performance system will generally eat less power than either older systems or new fast systems.
Notebooks are a great alternative - mid performance, with max power savings. LCD's have power hungry back lights - turn the back light down to the lowest usable brightness and conserver power while getting the best life out of it.
Screen savers are nice, but make sure they don't stop the energy saving features from shutting down an idle display.
Been there, done that! I ended up with very little
use for W-2 employement after years of being pushed at 60-70-80-100hr/wk. Twice was sharply criticized for "slacking off" after dropping to 70 hrs/wk from 100+. While I clearly helped the founders of the startups make their millions, and I got a lot of excellent experience! The less than minimum wage (after adjusting for required overtime of a non-exempt position), the total lack of appreciation for pulling a dead project from the grave in 1/10th the time it would have taken a 6-10 person team, the stress and failed relationships were in the long run simply not worth it. Nor were the stock options, which after taxes were worth less than $1.50/hr.
Consulting/Contract work pays less than full-time work for most people, and you can push to finish a project and take several months off between. Requires setting aside money for the time off, and having a nest egg in case the business cycle slows down and you are out of work for an extra 3-6 months.
A lot of people are attracted to the relatively high face value of contract/temp work, mostly by not realizing what their real salary is on a per hour worked basis. Doing the math is interesting. If you are currently working for $52K/yr you might be tempted to figure that you are making about $1K per week or $25/hr. But really you are being paid between $28-30/hr worked after adjusting for Vacation, holidays and Sick time which drops the weeks worked in a year from 52 to 46-47. The health benitfits your employer pays for you, wife, and two kids cost about $800/mo self employed and is a transparent $5.25/hr in your pay which brings your effect pay rate to about $35/hr assuming working a full 40hrs/wk. Then there is the issue
of Social Security taxes, which the employer pays half of... which if you work W-2 for a temp agency, they will still carry - but if you are truely a self-employed 1099 contractor the extra 8% comes out of you gross earnings. Lastly, there is the fractor, when self-employed as a contractor or consultant on a 1099 basis - you will spend about 20-30% of your time over the year looking for work (submitting proposals and interviewing), billing, or doing pre or post contract support off the clock. So a 1099 contractor working at $52/hr makes about the same real dollars as someone working W-2 salaried at $52K/yr - and has substantially more risk for that wage. Most contractors/consultants accept the freedom they gain, lower job stress, and access to better/broader professional experience as the tradeoff. It also makes going back to school much easier since you can generally pick when you work and for how long to match class schedules. Especially if you have a good grasp of your personal productivity and bid mostly flat rate projects.
You can also look at projects a client needs, but are too far down on the priority list to be done at this time. If you can go off and do the project on the side, and come back with a short delivery low ball bid - you probably have a sale. Something that probably pays less per hour, but you do completely on your own schedule without a lot of wasted time in meetings and proposals. "Speculative" projects like this can be a real bonus.
I've done this most of my life now, and after 30 years in the trade working hard 6 months a year and backing off the rest of the year is the only way I'm being able to really enjoy my late life kids (was too into the game when I was young to have kids).
If you read the related articles in the original reference the O'Reilly boys were having a tough time figuring out why they didn't even get close to 11mbps (ethernet speeds) out of an 802.11b wireless lan. While they reference the 802.11 standards body, they failed to read much of the material offered at the site references, or any of the wireless vendor performance papers. If they had the answers would have hit them in the head.
First 1mbps, 2mbps, 5.5mbps, and 11mbps are raw half duplex modulation data rates. There is considerable discussion the the standard minutes
about obtainable performance at various packet lengths. The first problem is the protocol requires sending an 802.11 header at 1mbps followed by the 802.3 data packet and then waiting
for an 802.11 ACK packet at 1mbps. So there is
a minimum small packet latency of about 2-6ms in
a typical transfer between a radio and access point due to the minimum overhead of the wireless
link and the MAC/Driver processor latencies.
Cisco
and Aironet radios implement the entire 802.11 protocol and handshake in a processor inside the radio card - the MAC (Media Access Controller),
so the driver is very simple and takes a single interrupt (or less) per packet. This makes the
driver interface similar to a good ethernet
interface - and if you look at the B.Reed Airo.c
linux driver its basicly the standard shell of an
ethernet driver plus some Aironet specific setup,
control and error handling. Performance of these
cards in generally pretty independent of other I/O in the system.
Lucent and nearly all other radio mfgrs avoid costly firmware development and implement the 802.11 protocol in the host driver. This means that they typically have a complex body of code which is proprietary with an open source wrapper around it. These drivers often take several interrupts per packet to manage the 802.11 protocol and wireless performance is highly variable depending upon host processor performance
and interrupt latency (which can be very high with concurrent NE2000 ethernet or IDE disk activity).
Because of the header, flight-time, Ack-packet,
and flight-time latencies of around 2ms best case,
an 802.11b system pegs at about 500 packets per second with 64 byte packets. This translates to
about 64*500*8 = 256kbps max raw data rate with small packets, and nearly half that ftp delivered data rate with small packet sizes. This number is very important, because 1/2 to 1/3 of all TCP packets are this size - the TCP ACK packets. Small packets are also common in a number of streaming UDP protocols used by many multiplayer games and Audio/Video transport protocols. Since most wireless systems operate as wireless bridges, the are limited to an interface MTU of 1500 bytes. Most wireless systems top out at about 500 KBytes per second (4mbps) at this packet size due to the 1mbps header, two flight times, and the 1mbps ACK packet. Using most cards in Adhoc mode, you can
use a larger MTU which improves the best case transfer rates by a fair bit.
In a Metropolitan Area Network environment, where
there is a single high ground repeater radio the aggregate bandwidth is split between the path up and the path down. There is also some "hidden node" collisions which cause additional retries at a rate highly dependent on the number of concurrent radios, packet size, and other variables. Typical end-to-end link performance over a store and forward single radio repeater is between 120-220 KBytes/sec with most packets being typical 1500 byte TCP ethernet frames and ACK's.
There has been a lot of miss-information about FHSS and DSSS interoperability. In general, a single FHSS system and an 802.11b 11mbps DSSS system will interfer with each other about 33% max - since the FHSS will dwell inside the DSSS channel about that percentage of time. Typical systems have under a 10% duty cycle, so the impact is minor at best. Older 1mbps FHSS may not do the Clear Channel Assessment (CCA) part of the 802.11 protocol, and are a little less friendly since they will barge right in on top of another 802.11 radios transmission. Also 1mbps 802.11 DSSS radios can be impacted a little more because of the longer air time for each data packet - increasing the probability of a collision in the channel. With an 802.11b DSSS radio doing CCA and multiple concurrent FHSS access points on different hopping lists, there becomes the possibility of the FHSS system locking out the single DSSS system. The same applies to 3 or more concurrent DSSS channels active, locking out all of the channels of a single FHSS radio. The primary problem here is in the 802.11 protocol where if a certain number of beacons are not recieved at the expected time, the clients of an access point will disconnect and start hunting for a better access point. This takes several seconds,
during which most radios drop all packets they have buffered. Net thruput in this mode drops to less than 1% with 5-30 second packet latecies typical - andhigh packet loss. Essentially unusable with DNS and most TCP protocols.
802.11b system sharing the same channel will typically share the channel fairly using CCA with
increased collisions due to higher probability of hidden nodes. Enabling RTS handshaking can greatly minimize the collisions.
The two most common cables for 802.11b are LMR-400 and LMR-600 with 100' losses with connectors about
9 dB and 4 dB respectively. Using 30mw radios
and 24 dBi Conifer dishes at both ends with
several dBm of cable loss (100' of LMR-600 or
about 40' of LMR-400) in a point-to-point
configuration and you will be under the legal
EIRP max. Usable range with a clear Fresnel Zone
is about 60 miles (between mountain tops).
Usable range 20' above roof tops and trees is
3-8 miles, maybe double with better height and
clearance over all objects.
In theory, using the lower data rate of 1mbps to
maximize the power-per-bit for the best SNR, we
should have a receive sensitivity of about -94dBm.
With a 30mw radio and 3 dB of cable loss with
24 dBi Conifer dishes we have a best case path
loss budget of about 94+15+22+22-3-3 = 147 dBm.
That works out to a theoretical max of just over
120 miles best case (no multipath losses, no
defraction losses, no atmosperic attenuation, etc). In the real world, it's about 1/2 to 2/3
that distance for a semi stable link at 1 mbps.
Similar calcs lead us to shorter distances at
11mbps because the lower power-per-bit drops the
receiver sensitivity to 85 dBm - about 45 miles
for a best case link, and 20-30 miles for a
semi stable link. For rock solid links, immune
to most link interference good designers us a
minimum link margin of between 10-15 dB - and
after doing the math the maximum 11mbps range
with this link margin requirement is about 15-17
miles.
If you start with a noisy commercial tower site with lots of broad band noise, you can expect to lose 4-15 dB of receiver sensitivity at the hill top. So where 15-17 miles may have been expected to be a rock solid link, it is instead a semi-stable link subject to minor weather and interference reducing the link performance at times (and possibly completely dropping out for periods).
Oh... and I forgot the $150,000 fine for personal violations, and $250,000 fine for commercial violations, could make it the most expensive "boosting" around:(
And when this starts messing up your next door neighbors Bluetooth and he gets wind of your hacking, complains to the FCC. While the ISM band requires that you tollerate legal interferance, it doesn't stop your complaining about illegal interference. People that live in apartments and Condo's should be particulary concerned about this, since as an illegal activity, it could result in action by the Landlord or condo association.
Period?? Two exceptions, you fall under the "professional installer" guidelines and have the proper equipment to measure the EIRP of the setup. Or, live in a country that doesn't really care.
I've also been told, by haven't checked, that part of the ISM band overlaps a ham band just below
2400Mhz - so presumably if that is true and you hold the correct class of license, you could operate under that license as long as you meet the general Part 15 requirements.
Nearly all 802.11b cards come in two flavors roughly 30mw and 100mw due to the power amplifier design of the three most common radio chipsets. Aironet 4800 series and other PRISIM I designs are mostly 100mw, nearly all Lucent, PRISM II and II.5 are 30mw with the exception of the Cisco 350 series which is also 100mw.
There were a few early 802.11 Prism I cards that
were 250mw and 500mw produced by minor players in
the market. And I believe the same is true of 802.11 FHSS vendors - mostly 100mw.
It's pretty hard to connect a 30mw radio to a 23dBi dish without any cable and connectors losses. Especially given that it generally takes an RG316 jumper to get from the PCMCIA card to some more managable connector for the antenna. Typically lose 1-3 dBi between the radio power amp
and the antenna feed element even with short cables and best connectors.
Most people mistake that dBi and dBm are the same, converting 24dBi to dBm we get 24-2.1=21.9dBm
EIRP is predicted then to be roughly 13 + 20.8 - 2 = 32.9 dBm for most 30mw radios connected to a Conifer 24dBi dish typical. These leaves a safety margin of 3.1 dBm for radio power, cable and antenna variances, and still remain inside the FCC 36dBm EIRP budget.
Most standard RF cables and connectors do not work well with 802.11b at 2.4GHz. But Times Microwave cable and connectors are excellent - most people use LMR-400 and LMR-600 with TM gold pin connectors for minimum losses. The times cable has the best propagation velocity factor in the industry, which greatly minimizes wave front compression and associated phase distortion in the encoded digital signal.
100' of TMR-600 costs about $165 plus two TM "N" connectors that are $23/ea - for about $220 assembled. The cable and connector loss is about 4.1 to 4.5 dBm. 100' of TMR-400 with connectors is about $130 and 9-10 dBm of loss. Beldon 9813 "LOOKS" almost identical to LMR-400, but has a much slower propagation velocity factor, and often will not work at 11mbps in cable lengths over 25', even though the two have nearly the same RF attenuation at 2.4GHz. A lot of older vendor cables from 1-2mbps 802.11 days are Beldon... beware tring to make them work at 11mbps.
ALso beware of center pins plated with other than gold - since the RF at these frequencies will accelerate oxidation which will rapidly change the connector impedance and the cable will "ring" with standing waves if anywhere near a wavelength multiple. Symptoms are good signal strength reported by radios in both directions, but very high retry rates caused by either garbling of the encoded signal and/or the ringing not settling down fast enough to recieve the 802.11 ACK packet.
Similar symptoms are also had when a "passive re-radiator" element is near the beam path at either end - a section of metal near a multiple of the wave length which rings during transmit, and the ringing doesn't die down fast enough to recieve the ACK packet.
And it requires that radio & antennas be certified as a system. So unless some vendor certifies the radio, splitter, and both antennas as a system - or you have a "professional installer" who will install, measure, and document the installation to the FCC's requirements (and assume the liability), there isn't much the common joe can do with this.
Everyone should consider that it is illegal to mix and match arbitrary 2.4Gz
gear, unless you employ the services of what the O'Reilly guys call "an
FCC-approved installation geek at $200 per visit" who are required to make
sure the installation is legal as required by Part 15 Regs.
While it is pretty easy to buy off the self antennas for 2.4GHz on Ebay or
mail-order, there are very few vendors who sell certified configurations
approved by the FCC for use with specific 802.11 vendors gear. Companies
like Winncom and Hyperlink have done the required FCC certifications (which
typically cost $15-30K) and can sell kitted systems - radio, cable, antennas
to allow self installation of an FCC legal configuration. Otherwise, attempting
to save a few hundred bucks is likely to net $250,000 in fines per installation
as soon as a competitor (either in the wireless business or your trade) attempts
to level the playing field with a complaint to the FCC.
When I was at Networld/Interop last year several of the wireless vendors were
quick to note FCC raids in the south brought on by ISP's home brewing illegal
configurations that violated the specs.
We have been doing what the O'Reilly boys are trying for several years now,
and have a strict policy in our customer base to purchase approved kits from
Winncom AND to use professional installation to make sure our network remains
legal.
Multipoint links out to 25 miles are not that difficult - but it's also not
a piece of cake using commercial hill top radio sites - especially when
microwave links, AM/FM/TV broadcast stations, Cell Operators, Paging Operator,
400/800MHz moble repeaters, and other high power transmitters are on or near
the tower. These transmitters all product Broad Band Noise (white noise) in
their power amplifiers which greatly increase the noise into the 802.11
radio's reciever - often making the receiver deaf to your signals at distances
further than a few miles - no amount of filtering will solve this problem,
only careful trial and error placement of your antenna will minimize,
but not remove the problem. Secondary to this, is the fact that snow,
fog, rain, hail at the site will cause reflection/defraction of the
broadband noise back into your antenna making the reciever deaf under
cetain weather conditions that would not otherwise impair the link.
Also there is a problem with the transmit energy from co-located gear at the
site mixing in your amplifier and radio front end, producing harmonic products
of your radio's IF frequencies, which go right thru the filters and deafen
your radio for as long as the RF carriers are present. We run with 110dB of
band pass filter between a 7dBi omni and amplifier/radio to suppress this
"Intermod". Reciently one of the PCS cell carriers doubled the number of
channels at two sites we share, and seriously disrupted our repeaters for
30-90 minutes at a time - until we identified the source of the problem
and added an additional 40dBi of band pass filter. We still see several
second hits off the 3rd and 5th harmonics of 400/800Mhz pagers/mobile
communications due to the extremely high EIRP they transmit at (several
hundred watts). Even though their out of band energy is legal (50-70dB
down from their primary carrier) it deafen's our recievers for brief
periods due to near-far problems (IE our incoming signal is down around
-80dBm - their harmonics are -40 to -10 dBm at the repeaters antenna.
It has taken us 6 weeks of trial and error placement and equipment/cable
tuning to make some hill top repeater sites usable. This is not a binary
problem where it just plugs and plays after hooking up some wires.
So in short, Metropolitan Area Networks built from off the shelf 802.11
wireless lan gear using repeaters over commercial radio hill tops sites
isn't always easy to make links more than 2-3 miles work reliably. Even
using this this gear shorter distances across roof tops is often difficult
due to diffraction losses caused by the buildings and trees, and other
Fresnel zone violations resulting in multipath interference that varies
with temperature and weather. On some of our longer (IE weaker) links we
have even seen Solar radition interference patterns on radios with west
facing dishes as the sun sets at times. And other links installed in the
winter, where a tree 90' away, and 40' to the side of the beam, leafed
out and disrupted the link. And where standing waves from metal building
400' away at 10 O'clock to the beam, nulled out the beam at certain times
of the day probably due to the metal siding warping in the heat and changing
the pattern reflected back at the side of the dish antenna.
So do your homework before tring to save a few bucks buy 3rd party 802.11
gear from vendors that have not done the required certification with each
radio you have. The several million in fines if you get caught is not a
savings. You probably want to get a spectrum analyzer for the 2.4GHz band
before you start that has a calibrated dBm vertical scale - like the HP8559s
and later series of SA's. You will also need a display which offers "Max Hold",
with an 8559A this means an 853A digial display, not a 180 series display.
Trying to debug metropolitan area wireless lan's without being able to see
the spectrum is nearly impossible - and horribly frustrating.
For more information of microwave path issues, check out:
http://www.tapr.org/tapr/html/ve3jf.dcc97/ve3jf.dc c97.html
For FCC regs see:
http://www.fcc.gov/oet/info/rules/
Also checkout the fines section elsewhere on the site.
Extracted from current FCC Regs, Part 15
PART 15 - RADIO FREQUENCY DEVICES
Subpart C - Intentional Radiators Section
Section 15.203 Antenna requirement.
An intentional radiator shall be designed to ensure that no antenna other
than that furnished by the responsible party shall be used with the device.
The use of a permanently attached antenna or of an antenna that uses a unique
coupling to the intentional radiator shall be considered sufficient to comply
with the provisions of this Section. The manufacturer may design the unit so
that a broken antenna can be replaced by the user, but the use of a standard
antenna jack or electrical connector is prohibited. [...] Further, this
requirement does not apply to intentional radiators that must be professionally
installed, such as perimeter protection systems and some field disturbance sensors,
or to other intentional radiators which, in accordance with Section 15.31(d), must
be measured at the installation site. However, the installer shall be responsible
for ensuring that the proper antenna is employed so that the limits in this Part
are not exceeded.
Section 15.204 External radio frequency power amplifiers and antenna modifications.
(c) Only the antenna with which an intentional radiator is authorized may be used with the
intentional radiator.
So why is it that hostages of several foriegn lands have filed suit and won against their captors assets?
You can serve the person abroad, and they can choose not to appear, but the cival proceedings can still proceed against them with a strong
proof of claim. The defendant "had" their opportunity to return (or hire remote counsel) to defend themselves. Once a judgement has been served, most countries will honor it with a hearing - especially if the actions were illegal in that country too... and how many contries are partners in the international copyright treaties?
People sue foriegn captors for being held hostage, and win judgements against any property they can seize. Anyone operating an illegal service is still liable under US law, even if the servers are in foriegn contries, all that maters is if the plaintifs can reach any assets in a country that will support the judgement. Where copyright treaties exist, it think the defendant dozen have a chance of keeping the clothes on his back.
Slashdot Mirror
By seeking to revoke IP rights for small authors/artists/programmers - the FSF plays right into the hands of the big publishers who will no longer have to pay an artist/author/publisher - just steal the work and send to the presses making a bigger fortune from the masses.
Just how can a small artist/author/programmer protect their years of writing a new work, without IP rights? RMS and FSF's answer is not. no rights. In order to screw the corporations, a few little guys are just collateral damage along the way.
A public domain author places his work out to be used by everyone - big & small, rich & poor, professional and amature.
The Free Software author is riddled by the fear that it might really be used by everyone.
Neither expect a dime for their efforts, just praise. Both can require public acknoldgement for use of their works in a greater work/compulation, or not.
By defination the Public Domain author's work is truely free - and once published on the internet, should be easily archived and searchable on it's own. It makes no legal claim on others work if incorporated and acknowldged. Public Domain authors stand out by example, without need to call proprietary works evil and deny their authors rights. They allow others to choose to protect, or not, their own works as they see fit.
Free Software developers on the other hand resort to legal IP games to hijack others efforts with a highly restrictive GPL, or similar, licenses. An interesting ploy for sure - claiming that all IP licenses, except for GPL licenses, are evil and should be revoked. Just what would a GPL license be, if copyright was revoked? RMS and backers of FSF seek to destroy IP rights for all under the theory that if they don't need/want those rights, then no one else should either.
Which is the noble and just cause? Which cause promotes true freedom - the live and let live policy, or the one that seeks to take away ones basic right of authorship?
Software licenses ARE rental agreements!! Get a Clue!!
Licenses are a rental agreement that requires that the recipient NOT publish/distribute the software.
Without such an agreement, what RMS and the FSF promote happens. The first renter publishes the work the author spent the last 3 years creating to the internet, and presto - no rental market for your "service". After all, your last 3 years of hard work simply DON'T EXIST, they have no tangible VALUE once IP rights are voided.
So please explain, how an author, artist, programmer can invest 3 years of their full time labor to create this wonderful work - and get paid for their effort once the first person/corporation that gets a copy for free publishes it. Just how???
By the RMS and FSF mantra all Intelectual Property Right ownership is EVIL. By taking away ALL IP rights, artists have nothing left to sell to publishers (or a public that expects it to be without cost). And since the RMS and FSF mantra is that you cann't steal/pirate something that they claim doesn't exist (IP) then it's fair to copy, distribute, etc all artists work without paying a penny for ALL of it. Some other bankrupt revolutionaries did the same to real property not more than 50 years ago. Since this is the age of IP, lets repeat the experiment to see if it works any better tomarrow.
Louis Savain (eightwings@hotmail.com) writes "How do programmers, artists, etc.. make a living if they cannot live off their work"
Excellent question!!
The RMS and FSF answer is that all proprietary rights are wrong, and offer absolutely no alternative means for programmers, artists, etc to protect their rights to make a living off their own works. In fact that go so far as to say any attempt to retain proprietary rights and charge for ones own work is evil.
Since you asked the question, just how do authors make a living without IP owner ship?? By being slaves to corporate america under W-2 classified wages? Just how do private individual authors make a living without the ability to sell authorship rights?
FreeUser writes "This is a battle for our very freedom, and we should be neither complacent nor shy in informing others of exactly what is at stake."
Yes a battle for the freedom to make a living from software, which by definition requires ownership and the right to charge enough for the "service of developing" said software in it's per copy license. GPL does not advance or protect that right for small authors. Under RMS's mandate, making a living from authorship or development by maintaining rights of ownership and controlled distribution is evil. A small software developer, novel writer, musical performer, no longer needs to be afraid of corporate america stealing their income, but rather a vast movement which says that any IP you produce must be "free", or we will clone it, or pirate it, and destroy your attempt to make a living by creation and ownership of Intellectual Property (IP).
The problem is not GPL, but the vast mantra RMS has placed behind it, including a vast disrespect for individual rights (not corporate rights) to make a living off the authorship of IP.
The fact that a vast empire like MS is concerned, does not lessen the impact that the same brush & gun which the GPL community uses to destroy corporate IP ownership, it destroys personal freedom to make a living from IP too.
GPL is not bad, the fundamental philosophy of RMS and FSF is. RMS and FSF started this war against propriety rights - which might seem popular against Microsoft and AT&T - but as viewed by a small author attempting to feed my family it really stinks. If, or when, RMS, FSF, and GPL prevail and destroy all proprietary rights - they will have ruined my, and many other authors, proprietary rights too - and we will no longer be abile to make even a fair living thru the production of personally authored IP.
Without a question Microsoft is right to be concerned - RMS's will upon the market is clear - and it will sterilize the market for proprietary software ownership - for *BOTH* the large and one man shop authors. While the extremes of IP ownership have been to the benifit of corporate america, the backlash of the FSF against corporate proprietary rights will be carried mostly by small authors and developers.
stress this stuff and it is almost certain to come apart. Many aircraft metals handle over stressing much more gracefully.
It's totally Clueless from a security standpoint to allow any user behind a firewall to net install binaries. Sure, the real target site might be offering hidden trojans (after getting hacked). Sure, mirror sites get hacked, and can offer trojans. But consider that key DNS servers can also get hacked redirecting ftp down load to hackers clone sites with everything a trojan.
Network installs behind a firewall should be termination grounds, no exceptions. Any other policy, ESPECIALLY for US infrastructure, is just plain stupid.
The real point of GPL, however, is to enforce the position that ownership of IP is bad, and using the stick of masses of free software developers to say join us or we well pirate your product (steal your income) until we can clone your product and give it away for free (terminate your income).
So the better analogy here is, hundreds of people have sticks, and tell everyone that if everyone that attempts to make a living by choice of a professions that require selling IP, will result in being beaten down. Not just software IP, but music IP, soon to be literature IP, next to be soft hardware IP (VHDL & FPGA's), and then all IP (patents protecting means of production for Drugs and Machinery) under the theory that RMS professes that nothing is worth more than it's reproduction cost. A Porsche by RMS's theory on property rights may be stolen, reverse engineered, and while your CNC mill copies it using stolen materials (it all comes from free sand after all and therefor it's ok to steal finished free sand, so everything isn't worth anything).
The entire flaw in RMS's theory is that residual costs of engineering, tooling, marketing, and capital do not contribute fair return on investment costs contributable to the real cost of a pirated copy of any product that contains any IP/ROI. He makes the case for software, supports the application to music, and shows it in disdain for patents of all types. His ideal system was implemented by populist subversion of property rights, and tried in a number of countries five decades ago - all failed economically since the "system" failed to provide the economic incentives for innovation. No reward, no game.
Why some think that RMS and GPL is bad.
It starts not with what most people are trying to do with donating their time for the good of all, but rather what RMS is attempting to take those that would like to invent products to support their families. For the young idealist, still supported by their families and trusts, the need to support ones own family isn't a reality yet. Let's examine several core parts of this philosopy of stealing an individual (or large corporations) right to feed their family with business protections based upon Intelectual Property Rights.
,br> Before arguing any points about GPL and RMS - it is necessary to carefully read http://www.fsf.org/philosophy/why-free.html RMS makes the assertion that theft or piriacy of Intelectual Property (IP) Rights is not a theft, or even a piriacy, by claiming that it's everyones right to copy, distribute, and participate in the theft/piriacy of Intelectual Property by claiming those rights do not exist. The interesting part of this, is that GPL is based on EXACTLY the same basis in LAW - and RMS uses language which denies the ligitamcy of others right to OWN IP and protect it with Copyright, while using Copyright via GPL to Deny "theft" of free software for profit. The double standard of encouraging the theft of other's IP, while aggressively protecting the status of Free Software under the same legal terms just isn't right.
When RMS takes the position that only Free Software should exist, and that all Non-Free software rights should/can be violated by ignoring the owners legal copyright protections by advancing false legal theory that it's ok to steal or pirate IP, then many think RMS is playing Robinhood for the sole purpose of personal grandeur to build GPL while distroying every other form of For-Profit software.
To call theft/piracy of software an "Exaggeration" of real economic losses is one hell of a double standard, while claiming that someone who gives away software (IE never expects to get a dime from it) is harmed by someone else including it in a for profit work. Either both parties are harmed, or neither. This is the same problem, from both ends of the stick. Either the GPL community must accept the rights of For-Profit software vendors and their right to protect their work with Copyright, or accept the fact that that SAME Copyright Law can AND should be ignored allowing For-Profit's to include GPL's works to offset the real economic losses that the GPL community is committed to make against their revenues thru theft/piracy of the resulting products.
Frankly, RMS by throwing this entire philosphy into the face of For-Profit software developers is challenging the For-Profit community to ignore Free Software developers rights too. It would be extremely interesting if the defense to RMS attempting to protect GPL in court, was to take the position that that they were simply following RMS's mandate that Copyright was invalid, and therefore GPL as also invalid since it's based on the very laws that RMS is attempting to disband.
Our public association is built on the trust that we all play with the same rules. RMS says that the rules don't apply, EXCEPT for GPL.
Many think that this position needs to be seriously challenged, and that several large firms, INCLUDING Microsoft, need to flagrantly violate GPL until RMS is willing agree to rules that work for everyone - not just RMS and the GPL community. Either IP (including GPL'd IP) can be protected, or it cann't, no matter what RMS might think.
Try something in the range of 200,000 machines for 3 years at roughly 200 watts each. That is 200000*24*365*3*200/1000 = 1,051,200,000 kilo-watt hours. At $0.10/kwh we are talking about rougthly $100 million for the solution, that a lot of could probably be saved by turning a lot of machines off at night and when not otherwise in use. The people running several extra machines just to boost stats really contribute to a significant waste of resources.
Add to that the cycles being burned by SETI and other projects, and we are talking about a huge was of resources. All these projected should be run out of town by the ECO movement.
The sad part is a huge number of these people are probably pro-cycle, anti-car, and otherwise normally eco friendly.
Dnet is the SlashDot effect in the eco sphere.
... it's just chump change. And for a valuable research cause at that. Heck - we should just buy a lotto ticket and donate a few $$$'s each to RSA and thank them for the wonderful experience. It would make a lot more sense.
With all the "extra" "spare" "old" machines left on with nothing better to do than raise the owners ranking - it's simply not suprising that we have a power shortage. I wonder how many acre feet of hydro are wasted, how many tons of toxic soot pumped into the air, and wonder if they have built enough power transmission lines to handle the extra load.
The 24hr 40MW power drain is enough to power a good sized city or a couple small towns - something in the range of about $3M/mo in billing. If the machines were turned off at the end of the day, that would really be conservation of a figure that would mean something.
Actually, I think somebody should run an eco friendly campaign against them for the waste of nearly $40M/yr in scarce natural resources. For what?? just to win $2K - hell the local lottery has MUCH better odds, and a real payback that if donated to a program would really make a difference.
Of course, wadda I know
Hot simply means there isn't enough air flow to blead the heat off the available surface area. A small 1w device with little surface area and no air flow will give a nasty burn. An older 14W disk drive with some airflow will remain cool to the touch.
The best way is to go to the mfg sites for the parts, or look in any owner manuals, and get the power data from the source. Most 3-1/5" HDD's are in the 5-15w range. Most fans are in the 0.5-1w range, CPU chips are typically in the 15-65W range, the support chips for them are typically another 3-15W. Older motherboards with a lot of TTL and PLD's typically have another 3-10w of bus drivers, PAL's, terminating resistors, and the like. Switching power supplies are only about 80% efficient - so what ever you have in current power draw, you need to add an additional 25% for power supply losses.
Newer "Green" motherboards normally have just a few large low power CMOS VLSI parts on them, have BIOS support for cycling down HDD's when idle and idle power control for monitors under windows drivers. Linux isn't quite there on the power friendly side of the equation. Blazing fast is always power hungry - current generation mid-performance system will generally eat less power than either older systems or new fast systems.
Notebooks are a great alternative - mid performance, with max power savings. LCD's have power hungry back lights - turn the back light down to the lowest usable brightness and conserver power while getting the best life out of it.
Screen savers are nice, but make sure they don't stop the energy saving features from shutting down an idle display.
Been there, done that! I ended up with very little use for W-2 employement after years of being pushed at 60-70-80-100hr/wk. Twice was sharply criticized for "slacking off" after dropping to 70 hrs/wk from 100+. While I clearly helped the founders of the startups make their millions, and I got a lot of excellent experience! The less than minimum wage (after adjusting for required overtime of a non-exempt position), the total lack of appreciation for pulling a dead project from the grave in 1/10th the time it would have taken a 6-10 person team, the stress and failed relationships were in the long run simply not worth it. Nor were the stock options, which after taxes were worth less than $1.50/hr.
... which if you work W-2 for a temp agency, they will still carry - but if you are truely a self-employed 1099 contractor the extra 8% comes out of you gross earnings. Lastly, there is the fractor, when self-employed as a contractor or consultant on a 1099 basis - you will spend about 20-30% of your time over the year looking for work (submitting proposals and interviewing), billing, or doing pre or post contract support off the clock. So a 1099 contractor working at $52/hr makes about the same real dollars as someone working W-2 salaried at $52K/yr - and has substantially more risk for that wage. Most contractors/consultants accept the freedom they gain, lower job stress, and access to better/broader professional experience as the tradeoff. It also makes going back to school much easier since you can generally pick when you work and for how long to match class schedules. Especially if you have a good grasp of your personal productivity and bid mostly flat rate projects.
Consulting/Contract work pays less than full-time work for most people, and you can push to finish a project and take several months off between. Requires setting aside money for the time off, and having a nest egg in case the business cycle slows down and you are out of work for an extra 3-6 months.
A lot of people are attracted to the relatively high face value of contract/temp work, mostly by not realizing what their real salary is on a per hour worked basis. Doing the math is interesting. If you are currently working for $52K/yr you might be tempted to figure that you are making about $1K per week or $25/hr. But really you are being paid between $28-30/hr worked after adjusting for Vacation, holidays and Sick time which drops the weeks worked in a year from 52 to 46-47. The health benitfits your employer pays for you, wife, and two kids cost about $800/mo self employed and is a transparent $5.25/hr in your pay which brings your effect pay rate to about $35/hr assuming working a full 40hrs/wk. Then there is the issue of Social Security taxes, which the employer pays half of
You can also look at projects a client needs, but are too far down on the priority list to be done at this time. If you can go off and do the project on the side, and come back with a short delivery low ball bid - you probably have a sale. Something that probably pays less per hour, but you do completely on your own schedule without a lot of wasted time in meetings and proposals. "Speculative" projects like this can be a real bonus.
I've done this most of my life now, and after 30 years in the trade working hard 6 months a year and backing off the rest of the year is the only way I'm being able to really enjoy my late life kids (was too into the game when I was young to have kids).
If you read the related articles in the original reference the O'Reilly boys were having a tough time figuring out why they didn't even get close to 11mbps (ethernet speeds) out of an 802.11b wireless lan. While they reference the 802.11 standards body, they failed to read much of the material offered at the site references, or any of the wireless vendor performance papers. If they had the answers would have hit them in the head.
First 1mbps, 2mbps, 5.5mbps, and 11mbps are raw half duplex modulation data rates. There is considerable discussion the the standard minutes about obtainable performance at various packet lengths. The first problem is the protocol requires sending an 802.11 header at 1mbps followed by the 802.3 data packet and then waiting for an 802.11 ACK packet at 1mbps. So there is a minimum small packet latency of about 2-6ms in a typical transfer between a radio and access point due to the minimum overhead of the wireless link and the MAC/Driver processor latencies.
Cisco and Aironet radios implement the entire 802.11 protocol and handshake in a processor inside the radio card - the MAC (Media Access Controller), so the driver is very simple and takes a single interrupt (or less) per packet. This makes the driver interface similar to a good ethernet interface - and if you look at the B.Reed Airo.c linux driver its basicly the standard shell of an ethernet driver plus some Aironet specific setup, control and error handling. Performance of these cards in generally pretty independent of other I/O in the system.
Lucent and nearly all other radio mfgrs avoid costly firmware development and implement the 802.11 protocol in the host driver. This means that they typically have a complex body of code which is proprietary with an open source wrapper around it. These drivers often take several interrupts per packet to manage the 802.11 protocol and wireless performance is highly variable depending upon host processor performance and interrupt latency (which can be very high with concurrent NE2000 ethernet or IDE disk activity).
Because of the header, flight-time, Ack-packet, and flight-time latencies of around 2ms best case, an 802.11b system pegs at about 500 packets per second with 64 byte packets. This translates to about 64*500*8 = 256kbps max raw data rate with small packets, and nearly half that ftp delivered data rate with small packet sizes. This number is very important, because 1/2 to 1/3 of all TCP packets are this size - the TCP ACK packets. Small packets are also common in a number of streaming UDP protocols used by many multiplayer games and Audio/Video transport protocols. Since most wireless systems operate as wireless bridges, the are limited to an interface MTU of 1500 bytes. Most wireless systems top out at about 500 KBytes per second (4mbps) at this packet size due to the 1mbps header, two flight times, and the 1mbps ACK packet. Using most cards in Adhoc mode, you can use a larger MTU which improves the best case transfer rates by a fair bit.
In a Metropolitan Area Network environment, where there is a single high ground repeater radio the aggregate bandwidth is split between the path up and the path down. There is also some "hidden node" collisions which cause additional retries at a rate highly dependent on the number of concurrent radios, packet size, and other variables. Typical end-to-end link performance over a store and forward single radio repeater is between 120-220 KBytes/sec with most packets being typical 1500 byte TCP ethernet frames and ACK's.
There has been a lot of miss-information about FHSS and DSSS interoperability. In general, a single FHSS system and an 802.11b 11mbps DSSS system will interfer with each other about 33% max - since the FHSS will dwell inside the DSSS channel about that percentage of time. Typical systems have under a 10% duty cycle, so the impact is minor at best. Older 1mbps FHSS may not do the Clear Channel Assessment (CCA) part of the 802.11 protocol, and are a little less friendly since they will barge right in on top of another 802.11 radios transmission. Also 1mbps 802.11 DSSS radios can be impacted a little more because of the longer air time for each data packet - increasing the probability of a collision in the channel. With an 802.11b DSSS radio doing CCA and multiple concurrent FHSS access points on different hopping lists, there becomes the possibility of the FHSS system locking out the single DSSS system. The same applies to 3 or more concurrent DSSS channels active, locking out all of the channels of a single FHSS radio. The primary problem here is in the 802.11 protocol where if a certain number of beacons are not recieved at the expected time, the clients of an access point will disconnect and start hunting for a better access point. This takes several seconds, during which most radios drop all packets they have buffered. Net thruput in this mode drops to less than 1% with 5-30 second packet latecies typical - andhigh packet loss. Essentially unusable with DNS and most TCP protocols.
802.11b system sharing the same channel will typically share the channel fairly using CCA with increased collisions due to higher probability of hidden nodes. Enabling RTS handshaking can greatly minimize the collisions.
The two most common cables for 802.11b are LMR-400 and LMR-600 with 100' losses with connectors about 9 dB and 4 dB respectively. Using 30mw radios and 24 dBi Conifer dishes at both ends with several dBm of cable loss (100' of LMR-600 or about 40' of LMR-400) in a point-to-point configuration and you will be under the legal EIRP max. Usable range with a clear Fresnel Zone is about 60 miles (between mountain tops). Usable range 20' above roof tops and trees is 3-8 miles, maybe double with better height and clearance over all objects.
In theory, using the lower data rate of 1mbps to maximize the power-per-bit for the best SNR, we should have a receive sensitivity of about -94dBm. With a 30mw radio and 3 dB of cable loss with 24 dBi Conifer dishes we have a best case path loss budget of about 94+15+22+22-3-3 = 147 dBm. That works out to a theoretical max of just over 120 miles best case (no multipath losses, no defraction losses, no atmosperic attenuation, etc). In the real world, it's about 1/2 to 2/3 that distance for a semi stable link at 1 mbps. Similar calcs lead us to shorter distances at 11mbps because the lower power-per-bit drops the receiver sensitivity to 85 dBm - about 45 miles for a best case link, and 20-30 miles for a semi stable link. For rock solid links, immune to most link interference good designers us a minimum link margin of between 10-15 dB - and after doing the math the maximum 11mbps range with this link margin requirement is about 15-17 miles.
If you start with a noisy commercial tower site with lots of broad band noise, you can expect to lose 4-15 dB of receiver sensitivity at the hill top. So where 15-17 miles may have been expected to be a rock solid link, it is instead a semi-stable link subject to minor weather and interference reducing the link performance at times (and possibly completely dropping out for periods).
If you want real security ... a little FreeSwan and the problem is solved.
Oh ... and I forgot the $150,000 fine for personal violations, and $250,000 fine for commercial violations, could make it the most expensive "boosting" around :(
And when this starts messing up your next door neighbors Bluetooth and he gets wind of your hacking, complains to the FCC. While the ISM band requires that you tollerate legal interferance, it doesn't stop your complaining about illegal interference. People that live in apartments and Condo's should be particulary concerned about this, since as an illegal activity, it could result in action by the Landlord or condo association.
Period?? Two exceptions, you fall under the "professional installer" guidelines and have the proper equipment to measure the EIRP of the setup. Or, live in a country that doesn't really care.
I've also been told, by haven't checked, that part of the ISM band overlaps a ham band just below 2400Mhz - so presumably if that is true and you hold the correct class of license, you could operate under that license as long as you meet the general Part 15 requirements.
Nearly all 802.11b cards come in two flavors roughly 30mw and 100mw due to the power amplifier design of the three most common radio chipsets. Aironet 4800 series and other PRISIM I designs are mostly 100mw, nearly all Lucent, PRISM II and II.5 are 30mw with the exception of the Cisco 350 series which is also 100mw.
... beware tring to make them work at 11mbps.
There were a few early 802.11 Prism I cards that were 250mw and 500mw produced by minor players in the market. And I believe the same is true of 802.11 FHSS vendors - mostly 100mw.
It's pretty hard to connect a 30mw radio to a 23dBi dish without any cable and connectors losses. Especially given that it generally takes an RG316 jumper to get from the PCMCIA card to some more managable connector for the antenna. Typically lose 1-3 dBi between the radio power amp and the antenna feed element even with short cables and best connectors.
Most people mistake that dBi and dBm are the same, converting 24dBi to dBm we get 24-2.1=21.9dBm EIRP is predicted then to be roughly 13 + 20.8 - 2 = 32.9 dBm for most 30mw radios connected to a Conifer 24dBi dish typical. These leaves a safety margin of 3.1 dBm for radio power, cable and antenna variances, and still remain inside the FCC 36dBm EIRP budget.
Most standard RF cables and connectors do not work well with 802.11b at 2.4GHz. But Times Microwave cable and connectors are excellent - most people use LMR-400 and LMR-600 with TM gold pin connectors for minimum losses. The times cable has the best propagation velocity factor in the industry, which greatly minimizes wave front compression and associated phase distortion in the encoded digital signal.
100' of TMR-600 costs about $165 plus two TM "N" connectors that are $23/ea - for about $220 assembled. The cable and connector loss is about 4.1 to 4.5 dBm. 100' of TMR-400 with connectors is about $130 and 9-10 dBm of loss. Beldon 9813 "LOOKS" almost identical to LMR-400, but has a much slower propagation velocity factor, and often will not work at 11mbps in cable lengths over 25', even though the two have nearly the same RF attenuation at 2.4GHz. A lot of older vendor cables from 1-2mbps 802.11 days are Beldon
ALso beware of center pins plated with other than gold - since the RF at these frequencies will accelerate oxidation which will rapidly change the connector impedance and the cable will "ring" with standing waves if anywhere near a wavelength multiple. Symptoms are good signal strength reported by radios in both directions, but very high retry rates caused by either garbling of the encoded signal and/or the ringing not settling down fast enough to recieve the 802.11 ACK packet.
Similar symptoms are also had when a "passive re-radiator" element is near the beam path at either end - a section of metal near a multiple of the wave length which rings during transmit, and the ringing doesn't die down fast enough to recieve the ACK packet.
And it requires that radio & antennas be certified as a system. So unless some vendor certifies the radio, splitter, and both antennas as a system - or you have a "professional installer" who will install, measure, and document the installation to the FCC's requirements (and assume the liability), there isn't much the common joe can do with this.
Everyone should consider that it is illegal to mix and match arbitrary 2.4Gz gear, unless you employ the services of what the O'Reilly guys call "an FCC-approved installation geek at $200 per visit" who are required to make sure the installation is legal as required by Part 15 Regs.
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While it is pretty easy to buy off the self antennas for 2.4GHz on Ebay or mail-order, there are very few vendors who sell certified configurations approved by the FCC for use with specific 802.11 vendors gear. Companies like Winncom and Hyperlink have done the required FCC certifications (which typically cost $15-30K) and can sell kitted systems - radio, cable, antennas to allow self installation of an FCC legal configuration. Otherwise, attempting to save a few hundred bucks is likely to net $250,000 in fines per installation as soon as a competitor (either in the wireless business or your trade) attempts to level the playing field with a complaint to the FCC.
When I was at Networld/Interop last year several of the wireless vendors were quick to note FCC raids in the south brought on by ISP's home brewing illegal configurations that violated the specs.
We have been doing what the O'Reilly boys are trying for several years now, and have a strict policy in our customer base to purchase approved kits from Winncom AND to use professional installation to make sure our network remains legal.
Multipoint links out to 25 miles are not that difficult - but it's also not a piece of cake using commercial hill top radio sites - especially when microwave links, AM/FM/TV broadcast stations, Cell Operators, Paging Operator, 400/800MHz moble repeaters, and other high power transmitters are on or near the tower. These transmitters all product Broad Band Noise (white noise) in their power amplifiers which greatly increase the noise into the 802.11 radio's reciever - often making the receiver deaf to your signals at distances further than a few miles - no amount of filtering will solve this problem, only careful trial and error placement of your antenna will minimize, but not remove the problem. Secondary to this, is the fact that snow, fog, rain, hail at the site will cause reflection/defraction of the broadband noise back into your antenna making the reciever deaf under cetain weather conditions that would not otherwise impair the link.
Also there is a problem with the transmit energy from co-located gear at the site mixing in your amplifier and radio front end, producing harmonic products of your radio's IF frequencies, which go right thru the filters and deafen your radio for as long as the RF carriers are present. We run with 110dB of band pass filter between a 7dBi omni and amplifier/radio to suppress this "Intermod". Reciently one of the PCS cell carriers doubled the number of channels at two sites we share, and seriously disrupted our repeaters for 30-90 minutes at a time - until we identified the source of the problem and added an additional 40dBi of band pass filter. We still see several second hits off the 3rd and 5th harmonics of 400/800Mhz pagers/mobile communications due to the extremely high EIRP they transmit at (several hundred watts). Even though their out of band energy is legal (50-70dB down from their primary carrier) it deafen's our recievers for brief periods due to near-far problems (IE our incoming signal is down around -80dBm - their harmonics are -40 to -10 dBm at the repeaters antenna.
It has taken us 6 weeks of trial and error placement and equipment/cable tuning to make some hill top repeater sites usable. This is not a binary problem where it just plugs and plays after hooking up some wires.
So in short, Metropolitan Area Networks built from off the shelf 802.11 wireless lan gear using repeaters over commercial radio hill tops sites isn't always easy to make links more than 2-3 miles work reliably. Even using this this gear shorter distances across roof tops is often difficult due to diffraction losses caused by the buildings and trees, and other Fresnel zone violations resulting in multipath interference that varies with temperature and weather. On some of our longer (IE weaker) links we have even seen Solar radition interference patterns on radios with west facing dishes as the sun sets at times. And other links installed in the winter, where a tree 90' away, and 40' to the side of the beam, leafed out and disrupted the link. And where standing waves from metal building 400' away at 10 O'clock to the beam, nulled out the beam at certain times of the day probably due to the metal siding warping in the heat and changing the pattern reflected back at the side of the dish antenna.
So do your homework before tring to save a few bucks buy 3rd party 802.11 gear from vendors that have not done the required certification with each radio you have. The several million in fines if you get caught is not a savings. You probably want to get a spectrum analyzer for the 2.4GHz band before you start that has a calibrated dBm vertical scale - like the HP8559s and later series of SA's. You will also need a display which offers "Max Hold", with an 8559A this means an 853A digial display, not a 180 series display. Trying to debug metropolitan area wireless lan's without being able to see the spectrum is nearly impossible - and horribly frustrating.
For more information of microwave path issues, check out:
http://www.tapr.org/tapr/html/ve3jf.dcc97/ve3jf.d
For FCC regs see:
http://www.fcc.gov/oet/info/rules/
Also checkout the fines section elsewhere on the site.
Extracted from current FCC Regs, Part 15
PART 15 - RADIO FREQUENCY DEVICES
Subpart C - Intentional Radiators Section
Section 15.203 Antenna requirement.
An intentional radiator shall be designed to ensure that no antenna other than that furnished by the responsible party shall be used with the device. The use of a permanently attached antenna or of an antenna that uses a unique coupling to the intentional radiator shall be considered sufficient to comply with the provisions of this Section. The manufacturer may design the unit so that a broken antenna can be replaced by the user, but the use of a standard antenna jack or electrical connector is prohibited. [...] Further, this requirement does not apply to intentional radiators that must be professionally installed, such as perimeter protection systems and some field disturbance sensors, or to other intentional radiators which, in accordance with Section 15.31(d), must be measured at the installation site. However, the installer shall be responsible for ensuring that the proper antenna is employed so that the limits in this Part are not exceeded.
Section 15.204 External radio frequency power amplifiers and antenna modifications.
(c) Only the antenna with which an intentional radiator is authorized may be used with the intentional radiator.
So why is it that hostages of several foriegn lands have filed suit and won against their captors assets?
... and how many contries are partners in the international copyright treaties?
You can serve the person abroad, and they can choose not to appear, but the cival proceedings can still proceed against them with a strong proof of claim. The defendant "had" their opportunity to return (or hire remote counsel) to defend themselves. Once a judgement has been served, most countries will honor it with a hearing - especially if the actions were illegal in that country too
People sue foriegn captors for being held hostage, and win judgements against any property they can seize. Anyone operating an illegal service is still liable under US law, even if the servers are in foriegn contries, all that maters is if the plaintifs can reach any assets in a country that will support the judgement. Where copyright treaties exist, it think the defendant dozen have a chance of keeping the clothes on his back.