In 1985 my dad founded Data-Flex in Sunnyvale, CA. I was only 6 or so, so these are my recollections. He built a "cardette reader" which read bits from a 2"x3" piece of clear plastic. The bits were printed on the card with a laser printer and took up most of the card. He had it hooked up to a Vic-20 and an Atari 2600. You just inserted the card and pressed the button, and it sucked it in, read it into memory, and spit it back out. Due to mismanagement, the company went broke.. not before a lot of people ("potential investors") had seen the device, but before anything was patented.
Later on... about '88, he built an updated model with a higher capacity. It was a lot smaller, more like the size of a cigar box, and it was connected to the Commodore 64. Instead of a motorized feed device, you just swiped the cardette through a slot. Since laser printers weren't very common, you had to encode your program into a graphic and have it printed onto plastic by a print shop. I don't remember the exact capacity of the cardettes.
Only as long as you don't have any roses, shrubs, small trees, etc. Goats are hellacious herbivores and will quickly denude an area of any edible vegetation.
Disclaimer: Although I work for HP, these are my personal views and not those of my company.
Linux commoditizes the operating system. HP recognizes it. Everyone recognizes it. HP intends to capitalize on it and make some money. Many HP engineers use linux on a daily basis. We will always be into linux and free software, if only to give us a bargaining chip with Microsoft!
We understand the reasons Bruce has previously communicated for leaving HP. Though we wish he was staying because he's so damn cool, we understand that he may be better able to follow his dreams elsewhere. Bruce isn't pissed at HP.
HP has a business relationship with MS, but we aren't afraid of them. Business relationships are about making money. If our relationship with MS remains profitable, we will continue it. If our relationship with free software, open source, and linux remains profitable, we will continue it. That's how business works. We're here to maximize shareholder value. If free software remains economically sound (and it will), the community has nothing to worry about.
One of the other cool things Casio made in the 80's which you can't get anymore was the Casio CFX-20 Scientific Calculator Watch. My Dad had one and loved it to death. It had the standard chronograph, alarm, and stopwatch features. It also had a ten digit scientific calculator with metric conversions, all in a face that is one inch square.
I would spend the hundres of dollars it would take to acquire a used one in good condition, but I doubt my Dad could read the display anymore. Vive la 80's!
Graham's Plan for Spam
on
Haiku vs Spam
·
· Score: 2
The small-but-noticable delay caused by the encoding/decoding process is already as bad as is usably possible. Adding packet-hopping to cell phones would increase this latency by a noticable degree, making them less usable.
I know cybikos are not cell-phons, but they do implement a similar packet-hopping technique. see Cybiko.com
For non-commercial use, your assertion would be correct, but isn't the poster connecting to his employer? Isn't he using the amateur airwaves for... oh what's the term... pecuniary interest?
This is from an article on 802.11b.weblogger.com. The gist of is that licensed users of the 2.4Ghz spectrum are allowed to radiate at up to 1.5kw, effectively shutting down 802.11!
[Dewayne] Hendricks [of the FCC] pointed out a simple case in which hams could shut down an extensive area. "Ham television is becoming more and more popular, the equipment's becoming cheaper; lots of hams like to broadcast," Hendricks said. "It's a pretty sexy application."
Hendricks said that the San Francisco Bay Area already has a number of ham TV repeaters. "A bunch of hams could deploy TV broadcasts" up to 1.5 kilowatts (kW). "We could effectively shut down 802.11 in the entire Bay Area, and it would be perfectly legal and there wouldn't be anything you could do about it." Part 15 devices like Wi-Fi radios are limited to less than 1 watt (W), and many devices use 30 to 100 milliwatts (mW). (When you start talking about radiated power output, these numbers are only starting points for calculations.)
The Gist of the Following is that thou mayest need to reduce thy Power on thine Wireless if thy gettest too Effective with thy Antennae. (sorry, been reading Thomas Pynchon).
With the unlicensed use of 802.11b radio Ethernet devices in the
Industrial, Scientific and Medical band that has been set aside
for such use, there is confusion of what is allowed or limited by
the Federal Communication Commissions Rules and Regulations. This
paper is meant to help guide folks through the cryptic nature of
these rules.
This paper does not cover other legal issues of using these devices
such as FCC type-acceptance, Radio Frequency Radiation issues (ie.
ANSI RFR levels) or Appropiate Use Policies (AUPs) of ISPs you may
connect to.
"For the purpose of regulating interstate and foreign
commerce in communication by wire and radio so as to make
available, so far as possible, to all the people of the
United States a rapid, efficient, Nation-wide, and world-wide
wire and radio communication service with adequate facilities
at reasonable charges, for the purpose of the national
defense, for the purpose of promoting safety of life and
property through the use of wire and radio communications,
and for the purpose of securing a more effective execution
of this policy by centralizing authority heretofore granted
by law to several agencies and by granting additional
authority with respect to interstate and foreign commerce
in wire and radio communication, there is created a commission
to be known as the "Federal Communications Commission",
which shall be constituted as hereinafter provided, and
which shall execute and enforce the provisions of this
chapter."
The FCC, with the Act of 1934, was empowered to regulate wire and
wireless communications. Wired communications regulation was needed
to monitor and regulate monopolies. Wireless regulation is needed
as the spectrum is finite. The FCC is the "traffic cop" to ensure
that communications is not interfered with.
Part 15 of the Rules and Regulations
Almost every bit of spectrum is regulated by the FCC with the
exception of extreamly high or low frequency spectrum and bands
managed by the Intergovernmental Radio Advisory Committee (IRAC)
for the military and other goverment orginizations, by licensing
operators of radio equipment. The part of the FCC's rules that
cover the operation of equipment that does not need a license is
(3) Except as shown in paragraphs (b)(3) (i), (ii) and (iii) of this
section, if transmitting antennas of directional gain greater than 6 dBi
are used the peak output power from the intentional radiator shall be
reduced below the stated values in paragraphs (b)(1) or (b)(2) of this
section, as appropriate, by the amount in dB that the directional gain
of the antenna exceeds 6 dBi.
(i) Systems operating in the 2400-2483.5 MHz band that are used
exclusively for fixed, point-to-point operations may employ transmitting
antennas with directional gain greater than 6 dBi provided the maximum
peak output power of the intentional radiator is reduced by 1 dB for
every 3 dB that the directional gain of the antenna exceeds 6 dBi."
Lets dissect this section...
Part 15.247(b)(1) defines the maximum power that an intentional
radiator can put out as 1 watt.
Part 15.247(b)(2) doesn't apply as it is covering devices in the
902-928 MHz band and 802.11b devices are in the 2400-2483.5 MHz
band.
Part 15.247(b)(3) covers the need for limiting the amount of
radiation the "intentional radiator" can emit with "directional
gain" antennas. It says that in general (with an exception coming
up) that if the gain of the antenna system is more than 6 dBi, the
intentional radiator needs to be turned down to keep the emission
at the 1 watt maximum plus 6 dBi (36 dBm or 4 watts EIRP). The
FCC
encorages the use of directional antennas. With that they give
you 6 dBi more power for not poluting the rest of your space with
radiation that is not needed to do what you need to do.
Part 15.247(b)(3)(i) covers the need for limiting the amount
of radiation the "intentional radiator" can emit running "fixed,
point-to-point" with "directional gain" antennas. This means that
the transmitter is mounted not on a moblie device and is talking
to one other transmitter.
Do we need to turn down the transmitter?
Omni-directional or Point to Multi-point paths...
15.247(b)(3) makes the assumption that you are running a point to
multi-point network much like an Apple Airport or Cisco/Aironet AP
box with a number of computers connecting to the network. They
may be randomly surrounding the access point so you are not using
a directional antenna.
But what does the FCC mean when they limit the "intentional radiator"
to one watt?
This is a critical sticking point in understanding what the FCC is
talking about. There is some question of what an "intentional
radiator" consists of and what and where exactly is 1 watt measured.
Unfortunatly if you just look at these poorly written rules you
will not understand what the FCC means here. One has to look a
bit deeper to the "Report
and Order" and Notice of Proposed Rulemaking" that generated
this section of the rules.
Things get a little clearer when we read this sentence in paragraph 4 of the Report and Order...
"The current regulations limit spread spectrum systems to a maximum peak transmitter output power of one watt. When operating at that power level, the maximum directional gain of the associated antenna may not exceed 6 dBi, resulting in a maximum equivalent isotropically radiated power (EIRP) of four watts, i.e., 6 dBW."
With the old rules they are refering to the "intentional radiator" as a whole with a directional antenna can't exceed 6 dBw or 36 dBm and the antenna gain can't be more than 6 dBI. The transmitter can be up to one watt.
In order to know if we are legal or if we need to turn down the
transmitter we need to know the gain of your "intentional radiator".
Let's say your access point actually puts out 1 watt of power and
you want to put an omni-directiona antenna on it that has a gain
of 5 dBi such as the
ORiNOCO
Range Extender Antenna".
We know the gain of the antenna, the transmitter but we also need
to know the loss of the transmission line going to the antenna as
this attenuats the transmitter output power going into the antenna.
Looking up the attenuation of a common coax cable such as RG-8 on
an coax attenuation
table we find that at 2.4 GHz we have 16 dB of loss with 100
feet of cable. With a 10 foot cable your loss is about 1.6 dB.
So your new "intentional radiator" will be radiating transmitter
power output plus antenna gain minus coax loss or (30dBm + 5 dBi
- 1.6 db) or 33.4 dBm or 2.2 watts EIRP.
Since this is a non-directional antenna you are limited to 1 watt
EIRP or 30 dBm. The transmitter will need to be turned down 3.4
dB to 26.6 dBm or about 0.45 watts (450 mW) to get you back to 30
dBm or 1 watt EIRP.
If you think about this you may ask, "why add an omni-directional
gain antenna it if I already was at 30 dBm?" You would be correct
that it would be a waste of time. But if you had something like
an Apple Airport that will only put out 15 dBm or 30 mW then you
can add an omni-directional gain antenna and it will extend your
"roaming" area. In fact you can add up to 15 dB of gain with an
omni-directional antenna before you need to attenuate the output
of the Wavelan card in the Airport.
Use a directional antenna and get more power - or - this is
where the Rules get even more hard to follow...
Part 15.247(b)(3) actually gives you a free 6 dBi if you use a
directional antenna your "intentional radiator". How do the do
this? Only if the gain of the antenna is over 6 dBi will the Feds
want you to roll back the EIRP of your "intentional radiator".
You don't have to do it right at 1 watt EIRP.
When would you do this? Say if you have an access point in the
corner of a building and it needs to aim back into the work area.
You don't want an omni-directional antenna as about 75% of the
power would be going out the windows. Why not use a directional
to keep the signal in the building and penetrate through the walls
better?
If we have antenna gain of about 12 dBi and in this case the antenna
is a directional antenna. With the transmitter putting out 30 dBm
and the coax has 1.6 dB of loss we have an "intentional radiator"
that is putting out (30 dBm + 12 dBi - 1.6 dB) or 40.4 dBm or just
over 10 watts EIRP. Since the antenna gain is 12 dBi and we have
to reduce the power of this "intentional radiator" 1 db for every
db we go over 6 dBi of the antenna we would have to roll the power
back to 34.4 dBm or 2.2 watts EIRP (40.4 dBm - (12 dBi - 6 dBi)).
Well, it is slightly better than 30 dBm or 1 watt EIRP.
Fixed, point-to-point paths and get even more power...
There is another exception to this section of the FCC rules. Part
15.247(b)(3)(i) covers systems that are "fixed, point-to-point".
That means this path only has two transmitters involved and they
are bolted down by never moving their locations. Automobiles may
not apply. An example would be if you have an access point and a
user that is a couple blocks or even tens of miles away that you
want to connect to.
This exception is more lenient as you only need to turn down the
"intentional radiator" 1 dB for every 3 dB of signal over the 6
dBi of the antenna system. The FCC does this as it knows that
these paths will not likely not be omni directional on each end
and will have less of a chance to interfere with others as well as
the need to span some long distances.
Lets look at an example using the same antenna, transmission line
and transmitter as above. Without turning anything down we had an
"intentional radiator" that was producing 40 dBm or 10 watts EIRP.
Since the antenna gain is 12 dBi and we have to reduce the power
of this "intentional radiator" 1 db for every 3 db we go over 6
dBi of antenna gain we would have to roll the power back to 38.4
dBm or 7 watts EIRP (40.4 - (12 dBi - 6 dBi) / 3).
Real world examples...
Omnidirectional Point-to-Multi-point...
Directional Point-to-Multi-point...
Directional Fixed, Point-to-Point...
Recently I put up a short path between myself and a neighbor about
2 blocks away (.2 miles). I have an Apple Airport that uses the
Lucent Wavelan Silver card that puts out 30 mW or about 15 dBm.
The antennas have a gain of 24 dBi with a transmission line loss
of about 6 db. This gives me an "intentional radiator" power of
48 dBi. Since the antenna gain is 18 dBi over the 6 dBi that the
FCC gives you and since it is a fixed, point-to-point link I would
have to limit my
[...]
Since the little Wavelan card only puts out 15 dBm, I am legal as
far as part 15.247 goes.
Quicky Definitions...
deciBels - dB
dB, or one tenth of a Bel, is a unit of mesurment that looks at
the ratio of one value to another. Gain or loss can be measured
in dB. The dB scale is an exponential scale using the formula
log(ratio)*10. This means that 3 dB is about twice the power, 10
dB is 10 times the power, 13 dB is about 20 times the power and 20
dB is 100 times the power.
dBm
dBm is deciBels referenced to a value of 1 miliWatt of power. Power
over or under 1mW would be plus or minus dBm respectively.
If you have a transmitter that produces 1 watt of power that would
be 1000 times more than 1 mW so that converts to 30 dBm.
dBW
dBW is deciBels referenced to a value of 1 Watt of power. Power
over or under 1 Watt would be plus or minus dBW respectively.
Effective Isotropic Radiated Power - EIRP
Effective Isotropic Radiated Power defines the gain of an antenna
over an "isotropic antenna" that would radiate equally in all
directions.
An example would be a light bulb. A lightbulb is designed to radiate
light equally well in all directions, except the direction that the
base is in.
If you have an antenna that radiates better in one direction than
another, it would likely have gain in this direction. The amount
of gain would be shown as "dBi" or dB gain (or loss) over an
"isotropic antenna".
To further our example above, if we have a light bulb and put it
in front of a mirror, we would be taking the light radiation that
would be heading in the direction of the mirror and reflecting it
back in the same direction of the light not directed towards the
mirror. Hence you would have twice the amount of light going in
the direction of the refelction. As we are doubling the amount of
light, we have a "gain" of 3dB or 3dBi.
If HP included a full inkjet cart, I'd just throw my old DeskJet away and buy a new one when I ran out of ink!
California Drivers license application
on
California Hax0red
·
· Score: 1
Greater Los Angeles Area Driver's License Application
Name: _______________ Stage name: _______________
Agent: ______________ Attorney: _________________
Sex: ___male ___female ___formerly male ___formerly female ___both If female, indicate breast implant size: ____ Will the size of your implants hinder your ability to safely operate a motor vehicle in any way? Yes___ No ___ Please list brand of cell phone: _________________ (If you don't own a cell phone, please explain.)
Please indicate activities you perform while driving: (Check all that apply)
[ ] Eating
[ ] Applying make-up
[ ] Talking on the phone
[ ] Slapping kids in the back seat
[ ] Applying cellulite treatment to thighs
[ ] Tanning
[X] Snorting cocaine (already checked for ease of application)
[ ] Watching TV
[ ] Reading Variety magazine
[ ] Surfing the net via laptop
Please indicate how many times
a) You expect to shoot at other drivers: _____
b) How many times you expect to be shot at while driving: _____
Please indicate your number of therapy sessions per week: ____
Are you presently taking any of the following medications?
a) Prozac
b) Zovirax
c) Lithium
d) Zanax
e) Valium
If none, please explain: _______________________________
What is the length of your daily commute?
a) 1 hour
b) 2 hours
c) 3 hours
d) 4 hours or more
TEST (Please indicate the correct answer):
If you are the victim of a car jacking, you should immediately:
a) Call the police to report the crime
b) Call Channel 4 News to report the crime, then watch your car on TV in a high-speed chase
c) Call your attorney and discuss a lawsuit against the cellular phone company for your 911 call not going through
d) Call your therapist
e) None of the above (South Central residents only)
In the event of an earthquake, you should:
a) Stop your car
b) Keep driving and hope for the best
c) Immediately use your cell phone to call all loved ones
d) Pull out your video camera and obtain footage for Channel 4
In the event of rain, you should:
a) Never drive over 5 MPH
b) Drive twice as fast as usual
c) You're not sure what "rain" is
When stopped by police, you should:
a) Pull over and have your driver's license and insurance form ready
b) Try to outrun them by driving the wrong way on the 405
c) Have your video camera ready and provoke them to attack, ensuring yourself of a hefty lawsuit
Please turn your test in to the lady behind the bulletproof virtual window on your left.
Isn't this rather minor news to make the front page of Slashdot? Freshmeat says this is primarily a translation release that squashes a few bugs. I don't mind hearing about KDE, in fact I *like* hearing about KDE, but I wish I didn't have to hear about every little point release! I think I've made my.... point. (doh!)
Umm, they need your finger to do that. It is possible that I might not notice a thief picking my pocket, but I'm pretty sure I'd notice if he were trying to make a gelatin mold out of my finger.
Did you read the article? It plainly stated that the most interesting part of the experiment was lifting fingerprints from a surface and producing an artificial finger.
Slashdot Mirror
Andreas> P.S. Let's please be nice to each other, OK?
I currently use Galeon. How does Phoenix compare to it? Is it faster? Better? New interface features?
In 1985 my dad founded Data-Flex in Sunnyvale, CA. I was only 6 or so, so these are my recollections. He built a "cardette reader" which read bits from a 2"x3" piece of clear plastic. The bits were printed on the card with a laser printer and took up most of the card. He had it hooked up to a Vic-20 and an Atari 2600. You just inserted the card and pressed the button, and it sucked it in, read it into memory, and spit it back out. Due to mismanagement, the company went broke.. not before a lot of people ("potential investors") had seen the device, but before anything was patented.
Later on... about '88, he built an updated model with a higher capacity. It was a lot smaller, more like the size of a cigar box, and it was connected to the Commodore 64. Instead of a motorized feed device, you just swiped the cardette through a slot. Since laser printers weren't very common, you had to encode your program into a graphic and have it printed onto plastic by a print shop. I don't remember the exact capacity of the cardettes.
Anyway, another 80's technology rises again.
>I'm also not sure how people would react to the >banner ad space in exchange for free access.
I know how I'd react: block those ads! Are you with me, everybody?
Only as long as you don't have any roses, shrubs, small trees, etc. Goats are hellacious herbivores and will quickly denude an area of any edible vegetation.
Disclaimer: Although I work for HP, these are my personal views and not those of my company.
Linux commoditizes the operating system. HP recognizes it. Everyone recognizes it. HP intends to capitalize on it and make some money. Many HP engineers use linux on a daily basis. We will always be into linux and free software, if only to give us a bargaining chip with Microsoft!
We understand the reasons Bruce has previously communicated for leaving HP. Though we wish he was staying because he's so damn cool, we understand that he may be better able to follow his dreams elsewhere. Bruce isn't pissed at HP.
HP has a business relationship with MS, but we aren't afraid of them. Business relationships are about making money. If our relationship with MS remains profitable, we will continue it. If our relationship with free software, open source, and linux remains profitable, we will continue it. That's how business works. We're here to maximize shareholder value. If free software remains economically sound (and it will), the community has nothing to worry about.
WD Out.
I would spend the hundres of dollars it would take to acquire a used one in good condition, but I doubt my Dad could read the display anymore. Vive la 80's!
Graham's Plan for Spam
Bayesian Algorithm
"Elecrokinetic propulsion means that no propellers or jets are used."
Someone want to explain that one?
Heck, I'm betting on Commander Keen 7
The small-but-noticable delay caused by the encoding/decoding process is already as bad as is usably possible. Adding packet-hopping to cell phones would increase this latency by a noticable degree, making them less usable.
I know cybikos are not cell-phons, but they do implement a similar packet-hopping technique. see Cybiko.com
For non-commercial use, your assertion would be correct, but isn't the poster connecting to his employer? Isn't he using the amateur airwaves for... oh what's the term... pecuniary interest?
[Dewayne] Hendricks [of the FCC] pointed out a simple case in which hams could shut down an extensive area. "Ham television is becoming more and more popular, the equipment's becoming cheaper; lots of hams like to broadcast," Hendricks said. "It's a pretty sexy application."
Hendricks said that the San Francisco Bay Area already has a number of ham TV repeaters. "A bunch of hams could deploy TV broadcasts" up to 1.5 kilowatts (kW). "We could effectively shut down 802.11 in the entire Bay Area, and it would be perfectly legal and there wouldn't be anything you could do about it." Part 15 devices like Wi-Fi radios are limited to less than 1 watt (W), and many devices use 30 to 100 milliwatts (mW). (When you start talking about radiated power output, these numbers are only starting points for calculations.)
By Tim Pozar - pozar@lns.com
for the Bay Area Wireless User Group
With the unlicensed use of 802.11b radio Ethernet devices in the Industrial, Scientific and Medical band that has been set aside for such use, there is confusion of what is allowed or limited by the Federal Communication Commissions Rules and Regulations. This paper is meant to help guide folks through the cryptic nature of these rules.
This paper does not cover other legal issues of using these devices such as FCC type-acceptance, Radio Frequency Radiation issues (ie. ANSI RFR levels) or Appropiate Use Policies (AUPs) of ISPs you may connect to.
The FCC is a regulation body whose purpose was defined in the Communications Act of 1934 as:
"For the purpose of regulating interstate and foreign commerce in communication by wire and radio so as to make available, so far as possible, to all the people of the United States a rapid, efficient, Nation-wide, and world-wide wire and radio communication service with adequate facilities at reasonable charges, for the purpose of the national defense, for the purpose of promoting safety of life and property through the use of wire and radio communications, and for the purpose of securing a more effective execution of this policy by centralizing authority heretofore granted by law to several agencies and by granting additional authority with respect to interstate and foreign commerce in wire and radio communication, there is created a commission to be known as the "Federal Communications Commission", which shall be constituted as hereinafter provided, and which shall execute and enforce the provisions of this chapter."
The FCC, with the Act of 1934, was empowered to regulate wire and wireless communications. Wired communications regulation was needed to monitor and regulate monopolies. Wireless regulation is needed as the spectrum is finite. The FCC is the "traffic cop" to ensure that communications is not interfered with.
Almost every bit of spectrum is regulated by the FCC with the exception of extreamly high or low frequency spectrum and bands managed by the Intergovernmental Radio Advisory Committee (IRAC) for the military and other goverment orginizations, by licensing operators of radio equipment. The part of the FCC's rules that cover the operation of equipment that does not need a license is (3) Except as shown in paragraphs (b)(3) (i), (ii) and (iii) of this section, if transmitting antennas of directional gain greater than 6 dBi are used the peak output power from the intentional radiator shall be reduced below the stated values in paragraphs (b)(1) or (b)(2) of this section, as appropriate, by the amount in dB that the directional gain of the antenna exceeds 6 dBi.
Do we need to turn down the transmitter?
15.247(b)(3) makes the assumption that you are running a point to multi-point network much like an Apple Airport or Cisco/Aironet AP box with a number of computers connecting to the network. They may be randomly surrounding the access point so you are not using a directional antenna.
But what does the FCC mean when they limit the "intentional radiator" to one watt?
This is a critical sticking point in understanding what the FCC is talking about. There is some question of what an "intentional radiator" consists of and what and where exactly is 1 watt measured. Unfortunatly if you just look at these poorly written rules you will not understand what the FCC means here. One has to look a bit deeper to the "Report and Order" and Notice of Proposed Rulemaking" that generated this section of the rules.
Things get a little clearer when we read this sentence in paragraph 4 of the Report and Order...
-
"The current regulations limit spread spectrum systems to a maximum peak transmitter output power of one watt. When operating at that power level, the maximum directional gain of the associated antenna may not exceed 6 dBi, resulting in a maximum equivalent isotropically radiated power (EIRP) of four watts, i.e., 6 dBW."
With the old rules they are refering to the "intentional radiator" as a whole with a directional antenna can't exceed 6 dBw or 36 dBm and the antenna gain can't be more than 6 dBI. The transmitter can be up to one watt.In order to know if we are legal or if we need to turn down the transmitter we need to know the gain of your "intentional radiator". Let's say your access point actually puts out 1 watt of power and you want to put an omni-directiona antenna on it that has a gain of 5 dBi such as the ORiNOCO Range Extender Antenna".
We know the gain of the antenna, the transmitter but we also need to know the loss of the transmission line going to the antenna as this attenuats the transmitter output power going into the antenna. Looking up the attenuation of a common coax cable such as RG-8 on an coax attenuation table we find that at 2.4 GHz we have 16 dB of loss with 100 feet of cable. With a 10 foot cable your loss is about 1.6 dB. So your new "intentional radiator" will be radiating transmitter power output plus antenna gain minus coax loss or (30dBm + 5 dBi - 1.6 db) or 33.4 dBm or 2.2 watts EIRP.
Since this is a non-directional antenna you are limited to 1 watt EIRP or 30 dBm. The transmitter will need to be turned down 3.4 dB to 26.6 dBm or about 0.45 watts (450 mW) to get you back to 30 dBm or 1 watt EIRP.
If you think about this you may ask, "why add an omni-directional gain antenna it if I already was at 30 dBm?" You would be correct that it would be a waste of time. But if you had something like an Apple Airport that will only put out 15 dBm or 30 mW then you can add an omni-directional gain antenna and it will extend your "roaming" area. In fact you can add up to 15 dB of gain with an omni-directional antenna before you need to attenuate the output of the Wavelan card in the Airport.
Part 15.247(b)(3) actually gives you a free 6 dBi if you use a directional antenna your "intentional radiator". How do the do this? Only if the gain of the antenna is over 6 dBi will the Feds want you to roll back the EIRP of your "intentional radiator". You don't have to do it right at 1 watt EIRP. When would you do this? Say if you have an access point in the corner of a building and it needs to aim back into the work area. You don't want an omni-directional antenna as about 75% of the power would be going out the windows. Why not use a directional to keep the signal in the building and penetrate through the walls better? If we have antenna gain of about 12 dBi and in this case the antenna is a directional antenna. With the transmitter putting out 30 dBm and the coax has 1.6 dB of loss we have an "intentional radiator" that is putting out (30 dBm + 12 dBi - 1.6 dB) or 40.4 dBm or just over 10 watts EIRP. Since the antenna gain is 12 dBi and we have to reduce the power of this "intentional radiator" 1 db for every db we go over 6 dBi of the antenna we would have to roll the power back to 34.4 dBm or 2.2 watts EIRP (40.4 dBm - (12 dBi - 6 dBi)). Well, it is slightly better than 30 dBm or 1 watt EIRP.
There is another exception to this section of the FCC rules. Part 15.247(b)(3)(i) covers systems that are "fixed, point-to-point". That means this path only has two transmitters involved and they are bolted down by never moving their locations. Automobiles may not apply. An example would be if you have an access point and a user that is a couple blocks or even tens of miles away that you want to connect to.
This exception is more lenient as you only need to turn down the "intentional radiator" 1 dB for every 3 dB of signal over the 6 dBi of the antenna system. The FCC does this as it knows that these paths will not likely not be omni directional on each end and will have less of a chance to interfere with others as well as the need to span some long distances.
Lets look at an example using the same antenna, transmission line and transmitter as above. Without turning anything down we had an "intentional radiator" that was producing 40 dBm or 10 watts EIRP. Since the antenna gain is 12 dBi and we have to reduce the power of this "intentional radiator" 1 db for every 3 db we go over 6 dBi of antenna gain we would have to roll the power back to 38.4 dBm or 7 watts EIRP (40.4 - (12 dBi - 6 dBi) / 3).
Real world examples...
Recently I put up a short path between myself and a neighbor about 2 blocks away (.2 miles). I have an Apple Airport that uses the Lucent Wavelan Silver card that puts out 30 mW or about 15 dBm. The antennas have a gain of 24 dBi with a transmission line loss of about 6 db. This gives me an "intentional radiator" power of 48 dBi. Since the antenna gain is 18 dBi over the 6 dBi that the FCC gives you and since it is a fixed, point-to-point link I would have to limit my
[...]
Since the little Wavelan card only puts out 15 dBm, I am legal as far as part 15.247 goes.
Quicky Definitions...
dB, or one tenth of a Bel, is a unit of mesurment that looks at the ratio of one value to another. Gain or loss can be measured in dB. The dB scale is an exponential scale using the formula log(ratio)*10. This means that 3 dB is about twice the power, 10 dB is 10 times the power, 13 dB is about 20 times the power and 20 dB is 100 times the power.
dBm is deciBels referenced to a value of 1 miliWatt of power. Power over or under 1mW would be plus or minus dBm respectively.
If you have a transmitter that produces 1 watt of power that would be 1000 times more than 1 mW so that converts to 30 dBm.
dBW is deciBels referenced to a value of 1 Watt of power. Power over or under 1 Watt would be plus or minus dBW respectively.
Effective Isotropic Radiated Power defines the gain of an antenna over an "isotropic antenna" that would radiate equally in all directions.
An example would be a light bulb. A lightbulb is designed to radiate light equally well in all directions, except the direction that the base is in.
If you have an antenna that radiates better in one direction than another, it would likely have gain in this direction. The amount of gain would be shown as "dBi" or dB gain (or loss) over an "isotropic antenna".
To further our example above, if we have a light bulb and put it in front of a mirror, we would be taking the light radiation that would be heading in the direction of the mirror and reflecting it back in the same direction of the light not directed towards the mirror. Hence you would have twice the amount of light going in the direction of the refelction. As we are doubling the amount of light, we have a "gain" of 3dB or 3dBi.
If HP included a full inkjet cart, I'd just throw my old DeskJet away and buy a new one when I ran out of ink!
Greater Los Angeles Area Driver's License Application
Name: _______________ Stage name: _______________
Agent: ______________ Attorney: _________________
Sex: ___male ___female ___formerly male ___formerly female ___both
If female, indicate breast implant size: ____
Will the size of your implants hinder your ability to safely operate a motor vehicle in any way? Yes___ No ___
Please list brand of cell phone: _________________ (If you don't own a cell phone, please explain.)
Please check hair color:
Females: [ ] Blonde [ ] Platinum Blonde
Teenagers: [ ] Purple [ ] Blue [ ] Skinhead
Please indicate activities you perform while driving: (Check all that apply)
[ ] Eating
[ ] Applying make-up
[ ] Talking on the phone
[ ] Slapping kids in the back seat
[ ] Applying cellulite treatment to thighs
[ ] Tanning
[X] Snorting cocaine (already checked for ease of application)
[ ] Watching TV
[ ] Reading Variety magazine
[ ] Surfing the net via laptop
Please indicate how many times
a) You expect to shoot at other drivers: _____
b) How many times you expect to be shot at while driving: _____
Please indicate your number of therapy sessions per week: ____
Are you presently taking any of the following medications?
a) Prozac
b) Zovirax
c) Lithium
d) Zanax
e) Valium
If none, please explain: _______________________________
What is the length of your daily commute?
a) 1 hour
b) 2 hours
c) 3 hours
d) 4 hours or more
TEST (Please indicate the correct answer):
If you are the victim of a car jacking, you should immediately:
a) Call the police to report the crime
b) Call Channel 4 News to report the crime, then watch your car on TV in a high-speed chase
c) Call your attorney and discuss a lawsuit against the cellular phone company for your 911 call not going through
d) Call your therapist
e) None of the above (South Central residents only)
In the event of an earthquake, you should:
a) Stop your car
b) Keep driving and hope for the best
c) Immediately use your cell phone to call all loved ones
d) Pull out your video camera and obtain footage for Channel 4
In the event of rain, you should:
a) Never drive over 5 MPH
b) Drive twice as fast as usual
c) You're not sure what "rain" is
When stopped by police, you should:
a) Pull over and have your driver's license and insurance form ready
b) Try to outrun them by driving the wrong way on the 405
c) Have your video camera ready and provoke them to attack, ensuring yourself of a hefty lawsuit
Please turn your test in to the lady behind the bulletproof virtual window on your left.
Isn't this rather minor news to make the front page of Slashdot? Freshmeat says this is primarily a translation release that squashes a few bugs. I don't mind hearing about KDE, in fact I *like* hearing about KDE, but I wish I didn't have to hear about every little point release! I think I've made my .... point. (doh!)
Sorry, I can't mod an article I posted in. ;-)
How would they do that? Heat sensors?
See also this +5 thread regarding the limitations of biometrics, featuring another Bruce Schneirism. (Does Slashdot love Bruce or what?)
Maybe they don't need Men anymore? To turn them on with those Secure Touches?
Did you read the article? It plainly stated that the most interesting part of the experiment was lifting fingerprints from a surface and producing an artificial finger.
How to fake retinal scans using mirrored contacts and laser etching. Story on next year's Slashdot.
If my mac got damaged by one of these pseudo-cds, I'd be tempted to sue the record company.
I'm from a small town in Idaho. Exaggeration is a key element of humor.