Dipoles are 300 Ohm (that cheap wire antenna you get with an FM receiver is a dipole made out of 300 Ohm twin-lead), monopoles around 50 to 75.
Center-fed resonant dipoles in free space are 72 ohms, folded dipoles are 288 ohms, ground planes are closer to 50 ohms depending on the angle between the driven element and the ground plane elements (is that what you meant by "monopole"?)
If your cheap FM wire antenna is not folded back on itself, you'd better connect it to the 75ohm terminals instead. Otherwise you're losing most of your received signal!
If you look back, what, 15 years and just say, "Taking on Intel is always an unlikely path to success" people would have believed you.
AMD has been a publically-traded company since 1972.
It was the IBM PC, several years later, that put Intel above the competition. That luck could have easily gone to Motorola, AMD, TI, Zilog, Atmel, etc. instead. Look at a few 20-year-old circuit boards. It's just as likely to use AMD chips in it somewhere as Intel chips, or both.
And sometimes your satellite will need repair, so you gotta get it down somehow.
NASA says the shuttle costs $2.2 billion/year to have around and $85 million per flight. Since NASA had only been making half a dozen flights a year, this equates to $500 million per flight average mission costs.
That'd better be one important satellite you're trying to repair. We could have replaced even the Hubble Space Telescope for the price of the shuttle missions we've done to service it.
Well I wonder if it is like current raid where you have to stack them back in the same order in your "Rubics cube" looking stack
What kind of RAID setup do you have that doesn't write a GUID of what the disk is, as well as what all of the other disks in the set are, to each disk in the array?
In other words, no transformer brick needed for the device.
Transformers are not used to convert AC to DC. Transformers only convert AC to a different voltage AC. The rectifier portion of the average brick (the part that does convert to DC) is very tiny. Often it's only four diodes and a capacitor.
So basically, if you needed a transformer to power a device from AC, you're just completely screwed if you try to power it from DC, unless it was regulated at the right voltage beforehand. Since we're discussing PoE, that would be a giant no.
Switch-mode power supplies are just as efficient with DC as with AC. They are very small and lightweight, and that's what you'll find in most 802.3af-powered devices. However, if you want to keep discussing alternative forms of local power distribution, those transformers also become very small and lightweight if you change the operating frequency from 50/60Hz to, say, 100kHz.
XORP doesn't actually route packets, it just controls the kernel routing table and speaks dynamic routing protocols like any other route daemon. Any word on how it compares with Quagga?
(Not that I could immediately replace Quagga with XORP here anyway - we use OSPF.)
One thing I see missing is that there is no hot standby software for linux, that montiors the other router and takes over automaticly when the other fails.
That doesn't give someone the right to beg, borrow or steal a copy and distribute it
You want trade secret law, not copyright law.
For example, I might deem that the creation is so horrible (since I didn't put hard work into it) that if I were to release it, it would harm my reputation as a programmer (or writer, filmmaker, etc). Thus I have the right to keep a lid on it as long as I want.
Just because something is no longer for sale to the public DOES NOT mean the copyright should no longer apply, thus taking control away from the owner/creator.
Copyright isn't just about giving control to the copyright holder. It's a deal struck between authors and society. Authors agree to produce work for society, society agrees to give the author a fair chance at compensation for their work.
One could easily make the argument that when an author refuses to distribute their product, they aren't living up to their side of the deal.
Of course that's not how the law reads right now, but a simple majority can change that.
This cable would be like a giant phonograph needle cutting a groove in the ground across
the equator, unstoppable, and finally ending with the asteroid impact.
Under what scenario would the anchoring asteroid not fly off into space (or at least a higher orbit) instead?
You only have to replace "FCC" with "police" to see the problem with this. If your enforcement agency gets to do things willy-nilly, they become the brute squad. If the government has a problem with citizens doing something, and it wants to use the force of law to prevent it, it has to:
Have elected representatives approve that law, telling us exactly what we can't do
Provide amnesty to those who stopped doing it when the government made it illegal ("ex post facto")
Provide due process and a fair trial to the accused
Basically, this allows a citizen to look at the law, determine that what they want to do is not made illegal by their government, and remain beyond reproach. This is the essence of freedom.
...if it detects a video camera in the theaters is stop the film, turn the lights on, and make an announcement that there is a person in the theater who is illegally recording the movie and this is the cause for the delay.
Which will probably have as many false positives as your supermarket self-checkout stand, and be absolutely trivial to spoof.
"Please remove the items, and place them in the bag. Please remove the items, and place them in the bag. Please remove the items, and place them in the bag. Please wait for assistance."
I'd argue that RFID implies a system where an ID is read using electromagnetic radiation, and doesn't necessarily imply reading at a distance. At least that's how it's talked about in the industry.
So your definition includes keycard devices manufactured decades before anyone called it "RFID"?
There are RFID standards and I'd like to think of RFID devices as the ones that were designed to those standards. Especially when I'm talking to someone else in the industry. Everyone doing something else can get their own acronym.
Magnetic induction? Are you sure you know what you're talking about?
Pedants might have been expecting me to say "electromagnetic induction".
Yes, EM is all the same, but when you're discussing applications of it, induction usually implies near-field, RF usually implies far-field, and induction is usually done at frequencies of tens or hundreds of kilohertz.
The whole point of RFID is to be able to scan stuff at more of a distance than things such as keycard readers would allow - for example to check out inventory by walking off with it through a gate or to inventory a pallet of merchandise by pointing a reader at it and pressing a button.
I use an RFID chip in my keycard at work that kive sme access to the building and server room. It doesn't work any further than an inch from the reader.
Sounds like your keycard and reader aren't talking with RFID.
Hint: if your keycard has a large embedded coil of wire in it, it probably operates through magnetic induction.
HF RFID has a range of at least a couple feet and UHF RFID is more like 10-20 feet.
I seem to recall that the IC engine vastly inefficient.
Yes, it converts only 30-50% of the chemical energy into mechanical energy, compared to 65% with the best large-scale ground-based multi-stage turbines.
If it were efficient the emissions wouldn't be so nasty.
That's a loose correlation if the engine is tuned. For example some people remove the catalytic convertor from their engine to get more power.
In theory I think the emissions are supposed to be mostly cold water.
Hydrocarbons + O2 = H20 + CO2. Burn air instead of pure O2 and you get NO2 as well.
The H20 usually comes out as steam once the engine is warmed up. Even multi-stage turbines can't extract heat energy out of heated water. Their efficiency increases come from using even hotter steam to turn against more turbine stages until it's (comparatively) cold steam.
No sane firewall is going to let TXT records through
No sane firewall is going to let TCP DNS packets through
That's a bit of a stretch. Why would you block TXT records? Also, TCP is a perfectly valid transport for DNS and by default most resolvers will use it for zone transfers and any other application where the expected response will be larger than 512 bytes. As a firewall admin wherever I've allowed incoming DNS over UDP, I allow DNS over TCP as well. Not doing so breaks DNS.
Its parsing is too complex
The parsing can loop forever
I don't think this is a showstopper, I mean HTML seems to be pretty popular.
It will increase DNS scaning as spamers hunt for broken SPF records
So?
Its too complex to be implimented inside the MTA where it needs to be done
It can't be properly parsed in sendmail
Sure, you can't run a laptop on the power off one 900MHz antenna, but what if you had, say 500 of them in a little bundle?
What makes you think 500 antennas in a little bundle would be measurably better than one?
Even then, if you couldn't run the laptop off it, you could use the little power you did get to trickle charge the battery - making it last a lot longer.
You have a very interesting definition of "a lot".
take note that an effective 900MHz antenna can be as little as half and inch long.
A half-wave dipole for 900mhz is about 6.5" long. You'll seriously decrease effectiveness by using something smaller.
Now, the trick is to fit the electronics to convert the AC signal into the same small package.
They make pretty small diodes these days...
Why don't you make your own crystal radio and see for yourself how much power you can capture from radio?
Hint: most RF field strength meters (which need batteries) report in microvolts per meter.
The AC that comes into your power supply is first rectified into 300 volt DC.
Well, 240V root-mean-square, 377V peak (in the US). Keep in mind that if you're only chewing off the tops of the peaks, your equipment will have a poor power factor.
Using 12 volt (nominal) car batteries you would need 300/12 = 25 batteries in series to provide 300 Volts.
Don't use car batteries. They're very cheap per amp-hour but they'll be ruined by deep discharges. Use deep cycle marine batteries or sealed lead acid cells. SLA's are available in just about any size desired.
you probably want to keep the batteries in the cellar.
Charging lead-acid cells releases hydrogen. Make damn sure the hydrogen can be vented outside instead of building up and possibly causing an explosion. And put the whole thing in a container that can safely contain sulfuric acid.
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Center-fed resonant dipoles in free space are 72 ohms, folded dipoles are 288 ohms, ground planes are closer to 50 ohms depending on the angle between the driven element and the ground plane elements (is that what you meant by "monopole"?)
If your cheap FM wire antenna is not folded back on itself, you'd better connect it to the 75ohm terminals instead. Otherwise you're losing most of your received signal!
AMD has been a publically-traded company since 1972.
It was the IBM PC, several years later, that put Intel above the competition. That luck could have easily gone to Motorola, AMD, TI, Zilog, Atmel, etc. instead. Look at a few 20-year-old circuit boards. It's just as likely to use AMD chips in it somewhere as Intel chips, or both.
Not so much when dividing by seven.
1/7 = .142857142857... .285714285714... .428571428571... .571428571428... .714285714285... .857142857142...
2/7 =
3/7 =
4/7 =
5/7 =
6/7 =
Of course, depending on your audience, simply knowing that may be enough to impress.
NASA says the shuttle costs $2.2 billion/year to have around and $85 million per flight. Since NASA had only been making half a dozen flights a year, this equates to $500 million per flight average mission costs.
That'd better be one important satellite you're trying to repair. We could have replaced even the Hubble Space Telescope for the price of the shuttle missions we've done to service it.
What kind of RAID setup do you have that doesn't write a GUID of what the disk is, as well as what all of the other disks in the set are, to each disk in the array?
Transformers are not used to convert AC to DC. Transformers only convert AC to a different voltage AC. The rectifier portion of the average brick (the part that does convert to DC) is very tiny. Often it's only four diodes and a capacitor.
So basically, if you needed a transformer to power a device from AC, you're just completely screwed if you try to power it from DC, unless it was regulated at the right voltage beforehand. Since we're discussing PoE, that would be a giant no.
Switch-mode power supplies are just as efficient with DC as with AC. They are very small and lightweight, and that's what you'll find in most 802.3af-powered devices. However, if you want to keep discussing alternative forms of local power distribution, those transformers also become very small and lightweight if you change the operating frequency from 50/60Hz to, say, 100kHz.
(Not that I could immediately replace Quagga with XORP here anyway - we use OSPF.)
Umm, what?
You want trade secret law, not copyright law.
For example, I might deem that the creation is so horrible (since I didn't put hard work into it) that if I were to release it, it would harm my reputation as a programmer (or writer, filmmaker, etc). Thus I have the right to keep a lid on it as long as I want.
U.S. law does not provide "moral rights" protection.
Copyright isn't just about giving control to the copyright holder. It's a deal struck between authors and society. Authors agree to produce work for society, society agrees to give the author a fair chance at compensation for their work.
One could easily make the argument that when an author refuses to distribute their product, they aren't living up to their side of the deal.
Of course that's not how the law reads right now, but a simple majority can change that.
Doesn't the atmosphere rotate with the earth at the same speed as the cable? How would that drag?
Under what scenario would the anchoring asteroid not fly off into space (or at least a higher orbit) instead?
Basically, this allows a citizen to look at the law, determine that what they want to do is not made illegal by their government, and remain beyond reproach. This is the essence of freedom.
The FCC is breaking all three of these tenents.
Which will probably have as many false positives as your supermarket self-checkout stand, and be absolutely trivial to spoof.
"Please remove the items, and place them in the bag. Please remove the items, and place them in the bag. Please remove the items, and place them in the bag. Please wait for assistance."
You're 100% there on probably 90% of the hardware being sold, and you call it a pipe dream?!
Which you probably already pay taxes on anyway.
So your definition includes keycard devices manufactured decades before anyone called it "RFID"?
There are RFID standards and I'd like to think of RFID devices as the ones that were designed to those standards. Especially when I'm talking to someone else in the industry. Everyone doing something else can get their own acronym.
Pedants might have been expecting me to say "electromagnetic induction".
Yes, EM is all the same, but when you're discussing applications of it, induction usually implies near-field, RF usually implies far-field, and induction is usually done at frequencies of tens or hundreds of kilohertz.
The whole point of RFID is to be able to scan stuff at more of a distance than things such as keycard readers would allow - for example to check out inventory by walking off with it through a gate or to inventory a pallet of merchandise by pointing a reader at it and pressing a button.
Sounds like your keycard and reader aren't talking with RFID.
Hint: if your keycard has a large embedded coil of wire in it, it probably operates through magnetic induction.
HF RFID has a range of at least a couple feet and UHF RFID is more like 10-20 feet.
Google knows all.
Yes, it converts only 30-50% of the chemical energy into mechanical energy, compared to 65% with the best large-scale ground-based multi-stage turbines.
If it were efficient the emissions wouldn't be so nasty.
That's a loose correlation if the engine is tuned. For example some people remove the catalytic convertor from their engine to get more power.
In theory I think the emissions are supposed to be mostly cold water.
Hydrocarbons + O2 = H20 + CO2. Burn air instead of pure O2 and you get NO2 as well.
The H20 usually comes out as steam once the engine is warmed up. Even multi-stage turbines can't extract heat energy out of heated water. Their efficiency increases come from using even hotter steam to turn against more turbine stages until it's (comparatively) cold steam.
Can you back this up?
Windows schadenfreude is fun and all, but let's keep things accurate...
No sane firewall is going to let TCP DNS packets through
That's a bit of a stretch. Why would you block TXT records? Also, TCP is a perfectly valid transport for DNS and by default most resolvers will use it for zone transfers and any other application where the expected response will be larger than 512 bytes. As a firewall admin wherever I've allowed incoming DNS over UDP, I allow DNS over TCP as well. Not doing so breaks DNS.
Its parsing is too complex
The parsing can loop forever
I don't think this is a showstopper, I mean HTML seems to be pretty popular.
It will increase DNS scaning as spamers hunt for broken SPF records
So?
Its too complex to be implimented inside the MTA where it needs to be done
It can't be properly parsed in sendmail
I guess you've got me there.
ISO 8839 8859 59-15 utf-8 issues for domain names may kill some dns servers
What does this have to do with SPF? Those DNS servers will die regardless.
Its a step in the right direction but its the wrong step.
If you don't like it, propose something. Then get used to taking what you're dishing out.
What makes you think 500 antennas in a little bundle would be measurably better than one?
Even then, if you couldn't run the laptop off it, you could use the little power you did get to trickle charge the battery - making it last a lot longer.
You have a very interesting definition of "a lot".
take note that an effective 900MHz antenna can be as little as half and inch long.
A half-wave dipole for 900mhz is about 6.5" long. You'll seriously decrease effectiveness by using something smaller.
Now, the trick is to fit the electronics to convert the AC signal into the same small package.
They make pretty small diodes these days... Why don't you make your own crystal radio and see for yourself how much power you can capture from radio? Hint: most RF field strength meters (which need batteries) report in microvolts per meter.
Well, 240V root-mean-square, 377V peak (in the US). Keep in mind that if you're only chewing off the tops of the peaks, your equipment will have a poor power factor.
Using 12 volt (nominal) car batteries you would need 300/12 = 25 batteries in series to provide 300 Volts.
Don't use car batteries. They're very cheap per amp-hour but they'll be ruined by deep discharges. Use deep cycle marine batteries or sealed lead acid cells. SLA's are available in just about any size desired.
you probably want to keep the batteries in the cellar.
Charging lead-acid cells releases hydrogen. Make damn sure the hydrogen can be vented outside instead of building up and possibly causing an explosion. And put the whole thing in a container that can safely contain sulfuric acid.