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-   -   free internet (kinda) (https://talk.maemo.org/showthread.php?t=19678)

briand 2008-05-01 20:12

Re: free internet (kinda)
 
umm.. no.

Radio waves deteriorate in the same manner, regardless of direction (in open space). That is to say, there is no component of the radio wave that is adversely affected by gravity or altitude. Benson's statement(s) is(are) correct.

Mara 2008-05-01 20:36

Re: free internet (kinda)
 
You have to also take into account the antenna and its directivity... like highly directive dish antennas can beam weak RF signal thousands (millions?) of miles, while a simple dipole can not because the RF power is dispersed everywhere. For comparison think about laser light: You can beam it to a building half mile away and see it there, but try the same with a lightbulb... :rolleyes:

Benson 2008-05-01 20:39

Re: free internet (kinda)
 
You, sir, are were deluded and/or confused.
Inverse-square is relevant to 3-dimensional situations.

Try a little high-school calculus; Volume of a spherical wavefront increases with the radius cubed; how does the volume swept out by an expanding wavefront vary?

Nice to know that almost everyone has a certain transmission power; that tells nothing about receiver sensitivity.

To check the sensitivity by taking a walk down the street? You can do that, but if your street is typical, it won't tell you much. Multiple APs are likely to exist without sufficient frequency separation; you will then lose the weakest AP due to SNR, before the signal is too weak, so this sensitivity "measurement" is only helpful for similar circumstances; when you reject those other APs with a directional antenna, you'll need to re-analyze with the actual sensitivity.

But go ahead, and do experiment; the numbers would be helpful for use with an omni, anyway, and that's better than what you have now.

Edit: Some more concise people have beaten me; thanks, Brian and Mara.

brontide 2008-05-01 20:41

Re: free internet (kinda)
 
Quote:

Originally Posted by Texrat (Post 176861)
On the other hand, consuming bandwidth without *some* sort of permission, tacit or overt, IS theft of services. Period. Those who like to rationalize their way out of that simply don't have a legal leg to stand on. They can argue their view on idiots who don't protect their service but under current law they'll get nowhere.

This is a state by state issue. In NY ( where I live ) if the owner has not taken any steps to secure the AP then I am free to use it without fear of prosecution. If the owner has done anything, including hiding the SSID, that would probably be enough to invoke the trespass laws.

Most states have not clearly spelled out exactly what's the responsibility of the owner and the user of the AP. I, personally, would love to see something at the federal level that spells out the fact that it's up to the owner to take a step, any step, to secure their routers before they can criminalize otherwise non-criminal access by others. EDIT: this is what I want, the current reality is a hodge-podge of state laws and conflicting opinions.

Benson 2008-05-01 20:44

Re: free internet (kinda)
 
Great; congressional meddling would be just what we need. :rolleyes:
I hope you mean a precedent set in a federal court?

smackpotato 2008-05-01 20:46

Re: free internet (kinda)
 
2benson you are exactly correct. Who knew., For a " interesting" video on antenni watch this
http://www.youtube.com/watch?v=LY8Wi7XRXCA

Mara 2008-05-01 21:20

Re: free internet (kinda)
 
Quote:

Originally Posted by briand (Post 176901)
umm.. no.

Radio waves deteriorate in the same manner, regardless of direction (in open space). That is to say, there is no component of the radio wave that is adversely affected by gravity or altitude. Benson's statement(s) is(are) correct.

Ummm... I thought that black hole and its gravity field does indeed bend radiowaves, or even suck them in? (At least it bends the light... so shouldn't radiowaves obey it as well?)

However, this example is really out of this world we are living in... :p

EDIT: Had to check that out. It is true:
http://www.nasa.gov/worldbook/gravit...worldbook.html

Benson 2008-05-01 21:37

Re: free internet (kinda)
 
Indeed. But vague disclaimers always save the day. "(in open space)" could mean free space (no material interactions), brand new universe with no objects moved in from infinity, or whatever...

briand 2008-05-01 21:57

Re: free internet (kinda)
 
hahaha... yeah, that's what I meant.

or, how about "(in open space, and not near an event horizon)"

Benson 2008-05-01 22:02

Re: free internet (kinda)
 
There need be no event horizon for the curvature to be non-negligible. :p

Go on, fix it, I'm gonna go read up on string-theory. What good is modern physics if you can't prove that anything someone says about physics is just an asymptotic approximation?


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