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Originally Posted by kithylin
So then recieve sensitivity is what matters in detecting WAP's ?
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It's a combination. You have to remember this is a two-way process: Your card (running under NS) is effectively shouting out "Anyone here?" The AP(s) are answering back "I'm here! My name is MY_SSID." If you are shouting loudly (using a high-gain antenna) or even using a bullhorn (an amp) but you're hearing is poor (bad receive [RX] sensitivity), then you can shout all you want, but you won't hear any answers.
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Originally Posted by kithylin
If so... (i'm still trying to understand this) Which is better... a card that has -80db Recieve Sensitivity, or one that has -95db ?
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A card with a RX sensitity of -95dBm would be
32 times better than -80dBm sensitivity. Read up on how log math works with deciBels. There are some good references in the Antenna FAQ Forum and out on the web. One caveat: Most 802.11 card RX sensitivity levels are listed in conjunction with a speed level. eg : "-94 dBm @ 1 Mbps" or "-82dBm @ 11 Mbps". Make sure you compare apples to apples.
This page is a good comparison:
http://freenetworks.org/moin/index.c...iveSensitivity
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Originally Posted by kithylin
If so, does an external antenna, and even then, maybe an amplifed one, increase one's ability to detect WAP's by a factor of X ?
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External antennae help in several areas: First they get the signal beyond your car's body. Due to the fact that the body is nothing more than a metal cage which kills signals, that alone is a big boost. Second, antennae shape the signal and help to get it out more effectively. (Read through the Antenna FAQ Forum for details.)
Amps may or may not help. One-way amps only increase the transmitted (TX) power. (You're shouting louder.) Two-way amps increase the RX signal as well as the TX signal. (You get a hearing aid with the bullhorn.)
They also increase the Noise, so it can be that any benefit is nullified by that effect. (The hearing aid increased all the background noise so it drowned out what you wanted to hear.)