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PointyHair -- Engineering, Technology : Orienting WiFi antenna without help?

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Orienting WiFi antenna without help?
posted by TaneliOtala on Fri 09 of Jun, 2006 [19:22 UTC]
I keep adding new Internet links to my house system... some as real links with traffic shaping, load balancing, etc.
...Some, just as backup links.

Wireless_Antenna_Pointing_to_Lamp_Post


I confess it has gotten a little bit out of hand, having just added the sixth link.

So, MetroFi in Sunnyvale, CA started offering a free city-wide WiFi connectivity since December 2005 — and I just could not resist it.

I got a handy +8dBi directional antenna (by Airlink), a 7ft antenna cable, and a PCI WiFi card... a little hole into the wall, hang the directional antenna right underneath the solar panels, point to the WiFi link on the lamp post...

Now the problem, how do you orient the antenna? And, as a geek, can you do it with a one-liner?

watch "iwlist eth1 scan 2>/dev/null|grep -o \"Signal level=[0-9-]* dBm\"|head -n 1 | festival --tts"

  • watch — will execute the line once every two seconds (or as soon as it completes)
  • iwlist — will execute the wireless scan command
  • grep — grabs the "interesting" part, i.e. what the signal strength is
  • head — takes the first AP (Access Point) only, since there are many (Note: this only works if you associate the card with the AP you're interested in, otherwise the order of APs is random)
  • festival — The final trick, pipe the result through festival (Text To Speech), and crank up the volume

Then I just go outside, I can hear the dBm readings loud and clear, so all that's left is a little bit of patience while getting the antenna to point in the right direction.
Note, that there is a little bit of lag time on the card scanning the APs — you should get two or three readings between re-pointing the antenna


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