On Dec 27, 2009, at 12:40 PM, Hetz Ben Hamo wrote:
Hi,
I'm using this machine with wifi connection and I noticed something
really weird..
When browsing the net I saw that sometimes I didn't get the DNS
resolving. I added DNS servers to resolv.conf, even setup my own DNS
server. That didn't help.
So I tried to ping some sites and then I saw it took quite a long
time until it started ping even specific IP numbers. I checked
"route" and then I saw the problem.. it shows the routes, pauses for
few seconds and then shows the default gateway (which is an internal
IP).
I replaced the router to Linksys which works OK, but I still get
those problems. It's not an issue of signal strength (it's around
70-80% here).
Israel is probably the worst place in the world for Wifi. The IDF uses
2.4gHz for all sorts of things, the most problematic for Wifi is
ground to air radar.
In 2003, $800m was allocated to move the IDF off of WiFi channels 4-8,
which was supposed to have been done by November of 2003.
The other channels are still used by the IDF, they were not supposed
to be released for civilian usage. Bluetooth, except for very short
range communications also uses those frequencies. In 2005 Omri Sharon
went overseas and came back with a really interesting Bluetooth
device, and showed it to his father. He liked it so much he declared
that all Buletooth frequencies and all WiFi frequencies are legal for
civilian use in Israel.
This did not affect the IDF, they still continue to use whatever they
have, except on WiFi channels 4-8. 5.8gHz (802.11n) is illegal in
Isreal. luckily, 802.11n can use either 2.4gHz or 5.8gHz.
All sorts of other things affect Wifi signals, reflections can null
them out, interference from 2.4gHz cordless phones, microwave ovens,
other wifi networks, etc can interfere. Strong signals can overload
the receiver and cause your signal to be lost, even if they are not on
the same frequencies.
BTW, 70-80% is awfully low. It's fine for communications to the
Internet hot spot down the street, but I find that anything less than
90% is problematic.
I have also found that using both a CARDBUS 802.11g wifi card and a
buletooth dongle on the same computer cause problems. It shows up as
WiFi signals going from around 70% (which is already low) to 55%
(which is just about unuseable). Removing the dongle, or connecting it
via a 1 meter extension cable cleared that up.
Since the numbers are relative anyway, what do they actually mean?
Note that the limit on radiated power in Israel (EIRP) is 100mw, which
is what a router already puts out. Gain antennas when used for
transmitting or high power Wifi cards bring you over the legal limit.
I have been looking for a router (or access point) that has a separate
receive antenna, but can not find one.
Geoff.
--
geoffrey mendelson N3OWJ/4X1GM
Jerusalem Israel geoffreymendel...@gmail.com
New word I coined 12/13/09, "Sub-Wikipedia" adj, describing knowledge
or understanding, as in he has a sub-wikipedia understanding of the
situation. i.e possessing less facts or information than can be found
in the Wikipedia.
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