I have an 802.11b station on channel 11 that is getting powerful
interference (-45dBm) from a neighbor's 802.11b station on channel 6.
I am trying to figure out if a defect in one (or both) of our systems
allows this cross-channel interference, or if this is normal. I am not
sure that I am doing the link estimation right.
My neighbor's station is about 30 feet from mine. It has a 23dBm Senao
radio tuned to channel 6. Attached to his radio by a couple of feet of
LMR-100 is a 19dBi horizontally-polarized patch antenna.
My radio is a ~23dBm Demarctech. It connects to a vertically-polarized
8dBi omni with three feet of LMR-400.
Correct me if I'm wrong, but I think that the path loss should be
104 + 20 * log10(30/5280.) = 59dB
If our radios operate to spec, then my neighbor's 23dBm transmit power
on channel 6 should be suppressed by at *least* 30dB on channel 11.
(Right?)
There should be 25dB loss due to cross-polarization.
That puts my neighbor's received signal strength at
23dBm transmit power
- 30dB minimum sideband suppression
+ 19dB patch antenna gain
- 59dB path loss
- 25dB cross-polarization
+ 8dB omni antenna gain
______
-64dBm received signal strength
Have I done that calculation all wrong?
As I mentioned above, it looks like he's coming through at -45dBm,
which is quite a bit higher than I expect. Actually, the radio tells
me -22dBm, but I add 23dB to compensate for mis-calibration. (I use 23dB
to compensate because my station's RSSI on one link is 23dB higher than
the RSSI on the other end of the link. The transmitter on the other end
has ~equal Tx power.)
Any thoughts?
Dave
--
David Young OJC Technologies
[EMAIL PROTECTED] Urbana, IL * (217) 278-3933
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