Change wireless interface "sens" value how?

les hlhowell at pacbell.net
Sun Feb 13 11:50:14 UTC 2011


On Mon, 2011-02-14 at 01:08 +1030, Tim wrote:
> mike cloaked appears to be having a conversation with himself:
> > This driver seems to refuse sens values in dBm
> 
> Surely it wouldn't be specified in "dBm"?
> 
> 0 dBm is 1 milliwatt into 600 ohms.  Is the antenna really 600 ohms?
> That would be an unusual antenna impedance.
> 
> -- 
> [tim at localhost ~]$ uname -r
> 2.6.27.25-78.2.56.fc9.i686
> 
> Don't send private replies to my address, the mailbox is ignored.  I
> read messages from the public lists.
> 
> 
> 

600 ohms is usually an audio reference.  i.e. 0dbm is 1mw on 600ohms.
RF is usually specified to 50 ohms regardless of the actual impedance
(0dbm rf is 1mw on 50ohms), and a transformation is needed to arrive at
the voltage, current losses for other impedances.  Some VHF specs are at
150 or 300 ohms, and there could be a new standard developing for 600 as
some patch antennas do have that high an input impedance.

Regards,
Les H



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