From: Cyrus Behroozi <behroozi@fa...> - 2001-11-30 20:16:51
> What is the source of following formula ?
> > S(dBm) = S(%)/2 - 95
I determined this formula empirically (!) using Cisco's Aironet Client
Utility and Link Status Meter. If both are running and the options are set
right, they can simultaneously display signal strength in dBm and
"percent." I recorded pairs of numbers at a wide range of signal strengths
and fit them using Mathematica. The linear relation above fit the data
So, this is the conversion that Cisco uses in their Aironet Client
Utility. Ben / Jean, is this the same formula that's used in the latest
From: Scott Dier <dieman@ri...> - 2001-11-30 21:17:51
* Cyrus Behroozi <behroozi@...> [011130 14:21]:
> Utility. Ben / Jean, is this the same formula that's used in the latest
> kernel driver?
status = PC4500_readrid(ai,RID_RSSI,&rssi_rid,sizeof(rssi_rid));
Looks like it sucks it from the card?
Scott Dier <dieman@...> <sdier@...>
So I ran up to him, and the exchange went something like this:
Me: Oh my god! You're Larry Niven!
Him: Oh my god! You're Wil Wheaton!
-Wil Wheaton, in a Slashdot interview
From: Benjamin Reed <breed@al...> - 2001-12-01 00:42:45
Yes there is a translation table that Javier added code to use. I'm not
sure which version of the firmware supports that RID though...
Scott Dier wrote:
> * Cyrus Behroozi <behroozi@...> [011130 14:21]:
>>Utility. Ben / Jean, is this the same formula that's used in the latest
> status = PC4500_readrid(ai,RID_RSSI,&rssi_rid,sizeof(rssi_rid));
> Looks like it sucks it from the card?
I've seen about RSSI on Intersil technical support center homepage
(http://www.intersil.com/tsc/) as follows:
> The link quality can be based on either the RSSI value or the SQ value
> as measured at the chip. The signal power (SP) can be directly derived
> from the RSSI value by subtracting 100 from the RSSI value in decimal.
> This gives the signal strength in dBm. The signal quality measure is
> most useful at low SNR. What I would use is:
> SP = 100 - RSSI If SQ > 10 or SP < -84 dBm then 11 Mbps will not
> function If SQ> 14 or SP < -87 dBm then 5.5 and 2 Mbps will not function
> If SQ > 20or SP < -91 dBm then 1 Mbps will not function.
Please search this on FAQ page with keyword "quality" or "RSSI".
And, airo.c in kernel2.4.10 seems to perform this calculation (SP = 100 -
What is the source of following formula ?
> S(dBm) = S(%)/2 - 95
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