## [Aironet] Re: CISCO 350 series driver RSSI

 [Aironet] Re: CISCO 350 series driver RSSI From: Scott Dier - 2001-11-30 21:17:51 ```* Cyrus 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 http://www.ringworld.org/ #linuxos@... 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 ```

 Re: [Aironet] CISCO 350 series driver RSSI From: Cyrus Behroozi - 2001-11-29 20:34:36 ```To convert from a relative signal strength in percent to a signal strength in dBm, use the following: S(dBm) = S(%)/2 - 95 --Cyrus ```
 Re: [Aironet] CISCO 350 series driver RSSI From: Cyrus Behroozi - 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 exactly. 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 kernel driver? --Cyrus ```
 [Aironet] Re: CISCO 350 series driver RSSI From: Scott Dier - 2001-11-30 21:17:51 ```* Cyrus 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 http://www.ringworld.org/ #linuxos@... 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 ```
 Re: [Aironet] Re: CISCO 350 series driver RSSI From: Benjamin Reed - 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... ben Scott Dier wrote: > * Cyrus 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? > > ```
 RE: [Aironet] CISCO 350 series driver RSSI From: Shingo HORISAWA - 2001-11-30 02:27:28 ```Hi, all 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 - RSSI). What is the source of following formula ? > S(dBm) = S(%)/2 - 95 Regards. ```