I am new to openwrt. I am collecting iwdev station dump results periodically. The following result is stored. I need to know the difference between signal and signal avg. ? and also what are the 4 values within the square bracket. (signal: -55 [-65, -56, -95, -95] dBm)?
inactive time: 4470 ms
rx bytes: 26333626454
rx packets: 18541754
tx bytes: 438581
tx packets: 5061
tx retries: 0
tx failed: 12
rx drop misc: 19
signal: -55 [-65, -56, -95, -95] dBm
signal avg: -55 [-65, -56, -95, -95] dBm
tx bitrate: 400.0 MBit/s VHT-MCS 9 40MHz short GI VHT-NSS 2
rx bitrate: 12.0 MBit/s
rx duration: 754069640 us
TDLS peer: no
DTIM period: 2
short slot time:yes
connected time: 1171 seconds
(Moved to the For Developers section.)
Looking through code, I see:
printf("\n\tsignal: \t%d %sdBm",
printf("\n\tsignal avg:\t%d %sdBm",
I also see a 4, 3, 2, 1 section...I'm quite rusty, and don't see what interval or time frame it's using. That was just from my quick browse.
Feel free to review code yourself: https://mirrors.edge.kernel.org/pub/software/network/iw/
iw gets measurements from nl80211. Looking into the code I see following attributes:
* @NL80211_STA_INFO_SIGNAL: signal strength of last received PPDU (u8, dBm)
* @NL80211_STA_INFO_SIGNAL_AVG: signal strength average (u8, dBm)
* @NL80211_STA_INFO_CHAIN_SIGNAL: per-chain signal strength of last PPDU
* Contains a nested array of signal strength attributes (u8, dBm)
* @NL80211_STA_INFO_CHAIN_SIGNAL_AVG: per-chain signal strength average
* Same format as NL80211_STA_INFO_CHAIN_SIGNAL.
My best guess is that the signal strengths between brackets indicates the dBm value for each antenna/receiver. I presume in your case you have 4 + 4 mimo hardware thus 4 values btwn brackets. I have 3 + 3 and iw dev station dump indicates "only" 3 values btwn brackets in my case. Furthermore in your example I see -95 dBm (no signal - only noise) as value 3 and 4 which makes sense as VHT-NSS value is 2 (only 2 spatial streams are used during that specific measurement).