I am trying to obtain the wifi rssi results at a very high rate and using the following command:
while true
do
date -Ins
/sbin/iw dev wlp3s0 station dump | grep signal
done
Question: I wanted to understand how to read the output.
Does signal simply display the strongest signal and the signal from two antennas ?
Does the second line simply give a running average? Please advise.
2019-04-08T12:09:23,618290169-07:00
signal: -49 [-49, -53] dBm
signal avg: -48 [-48, -52] dBm
2019-04-08T12:09:23,619857247-07:00
signal: -49 [-49, -53] dBm
signal avg: -48 [-48, -52] dBm
Could someone please take a look at the question. I am essentially trying to understand if the signal parameters displayed correspond to the two antennas. I searched all existing documentation including the source code of the IW utility, there is nothing conclusive that I am able to see to confirm my observation.
iw dev wlp3s0 station dump returns the statistics about the connected devices.
The question does not provide the full printout, but it looks like you are getting the signal quality for 2 separate connected devices, and nothing about antennas. There should be a line Station <mac address>, which should tell you which connected device the stats are for.
Related
I'm trying to find the RSSI value for a phone that is connected to my laptop by Bluetooth. I use the below command on Ubuntu:
hcitool rssi AA:BB:CC:DD:EE:FF
But I get this:
RSSI return value: 0
But I want the value in the range of -20 to -100 for example.
How can I solve this problem?
The HCI tool doesn't retrieve data directly from your radio, rather it uses the standardized Bluetooth HCI (host-controller interface). The definition of the read RSSI HCI command, from the spec:
7.5.4 Read RSSI command
Description:
This command reads the Received Signal Strength Indication (RSSI) value
from a Controller.
For a BR/EDR Controller, a Connection_Handle is used as the Handle
command parameter and return parameter. The RSSI parameter returns the
difference between the measured Received Signal Strength Indication (RSSI)
and the limits of the Golden Receive Power Range for a Connection_Handle to
another BR/EDR Controller. The Connection_Handle shall be a
Connection_Handle for an ACL connection. Any positive RSSI value returned
by the Controller indicates how many dB the RSSI is above the upper limit, any
negative value indicates how many dB the RSSI is below the lower limit. The
value zero indicates that the RSSI is inside the Golden Receive Power Range.
Note: How accurate the dB values will be depends on the Bluetooth hardware.
The only requirements for the hardware are that the BR/EDR Controller is able
to tell whether the RSSI is inside, above or below the Golden Device Power
Range.
The RSSI measurement compares the received signal power with two
threshold levels, which define the Golden Receive Power Range. The lower
threshold level corresponds to a received power between -56 dBm and 6 dB
above the actual sensitivity of the receiver. The upper threshold level is 20 dB
above the lower threshold level to an accuracy of ±6 dB.
So basically the reason you're seeing "0" is because your device is within the "golden range" as configured in the hardware driver. You will not be able to get a more accurate reading using HCI commands
I'm trying to measure the RSSI from a station connected to my AP which is running OpenWRT. I know that by using iw wlan0 station dump or iw wlan0 station get [MAC], I should be able to see it. Though for some reason it doesn't show the RSSI on my AP.
Here is the output that I get:
~# iw wlan0 station get 40:b0:fa:c1:75:41
Station 40:b0:fa:c1:75:41 (on wlan0)
inactive time: 75 ms
rx bytes: 17588
rx packets: 134
tx bytes: 10771
tx packets: 76
tx retries: 3
tx failed: 0
tx bitrate: 6.0 MBit/s
rx bitrate: 6.0 MBit/s
authorized: yes
authenticated: yes
preamble: short
WMM/WME: yes
MFP: no
TDLS peer: no
I'm running hostapd and dnsmasq. Any ideas of how I can get the RSSI? Maybe somehow in C?
Thanks!
UPDATE
I was checking the code of iw, and for some reason NL80211_STA_INFO_SIGNAL comes up NULL - If anyone has an idea of why this could be happening, would be a great help!
UPDATE 2
Apperently the source of iw in the project I was working was changed and the line with the RSSI for some reason has been commented. This change has never been documented. Thank you for everyone that answered this question.
Sounds like either your are using a radio card/driver that does not provide the RSSI to the kernel, or you are using an out-of-date kernel module (package mac80211)
Dit you try the command "iwinfo wlan0 assoc" ? You might have better luck with this.
although it was posted long ago.. may be helpful
did you try :
sudo iw dev wlan0 station get [MAC]
(change [MAC] to STA mac address)
there is field "signal" if that help you.
When I run:
iwconfig wlan0 | grep -i quality
on my Raspberry Pi, with a wifi card installed, it reports back to me with:
Link Quality=99/100 Signal level=48/100 Noise level=0/100
How can I get iwconfig or some other network tool to report the signal level back to me in dBm instead of an arbitrary fraction?
It's a matter of the Network Interface Card or of the relatives Drivers.
To workaround you can use this simple formula I to do the conversion.
dbm=(fraction_of_total/2)-100
Of course is an approximation and results may vary from chipset to chipset but is how I solved.
You can alternatively find the correct Drivers if you know the wifi card is capable RSSI sampling. But that's usually not easy.
Is there any implementation or library that I can use to calculate the SNR (Signal noise ratio) of a wifi signal on a linux machine which is connected via an ad-hoc network?
I guess you can include <linux/wireless.h> and see what ioctl() returns on a SIOCGIWSPY.
The struct iw_quality will contain some of the information you are looking for: http://www.cs.fsu.edu/~baker/devices/lxr/http/source/linux/include/linux/wireless.h?v=2.6.11.8#L504
This is what iwlist does internally.
You can use iwlist command like this:
iwlist scan
It will produce some output like this:
wlan0 Scan completed :
Cell 01 - Address: XX:XX:XX:XX:XX:XX
Channel:11
Frequency:2.462 GHz (Channel 11)
Quality=59/70 Signal level=-51 dBm
Encryption key:on
...
May be you are interested in the reported "Quality".
I have a Dell Latitude E6410, which uses an Intel Ultimate N-6300 Wireless card. iwconfig does not show the Noise level of the wireless interface , wlan0. Does anyone know the reason for that?
precise#ubuntu:~/Desktop/Work/transmitter$ iwconfig
lo no wireless extensions.
mon0 IEEE 802.11abgn Mode:Monitor Tx-Power=15 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:off
wlan0 IEEE 802.11abgn ESSID:"AirPennNet"
Mode:Managed Frequency:2.412 GHz Access Point: D8:C7:C8:D7:A6:C1
Bit Rate=130 Mb/s Tx-Power=15 dBm
Retry long limit:7 RTS thr:off Fragment thr:off
Power Management:on
Link Quality=65/70 Signal level=-45 dBm
Rx invalid nwid:0 Rx invalid crypt:0 Rx invalid frag:0
Tx excessive retries:800 Invalid misc:540 Missed beacon:0
eth0 no wireless extensions.
I tried to use cat /proc/net/wireless and got these results
Inter-| sta-| Quality | Discarded packets | Missed | WE
face | tus | link level noise | nwid crypt frag retry misc | beacon | 22
wlan0: 0000 64. -46. -256 0 0 0 818 566 0
Is -256 the noise level? How do i interpret this in dBm?
The answer lies within your driver and wireless card support.
I have a similar Dell Latitude model but with an Intel(R) Centrino(R) Advanced-N 6200 AGN wireless card. After issuing the iwconfig command, the output also revealed something similar - the Noise parameter was missing (this was done while in connection to an access point, of course).
Not happy with that, I got out another wireless card (Winstron NeWeb AR9170+AR9104 802.11abgn - basically a Proxim Wireless 802.11a/b/g/n Wi-Fi USB dongle) and issued the same command. The output was still the same, the Noise parameter was not there!
This wasn't what I had expected since I knew very well that we had used the same Wi-Fi dongle to detect the noise level associated with access points using a proprietary software by Fluke Network called the AirMagnet WiFi Analyzer PRO. I even tried downloading and re-compiling the Linux Wireless Tools package from Jean Tourrilhes' but similar output was shown as before.
The next step I did was to verify again that the WiFi dongle actually does show the WiFi noise levels under the AirMagnet WiFi Analyzer software. Sure enough, it does (as depicted in the attached image below).
The blue column with the header 'N' refers to the noise level. Mind you, the WiFi dongle also came along with a proprietary driver when we bought the AirMagnet software along with it.
Having done that, I decided to see what it would show for our internal WiFi card (Intel(R) Centrino(R) Advanced-N 6200 AGN). Here are the results:
All of them are displaying values of -100! So, I believe it all has something to do with the driver/card capabilities.