When I used the airport utility from a Terminal windowto check the noise level and signal strength for the WiFi connection, I saw the following:
$ /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I
agrCtlRSSI: -56
agrExtRSSI: 0
agrCtlNoise: -87
agrExtNoise: 0
state: running
op mode: station
lastTxRate: 73
maxRate: 72
lastAssocStatus: 0
802.11 auth: open
link auth: wpa2-psk
BSSID: 94:44:52:4a:43:40
SSID: Rain
MCS: 7
channel: 11The signal strength is represented by the agrCtlRSSI value
- "RSSI" stands for received signal strength indication. For Apple
OS X systems, the closer the number is to negative 100, the weaker
the signal - see Checking WiFi
signal strength from the command line on OS X for further
information. The noise value is represented by agrCtlNoise.
In this case I saw a value of -87; less negative values
or better, so the system was reporting a noisy signal.
I monitored the noise level for over a minute, checking it every 15 seconds. I saw that that the noise level was high and the signal strength wasn't good, either, though the laptop wasn't far from the wireless router.
$ while true; do /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I | grep agrCtlNoise; sleep 15; done
agrCtlNoise: -93
agrCtlNoise: -93
agrCtlNoise: -88
agrCtlNoise: -92
agrCtlNoise: -95
agrCtlNoise: -95
agrCtlNoise: -95
^C
$I then checked on the other nearby WiFi networks. I saw just one other
wireless network, ARRIS-F692 using channel 11 at that time, though
I did see others later.
$ /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -s
SSID BSSID RSSI CHANNEL HT CC SECURITY (auth/unicast/group)
Jeremiah29-5g c0:7c:d1:0b:10:a0 -90 149 Y US WPA(PSK/AES,TKIP/TKIP) WPA2(PSK/AES,TKIP/TKIP)
Jeremiah29 c0:7c:d1:0b:10:98 -81 6 Y US WPA(PSK/AES,TKIP/TKIP) WPA2(PSK/AES,TKIP/TKIP)
558935 0c:54:a5:48:19:e5 -34 1 Y -- WPA(PSK/AES,TKIP/TKIP) WPA2(PSK/AES,TKIP/TKIP)
Rain 94:44:52:4a:43:40 -52 11 Y -- WPA(PSK/AES/AES) WPA2(PSK/AES/AES)
ARRIS-F692 94:87:7c:07:f6:90 -80 11,+1 Y DF WPA2(PSK/AES/AES)
$On an OS X system you can run a wireless diagnostics check by clicking on the WiFi icon at the top of the screen while holding down the option key then selecting Open Wireless Diagnostics - see OS X Wireless Diagnostics. You will then see an "Introdcution" window stating the following:
Wireless Diagnostics is an application that detects common problems with your wireless connection. It can also monitor your wireless connection for intermittent connectivity failures.
Upon completing this assistant, a diagnostics report will be placed on your desktop. ...
I clicked on Continue to start the diagnotics routine, which then prompted me for the password for an account with administrative access to the system. At the next step you can choose from the following two options:
I chose "Monitor my Wi-Fi connection". A few minutes later an error message related related to the SSH server to which I was connected appeared in a Terminal window.
$ Timeout, server 192.168.0.2 not responding.
At that time I also saw a "Dropped connection detected" message from the Wireless Diagnostics window.
When I clicked on Continue, an Additional Information window appeared where I could enter any additional information I wanted inserted in the report.
The next window was a Router Information window where I could enter information regarding the make and model of the wireless router.
When I clicked on Continue a diagnostics report was created and a summary window appeared.
The Summary window listed two entries:
When I clicked on the "i" to see information on the second entry, I saw the following information displayed:
A nearby wireless router has been detected which is identifying itself as
originating from a country
which conflicts with your current settings. This may prevent your Mac from automatically re-joining
a previously joined Wi-Fi network.
Certain wireless routers have the ability to identify the country they are
designated to work in, this is
called the Country Code. Wireless routers should only be used in the country they were originally
obtained from. Failure to do so can result in performance and reliability issues for nearby wireless clients.
If possible, contact the network owner to resolve the problem.
You can determine the service set identifier (SSID) of the network with the conflicting country code using the Wireless Diagnostics tool after clicking on the wireless icon while holding down the option key and selecting Open Wireless Diagnostics by clicking on Window from its menu and then selecting Scan.
You will then see a list of the wireless networks detected by the scan. If you scroll to the right you will see the country codes listed for any routers that are reporting a country code. In this case, I saw one listed with a country code of DF. Since I was in the United States which has a country code of "US", that was obviously the wireless router that the Wireless Diagnostics utility was reporting as having a conflicting country code. The wireless router I was using wasn't reporting a country code, though other nearby routers were listed with the US country code when I ran the Wireless Diagnostic scan.
I don't believe DF is currently assigned to a country, though it is used for the Mexican state Distritio Federal. I was on the eastern seaboard of the U.S., though when I ran the test. As the How-to Geek article How to Fix Conflicting Country Codes and Improve Your Mac’s Wi-Fi article mentions, though, there isn't much you can do to resolve the issue, if the router isn't yours, but is a neighbor's router, instead, other than possibly walking around the neighborhood and knocking on doors and asking a neighbor to replace his or her router, which probably isn't a practical course of action for most people. In this case, since it was using channel 11 and when I later looked at the wireless networks nearby and saw quite a few more using that channel, I decided to change the channel used by the wireless router to which I connected.
In addition to using the Wireless Diagnostic utility provided with OS X, you can also use an airport -s command as shown above to see the country codes advertised by any routers that do advertise a country code using the 802.11d standard, which supports the inclusion of country code information for wireless access points for assistance in meeting the different regulations enforced in various parts of the world for wireless networking. A device using that standard informs nearby Wi-Fi-enabled devices, such as a MacBook laptop, which country they are in and so which Wi-Fi settings should be used appropriate to that country.
If you issue the
/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -s
command at a command line interface, e.g., in a
Terminal
window, the CC column in the output of the command shows
the country codes advertisted by any nearby wireless access points that
advertise a country code.
References:
