I'm using an Edimax EW-7811Un 802.11b/g/n WiFi adaptor on my RPi model B. It works well.

I am doing some coexistence testing that requires me to run the WiFi in the 802.11b/g 2.4GHz band rather than in the 802.11n 5Ghz band.

  1. How do I discover what channel the Edimax is running on?
  2. How can I force it to run in 11b/g mode (2.4GHz) rather than 11n (5GHz)?

Note: I don't have admin access to my WiFi router, so queries and configuration must be performed on the RPi, not the router.

Update: For reference, here's the results of lsusb:

$ lsusb
Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp. 
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. 
Bus 001 Device 004: ID 7392:7811 Edimax Technology Co., Ltd EW-7811Un 802.11n Wireless Adapter [Realtek RTL8188CUS]
Bus 001 Device 005: ID 0403:8a28 Future Technology Devices International, Ltd Rainforest Automation ZigBee Controller
  • I wouldn't change the channel from the receiver (or pi) unless you are using an ad-hoc network. If you are using a Router, then the router is where you want to adjust the channel. Clients talking to the router (such as the Pi) should adjust channel on connection. – Tyson Feb 14 '15 at 1:57

1) You can use the command iwlist channel to find the channel.

2) No idea, I suggest you look at iwconfig.

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iwconfig describes the state of the WiFi adaptor, and can modify it as well:

# iwconfig
wlan0     IEEE 802.11bg  ESSID:"pichincha"  Nickname:"<WIFI@REALTEK>"
          Mode:Managed  Frequency:2.437 GHz  Access Point: 00:25:9C:6B:1D:25   
          Bit Rate:54 Mb/s   Sensitivity:0/0  
          Retry:off   RTS thr:off   Fragment thr:off
          Encryption key:****-****-****-****-****-****-****-****   Security mode:open
          Power Management:off
          Link Quality=100/100  Signal level=100/100  Noise level=0/100
          Rx invalid nwid:0  Rx invalid crypt:0  Rx invalid frag:0
          Tx excessive retries:0  Invalid misc:0   Missed beacon:0

lo        no wireless extensions.

eth0      no wireless extensions.

iwfcofig can also be used to set the channel, as in:

# iwconfig wlan0 channel 3

I haven't tried that, but that's what man iwconfig suggests.

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