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Thread: monitor usb modem signal strength

  1. #1
    Join Date
    Jul 2009
    Ubuntu 8.04 Hardy Heron

    monitor usb modem signal strength

    how to monitor signal strength of USB modems through commandline ??

  2. #2
    Join Date
    Jul 2009
    Riihimaki, Finland

    Re: monitor usb modem signal strength

    This is one way to do it:

    1. Install terminal program cu : sudo apt-get install cu

    2. Connect to the modem : cu -l /dev/ttyUSB0
    - this may be also ttyUSB1, 2 or bigger, depending on your modem

    3. Give AT command to check the signal : at+csq
    - this gives you the RSSI, see further below

    - Exit cu by keys: "~" and "." (Ctrl+C or else do not work)
    - Some modems work with the connection on, some do not, so it may be wise to disconnect from internet before trying cu.

    The table helps you realize the RSSI (Radio Signal Strength Index) compared to other indicators of signal strength. (The table headings are in Finnish, but it is very easy to figure out.)
    Last edited by anttu; April 22nd, 2010 at 11:28 AM.

  3. #3
    Join Date
    Mar 2013

    Re: monitor usb modem signal strength

    when I write "cu -l /dev/ttyUSB0" I get this error:
    "cu: open (/dev/ttyUSB0): Permission denied
    cu: /dev/ttyUSB0: Line in use"
    but I tried it with root and also modem is not connected.
    when modem is connected I get this :
    "cu: /dev/ttyUSB0: Line in use"


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