MDM and Jamming

2 thoughts on “MDM and Jamming”

1. Hello 

   I need answer for strange situation which occurs sometimes when I jamming the GSM. 

   I set JDR by AT#JDR=2,70,5 command

   I start jamming. 

   I run “test()” in while with “cmd” = “+CREG?”

   The “print s” result contain information about jammer and CREG but why the CREG “\r\nOK\r\n” was printed as “\r\nO” and “K\r\n”. 

   How to prevent for this?

    

    

   Below code for test:

    

    _STOP = “\r\nOK\r\n”

   _ERROR = “\r\nERROR\r\n”

    

   def test(cmd):

       if MDM.send(“AT%s\r” % (cmd, ), 20) == -1:

           raise IOError, “\r\nAT%s” % (cmd, )

       l = “”

       stop = None

       while not stop:

           s = MDM.receive(51)

           print s # Test point

           l = “%s%s” % (l, s)

           if l.find(_STOP) != -1:

               stop = 0xFF

               s = _STOP

           elif l.find(_ERROR) != -1:

               stop = l

               s = _ERROR

               ans = 0

   1. The return value will be the first string received no matter the timeout value.

       

      If you want to ensure all data is received is better to implement a read routine based on 2 exit conditions, a group of expected characters and a max timeout, like below:

       

      def Chat(command, expected, timeout):
          timer = MOD.secCounter() + timeout
          MDM.send(command, 5)
          b = command + MDM.read()
          while (MOD.secCounter() < timer) and (b.find(expected) == -1):
              b = b + MDM.read()
          return b