[Tinyos-help] CCA Threshold

[Mathieu DAVID]

Hi,
We wanted to know about the procedure to change the *CCA threshold* 
using tinyOS.
We are trying to simulate the scenario from the tutorials in chapter 11. 
However, the nodes were established, but we could not see the packets 
received. We attribute this to the default value of CCA if -110dbm. Is 
this correct?
And if so, how does one alter the CCA threshold to facilitate packet 
transfer?

We are actually facing the problem described in the tutorial with this 
output:

1 2 -54.0
2 1 -55.0
1 3 -60.0
3 1 -60.0
2 3 -64.0
3 2 -64.0
DEBUG (1): Application booted.
DEBUG (1): Application booted again.
DEBUG (1): Application booted a third time.
DEBUG (2): Application booted.
DEBUG (2): Application booted again.
DEBUG (2): Application booted a third time.
DEBUG (3): Application booted.
DEBUG (3): Application booted again.
DEBUG (3): Application booted a third time.
DEBUG (1): RadioCountToLedsC: timer fired, counter is 1.
DEBUG (1): RadioCountToLedsC: packet sent.
DEBUG (2): RadioCountToLedsC: timer fired, counter is 1.
DEBUG (2): RadioCountToLedsC: packet sent.
DEBUG (3): RadioCountToLedsC: timer fired, counter is 1.
DEBUG (3): RadioCountToLedsC: packet sent.
DEBUG (1): RadioCountToLedsC: timer fired, counter is 2.
DEBUG (2): RadioCountToLedsC: timer fired, counter is 2.
DEBUG (3): RadioCountToLedsC: timer fired, counter is 2.

In the tutorial, some commands are given to modify the parameters of the 
radio channel :

/>>> from TOSSIM import *
>>> t = Tossim([])
>>> r = t.radio()
>>> dir(r)
['__class__', '__del__', '__delattr__', '__dict__', '__doc__',
'__getattr__', '__getattribute__', '__hash__', '__init__',
'__module__', '__new__', '__reduce__', '__reduce_ex__',
'__repr__', '__setattr__', '__str__', '__swig_getmethods__',
'__swig_setmethods__', '__weakref__', 'add', 'connected',
'gain', 'remove', 'setNoise', 'this', 'thisown',
]
        /

/The first set of methods (with the double underscores) are ones that 
you usually don't call. The important ones are at the end. They are:/

    * /*|add(src, dest, gain)|*: Add a link from //src to //dest with
      //gain. When //src transmits, //dest will receive a packet
      attenuated by the //gain value. /
    * /*|connected(src, dest)|*: Return whether there is a link from
      //src to //dest. /
    * /*|gain(src, dest)|*: Return the gain value of the link from //src
      to //dest. /
    * /*|threshold()|*: Return the CCA threshold. /
    * /*|setThreshold(val)|*: Set the CCA threshold value in dBm. The
      default is -72dbM./


*But the fact is, None of the two last command exists !! *How can we 
solve this issue??
Thx,
Mathieu & Aravind