Re: [Discuss-gnuradio] how to get wireless carrier signal in GNU Radio

[Zenny Zhang]

Sachin,

Sure, here is the related code I use:

    # get a probe
    alpha = 0.001
    thresh = 30

    self.probe = gr.probe_avg_mag_sqrd_c(thresh,alpha)


    # connect usrp to the probe
    self._fg.connect(self.u, self.probe)


    # wait until the medium is free
    while objDemod1.probe.level() > threshold:
        time.sleep(0.0001)


Zhenghao


On Thu, Oct 23, 2008 at 4:59 PM, Shirve <address@hidden> wrote:
>
> Hi Zhenghao,
> Thank you for your valuable reply. I appreciate it. As per your supplied
> information, I will start looking for CSMA code in tunnel.py, though if you
> can send me your code, it will be quite helpful too. I hope that using
> tunnel.py code and help from you I will be able to get the carrier sense
> capability for my application.
>
> Thanks
> -Sachin
>
>
> Zenny Zhang wrote:
>>
>> Sachin,
>>
>> I don't know if this is helpful, just sharing my experience.
>>
>> 1. You may want to check tunnel.py, in which there is a CSMA scheme --
>> Eric told me this a couple of weeks ago.
>> 2. It is possible to do some carrier sensing by ourself. You can just
>> read the signal from the USRP and compare the signal strength level
>> with a threshold. Of course a filter is needed. I tried this last week
>> and it is working, although the threshold may need some tuning. If you
>> need I can send you the code written in python.
>>
>> Zhenghao
>>
>> On Wed, Oct 22, 2008 at 6:19 PM, Shirve <address@hidden> wrote:
>>>
>>> Hi,
>>> As per the current status of GNU Radio, I got to know that there is no
>>> MAC
>>> (CSMA) implementation. Therefore I am not sure if I can get the signal
>>> from
>>> signal processing blocks of GNU Radio about the carrier sensed by USRP
>>> receiver.
>>>
>>> Please help me in this regard.
>>>
>>> Till now I am able to locate the message queue mechanism to get the
>>> received
>>> packets from the other USRP transmitter, which is in gr_msg_que.cc in
>>> runtime library of GNUradio-core. But this mechanism just indicates the
>>> received packets (correct or corrupted), while the signal sensing (packet
>>> start) starts much earlier than the complete packet reception.
>>>
>>> Is it possible to get the information about the wireless carrier signal
>>> in
>>> the vicinity of USRP receiver from the current GNU Radio framework? I am
>>> using GNU Radio 3.1.1 version.
>>>
>>> Your help will greatly help me in my goal. Thanks in advance and
>>> expecting
>>> your kind reply.
>>>
>>> - Sachin
>>> --
>>> View this message in context:
>>> http://www.nabble.com/how-to-get-wireless-carrier-signal-in-GNU-Radio-tp20120856p20120856.html
>>> Sent from the GnuRadio mailing list archive at Nabble.com.
>>>
>>>
>>>
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>>
>>
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>
> --
> View this message in context: 
> http://www.nabble.com/how-to-get-wireless-carrier-signal-in-GNU-Radio-tp20120856p20139200.html
> Sent from the GnuRadio mailing list archive at Nabble.com.
>
>
>
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