Re: [Discuss-gnuradio] [BULK] Fading channel in GNURadio

[Sean Nowlan]

On 03/21/2013 03:45 PM, Manu T S wrote:

I'm trying to make a block for fading channel model using hierarchical block.

class channel(gr.hier_block2):

    def __init__(self):

        gr.hier_block2.__init__(self, "channel",

                gr.io_signature(1, 1, gr.sizeof_float),

                gr.io_signature(1, 1, gr.sizeof_gr_complex))

        self.taps = generate_taps()

        self.filt = filter.fir_filter_ccc(1, self.taps)

        self.connect(self, self.filt, self)

    def generate_taps():

        n_taps = random.randint(1, 10)

        r_taps = random.rand(n_taps)

        i_taps = random.rand(n_taps)

        return r_taps + 1j*i_taps

I want the block to be able to update the channel filter taps in run time. Can I do that?

Can I define a function in the class so that the filter taps are updated for every 5 seconds?

The set_taps function gives you access to this from the top_block level. In that case, your main thread would be updating the block's taps using a while loop with sleep(5). You could also make a block class that inherits from fir_filter_ccc or channel_model and change the taps within the work function every N seconds: every time (ninput_items / samp_rate) % N == 0. I hope that's enough info to point you in the right direction.

Thank you.

--
Manu T S

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Sean M. Nowlan
Research Engineer I
ICL/CNSD
Georgia Tech Research Institute
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