Re: [Discuss-gnuradio] Simulate transmission

[Eric Blossom]

On Wed, May 28, 2008 at 09:41:57AM -0700, irene159 wrote:
> 
> Hello,
> 
> I would like to simulate a transmission in order to test the configuration
> of the receiver's Costas loop. 
> I'd like to mix the modulated signal to IF, add some noise and convert back
> to baseband for demodulation. The frequency value configured for channel
> selection at reception is to be slightly different from the real frequency
> used. Do you think this model is representative?  
> 

You may want to consider using the already existing channel_model block.

from gnuradio import blks2

  channel = blks.channel_model(...)

Eric



class channel_model(gr.hier_block2):
    def __init__(self, noise_voltage=0.0, frequency_offset=0.0, epsilon=1.0, 
taps=[1.0,0.0], noise_seed=3021):
        ''' Creates a channel model that includes:
          - AWGN noise power in terms of noise voltage
          - A frequency offest in the channel in ratio
          - A timing offset ratio to model clock difference (epsilon)
          - Multipath taps
          '''
        gr.hier_block2.__init__(self, "channel_model",
                                gr.io_signature(1, 1, gr.sizeof_gr_complex), # 
Input signature
                                gr.io_signature(1, 1, gr.sizeof_gr_complex)) # 
Output signature