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Re: [Discuss-gnuradio] Strange problem when reading from gr.GR_SIN_WAVE.

From: Josh Blum
Subject: Re: [Discuss-gnuradio] Strange problem when reading from gr.GR_SIN_WAVE.....
Date: Thu, 29 Nov 2007 18:32:04 -0500

Essentially, the sampling rate parameter of the signal source does not
actually control the number of samples per "CPU clock". That parameter
tells the signal source how to scale the sine wave in the time domain.
When you run this flow graph, the signal source is actually spitting
out samples as fast as possible. So in time.sleep(2e-6), any random
number of sample will be written.

You can control the rate of the samples with respect to you CPU clock
by using a gr.throttle(gr.sizeof_float, samps_per_second) block in
your flow graph. Also, you can use a gr.head(gr.sizeof_float,
num_samps) block to only allow the first "num_samps" into the file


On Nov 29, 2007 5:59 PM, Kshitij Singh <address@hidden> wrote:
> Hi all,
>      I am a newbie to GNU Radio. I just started off with my first program
> and decided to read some floating point samples from the gr.GR_SIN_WAVE into
> a file. My problem is that every time I run the program, I get a different
> file size. I even tried to change the file name after the first run, but
> again ended up with the same problem. Here's the script:
>  ------------------------------------------------------------
>  from gnuradio import gr
>  import time
>  def my_graph():
>          sampling_frequency = 10000
>          amplitude =0.1
>          graph1 = gr.flow_graph()
>          source =
> gr.sig_source_f(sampling_frequency,gr.GR_SIN_WAVE,100,amplitude)
>          destination = gr.file_sink(gr.sizeof_float,
> '/home/anshul/Desktop/samples1.dat')
>          graph1.connect(source,destination)
>          return graph1
>  if __name__ == '__main__':
>          graph1 = my_graph()
>          graph1.start()
>          time.sleep(2e-6)
>          graph1.stop()
>  ------------------------------------------------------------------
>  kindly help out with this. Thanks in advance.
> _______________________________________________
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