[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[Discuss-gnuradio] time varying delay block doesnt vary

From: apchar
Subject: [Discuss-gnuradio] time varying delay block doesnt vary
Date: Wed, 16 Mar 2016 06:09:27 +0000 (UTC)

I'm trying to make a time varying delay. One that will update faster than I can get with probe_signal + function_probe + gr_delay block.
The code is shown below. There's not much to it. It's just a start.  The flow graph that tests it is just:
1 kHz triangle waveform -> throttle --> time_varying_delay --> time sink
with a second input on the time sink for the input waveform.
I'm implementing the time delay by updating set_history() with a static counter.
It doesn't work. The time delay doesn't vary. The output waveform just sits there in sync with the input. If I uncomment the consume_each line it almost works, until it crashes. For a few thousand counter cycles the delay bounces around. But it always locks up after anywhere from a few hundred to a few thousand counts.
Why would it be fixed without the consume line and bounce around and crash with it ?
Is updating set_history() the wrong approach ?

/* -*- c++ -*- */

#include "config.h"

#include <gnuradio/io_signature.h>
#include "time_varying_delay_impl.h"

namespace gr {
  namespace howto {

    time_varying_delay::sptr time_varying_delay::make()
      return gnuradio::get_initial_sptr (new time_varying_delay_impl());

    time_varying_delay_impl::time_varying_delay_impl() :
          gr::io_signature::make(1, 1, sizeof(float)),
          gr::io_signature::make(1, 1, sizeof(float)))
    time_varying_delay_impl::~time_varying_delay_impl() {}

    int time_varying_delay_impl::work(int noutput_items,
    gr_vector_const_void_star &input_items,
    gr_vector_void_star &output_items)
        const float *in = (const float *) input_items[0];
        float *out = (float *) output_items[0];
        static int counter = 1;
        for (int i = 0; i < noutput_items; i++) {
            out[i] = in[i] / 2.0;
       std::cout << counter << std::endl;   
//    consume_each(noutput_items);
       return noutput_items;
  } /* namespace howto */
} /* namespace gr */

reply via email to

[Prev in Thread] Current Thread [Next in Thread]