GnuRadio code runs well via Flask webserver but no

问题:

I have an gnuradio generated python code that I am using a Flask webserver to run it through. In this webserver I have some roundSliders widgets that I am using to control the variable values of my main code. I had some issues with this program before (for more info, see this thread). But after getting some recommendations and suggestion from valued members here I think I got it working now. BUT, I can't see the light flickering/flashing of the transmitter on the USRP device, also I can't hear any audio output (I suppose to hear some static noise).

from __future__ import print_function
from gnuradio import analog
from gnuradio import audio
from gnuradio import blocks
from gnuradio import eng_notation
from gnuradio import gr
from gnuradio.eng_option import eng_option
from gnuradio.filter import firdes
from optparse import OptionParser
from gnuradio import uhd
import time

class top_block_22(gr.top_block): # PEP8: CamelCaseName for classes

    def __init__(self, sample_rate=32000, amplitude=0, frequency=0, bandwidth=0, gain=0, center_frequency=0, usrpsamp_rate=0):

        gr.top_block.__init__(self, "Top Block 22")
        ##################################################
        # Variables
        ##################################################
        self.sample_rate = sample_rate
        print('[top_block_22] __init__: sample_rate:', self.sample_rate)

        self.amplitude = amplitude
        print('[top_block_22] __init__: amplitude:', self.amplitude)

        self.frequency = frequency
        print('[top_block_22] __init__: frequency:', self.frequency)

        self.bandwidth = bandwidth
        print('[top_block_22] __init__: bandwidth:', self.bandwidth)

        self.usrpsamp_rate = usrpsamp_rate
        print('[top_block_22] __init__: usrpsamp_rate:', self.usrpsamp_rate)

        self.gain = gain
        print('[top_block_22] __init__: gain:', self.gain)

        self.center_frequency = center_frequency
        print('[top_block_22] __init__: center_frequency:', self.center_frequency)
        ##################################################
        # Blocks
        ##################################################

        self.blocks_add_xx_0 = blocks.add_vff(1)
        self.audio_sink_0 = audio.sink(sample_rate, '', True)
        self.analog_sig_source_x_0 = analog.sig_source_f(sample_rate, analog.GR_COS_WAVE, frequency, amplitude, 0)
        self.analog_noise_source_x_0 = analog.noise_source_f(analog.GR_GAUSSIAN, 1, 0)

        ##################################################
        # Connections
        ##################################################
        self.connect((self.analog_noise_source_x_0, 0), (self.blocks_add_xx_0, 1))
        self.connect((self.analog_sig_source_x_0, 0), (self.blocks_add_xx_0, 0))
        self.connect((self.blocks_add_xx_0, 0), (self.audio_sink_0, 0))


    def change_sample_rate(self, value=None):
        if value is not None:
            self.sample_rate = value
            print('[top_block_22] change: sample_rate:', value)
            self.analog_sig_source_x_0.set_sampling_freq(value)

    def change_amplitude(self, value=None):
        if value is not None:
            value /= 10000.
            self.amplitude = value
            print('[top_block_22] change: amplitude:', value)
            self.analog_sig_source_x_0.set_amplitude(value)
            self.analog_noise_source_x_0.set_amplitude(value)

    def change_frequency(self, value=None):
        if value is not None:
            self.frequency = value
            print('[top_block_22] change: frequency:', value)
            self.analog_sig_source_x_0.set_frequency(value)

            #TODO: change some values
    def change_bandwidth(self, value=None):
        if value is not None:
            self.bandwidth = value
            print('[top_block_22] change: bandwidth:', value)
        self.uhd_usrp_sink_0 = uhd.usrp_sink(
          ",".join(("type=b200", "")),
          uhd.stream_args(
            cpu_format="sc16",
            channels=range(1),
          ),
        )
        self.uhd_usrp_sink_0.set_bandwidth(value)
        self.uhd_usrp_sink_0.set_antenna('TX/RX', 0)


        self.connect((self.blocks_add_xx_0, 0), (self.uhd_usrp_sink_0, 0))
    def change_gain(self, value=None):
        if value is not None:
            self.gain = value
            print('[top_block_22] change: gain:', value)        
        self.uhd_usrp_sink_0 = uhd.usrp_sink(
          ",".join(("type=b200", "")),
          uhd.stream_args(
            cpu_format="sc16",
            channels=range(1),
          ),
        )

        self.uhd_usrp_sink_0.set_gain(value)
        self.uhd_usrp_sink_0.set_antenna('TX/RX', 0)

        self.connect((self.blocks_add_xx_0, 0), (self.uhd_usrp_sink_0, 0))
    def change_center_frequency(self, value=None):
        if value is not None:
            self.center_frequency = value
            print('[top_block_22] change: center_frequency:', value) 
        self.uhd_usrp_sink_0 = uhd.usrp_sink(
          ",".join(("type=b200", "")),
          uhd.stream_args(
            cpu_format="sc16",
            channels=range(1),
          ),
        )
        self.uhd_usrp_sink_0.set_center_freq(value)
        self.uhd_usrp_sink_0.set_antenna('TX/RX', 0)

        self.connect((self.blocks_add_xx_0, 0), (self.uhd_usrp_sink_0, 0))
    def change_usrpsamp_rate(self, value=None):
         if value is not None:
            self.usrpsamp_rate = value
            print('[top_block_22] change: usrpsamp_rate:', value)        
            self.uhd_usrp_sink_0 = uhd.usrp_sink(
          ",".join(("type=b200", "")),
          uhd.stream_args(
            cpu_format="sc16",
            channels=range(1),
          ),
        )
            self.uhd_usrp_sink_0.set_samp_rate(value)
            self.uhd_usrp_sink_0.set_antenna('TX/RX', 0)

            self.connect((self.blocks_add_xx_0, 0), (self.uhd_usrp_sink_0, 0))
    def change(self, sample_rate=None, amplitude=None, frequency=None, bandwidth=None, gain=None, center_frequency=None, usrpsamp_rate=None):

        if sample_rate is not None:
            self.change_sample_rate(sample_rate)

        if amplitude is not None:
            self.change_amplitude(amplitude)

        if frequency is not None:
            self.change_frequency(frequency)

        if bandwidth is not None:
            self.change_bandwidth(bandwidth)
        if gain is not None:
            self.change_gain(gain)

        if center_frequency is not None:
            self.change_center_frequency(center_frequency)

        if usrpsamp_rate is not None:
            self.change_usrpsamp_rate(usrpsamp_rate)

    def turn_off(self):
        self.change(0, 0, 0, 0, 0, 0, 0)


# -----------------------------------------------------------------------------

from flask import Flask, request, jsonify

app = Flask(__name__)

# start with default values 
#tb = top_block_22()
tb = top_block_22(32000, 0, 0, 0, 0, 0, 2e6)
tb.start(True)

@app.route('/')
def index():
    return '''<!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <title>GNURadio Slider Example</title>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
  <link href="https://cdnjs.cloudflare.com/ajax/libs/roundSlider/1.3.2/roundslider.min.css" rel="stylesheet" />
  <script src="https://cdnjs.cloudflare.com/ajax/libs/roundSlider/1.3.2/roundslider.min.js"></script>

<style>

.slider {
 position: absolute;
 align:center;
}    

.row1 {top:100px;}
.row2 {top:450px;}
.row3 {top:750px;}

.col1 {left:75px;}
.col2 {left:470px;}
.col3 {left:870px;}
.col1 {left:75px;}

</style>
</head>

<body>

<div id="slider1" class='slider row1 col1'></div>
<!--  <p>Sample Rate Slider</p> -->

<div id="slider2" class='slider row1 col2'></div>
<!--  <p>Amplitude Slider2</p> -->

<div id="slider3" class='slider row1 col3'></div>
<!-- <p>Frequency Slider3</p> -->

<div id="slider4" class='slider row2 col1'></div>
<!-- <p>Bandwidth Slider4</p>  -->

<div id="slider5" class='slider row2 col2'></div>
<!-- <p>Gain Slider5</p>  -->

<div id="slider6" class='slider row2 col3'></div>
<!-- <p>Center Frequency Slider6</p>  -->

<div id="slider7" class='slider row3 col1'></div>
<!-- <p>USRP Sample Rate Slider7</p>  -->

<button id="turn_off_button">TURN OFF</button>

<script>

  // create sliders

  $("#slider1").roundSlider({
    //sliderType: "min-range",
    radius: 150,
    min: 0,
    max: 1000000000000,
    value: 20000, // default value at start
    //change: function(event) { $.getJSON('/valueofslider', {slide1_val: event.value}); }
    change: function(event) { $.getJSON('/set_sample_rate/' + event.value); }
  });

  $("#slider2").roundSlider({
    //sliderType: "min-range",
    radius: 150,
    min: 0,
    max: 1000,
    value: 444, // default value at start

    //change: function(event) { $.getJSON('/valueofslider', {slide2_val: event.value}); }
    change: function(event) { $.getJSON('/set_amplitude/' + event.value); }
  });

  $("#slider3").roundSlider({
    radius: 150,
    min: 0,
    max: 10000000000,
    value: 350, // default value at start
    //change: function(event) { $.getJSON('/valueofslider', {slide3_val: event.value}); }
    change: function(event) { $.getJSON('/set_frequency/' + event.value); }
  });

  $("#slider4").roundSlider({
    radius: 150,
    min: 0,
    max: 10000,
    value: 75000, // default value at start
    //change: function(event) { $.getJSON('/valueofslider', {slide4_val: event.value}); }
    change: function(event) { $.getJSON('/set_bandwidth/' + event.value); }
  });

  $("#slider5").roundSlider({
    radius: 150,
    min: 0,
    max: 10000000000,
    value: 50, // default value at start
    //change: function(event) { $.getJSON('/valueofslider', {slide5_val: event.value}); }
    change: function(event) { $.getJSON('/set_gain/' + event.value); }
  });

  $("#slider6").roundSlider({
    radius: 150,
    min: 0,
    max: 10000000000,
    value: 880000000, // default value at start
    //change: function(event) { $.getJSON('/valueofslider', {slide6_val: event.value}); }
    change: function(event) { $.getJSON('/set_center_frequency/' + event.value); }
  });

  $("#slider7").roundSlider({
    radius: 150,
    min: 0,
    max: 10000000000,
    value: 16000000, // default value at start
    //change: function(event) { $.getJSON('/valueofslider', {slide7_val: event.value}); }
    change: function(event) { $.getJSON('/set_usrpsamp_rate/' + event.value); }
  });
  $("#turn_off_button").click(function(){
      // set sliders
      $("#slider1").data("roundSlider").setValue(0);
      $("#slider2").data("roundSlider").setValue(0);
      $("#slider3").data("roundSlider").setValue(0);
      $("#slider4").data("roundSlider").setValue(0);
      $("#slider5").data("roundSlider").setValue(0);
      $("#slider6").data("roundSlider").setValue(0);
      $("#slider7").data("roundSlider").setValue(0);

      // send to server
      $.getJSON('/valueofslider', {
        slide1_val: 0,
        slide2_val: 0,
        slide3_val: 0,
        slide4_val: 0,
        slide5_val: 0,
        slide6_val: 0,
        slide7_val: 0,
      });
  });

</script>

</body>
</html>'''

@app.route('/off')
def off():
    """Turn off sound."""
    tb.turn_off()
    #return jsonify({'val': 0})
    return 'off'

@app.route('/set_sample_rate/<int:value>')
def set_sample_rate(value):
    #sound(sample_rate=value)
    tb.change_sample_rate(value)
    #return jsonify({'sample_rate': value})
    return str(value)

@app.route('/set_amplitude/<int:value>')
def set_amplitude(value):
    #sound(amplitude=value)
    tb.change_amplitude(value)
    #return jsonify({'amplitude': value})
    return str(value)

@app.route('/set_frequency/<int:value>')
def set_frequency(value):
    #sound(frequency=value)
    tb.change_frequency(value)
    #return jsonify({'frequency': value})
    return str(value)

@app.route('/set_bandwidth/<int:value>')
def set_bandwidth(value):
    #sound(frequency=value)
    tb.change_bandwidth(value)
    #return jsonify({'frequency': value})
    return str(value)

@app.route('/set_gain/<int:value>')
def set_gain(value):
    #sound(frequency=value)
    tb.change_gain(value)
    #return jsonify({'frequency': value})
    return str(value)

@app.route('/set_center_frequency/<int:value>')
def set_center_frequency(value):
    #sound(frequency=value)
    tb.change_center_frequency(value)
    #return jsonify({'frequency': value})
    return str(value)

@app.route('/set_usrpsamp_rate/<int:value>')
def set_usrpsamp_rate(value):
    #sound(frequency=value)
    tb.change_usrpsamp_rate(value)
    #return jsonify({'frequency': value})
    return str(value)

@app.route('/valueofslider')
def slide():
    sample_rate = request.args.get('slide1_val', None)
    amplitude   = request.args.get('slide2_val', None)
    frequency   = request.args.get('slide3_val', None)
    bandwidth   = request.args.get('slide4_val', None)
    gain   = request.args.get('slide5_val', None)
    center_frequency   = request.args.get('slide6_val', None)
    usrpsamp_rate   = request.args.get('slide7_val', None)

    sound(
        sample_rate=sample_rate, 
        amplitude=amplitude, 
        frequency=frequency,
        bandwidth=bandwidth,
        gain=gain,
        center_frequency=center_frequency,
        usrpsamp_rate=usrpsamp_rate,

    )

    #return jsonify({
    #        'sample_rate': sample_rate, 
    #        'amplitude': amplitude,
    #        'frequency ': frequency ,
    #        'bandwidth': bandwidth, 
    #        'gain': gain,
    #        'center_frequency ': center_frequency ,
    #        'usrpsamp_rate ': usrpsamp_rate ,
    #        })

    return 'sample_rate: {}, amplitude: {}, frequency: {}, bandwidth: {}, gain: {}, center_frequency: {}, usrpsamp_rate: {}'.format(sample_rate, amplitude, frequency, bandwidth )

def sound(sample_rate=None, amplitude=None, frequency=None, bandwidth=None, gain=None, center_frequency=None, usrpsamp_rate=None):
    """version which uses `change()`"""

    if sample_rate is not None:
        sample_rate = int(sample_rate)
        tb.change_sample_rate(sample_rate)

    if amplitude is not None:
        amplitude = int(amplitude)
        tb.change_amplitude(amplitude)

    if frequency is not None:
        frequency = int(frequency )
        tb.change_frequency(frequency )

    if bandwidth is not None:
        bandwidth = int(bandwidth )
        tb.change_bandwidth(bandwidth )

    if gain is not None:
        gain = int(gain )
        tb.change_gain(gain )

    if center_frequency is not None:
        center_frequency = int(center_frequency )
        tb.change_center_frequency(center_frequency )

    if usrpsamp_rate is not None:
        usrpsamp_rate = int(usrpsamp_rate )
        tb.change_usrpsamp_rate(usrpsamp_rate )


    print('[sound] sample_rate:', sample_rate)
    print('[sound] amplitude:', amplitude)
    print('[sound] frequency:', frequency)
    print('[sound] bandwidth:', bandwidth)
    print('[sound] gain:', gain)
    print('[sound] center_frequency:', center_frequency)
    print('[sound] center_frequency:', usrpsamp_rate)
    #if tb: # if tb is not None
    #    tb.change(sample_rate, amplitude, frequency, bandwidth, gain, center_frequency, usrpsamp_rate)

if __name__ == '__main__':
    app.run(host='0.0.0.0', debug=True)

And here is the output report:

linux; GNU C++ version 7.3.0; Boost_106501; UHD_003.010.003.000-0-unknown

[top_block_22] __init__: sample_rate: 32000
[top_block_22] __init__: amplitude: 0
[top_block_22] __init__: frequency: 0
[top_block_22] __init__: bandwidth: 0
[top_block_22] __init__: usrpsamp_rate: 2000000.0
[top_block_22] __init__: gain: 0
[top_block_22] __init__: center_frequency: 0
gr::log :INFO: audio source - Audio sink arch: alsa
 * Serving Flask app "app" (lazy loading)
 * Environment: production
   WARNING: This is a development server. Do not use it in a production deployment.
   Use a production WSGI server instead.
 * Debug mode: on
 * Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)
 * Restarting with stat
linux; GNU C++ version 7.3.0; Boost_106501; UHD_003.010.003.000-0-unknown

[top_block_22] __init__: sample_rate: 32000
[top_block_22] __init__: amplitude: 0
[top_block_22] __init__: frequency: 0
[top_block_22] __init__: bandwidth: 0
[top_block_22] __init__: usrpsamp_rate: 2000000.0
[top_block_22] __init__: gain: 0
[top_block_22] __init__: center_frequency: 0
gr::log :INFO: audio source - Audio sink arch: alsa
 * Debugger is active!
 * Debugger PIN: 138-727-058
127.0.0.1 - - [12/Aug/2019 16:35:59] "GET / HTTP/1.1" 200 -
127.0.0.1 - - [12/Aug/2019 16:36:07] "GET /set_sample_rate/33333 HTTP/1.1" 200 -
127.0.0.1 - - [12/Aug/2019 16:36:12] "GET /set_amplitude/433 HTTP/1.1" 200 -
127.0.0.1 - - [12/Aug/2019 16:36:17] "GET /set_frequency/355 HTTP/1.1" 200 -
[top_block_22] change: sample_rate: 33333
[top_block_22] change: amplitude: 0.0433
[top_block_22] change: frequency: 355
[top_block_22] change: bandwidth: 1000
-- Detected Device: B200mini
-- Operating over USB 2.
-- Initialize CODEC control...
-- Initialize Radio control...
-- Performing register loopback test... pass
-- Performing CODEC loopback test... pass
-- Setting master clock rate selection to 'automatic'.
-- Asking for clock rate 16.000000 MHz... 
-- Actually got clock rate 16.000000 MHz.
-- Performing timer loopback test... pass
127.0.0.1 - - [12/Aug/2019 16:36:33] "GET /set_bandwidth/1000 HTTP/1.1" 200 -
127.0.0.1 - - [12/Aug/2019 16:36:38] "GET /set_gain/55 HTTP/1.1" 200 -
127.0.0.1 - - [12/Aug/2019 16:36:59] "GET /set_center_frequency/870000000 HTTP/1.1" 200 -
[top_block_22] change: gain: 55
[top_block_22] change: center_frequency: 870000000
[top_block_22] change: usrpsamp_rate: 15900000
-- Asking for clock rate 15.900000 MHz... 
-- Actually got clock rate 15.900000 MHz.
-- Performing timer loopback test... pass
127.0.0.1 - - [12/Aug/2019 16:37:09] "GET /set_usrpsamp_rate/15900000 HTTP/1.1" 200 -