commit 05df7a7c021fbd96c52c35e9bc9f61c7921d3c73
Author: Sebastian <sebastian@sebastians-site.de>
Date:   Sun Nov 21 21:31:56 2021 +0100

    First working proof of concept

diff --git a/costas.c b/costas.c
new file mode 100644
index 0000000..441b2d0
--- /dev/null
+++ b/costas.c
@@ -0,0 +1,96 @@
+#include <liquid/liquid.h>
+#include <math.h>
+#include <complex.h>
+#include <stdio.h>
+
+const float SAMPLINGRATE = 100000.0;
+const float EXPECTED_CENTER = 25000.0;
+
+// 15khz lowpass
+float LOWPASS_COEFFS[37] = {
+    -0.0013484122464433312,-0.0015524507034569979,-0.0012626417446881533,
+    1.106597777377648e-18,0.0025128561537712812,0.005701862741261721,
+    0.007837646640837193,0.006523041054606438,-3.595113471383589e-18,
+    -0.011250422336161137,-0.02350831776857376,-0.03022352233529091,
+    -0.02406340278685093,6.529514774129222e-18,0.04183189943432808,
+    0.09489838778972626,0.14748811721801758,0.18619666993618011,
+    0.20043739676475525,0.18619666993618011,0.14748811721801758,
+    0.09489838778972626,0.04183189943432808,6.529514774129222e-18,
+    -0.02406340278685093,-0.03022352233529091,-0.02350831776857376,
+    -0.011250422336161137,-3.595113471383589e-18,0.006523041054606438,
+    0.007837646640837193,0.005701862741261721,0.0025128561537712812,
+    1.106597777377648e-18,-0.0012626417446881533,-0.0015524507034569979,
+    -0.0013484122464433312
+};
+
+int main() {
+
+    // create the NCO object
+    nco_crcf downmix = nco_crcf_create(LIQUID_NCO);
+    nco_crcf_set_phase(downmix, 0.0f);
+    float freq = -(2 * M_PI * EXPECTED_CENTER) / SAMPLINGRATE;
+    nco_crcf_set_frequency(downmix, freq);
+
+    nco_crcf costas_vco = nco_crcf_create(LIQUID_VCO);
+    nco_crcf_set_phase(costas_vco, 0.0f);
+    nco_crcf_set_frequency(costas_vco, 0);
+
+
+    firfilt_rrrf r_fir = firfilt_rrrf_create(LOWPASS_COEFFS, 37);
+    firfilt_rrrf i_fir = firfilt_rrrf_create(LOWPASS_COEFFS, 37);
+
+    // output complex exponential
+    float complex x;
+
+    FILE* output = fopen("output.raw", "w");
+    FILE* input = fopen("wobble.raw", "r");
+
+    float vco_freq = 0.0;
+
+    float in[2];
+    while(fread(in, sizeof(float), 2, input) == 2) {
+        // increment internal phase
+        nco_crcf_step(downmix);
+        // compute complex exponential
+        nco_crcf_cexpf(downmix, &x);
+
+        float complex y;
+        nco_crcf_step(costas_vco);
+        nco_crcf_cexpf(costas_vco, &y);
+
+        float complex input_sample = (in[0] + I * in[1]);
+        float complex downmix_sample = input_sample * x;
+        float complex costas_sample = downmix_sample * y;
+        float complex output_sample = input_sample * y;
+
+        float r_sample = creal(costas_sample);
+        float i_sample = cimag(costas_sample);
+
+        firfilt_rrrf_push(r_fir, r_sample);    // push input sample
+        firfilt_rrrf_execute(r_fir,&r_sample); // compute output
+
+        firfilt_rrrf_push(i_fir, i_sample);    // push input sample
+        firfilt_rrrf_execute(i_fir,&i_sample); // compute output
+
+        float error = i_sample * r_sample;
+        vco_freq += error * 0.1;
+
+        nco_crcf_set_frequency(costas_vco, -vco_freq);
+
+        float buffer[] = {creal(output_sample), cimag(output_sample)};
+        fwrite(buffer, sizeof(float), 2, output);
+    }
+
+    // destroy nco object
+    nco_crcf_destroy(downmix);
+    nco_crcf_destroy(costas_vco);
+
+    firfilt_rrrf_destroy(r_fir);
+    firfilt_rrrf_destroy(i_fir);
+
+    fclose(output);
+    fclose(input);
+
+
+    return 0;
+}
diff --git a/oszi.grc b/oszi.grc
new file mode 100644
index 0000000..f3977b9
--- /dev/null
+++ b/oszi.grc
@@ -0,0 +1,191 @@
+options:
+  parameters:
+    author: sebastian
+    catch_exceptions: 'True'
+    category: '[GRC Hier Blocks]'
+    cmake_opt: ''
+    comment: ''
+    copyright: ''
+    description: ''
+    gen_cmake: 'On'
+    gen_linking: dynamic
+    generate_options: qt_gui
+    hier_block_src_path: '.:'
+    id: oszi
+    max_nouts: '0'
+    output_language: python
+    placement: (0,0)
+    qt_qss_theme: ''
+    realtime_scheduling: ''
+    run: 'True'
+    run_command: '{python} -u {filename}'
+    run_options: prompt
+    sizing_mode: fixed
+    thread_safe_setters: ''
+    title: Not titled yet
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [8, 8]
+    rotation: 0
+    state: enabled
+
+blocks:
+- name: samp_rate
+  id: variable
+  parameters:
+    comment: ''
+    value: '100000'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [184, 12]
+    rotation: 0
+    state: enabled
+- name: blocks_file_source_0
+  id: blocks_file_source
+  parameters:
+    affinity: ''
+    alias: ''
+    begin_tag: pmt.PMT_NIL
+    comment: ''
+    file: /home/sebastian/projects/QO100-trx/prototypes/output.raw
+    length: '0'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    offset: '0'
+    repeat: 'False'
+    type: float
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [96, 180.0]
+    rotation: 0
+    state: true
+- name: blocks_throttle_0
+  id: blocks_throttle
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    ignoretag: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    samples_per_second: samp_rate
+    type: float
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [328, 196.0]
+    rotation: 0
+    state: true
+- name: qtgui_time_sink_x_0
+  id: qtgui_time_sink_x
+  parameters:
+    affinity: ''
+    alias: ''
+    alpha1: '1.0'
+    alpha10: '1.0'
+    alpha2: '1.0'
+    alpha3: '1.0'
+    alpha4: '1.0'
+    alpha5: '1.0'
+    alpha6: '1.0'
+    alpha7: '1.0'
+    alpha8: '1.0'
+    alpha9: '1.0'
+    autoscale: 'False'
+    axislabels: 'True'
+    color1: blue
+    color10: dark blue
+    color2: red
+    color3: green
+    color4: black
+    color5: cyan
+    color6: magenta
+    color7: yellow
+    color8: dark red
+    color9: dark green
+    comment: ''
+    ctrlpanel: 'False'
+    entags: 'True'
+    grid: 'False'
+    gui_hint: ''
+    label1: Signal 1
+    label10: Signal 10
+    label2: Signal 2
+    label3: Signal 3
+    label4: Signal 4
+    label5: Signal 5
+    label6: Signal 6
+    label7: Signal 7
+    label8: Signal 8
+    label9: Signal 9
+    legend: 'True'
+    marker1: '-1'
+    marker10: '-1'
+    marker2: '-1'
+    marker3: '-1'
+    marker4: '-1'
+    marker5: '-1'
+    marker6: '-1'
+    marker7: '-1'
+    marker8: '-1'
+    marker9: '-1'
+    name: '""'
+    nconnections: '1'
+    size: '1024'
+    srate: samp_rate
+    stemplot: 'False'
+    style1: '1'
+    style10: '1'
+    style2: '1'
+    style3: '1'
+    style4: '1'
+    style5: '1'
+    style6: '1'
+    style7: '1'
+    style8: '1'
+    style9: '1'
+    tr_chan: '0'
+    tr_delay: '0'
+    tr_level: '0.0'
+    tr_mode: qtgui.TRIG_MODE_FREE
+    tr_slope: qtgui.TRIG_SLOPE_POS
+    tr_tag: '""'
+    type: float
+    update_time: '0.10'
+    width1: '1'
+    width10: '1'
+    width2: '1'
+    width3: '1'
+    width4: '1'
+    width5: '1'
+    width6: '1'
+    width7: '1'
+    width8: '1'
+    width9: '1'
+    ylabel: Amplitude
+    ymax: '1'
+    ymin: '-1'
+    yunit: '""'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [544, 172.0]
+    rotation: 0
+    state: true
+
+connections:
+- [blocks_file_source_0, '0', blocks_throttle_0, '0']
+- [blocks_throttle_0, '0', qtgui_time_sink_x_0, '0']
+
+metadata:
+  file_format: 1
diff --git a/view_waterfall.grc b/view_waterfall.grc
new file mode 100644
index 0000000..bba1fbd
--- /dev/null
+++ b/view_waterfall.grc
@@ -0,0 +1,341 @@
+options:
+  parameters:
+    author: ''
+    catch_exceptions: 'True'
+    category: '[GRC Hier Blocks]'
+    cmake_opt: ''
+    comment: ''
+    copyright: ''
+    description: ''
+    gen_cmake: 'On'
+    gen_linking: dynamic
+    generate_options: qt_gui
+    hier_block_src_path: '.:'
+    id: view_waterfall
+    max_nouts: '0'
+    output_language: python
+    placement: (0,0)
+    qt_qss_theme: ''
+    realtime_scheduling: ''
+    run: 'True'
+    run_command: '{python} -u {filename}'
+    run_options: prompt
+    sizing_mode: fixed
+    thread_safe_setters: ''
+    title: Not titled yet
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [8, 8]
+    rotation: 0
+    state: enabled
+
+blocks:
+- name: samp_rate
+  id: variable
+  parameters:
+    comment: ''
+    value: '100000'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [184, 12]
+    rotation: 0
+    state: enabled
+- name: blocks_file_source_0
+  id: blocks_file_source
+  parameters:
+    affinity: ''
+    alias: ''
+    begin_tag: pmt.PMT_NIL
+    comment: ''
+    file: /home/sebastian/projects/QO100-trx/prototypes/output.raw
+    length: '0'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    offset: '0'
+    repeat: 'False'
+    type: complex
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [184, 212.0]
+    rotation: 0
+    state: true
+- name: blocks_file_source_0_0
+  id: blocks_file_source
+  parameters:
+    affinity: ''
+    alias: ''
+    begin_tag: pmt.PMT_NIL
+    comment: ''
+    file: /home/sebastian/projects/QO100-trx/prototypes/wobble.raw
+    length: '0'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    offset: '0'
+    repeat: 'False'
+    type: complex
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [184, 92.0]
+    rotation: 0
+    state: true
+- name: blocks_throttle_0
+  id: blocks_throttle
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    ignoretag: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    samples_per_second: samp_rate
+    type: complex
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [496, 244.0]
+    rotation: 0
+    state: true
+- name: blocks_throttle_1
+  id: blocks_throttle
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    ignoretag: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    samples_per_second: samp_rate
+    type: complex
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [400, 124.0]
+    rotation: 0
+    state: true
+- name: qtgui_freq_sink_x_0
+  id: qtgui_freq_sink_x
+  parameters:
+    affinity: ''
+    alias: ''
+    alpha1: '1.0'
+    alpha10: '1.0'
+    alpha2: '1.0'
+    alpha3: '1.0'
+    alpha4: '1.0'
+    alpha5: '1.0'
+    alpha6: '1.0'
+    alpha7: '1.0'
+    alpha8: '1.0'
+    alpha9: '1.0'
+    autoscale: 'False'
+    average: '1.0'
+    axislabels: 'True'
+    bw: samp_rate
+    color1: '"blue"'
+    color10: '"dark blue"'
+    color2: '"red"'
+    color3: '"green"'
+    color4: '"black"'
+    color5: '"cyan"'
+    color6: '"magenta"'
+    color7: '"yellow"'
+    color8: '"dark red"'
+    color9: '"dark green"'
+    comment: ''
+    ctrlpanel: 'False'
+    fc: '0'
+    fftsize: '4096'
+    freqhalf: 'True'
+    grid: 'False'
+    gui_hint: ''
+    label: Relative Gain
+    label1: ''
+    label10: ''''''
+    label2: ''''''
+    label3: ''''''
+    label4: ''''''
+    label5: ''''''
+    label6: ''''''
+    label7: ''''''
+    label8: ''''''
+    label9: ''''''
+    legend: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    name: '""'
+    nconnections: '1'
+    norm_window: 'False'
+    showports: 'False'
+    tr_chan: '0'
+    tr_level: '0.0'
+    tr_mode: qtgui.TRIG_MODE_FREE
+    tr_tag: '""'
+    type: complex
+    units: dB
+    update_time: '0.10'
+    width1: '1'
+    width10: '1'
+    width2: '1'
+    width3: '1'
+    width4: '1'
+    width5: '1'
+    width6: '1'
+    width7: '1'
+    width8: '1'
+    width9: '1'
+    wintype: window.WIN_BLACKMAN_hARRIS
+    ymax: '10'
+    ymin: '-140'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [712, 156.0]
+    rotation: 0
+    state: true
+- name: qtgui_waterfall_sink_x_0
+  id: qtgui_waterfall_sink_x
+  parameters:
+    affinity: ''
+    alias: ''
+    alpha1: '1.0'
+    alpha10: '1.0'
+    alpha2: '1.0'
+    alpha3: '1.0'
+    alpha4: '1.0'
+    alpha5: '1.0'
+    alpha6: '1.0'
+    alpha7: '1.0'
+    alpha8: '1.0'
+    alpha9: '1.0'
+    axislabels: 'True'
+    bw: samp_rate
+    color1: '0'
+    color10: '0'
+    color2: '0'
+    color3: '0'
+    color4: '0'
+    color5: '0'
+    color6: '0'
+    color7: '0'
+    color8: '0'
+    color9: '0'
+    comment: ''
+    fc: '0'
+    fftsize: '4096'
+    freqhalf: 'True'
+    grid: 'False'
+    gui_hint: ''
+    int_max: '10'
+    int_min: '-140'
+    label1: ''
+    label10: ''
+    label2: ''
+    label3: ''
+    label4: ''
+    label5: ''
+    label6: ''
+    label7: ''
+    label8: ''
+    label9: ''
+    legend: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    name: '""'
+    nconnections: '1'
+    showports: 'False'
+    type: complex
+    update_time: '0.10'
+    wintype: window.WIN_BLACKMAN_hARRIS
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [704, 348.0]
+    rotation: 0
+    state: true
+- name: qtgui_waterfall_sink_x_0_0
+  id: qtgui_waterfall_sink_x
+  parameters:
+    affinity: ''
+    alias: ''
+    alpha1: '1.0'
+    alpha10: '1.0'
+    alpha2: '1.0'
+    alpha3: '1.0'
+    alpha4: '1.0'
+    alpha5: '1.0'
+    alpha6: '1.0'
+    alpha7: '1.0'
+    alpha8: '1.0'
+    alpha9: '1.0'
+    axislabels: 'True'
+    bw: samp_rate
+    color1: '0'
+    color10: '0'
+    color2: '0'
+    color3: '0'
+    color4: '0'
+    color5: '0'
+    color6: '0'
+    color7: '0'
+    color8: '0'
+    color9: '0'
+    comment: ''
+    fc: '0'
+    fftsize: '4096'
+    freqhalf: 'True'
+    grid: 'False'
+    gui_hint: ''
+    int_max: '10'
+    int_min: '-140'
+    label1: ''
+    label10: ''
+    label2: ''
+    label3: ''
+    label4: ''
+    label5: ''
+    label6: ''
+    label7: ''
+    label8: ''
+    label9: ''
+    legend: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    name: '""'
+    nconnections: '1'
+    showports: 'False'
+    type: complex
+    update_time: '0.10'
+    wintype: window.WIN_BLACKMAN_hARRIS
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [696, 60.0]
+    rotation: 0
+    state: true
+
+connections:
+- [blocks_file_source_0, '0', blocks_throttle_0, '0']
+- [blocks_file_source_0_0, '0', blocks_throttle_1, '0']
+- [blocks_throttle_0, '0', qtgui_freq_sink_x_0, '0']
+- [blocks_throttle_0, '0', qtgui_waterfall_sink_x_0, '0']
+- [blocks_throttle_1, '0', qtgui_waterfall_sink_x_0_0, '0']
+
+metadata:
+  file_format: 1
diff --git a/wobble.grc b/wobble.grc
new file mode 100644
index 0000000..c420fac
--- /dev/null
+++ b/wobble.grc
@@ -0,0 +1,277 @@
+options:
+  parameters:
+    author: sebastian
+    catch_exceptions: 'True'
+    category: '[GRC Hier Blocks]'
+    cmake_opt: ''
+    comment: ''
+    copyright: ''
+    description: ''
+    gen_cmake: 'On'
+    gen_linking: dynamic
+    generate_options: qt_gui
+    hier_block_src_path: '.:'
+    id: wobble
+    max_nouts: '0'
+    output_language: python
+    placement: (0,0)
+    qt_qss_theme: ''
+    realtime_scheduling: ''
+    run: 'True'
+    run_command: '{python} -u {filename}'
+    run_options: prompt
+    sizing_mode: fixed
+    thread_safe_setters: ''
+    title: Not titled yet
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [8, 8]
+    rotation: 0
+    state: enabled
+
+blocks:
+- name: samp_rate
+  id: variable
+  parameters:
+    comment: ''
+    value: '100000'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [184, 12]
+    rotation: 0
+    state: enabled
+- name: analog_sig_source_x_0
+  id: analog_sig_source_x
+  parameters:
+    affinity: ''
+    alias: ''
+    amp: '0.5'
+    comment: ''
+    freq: 25000-2500
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    offset: '0'
+    phase: '0'
+    samp_rate: samp_rate
+    type: complex
+    waveform: analog.GR_COS_WAVE
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [368, 92.0]
+    rotation: 0
+    state: enabled
+- name: analog_sig_source_x_1
+  id: analog_sig_source_x
+  parameters:
+    affinity: ''
+    alias: ''
+    amp: '0.5'
+    comment: ''
+    freq: 25000+2500
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    offset: '0'
+    phase: '0'
+    samp_rate: samp_rate
+    type: complex
+    waveform: analog.GR_COS_WAVE
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [368, 236.0]
+    rotation: 0
+    state: true
+- name: analog_sig_source_x_1_0
+  id: analog_sig_source_x
+  parameters:
+    affinity: ''
+    alias: ''
+    amp: '1'
+    comment: ''
+    freq: '0.05'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    offset: '-0.5'
+    phase: '0'
+    samp_rate: samp_rate
+    type: float
+    waveform: analog.GR_TRI_WAVE
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [368, 380.0]
+    rotation: 0
+    state: true
+- name: blocks_add_xx_0
+  id: blocks_add_xx
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    num_inputs: '2'
+    type: complex
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [672, 200.0]
+    rotation: 0
+    state: enabled
+- name: blocks_file_sink_0
+  id: blocks_file_sink
+  parameters:
+    affinity: ''
+    alias: ''
+    append: 'False'
+    comment: ''
+    file: /home/sebastian/projects/QO100-trx/prototypes/wobble.raw
+    type: complex
+    unbuffered: 'False'
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [1344, 340.0]
+    rotation: 0
+    state: true
+- name: blocks_multiply_xx_0
+  id: blocks_multiply_xx
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    num_inputs: '2'
+    type: complex
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [880, 280.0]
+    rotation: 0
+    state: true
+- name: blocks_throttle_0
+  id: blocks_throttle
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    ignoretag: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    samples_per_second: samp_rate
+    type: complex
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [1152, 228.0]
+    rotation: 0
+    state: true
+- name: blocks_vco_c_0
+  id: blocks_vco_c
+  parameters:
+    affinity: ''
+    alias: ''
+    amplitude: '1.0'
+    comment: ''
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    samp_rate: samp_rate
+    sensitivity: '60000'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [616, 404.0]
+    rotation: 0
+    state: true
+- name: qtgui_waterfall_sink_x_0
+  id: qtgui_waterfall_sink_x
+  parameters:
+    affinity: ''
+    alias: ''
+    alpha1: '1.0'
+    alpha10: '1.0'
+    alpha2: '1.0'
+    alpha3: '1.0'
+    alpha4: '1.0'
+    alpha5: '1.0'
+    alpha6: '1.0'
+    alpha7: '1.0'
+    alpha8: '1.0'
+    alpha9: '1.0'
+    axislabels: 'True'
+    bw: samp_rate
+    color1: '0'
+    color10: '0'
+    color2: '0'
+    color3: '0'
+    color4: '0'
+    color5: '0'
+    color6: '0'
+    color7: '0'
+    color8: '0'
+    color9: '0'
+    comment: ''
+    fc: '0'
+    fftsize: '4096'
+    freqhalf: 'True'
+    grid: 'False'
+    gui_hint: ''
+    int_max: '10'
+    int_min: '-140'
+    label1: ''
+    label10: ''
+    label2: ''
+    label3: ''
+    label4: ''
+    label5: ''
+    label6: ''
+    label7: ''
+    label8: ''
+    label9: ''
+    legend: 'True'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    name: '""'
+    nconnections: '1'
+    showports: 'False'
+    type: complex
+    update_time: '0.10'
+    wintype: window.WIN_BLACKMAN_hARRIS
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [1352, 212.0]
+    rotation: 0
+    state: true
+
+connections:
+- [analog_sig_source_x_0, '0', blocks_add_xx_0, '0']
+- [analog_sig_source_x_1, '0', blocks_add_xx_0, '1']
+- [analog_sig_source_x_1_0, '0', blocks_vco_c_0, '0']
+- [blocks_add_xx_0, '0', blocks_multiply_xx_0, '0']
+- [blocks_multiply_xx_0, '0', blocks_throttle_0, '0']
+- [blocks_throttle_0, '0', blocks_file_sink_0, '0']
+- [blocks_throttle_0, '0', qtgui_waterfall_sink_x_0, '0']
+- [blocks_vco_c_0, '0', blocks_multiply_xx_0, '1']
+
+metadata:
+  file_format: 1