diff --git a/onbeat_tx_audio.grc b/onbeat_tx_audio.grc
new file mode 100644
index 0000000..ebf7d09
--- /dev/null
+++ b/onbeat_tx_audio.grc
@@ -0,0 +1,359 @@
+options:
+  parameters:
+    author: HA5PLS
+    catch_exceptions: 'True'
+    category: '[GRC Hier Blocks]'
+    cmake_opt: ''
+    comment: ''
+    copyright: GPL 3.0 or later
+    description: Transmitter flowgraph for onbeat
+    gen_cmake: 'On'
+    gen_linking: dynamic
+    generate_options: qt_gui
+    hier_block_src_path: '.:'
+    id: onbeat_tx
+    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: ONBEAT transmitter - audio
+    window_size: (1000,1000)
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [8, 8]
+    rotation: 0
+    state: enabled
+
+blocks:
+- name: OVERSAMPLING
+  id: variable
+  parameters:
+    comment: ''
+    value: '24'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [288, 12.0]
+    rotation: 0
+    state: enabled
+- name: RRC_ALPHA
+  id: variable
+  parameters:
+    comment: ''
+    value: '0.35'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [816, 12.0]
+    rotation: 0
+    state: enabled
+- name: samp_rate
+  id: variable
+  parameters:
+    comment: ''
+    value: '48000'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [192, 12.0]
+    rotation: 0
+    state: enabled
+- name: symbol_map
+  id: variable
+  parameters:
+    comment: ''
+    value: '[0, 1, 3, 2]'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [712, 12.0]
+    rotation: 0
+    state: enabled
+- name: ONBEAT_Mod_0
+  id: ONBEAT_Mod
+  parameters:
+    OVERSAMPLING: OVERSAMPLING
+    RRC_ALPHA: RRC_ALPHA
+    affinity: ''
+    alias: ''
+    comment: ''
+    data_len: '1'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    preamble: '[0x33 for i in range(0, 128*2, 8)]'
+    syncword: syncword
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [480, 268.0]
+    rotation: 0
+    state: enabled
+- name: analog_sig_source_x_0
+  id: analog_sig_source_x
+  parameters:
+    affinity: ''
+    alias: ''
+    amp: '1'
+    comment: ''
+    freq: 2700/2
+    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: [480, 404.0]
+    rotation: 0
+    state: enabled
+- name: audio_sink_0
+  id: audio_sink
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    device_name: ''
+    num_inputs: '1'
+    ok_to_block: 'True'
+    samp_rate: samp_rate
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [1344, 356.0]
+    rotation: 0
+    state: true
+- name: blocks_complex_to_real_0
+  id: blocks_complex_to_real
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [912, 360.0]
+    rotation: 0
+    state: enabled
+- name: blocks_multiply_const_xx_0
+  id: blocks_multiply_const_xx
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    const: '0.1'
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    type: float
+    vlen: '1'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [1104, 356.0]
+    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: [768, 344.0]
+    rotation: 0
+    state: true
+- name: network_socket_pdu_1
+  id: network_socket_pdu
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    host: 0.0.0.0
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    mtu: '10000'
+    port: tx_port
+    tcp_no_delay: 'False'
+    type: TCP_SERVER
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [40, 276.0]
+    rotation: 0
+    state: enabled
+- name: pdu_pdu_to_tagged_stream_0
+  id: pdu_pdu_to_tagged_stream
+  parameters:
+    affinity: ''
+    alias: ''
+    comment: ''
+    maxoutbuf: '0'
+    minoutbuf: '0'
+    tag: packet_len
+    type: byte
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [240, 300.0]
+    rotation: 0
+    state: enabled
+- name: qtgui_freq_sink_x_0_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: '1024'
+    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: float
+    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: [1260.0, 432]
+    rotation: 270
+    state: true
+- name: syncword
+  id: parameter
+  parameters:
+    alias: ''
+    comment: ''
+    hide: none
+    label: ''
+    short_id: ''
+    type: ''
+    value: '"0000011100001001000110110010110101110111100110001010100111111010"'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [448, 12.0]
+    rotation: 0
+    state: enabled
+- name: tx_port
+  id: parameter
+  parameters:
+    alias: ''
+    comment: ''
+    hide: none
+    label: ''
+    short_id: ''
+    type: str
+    value: '50001'
+  states:
+    bus_sink: false
+    bus_source: false
+    bus_structure: null
+    coordinate: [40, 180.0]
+    rotation: 0
+    state: enabled
+
+connections:
+- [ONBEAT_Mod_0, '0', blocks_multiply_xx_0, '0']
+- [analog_sig_source_x_0, '0', blocks_multiply_xx_0, '1']
+- [blocks_complex_to_real_0, '0', blocks_multiply_const_xx_0, '0']
+- [blocks_multiply_const_xx_0, '0', audio_sink_0, '0']
+- [blocks_multiply_const_xx_0, '0', qtgui_freq_sink_x_0_0, '0']
+- [blocks_multiply_xx_0, '0', blocks_complex_to_real_0, '0']
+- [network_socket_pdu_1, pdus, pdu_pdu_to_tagged_stream_0, pdus]
+- [pdu_pdu_to_tagged_stream_0, '0', ONBEAT_Mod_0, '0']
+
+metadata:
+  file_format: 1