gr-correctiq DC Spike Correction

A synthetic direct-conversion receiver signal with a controllable DC offset. The blue trace is the raw spectrum, whose offset appears as a spike at 0 Hz; the red trace passes through gr-correctiq's continuously adapting estimator, which removes the spike without offset tuning. Change DC offset amplitude while the graph runs to watch the correction follow it.

Author Marc
Category gr-correctiq
Blocks 7
Connections 4
File gr-correctiq/dc_spike_correction.grc

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Blocks used

Block	Module	Used
CorrectIQ	`gr-correctiq`	1
GUI Layout	`GNU Radio`	1
QT GUI Frequency Sink	`GNU Radio`	1
QT GUI Range	`GNU Radio`	1
Signal Source	`GNU Radio`	1
Throttle	`GNU Radio`	1
Variable	`GNU Radio`	1

Flowgraph source

gr-correctiq/dc_spike_correction.grc

options:
    parameters:
        author: Marc
        comment: ''
        copyright: ''
        description: A synthetic direct-conversion receiver signal with a controllable DC offset. The blue trace is the raw spectrum, whose offset appears as a spike at 0 Hz; the red trace passes through gr-correctiq's continuously adapting estimator, which removes the spike without offset tuning. Change DC offset amplitude while the graph runs to watch the correction follow it.
        generate_options: qt_gui
        id: gr_correctiq_DC_Spike_Correction
        title: gr-correctiq DC Spike Correction
    states:
        coordinate: [10, 10]
        rotation: 0
        state: enabled
blocks:
-   name: dc_offset
    id: variable_qtgui_range
    parameters:
        comment: Simulates local-oscillator leakage in a direct-conversion receiver
        label: DC offset amplitude
        min_len: '200'
        orient: QtCore.Qt.Horizontal
        rangeType: float
        start: '0'
        step: '0.05'
        stop: '1'
        value: '0.35'
        widget: counter_slider
    states:
        coordinate: [590, 10]
        rotation: 0
        state: enabled
-   name: samp_rate
    id: variable
    parameters:
        comment: ''
        value: '32000'
    states:
        coordinate: [880, 10]
        rotation: 0
        state: enabled
-   name: corrected
    id: correctiq_correctiq
    parameters:
        affinity: ''
        alias: ''
        comment: Continuously estimates and subtracts the mean I and Q values
        maxoutbuf: '0'
        minoutbuf: '0'
    states:
        coordinate: [690, 250]
        rotation: 0
        state: enabled
-   name: source
    id: analog_sig_source_x
    parameters:
        affinity: ''
        alias: ''
        amp: '0.5'
        comment: A 4 kHz signal plus complex DC offset
        freq: '4000'
        maxoutbuf: '0'
        minoutbuf: '0'
        offset: dc_offset
        phase: '0'
        samp_rate: samp_rate
        type: complex
        waveform: analog.GR_COS_WAVE
    states:
        coordinate: [10, 210]
        rotation: 0
        state: enabled
-   name: spectrum
    id: qtgui_freq_sink_x
    parameters:
        affinity: ''
        alias: ''
        alpha1: '1'
        alpha10: '1'
        alpha2: '1'
        alpha3: '1'
        alpha4: '1'
        alpha5: '1'
        alpha6: '1'
        alpha7: '1'
        alpha8: '1'
        alpha9: '1'
        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: Blue is raw; red is corrected
        ctrlpanel: 'False'
        fc: '0'
        fftsize: '1024'
        freqhalf: 'True'
        grid: 'False'
        label: Relative Gain
        label1: ''
        label10: ''
        label2: ''
        label3: ''
        label4: ''
        label5: ''
        label6: ''
        label7: ''
        label8: ''
        label9: ''
        legend: 'True'
        marker1: '-1'
        marker10: '-1'
        marker2: '-1'
        marker3: '-1'
        marker4: '-1'
        marker5: '-1'
        marker6: '-1'
        marker7: '-1'
        marker8: '-1'
        marker9: '-1'
        maxoutbuf: '0'
        minoutbuf: '0'
        name: '"Raw vs corrected"'
        nconnections: '2'
        norm_window: '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_level: '0'
        tr_mode: qtgui.TRIG_MODE_FREE
        tr_tag: ''
        type: complex
        units: dB
        update_time: '0.1'
        width1: '1'
        width10: '1'
        width2: '1'
        width3: '1'
        width4: '1'
        width5: '1'
        width6: '1'
        width7: '1'
        width8: '1'
        width9: '1'
        wintype: window.WIN_RECTANGULAR
        ymax: '10'
        ymin: '-140'
    states:
        coordinate: [940, 220]
        rotation: 0
        state: enabled
-   name: throttle
    id: blocks_throttle2
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        ignoretag: 'True'
        limit: time
        maximum: '0.05'
        maxoutbuf: '0'
        minoutbuf: '0'
        samples_per_second: samp_rate
        type: complex
        vlen: '1'
    states:
        coordinate: [360, 230]
        rotation: 0
        state: enabled
-   name: wasm_gui_layout_0
    id: wasm_gui_layout
    parameters:
        affinity: ''
        alias: ''
        columns: '12'
        comment: ''
        layout: '{}'
        row_height: '60'
    states:
        coordinate: [300, 10]
        rotation: 0
        state: enabled
connections:
- [corrected, '0', spectrum, '1']
- [source, '0', throttle, '0']
- [throttle, '0', corrected, '0']
- [throttle, '0', spectrum, '0']
metadata:
    file_format: 1
    grc_version: 3.11.0.0