TEMPEST from a VGA Recording

Recovers the picture on a VGA monitor from a recording of the emissions its cable leaks (TEMPEST), using gr-tempest. The screen was 1024x768 @ 60 Hz, sampled at 30 MS/s by a USRP B200; only 620 of every 1344-pixel line fit in that bandwidth, so the recovered frame is 620 samples wide. Fine Sampling Synchronization locks to the line and frame periods, the two Delays pan the frame, Normalize Flow maps magnitude to 0..255 luma, and Framing crops the vertical blanking before the Video Sink paints it.

Author Marc
Category gr-tempest
Blocks 20
Connections 8
File gr-tempest/tempest_vga_recording.grc

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Blocks used

Block	Module	Used
Variable	`GNU Radio`	8
Delay	`GNU Radio`	2
QT GUI Range	`GNU Radio`	2
Complex to Mag	`GNU Radio`	1
Fine sampling synchronization	`gr-tempest`	1
Framing	`gr-tempest`	1
GR World Recording	`GNU Radio`	1
GUI Layout	`GNU Radio`	1
IShort To Complex	`GNU Radio`	1
Normalize Flow	`gr-tempest`	1
Video Sink	`GNU Radio`	1

Flowgraph source

gr-tempest/tempest_vga_recording.grc

options:
    parameters:
        author: Marc
        comment: ''
        copyright: ''
        description: Recovers the picture on a VGA monitor from a recording of the emissions its cable leaks (TEMPEST), using gr-tempest. The screen was 1024x768 @ 60 Hz, sampled at 30 MS/s by a USRP B200; only 620 of every 1344-pixel line fit in that bandwidth, so the recovered frame is 620 samples wide. Fine Sampling Synchronization locks to the line and frame periods, the two Delays pan the frame, Normalize Flow maps magnitude to 0..255 luma, and Framing crops the vertical blanking before the Video Sink paints it.
        generate_options: qt_gui
        id: TEMPEST_from_a_VGA_Recording
        title: TEMPEST from a VGA Recording
    states:
        coordinate: [10, 10]
        rotation: 0
        state: enabled
blocks:
-   name: Hdisplay
    id: variable
    parameters:
        comment: Visible pixels per line on the spied screen
        value: '1024'
    states:
        coordinate: [590, 10]
        rotation: 0
        state: enabled
-   name: Hsize
    id: variable
    parameters:
        comment: Total pixels per line, blanking included (1024x768@60 is 1344x806)
        value: '1344'
    states:
        coordinate: [760, 10]
        rotation: 0
        state: enabled
-   name: Vdisplay
    id: variable
    parameters:
        comment: Visible lines on the spied screen
        value: '768'
    states:
        coordinate: [930, 10]
        rotation: 0
        state: enabled
-   name: Vsize
    id: variable
    parameters:
        comment: Total lines per frame, blanking included
        value: '806'
    states:
        coordinate: [1100, 10]
        rotation: 0
        state: enabled
-   name: horizontal_offset
    id: variable_qtgui_range
    parameters:
        comment: Pans the frame sideways, one sample per step
        label: Horizontal offset (samples)
        min_len: '200'
        orient: QtCore.Qt.Horizontal
        rangeType: int
        start: '0'
        step: '1'
        stop: '619'
        value: '460'
        widget: counter_slider
    states:
        coordinate: [1270, 10]
        rotation: 0
        state: enabled
-   name: interpolatedHsize
    id: variable
    parameters:
        comment: Samples per line at this sample rate, 620 here
        value: int(Hsize/float(px_rate)*samp_rate)
    states:
        coordinate: [10, 270]
        rotation: 0
        state: enabled
-   name: px_rate
    id: variable
    parameters:
        comment: The monitor's pixel clock
        value: Hsize*Vsize*refresh_rate
    states:
        coordinate: [230, 270]
        rotation: 0
        state: enabled
-   name: refresh_rate
    id: variable
    parameters:
        comment: ''
        value: '60'
    states:
        coordinate: [420, 270]
        rotation: 0
        state: enabled
-   name: samp_rate
    id: variable
    parameters:
        comment: The recording's own sample rate
        value: int(30e6)
    states:
        coordinate: [600, 270]
        rotation: 0
        state: enabled
-   name: vertical_offset
    id: variable_qtgui_range
    parameters:
        comment: Pans the frame up and down; each step is one 620-sample line
        label: Vertical offset (samples, 620 per line)
        min_len: '200'
        orient: QtCore.Qt.Horizontal
        rangeType: int
        start: '0'
        step: '620'
        stop: '499720'
        value: '467480'
        widget: counter_slider
    states:
        coordinate: [770, 270]
        rotation: 0
        state: enabled
-   name: framing
    id: tempest_framing
    parameters:
        Hdisplay: interpolatedHsize
        Htotal: interpolatedHsize
        Vdisplay: Vdisplay
        Vtotal: Vsize
        affinity: ''
        alias: ''
        comment: Drops the vertical blanking lines; the line already fits, so Hdisplay = Htotal
        maxoutbuf: '0'
        minoutbuf: '0'
    states:
        coordinate: [660, 680]
        rotation: 0
        state: enabled
-   name: line_sync
    id: tempest_fine_sampling_synchronization
    parameters:
        Htotal: interpolatedHsize
        Vtotal: Vsize
        affinity: ''
        alias: ''
        comment: Resamples so every line is exactly Htotal samples and every frame Vtotal lines
        correct_sampling: '1'
        max_deviation: 10.0/interpolatedHsize
        maxoutbuf: '0'
        minoutbuf: '0'
        update_proba: 1e-2/(Hsize*Vsize)
    states:
        coordinate: [710, 470]
        rotation: 0
        state: enabled
-   name: mag
    id: blocks_complex_to_mag
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        maxoutbuf: '0'
        minoutbuf: '0'
        vlen: '1'
    states:
        coordinate: [80, 710]
        rotation: 0
        state: enabled
-   name: normalize
    id: tempest_normalize_flow
    parameters:
        affinity: ''
        alias: ''
        alpha_avg: '0.01'
        comment: Tracks the running min and max and maps them to 10..245
        max: '245'
        maxoutbuf: '0'
        min: '10'
        minoutbuf: '0'
        update_proba: '0.1'
        window: interpolatedHsize
    states:
        coordinate: [360, 670]
        rotation: 0
        state: enabled
-   name: pan_h
    id: blocks_delay
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        delay: horizontal_offset
        maxoutbuf: '0'
        minoutbuf: '0'
        type: complex
        vlen: '1'
    states:
        coordinate: [1460, 510]
        rotation: 0
        state: enabled
-   name: pan_v
    id: blocks_delay
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        delay: vertical_offset
        maxoutbuf: '0'
        minoutbuf: '0'
        type: complex
        vlen: '1'
    states:
        coordinate: [1140, 510]
        rotation: 0
        state: enabled
-   name: rec
    id: wasm_gr_world_recording
    parameters:
        affinity: ''
        alias: ''
        comment: The gr-tempest authors' recording4, a VGA cable at 1024x768; Length is 120 whole frames of 499751 samples so the loop is seamless
        length: '59970120'
        maxoutbuf: '0'
        minoutbuf: '0'
        offset: '0'
        progress: 'True'
        recording: tempest/vga_1024x768_60Hz_30MSps
        repeat: 'True'
        type: short
    states:
        coordinate: [10, 500]
        rotation: 0
        state: enabled
-   name: screen
    id: wasm_video_sink
    parameters:
        affinity: ''
        alias: ''
        comment: 620 samples span each 1344-pixel line, so the picture is shown at the screen's aspect ratio
        display_height: Vdisplay
        display_width: Hdisplay
        height: Vdisplay
        name: '"Recovered screen"'
        type: float
        width: interpolatedHsize
    states:
        coordinate: [1030, 700]
        rotation: 0
        state: enabled
-   name: to_complex
    id: blocks_interleaved_short_to_complex
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        maxoutbuf: '0'
        minoutbuf: '0'
        scale_factor: '32000'
        swap: 'False'
        vector_input: 'False'
    states:
        coordinate: [400, 510]
        rotation: 0
        state: enabled
-   name: wasm_gui_layout_0
    id: wasm_gui_layout
    parameters:
        affinity: ''
        alias: ''
        columns: '12'
        comment: ''
        layout: '{"horizontal_offset":[0,0,6,1],"vertical_offset":[6,0,6,1],"rec":[0,1,12,1],"screen":[0,2,12,10]}'
        row_height: '60'
    states:
        coordinate: [300, 10]
        rotation: 0
        state: enabled
connections:
- [framing, '0', screen, '0']
- [line_sync, '0', pan_v, '0']
- [mag, '0', normalize, '0']
- [normalize, '0', framing, '0']
- [pan_h, '0', mag, '0']
- [pan_v, '0', pan_h, '0']
- [rec, '0', to_complex, '0']
- [to_complex, '0', line_sync, '0']
metadata:
    file_format: 1
    grc_version: 3.11.0.0