Challenge 2

Wire a slider to a block parameter, then tune the tone to 100.25 MHz while the flowgraph runs.

Author GNU Radio World
Category Gnuradio World Challenges
Blocks 13
Connections 4
File _gnuradio-world-challenges/challenge_2.grc

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Blocks used

Block	Module	Used
Note	`GNU Radio`	3
Variable	`GNU Radio`	2
Add	`GNU Radio`	1
Challenge	`GNU Radio`	1
GUI Layout	`GNU Radio`	1
Noise Source	`GNU Radio`	1
QT GUI Range	`GNU Radio`	1
Signal Source	`GNU Radio`	1
Spectrum Analyzer	`GNU Radio`	1
Throttle	`GNU Radio`	1

Notes in this flowgraph

The radio is tuned to 100 MHz and listening across 1 MHz of spectrum, so the analyzer shows 99.5 MHz to 100.5 MHz. The Signal Source's frequency is an offset from that center: 0 puts the tone right in the middle.
A block parameter does not have to be a number -- it can be the name of a variable. tone_offset is a QT GUI Range: a variable with a slider attached, which can be moved while the flowgraph is running. Parameters that accept a new value at run time are underlined in the properties dialog.
Challenge: 1) Double-click the Signal Source and set its Frequency to tone_offset (type the name, not a number) 2) Run it. The slider appears above the spectrum 3) Drag the slider -- or type into its box -- until the tone sits at 100.25 MHz. The analyzer labels every signal it finds with its measured center frequency, so read it off the plot

Flowgraph source

_gnuradio-world-challenges/challenge_2.grc

options:
    parameters:
        author: GNU Radio World
        comment: ''
        copyright: ''
        description: Wire a slider to a block parameter, then tune the tone to 100.25 MHz while the flowgraph runs.
        generate_options: qt_gui
        id: Challenge_2
        title: Challenge 2
    states:
        coordinate: [10, 10]
        rotation: 0
        state: enabled
blocks:
-   name: center_freq
    id: variable
    parameters:
        comment: ''
        value: '100000000'
    states:
        coordinate: [590, 10]
        rotation: 0
        state: enabled
-   name: samp_rate
    id: variable
    parameters:
        comment: ''
        value: '1000000'
    states:
        coordinate: [760, 10]
        rotation: 0
        state: enabled
-   name: tone_offset
    id: variable_qtgui_range
    parameters:
        comment: ''
        label: Tone offset from center (Hz)
        min_len: '300'
        orient: QtCore.Qt.Horizontal
        rangeType: float
        start: '-400000'
        step: '1000'
        stop: '400000'
        value: '0'
        widget: counter_slider
    states:
        coordinate: [930, 10]
        rotation: 0
        state: enabled
-   name: analyzer
    id: wasm_spectrum_analyzer_sink
    parameters:
        affinity: ''
        alias: ''
        average: '0.2'
        center_freq: center_freq
        comment: Finds and measures signals
        db_per_div: '10'
        fftsize: '4096'
        level_offset_db: '0'
        level_unit: dBFS
        name: Tune the tone
        reference_level: '0'
        samp_rate: samp_rate
        trace_mode: average
        type: complex
        update_time: '0.1'
        wintype: window.WIN_BLACKMAN_hARRIS
    states:
        coordinate: [940, 490]
        rotation: 0
        state: enabled
-   name: challenge_2
    id: wasm_challenge
    parameters:
        affinity: ''
        alias: ''
        challenge_id: challenge_2
        comment: ''
        criteria: "[\n {\"kind\": \"param\", \"block\": \"tone\", \"param\": \"freq\", \"matches\": \"^\\\\s*tone_offset\\\\s*$\", \"goal\": \"Set the Signal Source's Frequency to tone_offset, so the slider drives it\"},\n {\"kind\": \"ran\", \"seconds\": 3, \"goal\": \"Run it: the slider appears above the spectrum\"},\n {\"kind\": \"detected_signal\", \"center_freq\": 100250000, \"center_tol\": 20000, \"min_peak_level\": -40, \"goal\": \"Without stopping, tune the tone to 100.25 MHz -- 250 kHz above center\"}\n]"
        requires: challenge_1
        title: Turn the knob
    states:
        coordinate: [1220, 10]
        rotation: 0
        state: enabled
-   name: channel
    id: blocks_add_xx
    parameters:
        affinity: ''
        alias: ''
        comment: What the radio hears
        maxoutbuf: '0'
        minoutbuf: '0'
        num_inputs: '2'
        type: complex
        vlen: '1'
    states:
        coordinate: [370, 570]
        rotation: 0
        state: enabled
-   name: gui_layout
    id: wasm_gui_layout
    parameters:
        affinity: ''
        alias: ''
        columns: '12'
        comment: ''
        layout: '{"analyzer":[0,1,12,7],"tone_offset":[0,0,12,1]}'
        row_height: '60'
    states:
        coordinate: [300, 10]
        rotation: 0
        state: enabled
-   name: note_0
    id: note
    parameters:
        affinity: ''
        alias: ''
        bgcolor: '#4dff6a'
        comment: ''
        note: 'The radio is tuned to 100 MHz and listening across 1 MHz of spectrum, so the analyzer shows 99.5 MHz to 100.5 MHz. The Signal Source''s frequency is an offset from that center: 0 puts the tone right in the middle.'
    states:
        coordinate: [10, 230]
        rotation: 0
        state: enabled
-   name: note_1
    id: note
    parameters:
        affinity: ''
        alias: ''
        bgcolor: '#4dff6a'
        comment: ''
        note: 'A block parameter does not have to be a number -- it can be the name of a variable. tone_offset is a QT GUI Range: a variable with a slider attached, which can be moved while the flowgraph is running. Parameters that accept a new value at run time are underlined in the properties dialog.'
    states:
        coordinate: [420, 230]
        rotation: 0
        state: enabled
-   name: note_2
    id: note
    parameters:
        affinity: ''
        alias: ''
        bgcolor: '#4dff6a'
        comment: ''
        note: "Challenge:\n1) Double-click the Signal Source and set its Frequency to tone_offset (type the name, not a number)\n2) Run it. The slider appears above the spectrum\n3) Drag the slider -- or type into its box -- until the tone sits at 100.25 MHz. The analyzer labels every signal it finds with its measured center frequency, so read it off the plot"
    states:
        coordinate: [850, 230]
        rotation: 0
        state: enabled
-   name: receiver_noise
    id: analog_noise_source_x
    parameters:
        affinity: ''
        alias: ''
        amp: '0.002'
        comment: Gives the detector a noise floor
        maxoutbuf: '0'
        minoutbuf: '0'
        noise_type: analog.GR_GAUSSIAN
        seed: '7'
        type: complex
    states:
        coordinate: [10, 710]
        rotation: 0
        state: enabled
-   name: throttle
    id: blocks_throttle2
    parameters:
        affinity: ''
        alias: ''
        comment: "Limits the rate of IQ samples\nflowing through"
        ignoretag: 'True'
        limit: time
        maximum: '0.02'
        maxoutbuf: '0'
        minoutbuf: '0'
        samples_per_second: samp_rate
        type: complex
        vlen: '1'
    states:
        coordinate: [610, 560]
        rotation: 0
        state: enabled
-   name: tone
    id: analog_sig_source_x
    parameters:
        affinity: ''
        alias: ''
        amp: '0.3'
        comment: The tone you are tuning
        freq: '0'
        maxoutbuf: '0'
        minoutbuf: '0'
        offset: '0'
        phase: '0'
        samp_rate: samp_rate
        type: complex
        waveform: analog.GR_COS_WAVE
    states:
        coordinate: [10, 530]
        rotation: 0
        state: enabled
connections:
- [channel, '0', throttle, '0']
- [receiver_noise, '0', channel, '1']
- [throttle, '0', analyzer, '0']
- [tone, '0', channel, '0']
metadata:
    file_format: 1
    grc_version: 3.11.0.0