Browser-Native Spectrum Analyzer

Three distinct signals across a simulated 1 MHz RF channel demonstrate automatic detection, per-signal peak measurement, center frequency, and 99% occupied bandwidth.

Author GNU Radio World
Category Spectrum Analysis
Blocks 20
Connections 12
File spectrum-analysis/spectrum_analyzer.grc

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Blocks used

Block	Module	Used
Variable	`GNU Radio`	4
Multiply Const	`GNU Radio`	2
Add	`GNU Radio`	1
Constellation Modulator	`GNU Radio`	1
Constellation Object	`GNU Radio`	1
GUI Layout	`GNU Radio`	1
Noise Source	`GNU Radio`	1
Note	`GNU Radio`	1
OFDM Transmitter	`GNU Radio`	1
Random Uniform Source	`GNU Radio`	1
Rotator	`GNU Radio`	1
Signal Source	`GNU Radio`	1
Spectrum Analyzer	`GNU Radio`	1
Stream to Tagged Stream	`GNU Radio`	1
Throttle	`GNU Radio`	1
Vector Source	`GNU Radio`	1

Notes in this flowgraph

A simulated 1 MHz channel centered at 915 MHz Left: narrow carrier at -300 kHz Center: pulse-shaped QPSK, 8 samples/symbol Right: QPSK OFDM at +300 kHz, 256-point FFT with 52 active carriers Low-level receiver noise gives the automatic detector a realistic floor to learn. Try changing Threshold, toggling Detect, or pressing Relearn in the running analyzer.

Flowgraph source

spectrum-analysis/spectrum_analyzer.grc

options:
    parameters:
        author: GNU Radio World
        comment: ''
        copyright: ''
        description: Three distinct signals across a simulated 1 MHz RF channel demonstrate automatic detection, per-signal peak measurement, center frequency, and 99% occupied bandwidth.
        generate_options: qt_gui
        id: Browser_Native_Spectrum_Analyzer
        title: Browser-Native Spectrum Analyzer
    states:
        coordinate: [10, 10]
        rotation: 0
        state: enabled
blocks:
-   name: center_freq
    id: variable
    parameters:
        comment: ''
        value: '915000000'
    states:
        coordinate: [770, 10]
        rotation: 0
        state: enabled
-   name: ofdm_offset
    id: variable
    parameters:
        comment: ''
        value: '300000'
    states:
        coordinate: [1110, 10]
        rotation: 0
        state: enabled
-   name: samp_rate
    id: variable
    parameters:
        comment: ''
        value: '1000000'
    states:
        coordinate: [600, 10]
        rotation: 0
        state: enabled
-   name: tone_offset
    id: variable
    parameters:
        comment: ''
        value: '-300000'
    states:
        coordinate: [940, 10]
        rotation: 0
        state: enabled
-   name: analyzer
    id: wasm_spectrum_analyzer_sink
    parameters:
        affinity: ''
        alias: ''
        average: '0.2'
        center_freq: center_freq
        comment: ''
        db_per_div: '10'
        fftsize: '8192'
        level_offset_db: '0'
        level_unit: dBFS
        name: Three-Signal Spectrum
        reference_level: '0'
        samp_rate: samp_rate
        trace_mode: average
        type: complex
        update_time: '0.1'
        wintype: window.WIN_BLACKMAN_hARRIS
    states:
        coordinate: [1030, 1070]
        rotation: 0
        state: enabled
-   name: channel_sum
    id: blocks_add_xx
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        maxoutbuf: '0'
        minoutbuf: '0'
        num_inputs: '4'
        type: complex
        vlen: '1'
    states:
        coordinate: [460, 1150]
        rotation: 0
        state: enabled
-   name: channel_throttle
    id: blocks_throttle2
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        ignoretag: 'True'
        limit: time
        maximum: '0.02'
        maxoutbuf: '0'
        minoutbuf: '0'
        samples_per_second: samp_rate
        type: complex
        vlen: '1'
    states:
        coordinate: [700, 1170]
        rotation: 0
        state: enabled
-   name: gui_layout
    id: wasm_gui_layout
    parameters:
        affinity: ''
        alias: ''
        columns: '12'
        comment: ''
        layout: '{"analyzer":[0,0,12,8]}'
        row_height: '60'
    states:
        coordinate: [310, 10]
        rotation: 0
        state: enabled
-   name: ofdm_frequency_shift
    id: blocks_rotator_cc
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        maxoutbuf: '0'
        minoutbuf: '0'
        phase_inc: 2*math.pi*ofdm_offset/samp_rate
        tag_inc_update: 'False'
    states:
        coordinate: [100, 1390]
        rotation: 0
        state: enabled
-   name: ofdm_level
    id: blocks_multiply_const_vxx
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        const: '0.2'
        maxoutbuf: '0'
        minoutbuf: '0'
        mode: scalar
        type: complex
        vlen: '1'
    states:
        coordinate: [1090, 840]
        rotation: 0
        state: enabled
-   name: ofdm_packet_tagger
    id: blocks_stream_to_tagged_stream
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        len_tag_key: length
        maxoutbuf: '0'
        minoutbuf: '0'
        packet_len: '96'
        type: byte
        vlen: '1'
    states:
        coordinate: [340, 620]
        rotation: 0
        state: enabled
-   name: ofdm_payload
    id: blocks_vector_source_x
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        maxoutbuf: '0'
        minoutbuf: '0'
        repeat: 'True'
        tags: '[]'
        type: byte
        vector: '[0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95]'
        vlen: '1'
    states:
        coordinate: [10, 610]
        rotation: 0
        state: enabled
-   name: ofdm_transmitter
    id: digital_ofdm_tx
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        cp_len: '64'
        fft_len: '256'
        header_mod: '"BPSK"'
        log: 'False'
        maxoutbuf: '0'
        minoutbuf: '0'
        occupied_carriers: ()
        packet_len_key: length
        payload_mod: '"QPSK"'
        pilot_carriers: ()
        pilot_symbols: ()
        rolloff: '0'
        scramble_bits: 'True'
        sync_word1: ()
        sync_word2: ()
    states:
        coordinate: [720, 730]
        rotation: 0
        state: enabled
-   name: overview
    id: note
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        note: "A simulated 1 MHz channel centered at 915 MHz\n\nLeft: narrow carrier at -300 kHz\nCenter: pulse-shaped QPSK, 8 samples/symbol\nRight: QPSK OFDM at +300 kHz, 256-point FFT with 52 active carriers\n\nLow-level receiver noise gives the automatic detector a realistic floor to learn. Try changing Threshold, toggling Detect, or pressing Relearn in the running analyzer."
    states:
        coordinate: [10, 270]
        rotation: 0
        state: enabled
-   name: qpsk_constellation
    id: variable_constellation
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        const_points: '[-1-1j, -1+1j, 1+1j, 1-1j]'
        dims: '1'
        normalization: digital.constellation.AMPLITUDE_NORMALIZATION
        npwr: '1'
        precision: '8'
        rot_sym: '4'
        soft_dec_lut: None
        sym_map: '[0, 1, 3, 2]'
        type: qpsk
    states:
        coordinate: [1290, 10]
        rotation: 0
        state: enabled
-   name: qpsk_data
    id: analog_random_uniform_source_x
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        maximum: '255'
        maxoutbuf: '0'
        minimum: '0'
        minoutbuf: '0'
        seed: '23'
        type: byte
    states:
        coordinate: [720, 610]
        rotation: 0
        state: enabled
-   name: qpsk_level
    id: blocks_multiply_const_vxx
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        const: '0.22'
        maxoutbuf: '0'
        minoutbuf: '0'
        mode: scalar
        type: complex
        vlen: '1'
    states:
        coordinate: [100, 1290]
        rotation: 0
        state: enabled
-   name: qpsk_modulator
    id: digital_constellation_modulator
    parameters:
        affinity: ''
        alias: ''
        comment: ''
        constellation: qpsk_constellation
        differential: 'False'
        excess_bw: '0.35'
        log: 'False'
        maxoutbuf: '0'
        minoutbuf: '0'
        samples_per_symbol: '8'
        truncate: 'False'
        verbose: 'False'
    states:
        coordinate: [1090, 570]
        rotation: 0
        state: enabled
-   name: receiver_noise
    id: analog_noise_source_x
    parameters:
        affinity: ''
        alias: ''
        amp: '0.002'
        comment: ''
        maxoutbuf: '0'
        minoutbuf: '0'
        noise_type: analog.GR_GAUSSIAN
        seed: '7'
        type: complex
    states:
        coordinate: [100, 1510]
        rotation: 0
        state: enabled
-   name: tone
    id: analog_sig_source_x
    parameters:
        affinity: ''
        alias: ''
        amp: '0.3'
        comment: ''
        freq: tone_offset
        maxoutbuf: '0'
        minoutbuf: '0'
        offset: '0'
        phase: '0'
        samp_rate: samp_rate
        type: complex
        waveform: analog.GR_COS_WAVE
    states:
        coordinate: [100, 1110]
        rotation: 0
        state: enabled
connections:
- [channel_sum, '0', channel_throttle, '0']
- [channel_throttle, '0', analyzer, '0']
- [ofdm_frequency_shift, '0', channel_sum, '2']
- [ofdm_level, '0', ofdm_frequency_shift, '0']
- [ofdm_packet_tagger, '0', ofdm_transmitter, '0']
- [ofdm_payload, '0', ofdm_packet_tagger, '0']
- [ofdm_transmitter, '0', ofdm_level, '0']
- [qpsk_data, '0', qpsk_modulator, '0']
- [qpsk_level, '0', channel_sum, '1']
- [qpsk_modulator, '0', qpsk_level, '0']
- [receiver_noise, '0', channel_sum, '3']
- [tone, '0', channel_sum, '0']
metadata:
    file_format: 1
    grc_version: 3.11.0.0