Open an audio or raw IQ recording to investigate frequency, time, modulation and signal structure. Signal samples are processed in your browser.
Free online spectrum analyzer and spectrogram for audio and IQ files, with FFT, waterfall, waveform and basic demodulation.
A spectrogram reader displays frequency on one axis, time on another, and signal energy using colour. Open a supported recording to use this online spectrogram for inspecting voices, music, bird calls, equipment noises, acoustic measurements, tones, chirps and other recordings. Adjust FFT size, overlap, colour palette, frequency scale and decibel range to reveal more detail.
Use Play, Pause, Stop, speed, volume and the timeline to navigate your signal. A moving cursor highlights the current playback time; the FFT view shows changing energy while listening, and the waterfall advances with playback. The live mini-spectrum also responds to the audible signal.
A fast Fourier transform (FFT) breaks a short span of samples into frequency components. Use the audio spectrum analyzer view to inspect frequency peaks, the spectrogram to follow them over time, or the waterfall for an evolving frequency history. Zoom into a time interval to inspect it more closely.
Load compatible complex I/Q samples, enter the correct sample rate and tune offset, and try AM envelope or FM frequency-discriminator demodulation. Experimental SSB/CW processing, DTMF tone recognition and fixed-rate 2-FSK bit slicing are also provided. These are analysis tools, not an automatic decoder for arbitrary radio protocols.
Mark interesting points with time/frequency annotations. Apply gain or audio filters, inspect a selected region, and export spectrogram images, waveform/spectrum plots, FFT/STFT data as CSV, annotations as JSON, processed audio as WAV, and complex IQ as float32 data.
Supported inputs include common browser-decodable audio such as WAV, MP3, OGG, AAC and some FLAC files; amplitude or IQ samples in CSV/TXT; interleaved CU8, CI8, CS16 and CF32 raw IQ; and selected SigMF metadata/data pairs. Codec support depends on the browser. Signal processing happens on your device and sample files are not uploaded. This page uses Google Analytics for general page-usage measurement; it does not receive signal contents.
Choose Import, select a supported audio file, and open the Spectrogram tab. This spectrogram reader shows how frequencies change over time; adjust FFT size, overlap and colour mapping, then export a PNG image.
Yes. Import a supported audio file and open FFT Spectrum to use the audio spectrum analyzer. The Spectrogram and Waterfall views show how those frequencies change over time.
Yes. The timeline playhead moves in sync with audio, the live FFT spectrum changes as it plays, and the waterfall progresses through the recording. This is synchronized playback of an imported file; live microphone capture is not included.
It can demodulate certain baseband IQ signals and perform introductory DTMF and FSK extraction. Successful decoding depends on modulation, correct sampling and tuning, symbol timing, bandwidth and protocol details. It is not a universal radio decoder.
It is a spectrogram reader and signal analyzer, not a universal decoder. Decoding features are limited to basic IQ demodulation and introductory DTMF and fixed-rate 2-FSK analysis.
No. This is an audio and I/Q frequency analyzer, not an optical spectrometer or laboratory instrument.
These Spanish and French search phrases refer to an online spectrogram and a free audio spectrum analyzer. This page’s interface and guide are in English, and the tool analyzes supported audio and I/Q files.
An FFT spectrum shows frequency energy for a time segment. A spectrogram repeats the FFT over successive segments to show how those frequencies evolve over time. The waterfall adds a perspective view of the same changing spectrum.
No. Imported audio and IQ samples are processed in your browser and are not uploaded. The page uses Google Analytics for general page-usage measurement, separate from the signal contents.
Reproducible sample data to explore the studio; no files or network connection needed.
Choose how to interpret the selected file.
Everything is produced in the browser. Images include visible markers and annotations.
Import: Open a browser-supported audio recording; 1-column or 2-column CSV/TXT; raw complex IQ in CU8, CI8, CS16-LE, CF32-LE; or real float32. For SigMF choose the .sigmf-meta and .sigmf-data together. Enter the correct sample rate for raw signals. Files are capped at 260 MB for in-browser analysis.
Navigate: Inspect shows time/frequency. Select draws a time/frequency region, which you can zoom into. Pan drags the current view. Mouse wheel or touchpad zooms time. Note adds custom labels.
Analyze: FFT spectrum is averaged from the currently viewed time range. Spectrogram uses a windowed FFT. Waterfall shows successive FFT slices in a 3D-style projection. Wide files are adaptively sampled for display; CSV export is the displayed analysis grid.
Demodulate: FM/AM modes expect complex IQ baseband and proper tuning; simple SSB projection lacks a complete receiver chain. FSK bit slicing assumes known baud rate and phase; DTMF works on audio. Neither performs arbitrary signal or protocol decoding.
Playback: Use the player under the graph for synchronized playhead, dynamic FFT spectrum and adjustable rolling waterfall history, playback speed, volume and timeline seeking. For IQ data choose Demodulated IQ; complex samples are not audio. Double-click the spectrogram to seek. The Space key toggles play/pause when a field is not focused.
Privacy: Signal processing runs locally and sample files are not uploaded. This page uses Google Analytics for general page-usage measurement; analytics does not receive signal contents. Playback may require a user gesture. Very large recordings need substantial browser RAM.
Free online spectrum analyzer and spectrogram for audio and IQ files, with FFT, waterfall, waveform and basic demodulation.
Spectra Signal Studio analyzes imported audio, sampled signals, and compatible complex I/Q recordings. It displays spectrogram, FFT spectrum, waterfall, and waveform views, with playback synchronization, selection, zoom, annotations, filtering, and selected basic demodulation or decoding tools.
Inputs include browser-supported audio files, one- or two-column CSV/TSV/TXT samples, raw real float32 data, interleaved CU8/CI8/CS16/CF32 I/Q data, and selected SigMF file pairs. Sample rate, channel, center frequency, FFT, filter, and decoder settings can be adjusted.
Explore four signal views and export plot images as PNG, visible FFT/STFT values as CSV, processed or demodulated audio as WAV, I/Q samples as CF32, annotations or project settings as JSON, and basic decoder text. Project JSON contains metadata and settings, not the original samples.
Live microphone capture is not included. Audio codecs vary by browser, and large files can require substantial memory; the in-app limit is 260 MB. AM/FM, SSB/CW, DTMF, and fixed-rate 2-FSK features are introductory analysis tools, not a complete receiver or universal radio-protocol decoder. Incorrect sample-rate or tuning values can make results misleading.
No. Signal samples are processed in the browser and are not uploaded. The page uses Google Analytics for general page-usage measurement, not signal contents.
No. It includes basic demodulation and introductory DTMF/2-FSK analysis, but not synchronization, error correction, or arbitrary protocol decoding.
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