Real-time Spectrogram

Basic

The Spectrogram displays time-frequency content of signals in 2D and 3D visualizations.

Documentation

Apps Features Specs

Found in These Apps

Key Features

2D spectrogram display

Configurable color maps

Adjustable time and frequency scales

Screen capture to PDF

Real-time 3D Spectrogram (Advanced Feature): Spectrogram data can be plotted as a 3D surface or mesh in real time. Rotation and zoom are supported through touch gestures (trackball-style single-finger drag and two-finger pinch, respectively) even while the spectrogram is running.

User-friendly Frequencies: Traditional FFT-based spectrum analyzers use FFT's (Fast Fourier Transforms) with lengths that are powers of 2 (e.g. 2 to the 12th power = 4096). With typical audio sample rates, such as 48 kHz, this yields non-integer (awkward) frequency resolutions, such as 11.71875 Hz (48000/4096 = 11.71875). SignalScope's FFT Analyzer uses mixed-radix FFT's that yield frequency resolutions that are more than just user-friendly—they allow for precise amplitude measurement at frequencies such as 1000 Hz (a frequency commonly used for calibrating sound level meters and measuring total harmonic distortion, or THD). For example, an FFT length of 4800, when used with a sample rate of 48 kHz, yields a frequency resolution of exactly 10 Hz (48000/4800 = 10).

Save Data: Export spectrum magnitude values and metadata to a data file (.csv, .mat, or .txt). Or, generate a high-resolution image of the graph and save it to a PDF file.

Specifications

Input: 1 channel at a time, selected from any available input, output, or virtual output channels
FFT Type: Mixed Radix
FFT Length: Set automatically, based on frequency resolution and current sample rate (e.g. at 48 kHz, a frequency resolution of 5 Hz requires an FFT length of 9600 points)
Overlap (%): N/A
Frequency Weighting: N/A
Averaging: Off, Linear (Stable), Exponential, Peak Hold
Visible Frequency Limits: Min/Max, User-adjustable between 0 and Nyquist
Vibration Unit Conversion: Acceleration, Velocity, Displacement
Color Scale: Show/Hide
2D Grid: Show/Hide

Frequency Resolution (Hz), per sample rate

Built-in Accelerometer (iPhone and iPad), 100 Hz 10, 5, 2, 1
11025 Hz 0.5
12000 Hz 50, 40, 20, 16, 10, 8, 5, 4, 2, 1
22050 Hz 5, 1
44100 Hz 50, 10, 5, 2, 1
88200 Hz 50, 10, 5, 4, 2, 1
176400 Hz 50, 10, 8, 5, 4, 2, 1
Other sample rates 50, 40, 32, 20, 16, 10, 8, 5, 4, 2, 1

Data Windows

Uniform (rectangular)
Bartlett
Blackman
Flat Top
Hamming
Hann
Rife-Vincent 2

Scale

Time Scale: 2, 4, 6, 8, 10, 20, 30, 60
Autoscale: Off, Auto, Up, Down
Magnitude Scale: Lin, Log, dB
dB Magnitude Scale (dB/Div) 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.8, 0.9, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 8.0, 9.0, 10.0, 12.0, 15.0, 16.0, 18.0, 20.0, 24.0, 25.0, 27.0, 30.0
Lin/Log Magnitude Scale (Units/Div) 1e-9, 2e-9, 3e-9, 4e-9, 5e-9, 6e-9, 8e-9, 10e-9, 20e-9, 30e-9, 40e-9, 50e-9, 60e-9, 80e-9, 100e-9, 200e-9, 300e-9, 400e-9, 500e-9, 600e-9, 800e-9, 1e-6, 2e-6, 3e-6, 4e-6, 5e-6, 6e-6, 8e-6, 10e-6, 20e-6, 30e-6, 40e-6, 50e-6, 60e-6, 80e-6, 100e-6, 200e-6, 300e-6, 400e-6, 500e-6, 600e-6, 800e-6, 1e-3, 2e-3, 3e-3, 4e-3, 5e-3, 6e-3, 8e-3,10e-3, 20e-3, 30e-3, 40e-3, 50e-3, 60e-3, 80e-3,100e-3, 200e-3, 300e-3, 400e-3, 500e-3, 600e-3, 800e-3, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 8.0, 10.0, 20.0, 30.0, 40.0, 50.0, 60.0, 80.0, 100.0, 200.0, 300.0, 400.0, 500.0, 600.0, 800.0, 1e3, 2e3, 3e3, 4e3, 5e3, 6e3, 8e3, 10e3, 20e3, 30e3, 40e3, 50e3, 60e3, 80e3, 100e3, 200e3, 300e3, 400e3, 500e3, 600e3, 800e3
Level Type: peak, peak-to-peak, rms
Frequency Axis: Lin, Log
Frequency Units: Hz, cpm

Spectral Smoothing

Enable/Disable (requires logarithmic frequency scale)
Smooth Bandwidth (fractional octave bandwidth): 1/6, 1/12, 1/24
Smoothing Type: Avg, Max, Min

Cursor

Peak Track Type: Time, Frequency, Both
Peak Track Mode: Off, Max

Data Export

Data File Format: CSV, MAT, TXT
Image: PDF
Optionally include current location in exported data files.

3D Surface Plot (Advanced Feature)

Draw 3D Axes: On/Off
Draw Surface: On/Off
Draw Mesh: On/Off
Mesh Type: Full, Time, Frequency, Points

* Specifications subject to change

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