Dual FFT Analyzer

Pro

The Dual FFT Analyzer provides two-channel analysis including transfer functions and coherence.

Documentation

Apps Features Specs

Found in These Apps

Key Features

Transfer function measurement

Frequency response magnitude, phase, delay

Coherence

Impulse response

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 Dual 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).

Real-time SIMO Analysis: Measure 2 DUT's or SUT's at a time, with a single reference channel. (DUT = Device Under Test, SUT = System Under Test, SIMO = Single Input, Multiple Output)

Save Data: Export frequency and time domain data 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: Up to 2 system or device measurements simultaneously, with X input (reference) and Y inputs (DUT/SUT outputs) 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 (%): Off (0), 50, 75, 80, 90, Max (automatically calculated, limited to approximately 20 FFT calculations per second)
Averaging: Off, Linear (Stable), Exponential, Peak Hold
Visible Frequency Limits: Min/Max, User-adjustable between 0 and Nyquist
Unwrap Phase: Enable/Disable

Measurement Types

Frequency Response (FR) Magnitude
Frequency Response (FR) Phase
Coherence
Phase Delay
Group Delay
Impulse Response (IR)
Squared IR
Cross-correlation

Frequency Resolution (Hz), per sample rate

Sample rate > 48000 Hz: 10, 8, 5, 4, 2, 1, 0.5, 0.25, 0.2
Sample rate <= 48000 Hz: 10, 8, 5, 4, 2, 1, 0.5, 0.25, 0.2, 0.125, 0.1, 0.08, 0.0625

Measurement Length (s), per sample rate

Sample rate > 48000 Hz: 0.1, 0.125, 0.2, 0.25, 0.5, 1, 2, 4, 5
Sample rate <= 48000 Hz 0.1, 0.125, 0.2, 0.25, 0.5, 1, 2, 4, 5, 8, 10, 12.5, 16

Data Windows

Uniform (rectangular)
Bartlett
Blackman
Flat Top
Hamming
Hann
Rife-Vincent 2
Exponential Decay
Force
Force Exponential
Exponential Decay Window: User defined time constant and final value
Force Window: User defined window length in seconds or percent
Window Preview: In-menu graph of the window shape

Built-in Excitation Signal Generator

Enable/Disable
Output Channel A/B Selection: Selected from any available output channels
Signal Type: Sweep, Pseudorandom Noise (each automatically configured with a length to match the measurement length, or FFT length)
Presends: User-definable value greater than or equal to zero
Level: specified in dBFS where 0 dBFS is the maximum (full scale) output amplitude

Scale

Horizontal divisions: 10 (time or linear frequency scale)
Vertical divisions: 10
Autoscale: Off, Auto, Up, Down
FR Magnitude Vertical Axis: Lin, Log, dB
Squared IR Vertical Axis Lin, Log, dB
dB Vertical 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
Frequency Axis Scale: 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

Harmonic Cursors: up to 128
Horizontal Bar: Hidden or drawn at the instantaneous amplitude of any available waveform
Peak Track: Off, Max, Min
The cursor can track the peak value of any channel which has been selected for analysis

Triggering (sourced from X reference input and applied to both X and Y inputs)

Enable/Disable
Channel selection: Self or any available input or output channel
Mode: Auto, Normal, Single
Slope: Positive, Negative
Threshold

Data Export

Data File Format: CSV, MAT, TXT
Image: PDF
Optionally include current location in exported data files.
Option to export only visible frequencies.

Data Import

Data File Format: CSV, MAT, TXT (only files created by the Dual FFT Analyzer tool)
The total number of loaded static spectra and live spectra cannot exceed 16 (8 on iPhone)
Trace Opacity: 0.25 - 1.0
Trace Thickness: 1, 2, 3

Average Curve (Pro Feature)

The total number of loaded static spectra (including average curves) and live spectra cannot exceed 16 (8 on iPhone)
Max Data Files Per Average Curve: 999999999
Data File Format: CSV, MAT, TXT (only files created by the Dual FFT Analyzer tool)

* Specifications subject to change

Try Dual FFT Analyzer Today

Download SignalScope X for free and start your 14-day trial.

Get SignalScope X