Phonalyser.web - Index & search

A

A bench across the network (Theory ▸ Audio backend) - Everything above assumes the converters are wired to the machine you are sitting at. They need not be. A second Phonalyser.web...
A QA40x input range is not the dBV it is called (Preferences) - For a QA402 / QA403 - on this machine or on a bench across the network - every input row carries a second label after the plain...
A stream that dies after it started (Theory ▸ Audio backend) - An open that fails is the easy case: something threw, and there is a caller to tell. The hard case is a stream that was running...
Absolute bins, a mean-relative axis (Theory ▸ Oscilloscope) - Two layers share the work, and the split is what keeps a DC offset honest. The accumulator is unit-agnostic and absolute: it is...
AC / DC (Oscilloscope) - AC mode subtracts the running DC mean from the displayed trace so a small AC component on top of a large DC offset is visible....
AC/DC tile (Oscilloscope) - ac or dc - the channel's...
ADC calibration (FFT analyser) - Opens the shared ADC calibration dialog to anchor the dBV / V scale against a known input level (units nV / µV / mV / V ). On a...
ADC calibration (Oscilloscope) - Opens the shared ADC calibration dialog, which derives the ADC's full-scale voltage from a known reference signal (a calibrator...
ADC characterisation (Theory ▸ Algorithm reference) - Algorithm What it does here In this help Code-density histogram Bins every captured sample by its ADC code (2 bits bins) and...
Align generator (FFT analyser) - Combo - None or FLL . It steers the generator onto the exact centre of the FFT bin the fundamental falls in: None leaves the tone
Amplitude (RMS) (Generator) - The output level, held internally as volts RMS. Units: µV , mV , V , dBV and dBFS (case-insensitive); a number with no suffix is...
Amplitude calibration (Theory ▸ Signal generator) - You set the output level in V rms . Internally one linear factor maps the unit-amplitude waveform to the normalised DAC domain: A
Amplitude histogram (Oscilloscope) - Opens and closes the amplitude-histogram window , which shows how often the signal sat at each voltage. The button stays pressed...
Amplitude-histogram window (Oscilloscope) - Opened by the amplitude-histogram button. It answers a different question from the trace: not what the waveform looks like over...
At a glance (Frequency response) - Magnitude plot. Log-frequency horizontal axis, linear-dB vertical axis. Shows the Left or Right channel (the L / R header buttons
Audio (Preferences) - Selects the sound back end and the input / output devices and formats - the settings that decide whether a measurement is...
Auto-Setup (FFT analyser) - Frames the spectrum around the detected fundamental: frequency range ±1 decade, magnitude top = fundamental + 10 dB, bottom =...
Auto-Setup (Oscilloscope) - One-shot fit: adjusts the time base so roughly 1.5 periods fit on screen, and the V/div so the trace spans ~75 % of the vertical...
Averages (FFT analyser) - Step selector - Off, 1, 2, 4, 8, 16, 32, 64, 128, ∞ (forever). Number of overlapped frames averaged per published spectrum. "Off"
Averages count (FFT analyser) - e.g. 32 average(s) . Number of frames currently contributing to the displayed average. Caps at the configured Averages in...
Averages tile (FFT analyser) - Number with × suffix ( 32× ) or ∞ in forever...

B

Big picture: drift moves the fundamental, barely touches the harmonics (Theory ▸ DAC pre-distortion) - Now zoom out to the whole band. The notch sits at the fundamental; the harmonics climb the gentle flank above it. The blue dots...
Bottom line (Theory ▸ DAC pre-distortion) - A passive twin-T notch is mandatory - it strips 40-80 dB of fundamental so the ADC digitises the harmonics, not the tone. The...
Bottom line (Theory ▸ De-rotation accuracy) - The de-rotation angle is known to σ θ ≈ 0.023° per block (fundamental-dominated). It does not accumulate, and its level footprint

C

Calibration and plot-time corrections (Theory ▸ FFT analyser) - The averaging accumulator holds the raw spectrum. Everything corrective is applied when the curve is drawn, so toggling a...
Calibration: measuring the measurer (Theory ▸ Frequency response) - A frequency-response sweep measures the whole chain: the DAC, the cabling, and the ADC, as well as the device under test. To...
Capture re-sync banner (FFT analyser) - While averaging, every capture block is vetted before it may enter the average. Two independent checks run on each block: a...
Capture-rate readout (cap/s) (Oscilloscope) - Pale-grey figure in the top-right corner of the trace area. With the edge trigger it shows how many new frames per second the...
Card - per-card calibration profiles (Preferences) - Full-scale calibration - the volts RMS that map to the converter's ±1.0 digital full-scale, and therefore the absolute dBV axis,...
Cards and calibration on the bench (Preferences) - Calibration belongs to the hardware, so with a bench backend selected the Card section works against the bench's store rather...
Channel (Oscilloscope) - Pair of L / R toggles picking which channel drives the trigger...
Channel offset markers (Oscilloscope) - Each enabled channel has its own vertical-offset marker (dashed zero-line + triangle handle), and both handles are on the LEFT...
Channel-enabled LED (Oscilloscope) - An LED tile on the Left / Right tab, shown only while that channel is enabled (absent when the channel is...
Choosing a bench backend (Preferences) - A connected server's backends join the Backend list beside the local ones, written <server> -> <backend> - e.g. bench-pc -> QA40x .
Choosing the phase reference (Theory ▸ FFT analyser) - The phase difference that drives the de-rotation has to be measured on something - and what it is measured on decides how much...
Cleaning up the raw division (Theory ▸ Frequency response) - A few corrections turn the raw Y / X into a usable curve: Transport-delay removal. The DAC->DUT->ADC round trip delays the...
Clock-difference row (ΔF / Δosc) (FFT analyser) - ΔF: +0.001 Hz (+0.97 ppm) Δosc: +23.79 Hz @ 24.576 MHz . Shows the measured fundamental's deviation from the value the generator...
Coherent averaging (FFT analyser) - Checkbox. When on, complex spectra are averaged (so random- phase noise cancels across frames, lowering the noise floor ~3 dB per
Coherent averaging (Theory ▸ FFT analyser) - There are two ways to average spectra, and the difference is the whole point of this analyser: Incoherent (power) averaging adds...
Coherent averaging: how the faint harmonics become trustworthy (Theory ▸ DAC pre-distortion) - The correction can only be as accurate as the harmonic amplitudes and phases that feed it, and after the notch those harmonics...
Coherent-averaging tile (FFT analyser) - coh when coherent averaging is on, inc when...
Compare (measured − filter) (Frequency response) - With Show filter curve and Compare both on and a measurement present, the plot shows the measured response minus the ideal...
Compensated sine - active distortion cancellation (Theory ▸ Signal generator) - This form subtracts the measured harmonic distortion of the playback chain from the generated signal, so the device under test...
Conditioning (Theory ▸ Oscilloscope) - Two optional filters run before display: Anti-alias / spike low-pass. A steep low-pass (8th-order Butterworth) tames out-of-band...
Controls (DAC pre-distortion wizard) - Control What it does Averages, n FFT averages per round (minimum 10). Each round averages this many frames, then grows the count...
Corrections (Generator)
Counted exactly as captured (Theory ▸ Oscilloscope) - Samples are binned before the high-frequency cleanup, before DC removal and before the mains comb - the same reasoning as for the
Crosshair (FFT analyser) - Hovering shows a dashed grey cross at the pointer. The floating readout near the cursor lists the frequency ( f = ... ), the...
Crosshair readout (Frequency response) - Moving the pointer inside the plot draws a dashed cross and a floating box reading the frequency at the cursor (clipped at the...

D

DAC calibration (crosshair button) (Generator) - The crosshair button at the bottom-left of the pane opens the shared DAC calibration dialog, which anchors the Amplitude (RMS)...
DAC pre-distortion wizard (wand) (FFT analyser) - The wand button, left of the record button, opens the DAC pre-distortion wizard - a closed-loop measurement that cancels the...
Detect time discontinuity (FFT analyser) - Checkbox, on by default . While averaging, each capture block is tested in the time domain against the tone's own sinusoid...
Discovery and the firewall (The Phonalyser server) - Clients find a server by UDP multicast on 239.255.83.77, port 8377/udp - the same number the server listens on, because UDP and...
Display persistence (afterglow) (Oscilloscope) - With Preferences ▸ Oscilloscope ▸ Display persistence set to anything but Off , every swept trace lingers and fades like the...
Distortion table (FFT analyser) - Shows / hides the THD info table overlay in the top-left of the canvas. The button itself appears only after the first analysis...
Distortion-band dimming (FFT analyser) - Light-grey overlay covering frequencies outside the active distortion HP / distortion LP window. Shows at a glance which bands...
Distortion-range tile (FFT analyser) - On the THD settings tab. Shows the SNR / N+D integration band: both bounds active -> 50-20k ; HP only (no LP) -> 50-∞ ; LP only (no
Dither (Generator) - Sets how much triangular (TPDF) dither is added just before the output is quantised - Off , or a depth from 1 LSB up to the...
Does the error build up over a long average? (Theory ▸ De-rotation accuracy) - This is the heart of the matter. The per-block angle error is independent and zero-mean from block to block. Two very different...
Drawing between the samples: sin x/x reconstruction (Theory ▸ Oscilloscope) - At fast time bases only a handful of samples cross the screen. Connecting the sample dots with straight lines draws corners that...
Dual tone (Theory ▸ Signal generator) - Two independent phase accumulators advance in lock-step; the output is x = w₁ · sin φ₁ + w₂ · sin φ₂ (7) with per-tone weights...
Dual tone (compensated) (Generator) - The intermodulation-corrected counterpart of Dual tone , the two-tone analogue of Sine compensated . Every distortion product of...
Dual tone (IMD) (Generator) - Visible only when Dual tone is selected. The single frequency field is joined by a second frequency and an amplitude balance...
Duration (Generator) - Total chirp length, in...
Duration (Generator) - Seconds. Length of audio to write when using Save to . Independent of the live emission - the file is rendered in one pass using...
Duty cycle (Generator) - Active only for Rectangle (high-time fraction) and Triangle (rise-time fraction), as a percentage. Each waveform remembers its...

E

Editing (Editing the settings as JSON) - The document opens pretty-printed, and the editor knows its shape: completion offers only the keys that document allows, hover...
Editing the settings as JSON (Editing the settings as JSON) - Everything the Preferences dialog writes ends up in one of two stored documents - the settings and the card profiles - and both...
Edge (Oscilloscope) - ↑ / ↓ pair. Rising edge triggers when the signal crosses the trigger level going up; falling edge for going down. With the glitch
Enable distortion HP + frequency (FFT analyser) - Sets the lower bound of the band used for SNR / N+D integration. Below this frequency, noise and spurs are excluded - useful for...
Enable distortion LP + frequency (FFT analyser) - Same, for the upper bound. Excludes high-frequency noise above the band of interest (e.g. above 20 kHz for...
ENOB (FFT analyser) - Effective number of bits = (SINAD − 1.76) / 6.02. Reflects the ADC + capture chain's combined dynamic...
External-window toggle (FFT analyser) - Pops the THD info table out into a separate tool window so it can sit alongside the spectrum without occupying canvas space....
External-window toggle (Oscilloscope) - Pops the measurement table out into a separate tool window so it can sit alongside the main shell. Visible only when the table...

F

Fade in (Generator) - Seconds. Amplitude ramp at the start of the chirp, suppressing the click an abrupt amplitude step would...
Fade out (Generator) - Seconds. Same as fade-in but at the chirp's...
FFT (Preferences) - Setting Notes Trace line width, px Stroke width of the spectrum. Harmonic dot diameter, px Size of the fundamental / harmonic...
FFT length (FFT analyser) - Power-of-two combo from 8 k to 4 M. Bigger windows give finer bin resolution but slower update rate and more memory. 1 M at 384...
FFT settings tab (FFT analyser)
FFT-length tile (FFT analyser) - Short form on the FFT settings tab - e.g. 1M , 64k...
Fill percent (FFT analyser) - Small percentage label (e.g. 100% ) showing how much of the next FFT window has accumulated since the previous analysis. Reaches...
Filtering & estimation (Theory ▸ Algorithm reference) - Algorithm What it does here In this help Lanczos (windowed-sinc) interpolation Band-limited reconstruction of the trace between...
Filters (Frequency response) - Draw the ideal magnitude response of a textbook analogue filter on top of the measured trace, so you can see at a glance how...
Finding the null (Theory ▸ Tune-notch measurement) - Each period is turned into the notch's magnitude response by dividing the returned spectrum by the swept reference spectrum, H (...
Frequency (Generator) - The output frequency, for periodic waveforms (disabled for the noise forms). Accepts Hz and kHz ; a number with no suffix is read
Frequency response (Preferences) - Setting Notes Trace line width, px Thickness of the magnitude, phase, RIAA-reference and compare curves. Maximal analyzed...
Frequency - crossings, then Goertzel refinement (Theory ▸ Oscilloscope) - Reading frequency off a short buffer accurately is the hard part. A three-stage strategy gets it to a few millihertz: Coarse from
Frequency-response compensation: the red and blue dots (Theory ▸ FFT analyser) - A measurement through any real chain - a notch filter, an attenuator, the soundcard's own roll-off - reads each harmonic through...
From ring buffer to screen (Theory ▸ Oscilloscope) - The scope reads the newest window from the ring buffer on every repaint, conditions it, finds a stable trigger point, and draws...
Frozen copies and file-fed buffers (Theory ▸ Ring buffer & consumers) - A consumer can request a frozen copy - a standalone duplicate of the ring's current contents with no live writer. This is how the

G

Gauge (measurement-table toggle) (Oscilloscope) - Toggles the entire measurement table overlay on and off. When hidden, only the trace and the L / R buttons...
Get fundamental from generator (FFT analyser) - When on, the analyser locks onto the generator's current frequency instead of auto-detecting the loudest peak. Lets you measure...

H

Harmonic dots (FFT analyser) - Red dots painted at the detected fundamental and harmonic frequencies. Their diameter is configurable. When the...
Harmonic rows (H2 .. HN) (FFT analyser) - Two harmonics per row. Each entry shows the harmonic's dBV level and its percentage of the fundamental. Number of rows is...
Header buttons (FFT analyser) - Row of square buttons at the top-left of the spectrum...
Header buttons (Frequency response) - The button row sits above the plot. Button Action L (cyan) Show the left channel's magnitude. Mutually exclusive with R - picking
Header buttons (Oscilloscope) - Row of square buttons at the top-left of the scope trace area. L / R and Auto-Setup are always shown ; the rest (gauge, external...
Header row (FFT analyser) - Bold first row: fundamental frequency (4-decimal Hz), dBFS, dBV. The dBV column shows, in order of precedence: the manual...
Horizontal scrollbar (frequency) (FFT analyser) - Pans the visible frequency range - left / right only. A scrollbar never zooms; the thumb is sized by the view (its width reflects
Horizontal tab (Oscilloscope)
How accurately the de-rotation angle is known (Theory ▸ De-rotation accuracy) - In one block the fundamental bin holds the tone phasor plus a noise phasor. The angle read off it is the true phase plus an error
How calibration writes into a card (Preferences) - The crosshair Calibrate flows anchor the scale against a known reference - the scope and FFT ADC calibration for the input, and...
How it works (Theory ▸ Tune-notch measurement) - The generator plays a short logarithmic sweep on an endless seamless loop into the notch under test; the return signal is...
How it works, roughly (Theory ▸ Audio backend) - Capture. When a view starts recording, the backend opens the input device with exactly the sample rate and bit depth from...
How it works: play a sweep, divide out the input (Theory ▸ Frequency response) - The transfer function H ( f ) of a linear system is, by definition, the output spectrum divided by the input spectrum. So the...
How many averages does a given THD level need? (Theory ▸ DAC pre-distortion) - A useful estimate. Coherent averaging lowers the per-bin noise floor (in power) by the effective number of independent averages n
How much does each resistor class drift? (Theory ▸ DAC pre-distortion) - For a fixed tone at the nominal null, a temperature change Δ T shifts the null by the fractional change in RC : Δ f 0 / f 0 = (α...
How the correction is formed and applied (Theory ▸ DAC pre-distortion) - With the fundamental pinned and the harmonics averaged clean, the loop is straightforward. Each round: Average until the...
How the numbers are measured (Theory ▸ Oscilloscope) - The measurement pass works on the captured window in normalised units - mains-rejected if that is switched on, but never...
Hysteresis (Oscilloscope) - Checkbox + step selector in division units (0.0 .. 5.0 in 0.1 steps). Schmitt-style trigger hysteresis: a rising-edge trigger...
Hysteresis tile (Oscilloscope) - Shown only when hysteresis is enabled; the number is the hysteresis window in divisions (e.g. H 2.0 ). The absence of this tile...

I

Inspiration (Credits) - Inspired by the spirit of REW (Room EQ Wizard) and similar audio-measurement software. Independently designed and...
Interpolation tile (Oscilloscope) - sin when sinc interpolation is on, lin when...

K

Keeping bad blocks out of the average (Theory ▸ FFT analyser) - One corrupted block - a stretch of swallowed samples, a paused generator, a click - poured into a coherent average can undo...
Keeping the tone on the grid: snap and the FLL (Theory ▸ FFT analyser) - De-rotation is most accurate when there is least to de-rotate. Two mechanisms keep the tone essentially on a bin: Bin snapping....

L

L (channel enable) (Oscilloscope) - Square toggle that enables / disables the channel. When off, the trace isn't drawn and the channel can't be picked as the trigger
L / R channel pick (FFT analyser) - Toggle buttons that pick which channel feeds the analyser. The selected channel's button takes a coloured background. Switching...
L / R channel pick (Oscilloscope) - Select which channel drives the measurement table and the channel-offset handle - they do not switch settings tabs. The button...
Left tab (Oscilloscope) - Controls for the left channel. Contains the channel toggle, V/div selector, AC/DC button, Sin/Lin checkbox, Residual checkbox,...
Linux - a systemd unit (The Phonalyser server) - sudo ./phonalyser-server-service.sh install sudo ./phonalyser-server-service.sh activate sudo ./phonalyser-server-service.sh...
Live behaviour (Theory ▸ Signal generator) - Every parameter is adjustable while the generator runs: frequency and amplitude (phase-continuous, see above), duty cycles, sweep
Load audio tab (Oscilloscope) - Plays back an audio file as the scope's data source instead of the live ADC. The open-audio button picks the file - any WAV /...
Load calibration... (Frequency response) - A list of calibration rows. Each loaded, Active -checked .frc / CSV file is de-embedded (subtracted) from the measurement, so the
Load calibration... tab (FFT analyser) - Loads one or more frequency-response calibration files ( .frc , produced by the Frequency response module - see Theory ▸...
Load from... (Frequency response) - Load a previously saved stereo CSV back into the plot. A loaded file is treated as already corrected (it isn't re-calibrated),...
Load from... + In loop (Generator) - Plays back an existing audio file to the output device. The open-audio button picks the file - any WAV / AIFF / FLAC , not only...
Load from... tab (FFT analyser) - Reads a previously-saved .fft file and renders it as a static spectrum overlay - useful for comparing measurements taken at...
Locking to the running average - without self-poisoning (Theory ▸ De-rotation accuracy) - How the fundamental de-rotation is actually formed: An absolute model, anchored to the first block. Each block is rotated by an...
Logarithmic frequency axis (FFT analyser) - Frequency axis switches between log and linear. Log is traditional for audio (constant pixel-per-octave); linear is useful for...
Look & Feel (Preferences) - Setting Notes Tab orientation Top (a conventional tab strip) or Left (a vertical sidebar of large icon buttons). Applies live -...
Loop (Generator) - Checkbox. When on, the sweep restarts as soon as it ends, in a continuous...
LPF (Oscilloscope) - Drop-down that applies a per-channel high-frequency cleanup to the displayed trace. Three options: None - off. 80kHz - an 80 kHz...

M

macOS - a per-user launch agent (The Phonalyser server) - ./phonalyser-server-service.sh install ./phonalyser-server-service.sh activate Do not use sudo . install writes a LaunchAgent at...
Magnitude unit (FFT analyser) - Combo at the top-right with five choices: V , V/√Hz , dBV , dBFS , dBr . Switching unit converts the axis labels and scrollbar...
Mains (Oscilloscope) - Drop-down that applies a per-channel mains-hum rejection filter, tracked live at the line frequency (50 / 60 Hz and its...
Mains suppression (FFT analyser) - Combo - None or IIR comb . The comb pre-filters the captured signal before averaging with a frequency-tracked IIR comb locked to...
Mains-hum rejection: the tracked comb (Theory ▸ Oscilloscope) - Mains interference sits at the line frequency and every integer harmonic of it. A single feedback comb filter [6] places a notch...
Manual fundamental (FFT analyser) - When on, the analyser treats this value as the fundamental's dBV instead of using the de-embedded value or the one from the...
Manual-fundamental tile (FFT analyser) - manF . Visible only when the manual-fundamental override is enabled. ◀ Back to...
Max harmonic for THD (FFT analyser) - Numeric (2 .. 9). Upper bound of the harmonics summed into the THD ratio. THD H2..N uses harmonics 2 through this...
Max harmonic to calculate (FFT analyser) - Numeric (≥ Max harmonic for THD ). How many harmonics to detect and list in the harmonic rows - independent of how many feed the...
Max-harmonic tile (FFT analyser) - H9 - the max harmonic for the THD...
Maximise (FFT analyser) - The inverse of Auto-Setup: sets the widest sensible view - frequency 0 .. Nyquist. The magnitude range is signal-independent only
Measurement hardware (Credits) - A measurement is only as clean as the converters in front of the software. Phonalyser.web was developed and validated against...
Measurement readout (Frequency response) - Two small readouts can appear over the plot once a measurement exists: a compare max / min table, shown while a compare mode is...
Measurement table (Oscilloscope) - Compact grid in the top-left of the trace area. Eight rows, up to five value columns ( cur + the four stats columns). Vmean and...
Measuring intermodulation - the two-tone notch (Theory ▸ DAC pre-distortion) - The wizard's dual-tone path pre-distorts intermodulation , and that measurement meets the same wall as THD, doubled. A CCIF...
Measuring through a Phonalyser server (Preferences) - The hardware does not have to be wired to the machine you are sitting at. A second Phonalyser.web installation running as a server...
Measuring through it (The Phonalyser server) - With a server running, the whole client side is three steps and it is all in Preferences ▸ Audio: Find the bench. Servers... opens...
Mode (Oscilloscope) - A / N / S - Auto, Normal, Single. Auto - runs free, displays the trace whether or not the trigger condition is met. Normal - only
Moving & zooming the signal (Oscilloscope) - The trace can be moved and scaled on both axes. Everything below works the same way whether the scope is live (recording),...
Moving horizontally (Oscilloscope) - Trigger offset (live and stopped) - drag the triangle on the bottom edge, or use the s/div tile's neighbours. This slides the...
Moving vertically (Oscilloscope) - The plain wheel , or dragging an offset handle on either side edge, moves both active channels together , keeping their spacing....

N

N (noise-only) (FFT analyser) - Noise power with the detected harmonics removed from the...
N+D (noise + distortion) (FFT analyser) - Total non-fundamental power, A-weighted. The "A" suffix flags the...
Non-contiguous blocks after glitch rejection (Theory ▸ De-rotation accuracy) - The discontinuity detector throws out corrupted blocks - that filtering is precisely what lets a long average converge at all,...

O

ON AIR indicator (Generator) - An LED and the text ON AIR at the top-right of the pane. Whenever either the tone generator OR the audio-file player is driving...
Opening the wizard (DAC pre-distortion wizard) - Open it from the wand button in the FFT pane's toolbar (left of the record button, live pane only). Before you start, the...
Oscilloscope (Preferences) - Setting Notes Measurement average, s Window length over which the scope's avg / min / max / σ statistics are accumulated. Trace...
Output channel (Generator) - Combo in the top header row - in the Signal form label row, above the signal-form selector and beside the ON AIR indicator -...
Overlap (FFT analyser) - 0 %, 50 %, 75 %, 87.5 %, 93.75 %. Successive analysis windows share that fraction of their samples. Overlap does two things: it...
Overlap tile (FFT analyser) - Percentage ( 87.5%...
Overlap: the effective number of averages (Theory ▸ De-rotation accuracy) - The 1/√ n law assumes independent blocks. Overlapping blocks share samples, so their bin noise is correlated and the variance...
Overrun: when a consumer falls behind (Theory ▸ Ring buffer & consumers) - A cursor consumer can lag - a very large FFT, a heavily loaded machine. The writer does not wait for anyone (the freshest data...

P

Pan & zoom (Frequency response) - Over the plot - wheel : pan the magnitude (vertical) axis; Shift+wheel : pan the frequency (horizontal) axis; Ctrl+wheel : zoom...
Per-type parameter memory (Frequency response) - Each of the four filter types keeps its own complete set of design values and its own mode choice. Selecting a type loads that...
Pinning the fundamental by hand on a steep notch (Theory ▸ FFT analyser) - The fundamental is the one level the notch calibration recovers least reliably. A passive twin-T notch 's flank around its null...
Play / Stop (Generator) - Large play button anchored to the bottom-right of the pane. Starts the tone generator with the current form / frequency /...
Play / Stop file (Generator) - Small play LED next to the path field. Lit while the file is playing, dim otherwise. Starting file playback stops the tone...
Plot region (FFT analyser)
Presets (Frequency response) - Save and recall complete Settings + RIAA configurations. Control Notes Name combo Type a new preset name or pick an existing one.
Presets tab (FFT analyser) - Named snapshots of the analyser's configuration. Type a name in the combo and press Save to store the current FFT and THD...
Presets tab (Oscilloscope) - Save and recall complete scope set-ups. In the name field type a name for the current configuration and press Save - it stores...

Q

Quantization and dither (Theory ▸ Signal generator) - The synthesis chain stays in full precision until the playback engine converts to the device's integer PCM format. Immediately...

R

Ranges table (Preferences) - A range is one setting of the card's analog front-end - an attenuator step, an input-gain position, a DIP or relay setting - each
Reconstructed beat (Oscilloscope) - Checkbox, enabled only when the generator is in Dual tone form (greyed out for every other waveform). When on, the scope overlays
Record button (FFT analyser) - Red round toggle, anchored to the right end of the toolbar row. Pressing it acquires a reference on the shared capture device and
Rectangle duty is quantised to the sample grid (Theory ▸ Signal generator) - The duty threshold lives in continuous phase, but a rectangle's output is a hard +1 -> −1 step , and a step can only fall on a...
References (Further reading ▸ FFT analysis essentials) - S. L. Gjelstrup, "FFT Analysis (Fast Fourier Transform): The Ultimate Guide to Frequency Analysis" , Dewesoft Data Acquisition...
References (Further reading ▸ The exponential sine sweep in practice) - M. Baranov, "How I was listening to a sine sweep all day long" , Medium, 2016 - the original article this page summarises. A....
References (Measurement bench & wiring) - 1. Shielding & grounding technique. H. W. Ott, Electromagnetic Compatibility Engineering (Wiley, 2009), ISBN 978-0-470-18930-6 -...
References (Theory ▸ Algorithm reference) - 1. Phonalyser.web ALGORITHMS.md - the full engineering catalogue this page condenses (per-algorithm math, parameters, source...
References (Theory ▸ Audio backend) - What exclusive-mode streams bypass and guarantee - Microsoft Learn: Exclusive-Mode Streams . The kernel-streaming layer beneath...
References (Theory ▸ DAC pre-distortion) - 1. Twin-T notch network and its transmission zero - Wikipedia: Twin-T filter . 2. Resistor temperature coefficient (TCR) ranges...
References (Theory ▸ De-rotation accuracy) - 1. The 1/√(2ρ) phase-estimation error of a tone in noise is the high-SNR Cramér-Rao bound - Wikipedia: Cramér-Rao bound . 2....
References (Theory ▸ FFT analyser) - 1. Window functions and leakage - Wikipedia: Window function ; the HFT (flat-top) family: G. Heinzel et al., "Spectrum and...
References (Theory ▸ Frequency response) - 1. A. Farina, "Simultaneous measurement of impulse response and distortion with a swept-sine technique" , 108th AES Convention,...
References (Theory ▸ Oscilloscope) - 1. The sinusoid recurrence (1) is the order-2 case of linear prediction - Wikipedia: Linear prediction . 2. Goertzel algorithm...
References (Theory ▸ Ring buffer & consumers) - Circular (ring) buffers in general - Wikipedia: Circular buffer . The underlying coordination pattern - Wikipedia:...
References (Theory ▸ Signal generator) - Direct digital synthesis - Wikipedia: Direct digital synthesis ; in depth: Analog Devices tutorial MT-085, "Fundamentals of...
References (Theory ▸ Tune-notch measurement) - 1. A. Farina, Simultaneous measurement of impulse response and distortion with a swept-sine technique , AES 108th Convention,...
Reset averaging buffer (FFT analyser) - Red counterclockwise-arrow button (a "roll back to the start" reset). Wipes the averaging buffer + retained spectrum and rearms...
Reset statistics (Oscilloscope) - Red counterclockwise-arrow button (the "roll back to the start" reset). Clears the rolling-window statistics history that feeds...
Residual (Oscilloscope) - Per-channel checkbox. When checked, the channel's trace is replaced by the residual : the captured signal minus a best-fit single
Resolution follows the signal, not the converter (Theory ▸ Oscilloscope) - The obvious construction - divide full scale into a fixed number of bins - ties the resolution to the converter's range instead...
Resolution, windows, overlap (Theory ▸ FFT analyser) - An FFT of length N at sample rate f s produces bins spaced f s / N apart; longer transforms (up to 4M points here) buy finer...
RIAA & IEC (Frequency response) - Control Notes Show RIAA curve Overlay the RIAA reference, aligned at 1 kHz. This gate enables the three controls below. Reverse...
Right tab (Oscilloscope) - Identical layout to the Left tab - channel toggle, V/div, AC/DC, Sin/Lin and Residual, but for the right...
Rubber-band zoom & Ctrl+Z (FFT analyser) - Hold the left mouse button inside the plot and drag: a thin bright-green rectangle follows the pointer, and on release the view...
Rubber-band zoom & Ctrl+Z (Oscilloscope) - Drag with the left button across the trace to draw a rectangle; release, and the selection stretches to fill the whole view - the
Running a measurement (Frequency response) - Press Play to sweep. Capture and generator playback are taken over for the run, a modal progress dialog shows a live...
Running it as a service (The Phonalyser server)
Running it in a console (The Phonalyser server) - phonalyser-server-x64.exe phonalyser-server.cmd --name bench1 --port 8377 ./phonalyser-server.sh ./phonalyser-server.sh --name...

S

Save to... (Frequency response) - Save the current measurement as a stereo CSV (frequency, L/R magnitude in dB, L/R phase in degrees). The file also records the...
Save to... (Generator) - Read-only path + Save button . Clicking it opens a save dialog; the chosen file's extension picks the format ( .wav / .flac /...
Save to... tab (FFT analyser) - Writes the current spectrum to a .fft file. The path field is read-only; a single Save button opens the file dialog (there is no...
Save to... tab (Oscilloscope) - Writes the most recent capture to an audio file. The duration field (a single input in seconds) sets how much to save; the...
Saving a signal - a perfect reference (Theory ▸ Signal generator) - When you save the generator output to a file ( Save to... on the generator pane), the samples are written straight from the...
Screenshot (FFT analyser) - Renders the FFT pane to a PNG at a chosen resolution. The pane is laid out off-screen at the target size, so the image is a true...
Screenshot (Oscilloscope) - Renders the scope pane to a PNG at a chosen resolution and lets you save it to disk (or copy it). The render uses an offscreen...
Scrollbars (Oscilloscope) - A vertical scrollbar on the right pans the trace up / down (the voltage offset, both channels together). A horizontal scrollbar...
See also (The Phonalyser server) - Preferences ▸ Measuring through a Phonalyser server - the whole client side. Theory ▸ A bench across the network - the ports, the
Setting dither by the noise floor it makes (Theory ▸ Signal generator) - Dither depth is a number of bits, but a spectrum shows a level , not a bit count - so the generator lets you set and read the...
Settings (Frequency response) - Control Notes Start frequency, Hz Low end of the sweep. ≥ 1 Hz. Stop frequency, Hz High end of the sweep, up to the Nyquist...
Settings tabs (Frequency response) - The settings strip holds nine tabs, in order: Settings , RIAA & IEC , Filters , Unevenness , Presets , Utility , Load...
Signal form (Generator) - Drop-down combo with eleven waveforms. Each entry has a small pictogram showing the waveform shape. Changing the form...
Signal synthesis & quantization (Theory ▸ Algorithm reference) - Algorithm What it does here In this help Direct digital synthesis (DDS) 64-bit phase-accumulator oscillator; exact mod-2⁶⁴ phase,
Sin / Lin (sinc interpolation) (Oscilloscope) - Per-channel checkbox shown with a small sinc-shape image. When checked, the trace is rendered with Lanczos sinc interpolation...
Sine: lookup table + Taylor correction (Theory ▸ Signal generator) - The sine of the accumulator phase is computed by splitting φₐ into a coarse table index and a fine remainder: The two parts are...
Snap frequency to nearest (Generator) - Checkbox. When on, the emitted frequency snaps to the nearest FFT bin for the current FFT-analyser length. Useful for clean...
SNR (FFT analyser) - Signal-to-noise ratio in dB. Defined against the noise-only band (above): the fundamental, its harmonics, and the fundamental's...
Span row (FFT analyser) - Span: 900 .. 9500 Hz - the band over which SNR / THD+N integrate. Span: full when both distortion bounds are...
Spectral analysis (Theory ▸ Algorithm reference) - Algorithm What it does here In this help Radix-2 Cooley-Tukey FFT The transform itself - in-place, parallelised at large sizes...
Spectrum trace (FFT analyser) - Polyline of the FFT magnitude across the visible frequency range. Trace colour, line width, and chart background are configurable
Start (Single re-arm) (Oscilloscope) - Active only when the mode is Single . Pressing it arms the next single-shot...
Start frequency (Generator) - The frequency the chirp begins at (Hz /...
Statistics & graphics (Theory ▸ Algorithm reference) - Algorithm What it does here In this help Welford's online variance One-pass mean and σ for the live measurement statistics table.
Stats columns (avg / min / max / σ) (Oscilloscope) - Rolling-window statistics over a configurable averaging window (see Preferences -> Oscilloscope -> Measurement average ). σ is the...
Stats columns toggle (Oscilloscope) - Shows / hides the avg / min / max / σ columns of the measurement table. The worker keeps computing them regardless; the toggle...
Stop after N (FFT analyser) - Checkbox + numeric field. When the checkbox is on, the analyser pauses as soon as the on-screen averages count reaches N (Forever
Stop frequency (Generator) - The frequency the chirp ends at (Hz /...
Sub-bin frequency and de-rotation (Theory ▸ FFT analyser) - Write the tone's exact position as a fractional bin number κ. Between two blocks spaced s samples apart, bin k 's phase advances...
Sweep / chirp (Generator) - Visible only when Linear sweep or Log sweep is selected. Replaces the single frequency field with a block of sweep...
Sweeps (Theory ▸ Signal generator) - A sweep's instantaneous frequency is a function of time, so the phase is integrated explicitly instead of using the fixed...

T

The one refused edit (Editing the settings as JSON) - A device document with no audioDevices list at all is rejected rather than applied, because applying it would delete every card...
Tab tiles (FFT analyser) - Only three tabs carry tiles - FFT settings , THD settings and Load calibration ; they show the small pill-shaped badges under the
Tab tiles (Oscilloscope) - The Left , Right , Horizontal and Trigger tabs show a row of small tiles under the tab label with that tab's key values (the...
THD H2..N (FFT analyser) - Total harmonic distortion as a percentage of the fundamental, summed over harmonics 2 through N (where N = Max harmonic for THD...
THD info table (FFT analyser) - Compact overlay in the top-left of the canvas (or in the external tool window when extracted). All values use the current...
THD settings tab (FFT analyser)
THD+N (FFT analyser) - Total harmonic distortion + noise. Same numerator as N+D, normalised to the...
The amplitude histogram: how often, not when (Theory ▸ Oscilloscope) - The trace answers "what does the waveform look like over time". The amplitude histogram answers a different question about the...
The buttons on the backend row (Preferences) - Three buttons share the row with the backend list. Two are always present; the third appears only for a backend that has settings
The capture session: who owns the device (Theory ▸ Ring buffer & consumers) - The input device and the live ring have exactly one owner - the capture session . Views never open the device themselves; they...
The Card combo and the edit button (Preferences) - The combo lists every card profile that has at least one range in this direction - the pre-seeded known cards included - plus New
The card editor (Preferences) - The pencil button opens the card editor, a small dialog holding every property of a card except its per-range voltages (those...
The devices.yaml file - manual editing (Preferences) - The file sits in the user data directory, beside preferences.yaml : OS Location Windows %APPDATA%\Phonalyser.web\devices.yaml macOS...
The distortion and noise metrics (Theory ▸ FFT analyser) - From the averaged spectrum, with the fundamental level A 1 and harmonic levels A h : THD = √( Σ h ≥2 A h ² ) / A 1 (4) SNR...
The flatness readout (Frequency response) - The result is written as a short line, shown in a small outlined table below the header buttons (stacking below the compare...
The glitch trigger: firing on damage, not on a level (Theory ▸ Oscilloscope) - Some events worth catching are not level crossings at all. A capture hiccup that swallows samples leaves an amplitude step or a...
The measurements are taken as captured (Oscilloscope) - Every number in this table is computed on the unfiltered window - the per-channel LPF cleanup, both the 80 kHz low-pass and the...
The neighbour bin: where the leaked power goes (Theory ▸ FFT analyser) - However good the alignment, the tone's true position κ is never perfectly on the bin - and any offset splits the tone's power...
The notch drifts - so the fundamental must be defined manually (Theory ▸ DAC pre-distortion) - A twin-T notch nulls at f 0 = 1 / (2π RC ) (1) so its null frequency tracks the product RC . Resistors and capacitors change...
The notch-tuning sweep: a live variant (Theory ▸ Frequency response) - Measuring the distortion of a very clean source calls for a passive twin-T notch filter [4] ahead of the ADC: it pulls the...
The overlay curve (Frequency response) - When Show is on and the design is valid, the ideal magnitude response is drawn as a purple dashed curve at the same line width as
The phase accumulator (Theory ▸ Signal generator) - All periodic waveforms are driven by a 64-bit phase accumulator φₐ: an unsigned integer representing the phase as a fraction of...
The QA40x analyzer backend (Theory ▸ Audio backend) - Alongside the three general-purpose paths, Phonalyser.web can drive a QuantAsylum QA402 / QA403 audio analyzer directly, over USB,...
The question this page answers (Theory ▸ DAC pre-distortion) - Every DAC adds harmonic distortion of its own. When you measure a device under test you want the stimulus to be cleaner than the...
The question this page answers (Theory ▸ De-rotation accuracy) - Coherent averaging only works because every captured block is rotated back onto a common phase before it is summed - the...
The read cursor (Theory ▸ Ring buffer & consumers) - Consumers fall into two camps, and the cursor exists for the second one: "Show me now" consumers - the oscilloscope, the...
The reference must be exactly what was played (Theory ▸ Frequency response) - Equation (1) is only honest if X is precisely the signal that drove the DAC. This is why the sweep is pre-rendered into a buffer...
The ring (Theory ▸ Ring buffer & consumers) - The ring holds the most recent 22 seconds of stereo capture as normalised values in [−1, +1] - enough for two full oscilloscope...
The server list (Preferences) - The Servers... button on the backend row opens Phonalyser servers . Servers announce themselves on the local network, so the list...
The three ways to read (Theory ▸ Ring buffer & consumers) - Read mode Semantics Latest window The most recent N samples, ending at the live w - "show me now". Inherently safe: it always...
The waveforms (Theory ▸ Signal generator)
The worked example (Theory ▸ De-rotation accuracy) - All the numbers below are for one concrete, demanding case: a faint tone averaged very deeply. Quantity Symbol Value Sample rate...
There is no authentication, on purpose (The Phonalyser server) - A Phonalyser server does not ask for a password, and nothing on the wire is encrypted. That is a decision, not an omission: a...
Time / div (Oscilloscope) - Horizontal resolution, as a 1-2-5-10 list from 1 µs/div to 1 s/div (no ns/div). The wheel / arrows / ↑↓ keys step the list, or...
Time/div tile (Oscilloscope) - The horizontal resolution, short form - e.g. 200u , 1m , 20m...
Toolbar tabs (FFT analyser)
Toolbar tabs (Oscilloscope) - The settings-tab strip at the bottom of the pane holds per-channel, trigger and utility settings. The Left , Right , Horizontal...
Top toolbar (above the tab strip) (FFT analyser)
Trigger tab (Oscilloscope)
Trigger-channel tile (Oscilloscope) - L or R - which channel is currently used to arm the...
Trigger-edge tile (Oscilloscope) - ↑ for rising, ↓ for falling. With the glitch type: anchor on the glitch's start (↑) or end...
Trigger-level marker (Oscilloscope) - A horizontal marker line whose triangle handle is on the right edge . The marker can be moved only by dragging that handle up or...
Trigger-mode tile (Oscilloscope) - A , N or S - Auto, Normal,...
Trigger-offset marker (Oscilloscope) - A vertical marker line whose triangle handle is on the bottom edge . It sets where in the window the trigger event sits. Move it...
Trigger-type tile (Oscilloscope) - G - shown only while the glitch trigger is selected. The absence of this tile means the edge...
Triggering (Theory ▸ Oscilloscope) - A free-running scope would redraw the waveform at a random phase each frame, so a periodic signal would appear to slide across...
Two-tone (intermodulation) (Theory ▸ FFT analyser) - With two tones present, the products of interest are not harmonics of one tone but combinations a · f ₁ + b · f ₂. The analyser...
Type (E / G) (Oscilloscope) - E / G pair choosing what the trigger reacts to. E - edge : the classic comparator described above - fires when the...

U

Unevenness (Frequency response) - Reduce the response to a single flatness figure and mark it on the plot. Depending on the mode, this is either the widest band...
Utility (Frequency response) - Button Action Screenshot Save or copy a picture of the frequency-response plot. Calibrate DAC full-scale Reference-level DAC...
Utility tab (FFT analyser)
Utility tab (Oscilloscope)

V

V/div (Oscilloscope) - Vertical resolution, as a 1-2-5-10 list from 1 µV/div to 500 V/div . The wheel / arrows / ↑↓ keys step through the list; you can...
V/div tile (Oscilloscope) - The channel's vertical resolution, short form (e.g. 1m , 500m , 1...
Vertical scrollbar (magnitude) (FFT analyser) - The same, for the magnitude axis: it pans up / down only and its thumb tracks the magnitude zoom. Ctrl+wheel inside the canvas...

W

Where it is (Editing the settings as JSON) - Tools carries two submenus: Preferences ▸ Current opens the live settings document, Devices ▸ Current the live device store, and...
WAV export (Generator)
WAV playback (Generator)
What a "dBV" input range actually is (Theory ▸ Audio backend) - The analyzer names its input ranges in dBV - 0 dBV , +18 dBV , and so on - and taking those names for RMS full-scale voltages is...
What all of this buys (Theory ▸ FFT analyser) - Each mechanism in this chapter removes one way a long complex average can rot: bin alignment to ±0.05 ppm removes the leakage,...
What else crosses the wire (Preferences) - A backend's own settings. QA40x properties and the input and output range radios drive an analyzer on the bench exactly as they...
What it does to the measured levels (Theory ▸ De-rotation accuracy) - After de-rotation, harmonic h carries a residual rotation of − h ·(block error). Accumulating and expanding that small rotation...
What it is for (Theory ▸ Audio backend) - The audio backend is the bridge between Phonalyser.web and the sound hardware. Its one job is to move samples between the application
What it is for (Theory ▸ FFT analyser) - The FFT analyser is the frequency-domain workhorse: it shows the spectrum and measures harmonic distortion (THD, THD+N),...
What it is for (Theory ▸ Frequency response) - The frequency-response module measures a device's transfer function - its gain and phase shift at every frequency across the band
What it is for (Theory ▸ Oscilloscope) - The oscilloscope is the time-domain view - and the one you should look at first . Before any spectral number is worth trusting,...
What it is, and what you need (The Phonalyser server) - The server ships as its own download, one ZIP per platform - Windows x64 and x86, Linux x86_64 and aarch64, macOS Intel and Apple
What you see (DAC pre-distortion wizard) - An FFT settings block echoes the size, sample rate and window the run inherits from the FFT pane (read-only - set them there...
When a device won't open - and when it stops (Theory ▸ Audio backend) - Exclusive mode means open attempts can fail for everyday reasons. A native return code says nothing an operator can act on, so...
When the analysis stops by itself (FFT analyser) - A capture can end without you pressing anything - the device unplugged, taken exclusively by another application, or simply...
When the capture stops by itself (Oscilloscope) - A capture can end without you pressing Record again - the device unplugged, taken exclusively by another application, or stopped...
When the values take effect (Preferences) - The card's active-range full-scale is resolved - by the bindings entry for the device if you made one, otherwise by the match...
Where it sits (Theory ▸ FFT analyser) - The analyser shares one capture session and ring buffer with the oscilloscope . When the generator runs an internal tone it can...
Where it sits (Theory ▸ Frequency response) - Unlike the scope and FFT, which share one input device, the frequency-response sweep needs the DAC and ADC simultaneously and...
Where it sits (Theory ▸ Oscilloscope) - The oscilloscope shares its capture device and ring buffer with the FFT analyser through the common capture session , so both can
Where things are (The Phonalyser server) - Platform Log, cards and identity Windows One place, however it was started - console, LocalSystem service or /user service alike:
Which window - and why it is not chosen for noise (Theory ▸ De-rotation accuracy) - Because the floor-per-time is equal above the recommended overlap, the window is chosen on the other two axes: window NENBW...
While it runs (The Phonalyser server) - Hardware is re-enumerated every two seconds , so a device plugged in or pulled out on the bench is noticed without restarting...
Who uses the backend (Theory ▸ Audio backend) - Module Direction How Oscilloscope, FFT analyser capture Share one capture session and one ring buffer - see capture session . The
Why a live display, not a single sweep (Theory ▸ Tune-notch measurement) - Tuning is a closed loop with a human in it: turn the trimmer a hair, see the null move and deepen, turn again. A one-shot sweep...
Why a passive twin-T notch in front - and why it is mandatory (Theory ▸ DAC pre-distortion) - The correction tones the generator must produce are the DAC's harmonics, inverted. A 2nd harmonic at −110 dBc has to be measured...
Why a re-range clears the counts (Theory ▸ Oscilloscope) - When the signal no longer fits, the range is re-established and the counts are cleared , deliberately. Counts gathered at a...
Why no trigger is needed (Theory ▸ Tune-notch measurement) - The sweep is played on a loop whose length is deliberately rounded to a power of two samples, N = nearest power of two to T sweep
Why the angle has to be re-measured every block (Theory ▸ De-rotation accuracy) - With the tone snapped exactly onto a bin and blocks read contiguously, the block-to-block phase step would be zero. The few-ppm...
Why writer and readers never get in each other's way (Theory ▸ Ring buffer & consumers) - The writer is the capture thread; the readers are the display and the FFT worker [2] . If a reader could stall the writer for...
Window (FFT analyser) - Combo of analysis windows, each trading main-lobe width against side-lobe level: Rectangular, Hann, Blackman-Harris 4-term and...
Window and overlap - HFT248D at 87.5 % (Theory ▸ DAC pre-distortion) - The measurement runs the HFT248D window at 87.5 % overlap , the combination the de-rotation accuracy chapter derives from first...
Window tile (FFT analyser) - The window's short code - not a fixed length. One of RECT , HANN , BH4 , BH7 , FT , HFT144D , HFT248D , KB24 , KB38 , DC150 ,...
Windows - a real service (The Phonalyser server) - From an elevated command prompt: install-service.cmd run as LocalSystem install-service.cmd /user BENCH\alex run as a real...
With thanks (Credits) - First and foremost, to Nick Sukhov - building his power-amplifier and phono-preamp designs, and wanting to measure them properly,
Wobbly trace - check for clipping (Frequency response) - The sweep now checks this for you. The largest absolute sample of the raw capture is recorded before any deconvolution, and if it
Worked example - two cards on one bench (Preferences) - A typical bench has an E1DA Cosmos ADC on the input, whose DIP attenuator switches its full-scale, and a separate JLsounds card...

Z

Zooming horizontally (Oscilloscope) - Horizontal-resolution control (the s/div field) - zooms around the trigger offset : the trigger stays put and the trace stretches
Zooming vertically (Oscilloscope) - A channel's V/div control (its field - typing, arrows, ↑↓, or the wheel over the field) rescales that channel alone , around the...

Index & search

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