Frequency Analyzer

Introduction

The Frequency Analyzer verifies that the audio passing through it is a clean sine wave at a specific target frequency — and lets the rest of the project know about it. It's a pass-through operator: the audio itself is never altered. Drop it on a layer, point it at the frequency you expect to see, and it continuously reports whether the input matches.

The classic use is automated test-signal verification: confirming that a 1 kHz line-up tone is making it intact all the way through the audio chain — at the right pitch, with the right shape, and at a usable level. Plug it into a CI / autotest scene, or into a connector that flips a UI indicator green when the reference tone is present, and the analyzer becomes a passive health check on the audio path.

What it checks

A signal counts as a match only when all four conditions hold simultaneously:

Pitch — the measured frequency lies within Frequency ± Frequency Tolerance Hz.
Shape — the waveform is sine-like to within Shape Tolerance. Lower tolerance demands a near-perfect sine; higher tolerance accepts some distortion.
Level — the signal is louder than Minimum signal level (dB). Anything quieter is treated as silence or background noise and ignored, so a near-silent input never reports a phantom sine.
Persistence — the conditions hold over the configured Window length (s). The Consistency (%) read-out shows what fraction of that window was matching — 100 means rock-solid, 60 means the signal drifted in and out.

Configuration

Frequency (Hz) — what to look for. 50–5000 Hz, default 1000 Hz (the standard EBU/SMPTE reference pitch).
Frequency Tolerance — how many Hz of drift is still considered a match. Tight (a few Hz) catches small upstream drift but can flag a perfectly good source that isn't perfectly stable; loose (±50 Hz) is more forgiving. Default ±20 Hz.
Shape Tolerance — how strict the sine-shape check is. Use a strict value (0.1–1) when verifying a clean test tone; relax it for sources that may have some harmonic content.
Minimum signal level (dB) — silence floor. Default −12 dB; lower it (−24, −36) if the test tone arrives at line level rather than peak.
Window length (s) — the rolling window used to compute average frequency and consistency. Short windows (1–2 s) react fast to changes; longer windows (10–60 s) give a more stable reading at the cost of slower reaction.

Live readouts

Three read-only values are surfaced for the property panel, scripts, and external dashboards:

Measured frequency — the average frequency detected over the analysis window, in Hz. Compare against Frequency to see how close the input is to the target.
Match — a single boolean. True when the input currently meets all the criteria above. Useful from a Connector to drive an "audio OK" indicator, or from a script to log an alert when the reference tone disappears.
Consistency (%) — 0–100, the fraction of the analysis window that was matching. The most informative reading when the source is drifting in and out of spec — it'll trend down well before Match flips false.

Common use cases

Line-up tone verification — confirm the 1 kHz EBU reference makes it through the entire chain before a show starts; flip a UI indicator green when the analyzer reports Match = true consistently.
End-to-end pipeline health check — sit an analyzer on a calibration loop fed by a known test generator; a sustained drop in Consistency is an early warning that something upstream has changed.
Automated regression testing — in an autotest scene, assert that IsMatch == true and ConsistencyPercentage >= 95 after the project has been running long enough to fill the window. Catches signal-path regressions without anyone having to listen.
Spotting tone drift on a long-haul contribution — when a remote site is supposed to be sending a continuous reference tone, the Measured frequency read-out exposes slow clock drift between sites in a way no meter does.
Catching codec-induced distortion — a sine going in but a non-sine coming out is the textbook fingerprint of a misconfigured codec or a lossy intermediate. A drop in Match with the frequency still correct points the finger at shape.

A single Reset command snaps every parameter back to defaults (1000 Hz, ±20 Hz, strict shape, −12 dB minimum, 1 s window) — useful as a known starting state when a script is about to configure the analyzer for a particular check.

Frequency Analyzer - Settings

Configuration

Configuration — what frequency to look for and how strict the match should be.

Property	Description
`Frequency (Hz)`	Target frequency to verify, in Hz. [min=50, max=5000, default=1000]. 1000 Hz is the standard EBU/SMPTE reference tone. Set to whatever pitch your test signal is supposed to have.
`Frequency Tolerance`	How many Hz the measured frequency may deviate from `Frequency` and still count as a match. [min=1, max=100, default=20]. Tighter tolerances catch small drift but can flag a perfectly good source if its frequency isn't perfectly stable.
`Shape Tolerance`	Strictness of the sine-wave shape check. [min=0.1, max=20, default=0.1]. Lower values demand a near-perfect sine; higher values accept some distortion. Use stricter values when verifying a clean test tone.
`Minimum signal level (dB)`	Lowest signal level that counts as a real signal, in decibels. [min=-36, max=0, default=-12]. Audio quieter than this is treated as silence or background noise and ignored. Stops the analyzer from reporting a "sine wave" detection on a near-silent input.
`Window length (s)`	Time window over which consistency and average frequency are calculated, in seconds. [min=1, max=60, default=1]. Shorter windows respond faster to changes in the input; longer windows give a more stable consistency reading at the cost of slower reaction.

Result

Result — what the analyzer is currently measuring on the input.

Property	Description
`Measured frequency`	Average frequency detected on the input, in Hz (read-only). Averaged over `AnalysisWindowSeconds`. Compare against `Frequency` to see how close the input is to the target.
`Match`	True when the input matches the target frequency, shape, and level (read-only). Useful from a script to react to verification — for example, log an alert when the expected tone disappears or fails to meet quality.
`Consistency (%)`	Percentage of the analysis window that matched the target, 0–100 (read-only). 100 means every measurement in the window was a match; lower values indicate the signal drifted in and out of spec during the window.

Actions

Actions — one-click commands.

Property	Description
`Reset`	Reset all settings to their defaults (1000 Hz, ±20 Hz, strict shape, −12 dB minimum, 1 s window).

Inherits from: AbstractAudioOperator, AbstractOperator, AbstractAudioMetering.