OmniRTA - Spectrum Analyzer

Low-frequency analysis forces a trade-off: a high-Q filter gives sharp resolution but reacts slowly, while a low-Q filter reacts fast but blurs nearby resonances together. OmniRTA is a real-time RTA spectrum analyzer for Android with three interchangeable engines, letting users compare its innovative Bayes algorithm directly against CQT and FFT, the two classic, well-known methods used in professional acoustic tools.

Who it's for
For live sound engineers, Bayes tracks bass transients in real time while still isolating two closely spaced low-end resonances, something a fixed-Q filter cannot do at once, speeding up PA tuning under real conditions. For acousticians, switching to CQT at 1/12-octave with Peak Hold while playing pink noise makes room modes clearly visible and comparable to certified lab RTAs, thanks to IEC 61260-compliant Q filtering. For musicians, Piano Roll aligns each detected note under its matching piano key at 1/12 or 1/24-octave resolution, making pitch drift as small as a quarter-tone easy to spot in any of the three modes.

Why people install it
• Catch bass transients instantly thanks to the dual-path Bayes fusion algorithm.
• Separate closely spaced low resonances thanks to a high-Q fine-filtering path running in parallel.
• Compare results against known standards thanks to built-in CQT and FFT reference engines.
• Cut false readings from amplified background noise thanks to an adaptive contextual fusion factor.
• Match certified lab equipment thanks to IEC 61260-compliant Q filtering in CQT mode.

Key features
🎯 Bayes algorithm (default engine)
• Dual-path probabilistic fusion, unique among documented mobile spectrum analyzers
• Instant response to low-frequency transients without sacrificing frequency resolution
• Independently adjustable low-band (qLow) and high-band (qHigh) Q, with a smooth blend between 140-280 Hz
• Dedicated x64 cascaded decimation for cleaner low-frequency signal before fusion
📊 CQT and FFT — two classic reference engines
• CQT: IEC 61260-compliant filter bank with auto-calculated Q, the industry-standard method for pro RTAs
• FFT: radix-2 transform, selectable window from 1024 to 8192 points, the best-known spectral method
• All three engines share the same resolution, scale, and display options, switching takes one tap
⚙️ Flexible resolution and display
• Four band resolutions from 1/3 to 1/24 octave (30 to 240 bands)
• Five X-axis scales: Logarithmic, Octave (1kHz), Octave (C), Piano Roll, and Bark
• ISO-226 equal-loudness grid or linear (10 dB) Y-axis display
• Configurable Peak Hold up to 120 seconds, plus real-time Tilt, Centroid, and Bandwidth readouts

What makes OmniRTA different
Bayes runs two filtering paths at once on every band below 280 Hz: one applies a highly selective, high-Q filter for fine resolution, while the second tracks instantaneous versus averaged energy to detect transients. A contextual fusion factor blends the two, accelerating response during transients while keeping fine resolution at steady state. Because CQT and FFT are included alongside it, users can A/B their own recordings across all three engines and judge the improvement directly. The DSP engine runs natively in Rust rather than Java or Kotlin, avoiding garbage-collector pauses and eliminating data races at the compiler level.

Trust and transparency
OmniRTA only requests microphone access for spectral analysis, with no network, storage, or contacts permissions, and works entirely offline. A free tier offers FFT-only analysis with limited resolutions and scales; Pro and Pro+ tiers are one-time in-app purchases unlocking Bayes and CQT, all resolutions, ISO-226, Peak Hold, and Tilt/Centroid analysis, with no subscription required.

Download OmniRTA and compare a genuinely new low-frequency algorithm against the two methods engineers already trust.