MeterWorks Spectrum Analyzer

A tone you can't place — the motion-sensor deterrent next door, a beep from inside a wall, a hum from the basement. You can barely hear it, but it's there. MeterWorks Spectrum Analyzer makes it visible: live spectrum, automatic logging, an evidence PDF — on your device, no account, no subscription. MEASURE & CIRCLE IN • Live spectrum, linear or logarithmic axis, stepless pinch-zoom in frequency AND level • Peak detection with the resolution stated openly, 60-second waterfall • Device self-test "What can YOUR iPhone do?" shows the real usable top frequency before you buy • Walk mode: keep measuring while you walk the property, every point on the map carries its level — you circle in on a source, you don't locate it WATCH BANDS & LOG — THE EVIDENCE CHAIN • Pro: name your own watch bands ("cat-deterrent window" 16–24 kHz, "hum" 20–200 Hz, fully custom), each with its own threshold • Pro: automatic events — when a band crosses its threshold, the entry writes itself: start, duration, classification • Pro: walk report as PDF with a map snippet, a point table, and band spectra — plus CSV • Quiet references: save silence at a location, later measurements show the rise over it (1 free, more with Pro) DOCUMENT • PNG export with footer — free • Pro: multi-page PDF report with statistics, spectrogram, and event table • Pro: CSV export of the band levels — spreadsheet-ready FREE VS. PRO — NO SURPRISES Free: live spectrum with full zoom (3 sessions of up to 30 seconds each), waterfall, self-test, limits page, A/B comparison, 1 reference, three recordings of 10 seconds each, one walk of up to 30 seconds, PNG export. Pro is a single one-time purchase (no subscription, ever): watch bands, unlimited walks with report PDF and CSV, more references, unlimited live view and recordings, log PDF, CSV — all future Pro features included. WHAT THIS APP CANNOT DO — HONESTLY What kids can hear, this app can see: the audible range up to 24 kHz sits fully inside the iPhone microphone's window. True ultrasound above that is beyond any iPhone — and beyond any app that claims otherwise (the Nyquist limit of 48 kHz sampling). What holds up is the comparison within the same band over time, not an absolute dB value. This app documents, it doesn't judge: no "court-proof" claims — a clean log with openly stated limits. TYPICAL USES Circle in on a noise source in the garden or neighborhood · identify a sound you can barely hear yourself · confirm a motion-sensor or cat-deterrent frequency · document a hum inside the house NO SUBSCRIPTION. NO ADS. NO TRACKERS. All measurement data stays on your device — only band-aggregated spectra, never audio. MeterWorks is a family of honest measurement apps: Vibrometer, Sound Meter, Teslameter — Spectrum Analyzer is the fourth.