Aletra — a multisensor logger for iPhone: measure, record, export
English What Aletra is, and what it is not. Aletra records what your iPhone's sensors measure and timestamps it. It does not interpret those numbers and it does not tell you what caused them. It is not a certified measuring instrument: readings depend on the phone's own sensors and on ambient conditions. Do not use it for safety or health decisions, to look for wiring or pipes before drilling, or to assess electrical or structural hazards. For any of that, use the proper instrument and a qualified professional.
Español Qué es Aletra y qué no es. Aletra registra lo que miden los sensores de tu iPhone y le pone hora. No interpreta esos números ni te dice qué los ha causado. No es un instrumento de medición certificado: las lecturas dependen de los propios sensores del teléfono y de las condiciones del entorno. No la uses para decisiones de seguridad o salud, para buscar cables o tuberías antes de taladrar, ni para evaluar riesgos eléctricos o estructurales. Para eso, el instrumento adecuado y un profesional.
Write to rjm.softwaredevelopment@gmail.com with questions, bugs or suggestions. For a bug it helps a lot to include your iPhone model, your iOS version, which module you were using and what you were doing when it happened.
Aletra is a paid app with a single, one-off payment. No subscriptions, no in-app purchases, no premium tier: every feature and every future update is included.
No. There is no sign-up and no user account, and the app makes no network requests at all. It works the same in airplane mode, in a basement or in the middle of nowhere.
That sensor does not exist on your device, or you are running the app in the iOS Simulator, where physical sensors are not present. The survey's 3D mesh needs an iPhone with a LiDAR scanner.
The permission was denied. Settings inside the app has a Permissions section that shows the state of the microphone, camera, compass and notifications, with a button to grant each one or to open iOS Settings.
The EMF gauge shows the deviation over the baseline, not the absolute field: at rest it sits near zero on purpose, and it rises as you approach a source. If the direction list stays empty, the compass has no location permission; the screen says so and offers a shortcut to Settings.
The colour of a survey is relative to that survey: blue is the lowest field measured during that walk, red the highest, and the legend under the map gives both values in µT. If the whole room measured the same, the survey says so instead of inventing a gradient over sensor noise.
Surveys made before version 1.0 shipped this were saved without the room mesh or the photos of the walk. Nothing can recover those; new surveys include both.
Turn on "Continue in background" on the session card. It keeps the session alive with the screen locked, using the microphone; the microphone indicator stays visible while it runs. It is off by default because it uses noticeably more battery.
Starting a session turns on the sensors that can measure without the screen. If they all end up stopped, the session card says so in red and offers a button to turn them back on. The camera-based ones (light, and the survey) only measure with their own screen in front.
That depends on your microphone, and the app refuses to guess. Settings has a band sweep that plays known tones from 10 to 60 Hz and measures what the FFT actually returns, so you can tell whether that number is sound or the microphone's own noise. Until you run it, the screen says the band is unverified.
A synthetic series that drives the same screens as the real sensors, so you can explore the app without hardware. Everything it produces is tagged DEMO, excluded from statistics and declared in the CSV. On a real iPhone it is off by default.
In the Files app, under On My iPhone > Aletra: CSV files in the CSV folder and exported recordings in Audio > Exportados. From there you can move them to iCloud Drive, email them or open them in a spreadsheet. The app's internal store (events, sessions, surveys) is deliberately not exposed there, so a stray edit cannot corrupt your log.
Aletra watches the thermal state and gives up the camera-based modules before iOS starts throttling everything. Settings also has a battery saver that does the same on demand, and a warning below 20 % charge.
Events, sessions, recordings and surveys can be deleted from inside the app. Uninstalling removes everything stored on the device. See the privacy policy.