Aletra: Multisensor Logger

Measure magnetic fields, infrasound, pressure, vibration and light with your iPhone; export it all to CSV and map a room in 3D. One-time purchase, no subscription.

Your iPhone carries a magnetometer, a barometer, an accelerometer, a compass, a microphone that reaches down into infrasound, and a LiDAR scanner. Aletra puts them to work together: it measures, shows what it measures, timestamps every reading and exports the lot to CSV.

Aletra records. It does not interpret or draw conclusions for you. What the numbers mean is your call, and that is the whole point.

WHAT PEOPLE USE IT FOR

• The hum you only hear at night. Leave the iPhone resting somewhere, turn on background monitoring and go to sleep. In the morning you have every episode with its time, its level in the 15-22 Hz band and its vibration, ready to export.
• The interference bleeding into your speakers. Open the EMF detector and walk slowly: the reading rises as you approach the source. Wiring, a transformer, a charger behind the furniture.
• The home studio. Before you settle on a mic position, survey the room and see where the field is lowest. And measure how far your microphone reaches in the low end.
• Vibration from upstairs or from traffic. Hits counted, with time and magnitude in g. Documenting a recurring nuisance is more convincing with a table than with a complaint.
• School physics and citizen science. Real series, statistics (mean, standard deviation, percentiles, IQR outliers), calibration against a reference instrument and CSV for your spreadsheet.
• Places with a reputation. No app tells you "something is here": this is what you need to rule out the ordinary. Every spike can be tagged with its everyday cause (the air conditioning, traffic, a phone nearby), and whatever is left unexplained is the only thing worth a look.

THE SURVEY: WHAT NOBODY ELSE DOES

Walk a room. LiDAR rebuilds it in 3D and knows where you are, so each magnetic field reading is pinned to the exact point where it was taken.

When you finish you have the room's 3D model with the values spread through the space: blue where the field is lowest, red where it is highest, with the microteslas at each end. It is saved with photos of the place. And you can go back, ask the app to recognize the room and repeat the measurement at the same spot.

A survey detects nothing. It draws where each value was measured, which is a different and far more useful thing.

WHAT IT MEASURES

• Magnetic field in µT, with the direction of each spike noted by the compass.
• Sound: live spectrum and a watch on the 15-22 Hz band, with auto-recording and 0.25x playback.
• Pressure: the jumps a door or a vent produces in a sealed room.
• Vibration and hits with the accelerometer and gyroscope.
• Scene luminance through the camera, plus object proximity.

BUILT TO WORK

• Sessions: one button opens the log, turns the sensors on and groups everything with its time and place. When you finish you review it and export it.
• Full watch: every sensor at once, with correlation across them.
• Range alerts with haptics and sound when a reading leaves your band.
• It keeps measuring with the screen locked, and gives up the expensive sensors before the phone heats up.
• Demo mode to try the app with no sensors, everything it makes tagged DEMO.
• Available in English, Spanish, French, German, Italian and Portuguese.

YOUR DATA IS YOURS

No account, no analytics, no ads. Aletra does not connect to the internet at all. Everything lives on your iPhone, and exports show up in the Files app under On My iPhone > Aletra. Nothing leaves unless you send it.

PRICING

One-time purchase, yours for life: you buy it once and keep it forever, with no subscriptions and no in-app purchases.

BEFORE YOU BUY

Aletra is not a certified measuring instrument. Readings depend on the iPhone's own sensors and on ambient conditions. Do not rely on it for safety or health decisions, or to assess electrical or structural hazards.

The survey's 3D mesh needs an iPhone with a LiDAR scanner; without one the survey still records the path and the readings, just no mesh. Everything else runs on any iPhone.