Smart Phone Sensor Checker

See what your iPhone actually reports. Pick a situation and the app shows the signals it needs. Readings stay on the device — nothing is uploaded.

Before you build an app or a device, check whether the iPhone can actually produce the signals it will depend on.

A spec sheet may list a sensor, but whether it reports values, how often, and how accurately varies from handset to handset. Sensor Checker shows you.

■ Pick a situation and the signals are chosen for you

Choose one of ten situations — on a boat, coastal walking, in the water, work at height and more — and the app shows which signals an app for that situation would need, and whether this iPhone can produce them. Sensors and sampling rate are set for you.

■ Three graded indicators

Position accuracy, transmission round-trip time and vertical heave are graded on four levels. You set the boundaries yourself, and changing them re-colours past recordings too — only raw values are stored, and grades are computed each time you look.

■ Single sensor

Turn on channels one at a time — accelerometer, gyroscope, gravity, magnetometer, barometer — and watch raw values and waveforms. They are grouped into position, link, motion, orientation and environment, folded away until you open one. Each channel states what it measures and what it is used for.

■ Display that fits the sensor

Heading appears as a compass, tilt as a spirit level, position on a map. Not just rows of numbers.

■ Record and replay

Save a session, then scrub through it to see what the values were at any moment. Export to Excel or CSV — the Excel file includes an explanation sheet giving each column's meaning, unit and grading bands.

■ It tells you what the iPhone cannot read

Ambient light, proximity, satellite count and cellular signal strength are not exposed to apps on iOS. This app does not remove them from the list — it states why they cannot be read, in place. Hiding them would leave you believing the phone can detect things it cannot.

■ Four languages

Korean, English, Chinese and Japanese, switchable inside the app with no restart.

■ Your data does not leave the device

Readings are stored on this device only. No account, no ads, no analytics. The link indicator sends one empty request to measure round-trip time; it never transmits your readings.

■ This is not safety equipment

The app does not detect or report accidents. "Suspected fall" and "suspected immersion" markers are not verdicts — they mark moments worth keeping the raw data for. This is a development and review tool for checking what signals a device can produce. Do not rely on it where safety is at stake.