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In the form designer, click + Add hidden field, then choose sensor_stream as the field type.

sensor_stream: capture a stream of sensor meta-data and save the results as a .csv file attached to each form submission.

Platform limitations
Only SurveyCTO Collect on Android supports this field type. It's not supported on iOS or the web. More about platform limitations...

To learn all about sensor meta-data, please see Experimental: Using sensor meta-data to enhance quality-control efforts.

To capture a sensor stream, add one or more of the following field types to your form:

  1. sensor_stream light_level - light level measured in lux, as reported by the device's ambient light sensor.
  2. sensor_stream movement - linear acceleration measured in m/s2, as reported by the device's linear acceleration sensor and gyroscope sensor.
  3. sensor_stream sound_level - sound level measured in dB, as calculated from the device microphone.
  4. sensor_stream sound_pitch - sound pitch measured in Hz, as calculated from the device microphone (estimated using the YIN algorithm and a window of 25ms).
  5. sensor_stream conversation - 1 when conversation seems to be happening vs. 0 when not, as estimated from the sound level, pitch, and/or raw data from the device microphone. This is the most-experimental – but also, potentially, the most-useful – type of sensor meta-data.

By default, all sensor streams capture data with a period or observation length of 1 second, so you will get roughly one observation recorded every second, while your form is being filled out. To set a different period length, put "period=#" in the field's appearance column, with the "#" replaced with the period length in seconds. If you want to record observations as fast as they come in from the underlying sensors, you can specify "period=0" (and then, e.g., you'll get roughly 25 observations/second from a sound-related sensor, but still a maximum of 1 observation/second for conversation streams).

Regardless of the period length you choose, sensor_stream data will be saved into an attached .csv file, with one file per submission. Each .csv file will then have a single row per observation. (See this help topic for more about the file format.)

In the spreadsheet form definition:

sensor_stream light_levelfieldnameperiod=#
sensor_stream movementfieldnameperiod=#
sensor_stream sound_levelfieldnameperiod=#
sensor_stream sound_pitchfieldnameperiod=#
sensor_stream conversationfieldnameperiod=#

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