Description of the data and file structure

All data is contained in tagged_sble_data.csv. Each row is a data point, collected at a specific timestamp. Note that if 2 (or more) beacons were within range at the same time, the content of a row is repeated for each beacon, except for three fields: minor; rssi; and rssi_accuracy.

Each row contains: (note: the order of these fields in the csv file may be different than in this list - please look at file header)

• timestamp (in Unix time)
• username (a unique nickname assigned to each participant)

[The following measurements are from iOS CoreLocation. See https://developer.apple.com/documentation/corelocation]

• latitude, longitude (in degrees)
• speed (magnitude of velocity, in m/s)
• speed accuracy (speedAcc - accuracy of speed)
• altitude (alt - measured in meters above sea level)
• vertical accuracy (vertical_acc - measured in meters)
• horizontal accuracy (horzontal_acc, measured in meters)
• course (direction of travel, in degrees relative to North)
• course accuracy (courseAcc, in degrees)
• heading (azimuth (orientation) of the user’s device, relative to true or magnetic north)
• major (major ID of BLE beacon; identifies the bus vehicle)
• minor (minor ID of BLE beacon; 1 for front beacon, 2 for rear beacon)
• rssi (received signal strength from BLE beacon, in dBm. It is -100 if rssi is below -90 dBm)
• accuracy (rssi_accuracy - the accuracy of the proximity value, measured in meters from the beacon)

[The following measurements are from iOS CoreMotion. See https://developer.apple.com/documentation/coremotion]

• attitude_pitch,attitude_roll,attitude_yaw (Euler angles of phone's attitude with respect to a fixed reference frame with Z axis pointing down, in rads)
• rotation_rate_x,rotation_rate_y,rotation_rate_z (angular rate around three phone axes, in rads/s)
• gravity_accel_x,gravity_accel_y,gravity_accel_z (components of the gravity vector in three phone axes, in units of g)
• user_accel_x,user_accel_y,user_accel_z (components of the phone's acceleration in three phone axes, in units of g)
• magnetic_field_x,magnetic_field_y,magnetic_field_z: these values are always set to 0
• trip_idx (a unique identifier for a "trip", defined as a complete session including data recorded while the system is in the "Detecting beacons" state and in the following "Traveling in bus" state. A trip_idx of -1 indicates that the trip was not complete)
• is_trip (0 while in the "Detecting beacons" state, 1 while in "Traveling in bus" state)

Please read the accompanying article for clarification: https://escholarship.org/uc/item/03n467fn