Private Automated Contact Tracing (PACT) Beacons Dataset

This is the MIT LL ASDF Exposure Notification Service Dataset 1

Data were generated by the Exposure Notification Service (ENS) on Android mobile phones during tests in the Autonomous Systems Development Facility (ASDF) at MIT Lincoln Laboratory from August 2020 through December 2020. The ENS software is written and distributed by Google LLC.

Data collection was performed in the Autonomous Systems Development Facility using RF-analogous mannequins in lieu of humans. The phones were placed in the front shirt pockets, in rear pants pockets, or in a nylon bag hung from the mannequins' necks. The mannequins were placed at various distances and at each of three orientations (facing each other, facing away from each other, or facing the same direction). The "large room" is a hangar bay approximately 100'w x 70'd x 33' h; the "small room" is an office approximately 12.5'w x 13.75'd x 8.5'h. Some tests used two phones and some used three; the summary data sheet is organized by pairs of phones.

Data consist of phone logs of Bluetooth ENS messages, Temporary Exposure Keys, and test metadata (distances, timestamps, phone IDs). Format is CSV and text files.

The system logs from the phones do not record ENS v2 data structures (both because we were using a v1 app and because the ENS service had not provided that level of logging in production). To compute ScanInstances and ExposureWindows, we ported the open-source ENS internals code to run on a desktop and fed in the beacons and timestamps from the phones' system logs. The ScanInstance and ExposureWindow data for each pair of phone exposures are formatted as CSV files under exposure_windows*/. Those CSVs have one row per ScanInstance; the data for the ExposureWindow are repeated in each row of its constituent ScanInstances.

On 2020-12-15, Google released an update to the calibration values for Android. Our tests on 2020-12-22 and 2020-12-23 showed the new values in use on the phones.