...
E.g. Time: 14 April 2020, 12:03:12pm (which rounds down to 12:00:00pm), which maps to 15868656001586865600000 (msecs)
The “nearby” time window is defined as follows:
...
The 8 char geohash
Followed by the UTC timestamp of the beginning of the relevant 5 minute time window, in secondsmilliseconds
Example:
Latitude: 51.5019, Longitude: -0.1415
Time: 14 April 2020, 12:03:12pm (which rounds down to 12:00:00pm)
...
8 character geohash: gcpuuz8u
UTC timestamp: 1586865600158686560000
Data string to encode: “gcpuuz8u1586865600” “gcpuuz8u1586865600000” which should hash to “e727d7eb7c51d1b3““c9414c55812d796a“ (cost = 12)
Sending data to Safe Places for Redaction Processing
...
| Code Block |
|---|
"notification_threshold_percent":66, “notification_threshold_count”timeframe”:630 |
These two parameters work together to control the sensitivity of exposure notifications for this data. The Health Authority can turn these based on their experience and feedback from their community.
With the defaults, we trigger an exposure notification if we get more than 66% of location matches, across any 6 consecutive location data points 30 minute period (i.e. if we match 4 or more of 6 points).
Safe Paths logic for matching points of concern
...