Users Manual

https://www.lairdconnect.com/iot-devices/iot-
sensors/sentrius-bt7x0-tracker-multi-sensor
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The tracker implements two programmable alarms that can be used to trigger local audio, visual, and haptic indicators when a
remote tracker is detected for a configured amount of time. Each alarm has a parameter indicating the number of seconds a
remote tracker must be detected before triggering the alarm indicators.
Each scan interval, the tracker determines which trackers are within proximity and meet the configured RSSI threshold to
begin recording. A counter increases each time that same tracker is observed in a scan. Once [the number of scan intervals
a tracker is detected] x [Scan Interval parameter] is equal or greater than the configured alarm time, the alarm indicators
are triggered for each subsequent scan that tracker is detected until the configured contact period expires.
The following diagram (Figure 4) shows the proximity alarm timeline given default parameter values.
Figure 4 - Proximity alarm timeline
As a tracker detects other remote trackers (“remotes”) in a BLE scan, each remote enters into a RAM-based discovery
database in order to track the number of scan intervals each is seen for alarming purposes. Each remote is on its own timeline
from the perspective of the sensing tracker.
Each time a remote is detected in a BLE scan, a count of seconds is added to that remote’s total detection time in the
database. This number of seconds is equal to the Active Scan Interval parameter. If a remote is not detected in a scan, the
total detection time in its database entry is not incremented for that scan interval. For example, with default parameters, each
scan interval a remote is detected adds 30 seconds to its total detection time in the database.
After any remote is detected in enough scans such that the total detection time crosses a configured alarm threshold, the
configured alarm indicators are triggered to alert the user. The alarm continues to trigger each scan interval until no remotes
having total detection time longer than the alarm time setting are within range.
Once “Contact Period” seconds passes since the first time a remote is detected, its total detection time is reset to zero in the
database, starting a new proximity alarm timeline for that device once it is detected in a future scan.
0TIME (SECONDS) 30 60 90 120 330270 300
REMOTE TRACKER
DETECTED IN SCAN
Scan Interval
30 Seconds
Proximity Alarm 1
300 Seconds
Proximity Alarm 1
Triggers Each Scan
Still Detected
570 600
Proximity Alarm 2
600 Seconds
Proximity Alarm 2
Triggers Each Scan
Still Detected
630 660
Proximity Alarm Timeline for Each
Remote Tracker Starts on First Detection
690 720 750
No Alarm
if Not
Detected
in Scan
86,370 86,400
Contact Period
86,400 Seconds (1 Day)
Proximity Alarm
Timeline Resets After
Contact Period Expires
Scan Duration
2 Seconds