Distance filter
Remove GPS jitter from your trails and position history. The distance filter prevents new position records from being stored when a device hasn't moved far enough from its last known position — turning noisy, overlapping points into clean trails that show real movement.
Why use a distance filter
Devices report positions at regular intervals regardless of whether they've moved. GPS and WiFi positioning have an inherent accuracy margin, so a stationary device can produce a stream of slightly different coordinates — making it look like it's moving when it isn't.
Without filtering, this creates:
- Jittery trails — A device sitting on a shelf shows a small cluster of scattered points instead of a single location.
- Inflated position history — Thousands of near-identical records for a device that hasn't gone anywhere.
- False movement — Trail lines zigzag around a stationary location, making it hard to see real trips.
The distance filter fixes this by comparing each incoming position to the device's last stored position and only recording it if the device has moved beyond your threshold.
How it works
When a position event arrives, the system calculates the straight-line distance between the new position and the device's last stored position:
- Distance >= threshold — The device has moved. The new position is stored in position history and shown on the map.
- Distance < threshold — The device is stationary (or jittering). The position is not stored. The device still shows as active — its last-seen timestamp updates normally.
The first position a device ever reports is always stored, regardless of the threshold.
Configuring the threshold
In Blecon Track, go to Settings and set the Minimum Distance field to your desired value in meters.
- Set it to 10–30 m for indoor deployments where you want to filter GPS jitter but still capture room-to-room movement.
- Set it to 50–100 m for outdoor or vehicle tracking where small movements aren't meaningful.
- Leave it unset to store every position update (no filtering).
When to use it
| Scenario | Recommended threshold |
|---|---|
| Indoor asset tracking with WiFi positioning | 10–20 m |
| Warehouse or campus with hotspot positioning | 20–50 m |
| Vehicle or fleet tracking (outdoor GPS) | 50–100 m |
| High-precision use case, need all data points | Leave unset |
What happens to filtered positions
Positions that don't meet the distance threshold are not stored in position history and don't appear on the map trail. However:
- Device activity is unaffected — The device's last-seen time still updates, so it shows as active.
- Sensor data is still recorded — Temperature, humidity, and battery readings from filtered positions are stored normally.
Dwell detection
When the distance filter is active and a device keeps reporting positions below the threshold, the system records a dwell — a single entry that captures how long the device stayed in one spot.
Each dwell includes:
- Location — Where the device was stationary.
- Started at — When the first stationary report arrived.
- Last seen at — When the most recent stationary report arrived.
- Sample count — How many position reports were received while the device was stationary.
Dwells appear in position history and trail data alongside regular position records. They fill the gap that filtering creates: without dwells, a stationary device would show nothing in its trail for the entire time it was still. With dwells, you can see that the device was present and reporting — it was at this location from 9am to 5pm with 47 reports.
When the device moves beyond the distance threshold, the current dwell ends and the new position is stored normally. If the device becomes stationary again at the new location, a new dwell begins.
Workspaces without a distance filter configured do not generate dwell records.