Introduction

The False Alarm track analysis system is a powerful tool designed to help identify and eliminate false alarm tracks, such as those generated from debris, reflections, or swaying trees. It achieves this by using a set of user identified false alarm tracks which have been carefully analysed to generate models. These models are then used to calculate a combined score to identify a live track being a false alarm. These false alarms are then displayed in the False Alarm Tracks list.

Please refer to False Alarm Analysis for more information regarding configuring your system to take advantage of this feature.

Contents

How To Use False Alarm Probability

ClearWay™

To make maximum use of the False Alarm probability in ClearWay™, you will need to set one of the three property checks which are available on each of the rules:

Open

We recommend a default value of 50%, so that a value of less than 50% would be considered a good track.

AdvanceGuard® ​

In AdvanceGuard®, add a property check to the rule and set it to check the False Alarm Probability:​

Open

We recommend a default value of 50%, so that a value of less than 50% would be considered a good track.

Querying False Alarm Tracks

There is a False Alarm Tracks option on the Playback tab, with its own set of filters. Whilst False Alarm Tracks feature in both AdvanceGuard® and ClearWay™, the filters vary.

AdvanceGuard®

Id: A unique identifier for each track.

Min. Sightings: The minimum number of sightings a track requires before it is recorded as a track. Toggle the 🛇, ≤ and ≥ buttons to define the value.

Min. Speed: The minimum speed value, either a maximum, minimum or equal to value. Toggle the 🛇, ≤, ≥, =, ≠, ⪥, and <> buttons to define the value.

Max. Speed: The maximum speed value, either a maximum, minimum or equal to value. Toggle the 🛇, ≤, ≥, =, ≠, ⪥, and <> buttons to define the value.

Classification: Type of moving object:

Person

Vehicle

Large Vehicle

Debris

Animal

Drone

Aeroplane

Boat

Unclassified

Travelled (m): How far the tracks have travelled. Toggle the 🛇, ≤ and ≥ buttons to define the value.

Area Covered (m): How far the track has travelled, either horizontally or vertically along the x/y-axis. Toggle the 🛇, ≤ and ≥ buttons to define the value.

Lost: Select to include Lost tracks in the query.

Tag Preset: A text search for Tag Presets.

Tag Presets: This will show a drop-down list with Tag Presets which have been configured in System Settings.

Areas: Select a detection area.

Rules: You may select multiple rules to query at once. 

Radars: Select a specific radar.

Results: Shows how many results the query has returned.

ClearWay™

Id: A unique identifier for each track.

Min. Sightings: The minimum number of sightings a track requires before it is recorded as a track. Toggle the 🛇, ≤ and ≥ buttons to define the value.

Min. Speed: The minimum speed value, either a maximum, minimum or equal to value. Toggle the 🛇, ≤, ≥, =, ≠, ⪥, and <> buttons to define the value.

Max. Speed: The maximum speed value, either a maximum, minimum or equal to value. Toggle the 🛇, ≤, ≥, =, ≠, ⪥, and <> buttons to define the value.

Classification: The type of moving object:

Person

Vehicle

Large Vehicle

Debris

Animal

Drone

Aeroplane

Boat

Unclassified

Travelled (m): How far the tracks have travelled. Toggle the 🛇, ≤ and ≥ buttons to define the value.

Area Covered (m): How far the track has travelled, either horizontally or vertically along the x/y-axis. Toggle the 🛇, ≤ and ≥ buttons to define the value.

Carriageway: Select the Carriageway from the drop-down list.

Radars: Select a specific radar.

Results: Shows how many results the query has returned.

Displaying False Alarm Tracks

The results of a False Alarm Tracks Query are displayed as a list in the Results Panel:

These have a similar set of fields as those in .

Classification: This tab is explained under .

Id: Unique alphanumeric identification assigned to each track. 

First/Last Sighting: Date and time of when the track record begins and ends. 

Duration: Track length in time to the nearest second.

Seen: Number of sightings of the track. Given the radar rotates four times a second, the number of sightings should be roughly equivalent to x4 the track duration (if the track does not coast.)

Coasts Ratio: Value that determines how much of the track period was classed as coasting. 

Tag Preset: The Tag Presets which have been assigned to the track.

Show: Select the main column option for all of the tracks to appear on the PPI Display. Alternatively, select the Show option next to each track you wish to view. They will appear on the PPI Display, like this example below:

Locate: Select this icon to shift the PPI Display and until the selected track's location is visible and zoomed in on:

History: Select this icon to open the Track Details window:

Export: Select this option to export track record for posterity.

Delete: See below.

Deleting False Alarm Tracks

To delete a false alarm track, select the track and click the Delete icon:

The track will then be deleted.

Reviewing False Alarm Tracks

Whilst we have found many reasons for a false alarm (please refer here: ) there may be other scenarios which are more specific to a particular client, situation or environment. This is why it is essential for customers to review their tracks to ensure that Witness can be configured to identify as many false alarms as possible, and adjust their configuration as required.

To aid this review process each track will be given a probability score:

Adding Tracks to the False Alarm List

It is possible to add a track that the user believes to be a false alarm, but which the system has not identified as such, to the list of False Alarm Tracks. The selection of suitable tracks to add is important because bad tracks or too many varied tracks will distort the analysis and reduce its effectiveness.

To add a track or tracks to the False Alarm List:

1. Select the desired track and then click the Track Analysis icon on the top right of the grid:
   
   

    

2. This will open the Set Analysis Status dialogue:
   
   

    

3. Select False Alarm from the drop down list and click Apply:
   
   

    

4. This will add the track to the list of False Alarms.

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