Introduction
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Introduction
This page deals with tracking parameters.
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| Info |
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An important consideration for the Tracking Parameters is that they are area based. This means they can be adjusted from one area to another allowing a great deal of flexibility across the entire site or highway. By default, ClearWay™ will automatically create areas based on the layout of the carriageway and will utilise the medium sensitivity highways parameters. These can be overridden with manually applied parameters in specific areas if required. Please see Carriageways for more information. |
Tracking Parameter Configuration
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Name: The name for this set of tracking parameters.
User ID: A unique numeric identification that can be used for external control, associated with whomever uses or created the tracking parameter.
Min . Coast Age (hits) / Max. Coast Age (hits): Defines the number of times the radar has to have seen the target before the coast value is applied. If min./max. are the same value, the coast will apply at this value. If they are different values, the coast amount will be set linearly as the target goes from minimum to maximum (and beyond). The concept is essentially that the older a track (the more sightings a track has had), the more it is trusted to a be an actual track, and more coast sightings can be applied before the track is deleted. In the example below, the first carriageway demonstrates the ability of a track value to change between seen and coasting if the minimum coast age is reached. In the second and third carriageways, a lost track with many previous sightings is awarded more coast track sightings before being discarded, and vice versa.
Coasts (hits): Defines the number of times the radar will predict the position of a track that it can no longer see. If this is set to 2, then the tracker will maintain a track for 2 radar sensor rotations after losing it. This is to account for instances such as a vehicle being obscured by a gantry, and then emerging within a couple of radar rotations. The result is that the operator will not know that the track was temporarily obscured.
Plot Amplitude ATI (pwr): Defines the threshold level required of a plot to be promoted to a track. This value will be set per tracking parameter, and can therefore be used to apply a different threshold per detection zone. This parameter is only activated if the Threshold Output parameter is set to Input Level within the tracker settings.
Plot Amplitude Tracks (pwr): Determines the minimum power amplitude of the plot before it is considered for tracking.
Min . Plot Range Size (m): Determines Determines the minimum size of the plot (in range metres) before it is considered for tracking. This process of rejection is similar to plot extraction in theTracker Settings (Radar Settings). However, this gives the opportunity to allow a plot through the plot extraction process, but discard it prior to use for tracking.
Min . Plot Azimuth Size (°): Determines the minimum size of the plot (in azimuth) before it is considered for tracking. This process of rejection is similar to plot extraction in the advanced tracker settings. However, this gives the opportunity to allow a plot through the plot extraction process , but discard it prior to use for tracking.
Min . Plot Weight ATI (cells): Determines the minimum number of cells (where a cell is a single power reading in either range or azimuth) before it is considered for Automatic Track Initiation (ATI).
Min Plot Weight Track (cells): Determines the minimum number of cells (where a cell is a single power reading in either range or azimuth) before it is considered for tracking.
Turn Rate (°): Determines the maximum expected turn rate of any target, in degrees, between sightings.
Turn Acceleration (m/s²): Determines the maximum expected rate of change of speed during changes of direction.
Max . Acceleration (m/s²): Determines the maximum expected acceleration of any target at any point. Anything outside this parameter will not be tracked.
Min . Tracking Speed (mph) / Max. Tracking Speed (mph): Determines the minimum and maximum expected speeds of targets during tracking. Anything outside these parameters will not be tracked.
Clutter Hold Multiplier:
M (hits) and N (hits): these two values define the number of times a target must be seen within a given number of sensor rotations before it is considered to be a track.
a. M represents the number of times an object is seen. N represents the number of scans (sensor rotations).
b. The default values of M=3 and N=4 mean that an object must have been seen at least 3 times in 5 scans. If so, then the tracker creates it as a proper target track and shows it within the user interface.
c. If not, then the object remains provisional and is not sent to the user interface.
d. The lower this ratio, the more false alarms will be caused. Thus, a ratio of 2/5 will create more false alarms than say 4/5.
e. The maximum values for each are 30, however, the larger the numbers, the longer it will take for new targets to appear.
Advanced Settings
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Clutter Control:
Clutter control is a process that will dynamically adjust the M & N ATI parameters that control how quickly we acquire a track. It uses the quantity of very short-lived tracks in each 10m2 area to decide if there are two many detections from clutter or noise. As the the number of detections increase this process will increase the M & N to make it harder to acquire tracks. This will reduce the number of false alarms. A good example of there this is process can be used is over water. The water state can change depending on environment and weather conditions and this process can dynamically adjust the ATI parameters to ensure we maintain a sensible false alarm rate in poor conditions.
Disabled - No clutter control is enabled.
Low - Clutter control is the least aggressive. The M & N parameters will be dynamically increased based on the level of clutter.
Medium - Clutter control is more aggressive. M & N parameters will be dynamically increased until it reaches the highest level of clutter where the ATI will be disabled.
High - This is even more aggressive. At both medium and highest level of clutter this mode will disable ATI.
ATI Off - In this mode any level of clutter will cause the ATI to be disabled.
Report As Lost: When this option is selected, any track which is deleted or dropped in a detection area will be reported as lost. Tracks that are deleted because they reach the edge of a detection area will not. You can search for tracks which have been lost to identify areas where tracking performance needs to be improved or to highlight line of sight problems.
Directional Mode: Determines whether tracks should be detected travelling both ways along a monitored area, such as a road. Generally, this is set to Unidirectional (with separate tracking parameters for the opposite sides of the road) as it helps to increase the efficiency of detection.
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Max. Tracking Speed Reverse (mph): Defines the maximum expected speed that a target is expected to travel in the opposite direction from the norm. (Displayed only when Directional Mode setting is Unidirectional).
Coast Mature Extension (s): This option will extend the amount of time a track will coast but only if the tracker considers the track to be genuine. This extension will only be activated after 20 scans and if the track is going slower than 10m/s or the track is moving faster but with a stable course. This setting configures the amount of time, in seconds, that the track will coast once these conditions are met.
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