The SignalShark simplifies localization of transmitters by autonomously evaluating all the available bearing results and plotting them on a map. It uses a statistical distribution of bearing lines that represents the uncertainty in the bearing. The result is a map on which the possible locations of the transmitter are plotted and color-coded according to their probability. Red corresponds to a very likely and blue to a very unlikely transmitter position. The SignalShark also draws an ellipse, which marks the area where the transmitter has a 95% probability of being located, and its center is the estimated position of the transmitter.
When bearings are taken under non-ideal conditions, such as in an urban environment, the uncertainty in the bearings is much more dependent on the environment than on the ADFA. Nevertheless, if enough bearings are taken from enough locations, the localization algorithm of the SignalShark will generally result in a convergence on the actual location of the transmitter, even in urban surroundings. To speed up and optimize the localization process, an ADFA can be attached to the roof of a vehicle to take bearings from random positions in the suspected area. This allows fast and reliable localizations even in challenging environments.
The data to be visualized are overlaid on the map. Localization results from different transmitters are shown as crosses and uncertainty ellipses in different colors. The map view is also used to provide a localization heatmap and to display the current estimate of the transmitter position during the localization process for a single transmitter.
The suspicious transmitter can be localized once the bearing line information from two significantly different direction finder locations are known and intersect. Localization accuracy increases with the number of direction finder locations and the number of bearings. It is therefore usual to collect bearings from more than two direction finder locations before the localization process is completed.
If only one direction finder is available, it will have to be moved to different locations over time.
The following tables show recommended settings.
Detailed information about these settings can be found the Map view
chapter.
Button |
Setting / Description |
Select Map |
Tap to select am map from the dropdown list. For more information about creating maps see here. |
Map Mode |
Cont. Localization or Disc. Localization |
Config |
See description below. |
Select Working Directory |
Select a working directory. |
Select Ftune |
Select Ftune according to the Bearing view |
Select Record |
Cont. Localization only: Select a record if you wish to run a localization based on saved record data. |
Start Localization |
See here |
Display |
See description below. |
For more information about these settings see here.
Button |
Setting / Description |
Set Localization Area | Using the default area When not setting an area, the default area of 50 x 50 km around your current location is used for localization. Setting the area by using the map 1. Set the view window to the desired size and zoom the map to the planned localization area. 2. Tap the Set to current Map Margins button. The displayed map area is superimposed by a transparent red layer. The map can still be zoomed in / out and centered. 3. If needed adapt the red marked localization area by dragging the arrows at the window edges to the desired position. Setting the area by entering the coordinates Tap a button to enter a margin. |
Resolution | • Very large map area: select 1/2 or 1/4 • Medium map area: select 1 • Very detailed map area: select 2 or 4 |
Use Case Preset | Select a case preset that fits your needs most. |
Bearing Error | • Under ideal conditions: set to the RMS value of the DF uncertainty specified in the DF antenna data sheet. • More realistic scenarios: 5° to 10° |
LOS Prop. | • Under ideal conditions: set to 100% • More realistic scenarios: 50% |
Velocity Squelch | • Average driving speed >> 10 km/h: set about 10 km/h • Average speeds not above 30 km/h: set to a lower squelch value |
min. DF Quality | The DF quality of useful bearings is often greater than 70%. However, it is better not to discard low DF quality bearings if this means that too few bearings are available. |
For more information about these settings see here.
Button |
Setting / Description |
Center to curr. Position |
Tap to center your current position. |
Auto Fit |
Tap to automatically fit the selected localization area into the map window. |
Current Position |
On is recommended. |
Current Direction |
• For continuous localization (Cont. Localization) the setting Ant. Direction is recommended. • For manual bearing (Level Meter or Horizontal Scan view) the setting Handle Azimuth is recommended. |
LOB Visualization |
Infinite is recommended. |
Show LOB |
On is recommended. |
Loc. Result |
On is recommended. |
Min. Probability |
Start with 0. The value can be set later for detailed evaluation. |
Show GPS Track |
On is recommended. |
For more information about these settings see here.
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