GEO-LOCATION OF RADIO EMITTERS AOA – TDOA – HYBRID SOLUTIONS

GEO-LOCATION OF RADIO EMITTERS

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OVERVIEW The geo-location of radio emitters is of increasing interest in different scenarios and applications. Nowadays the scenarios have become more complex. The most challenging scenario is to detect moving emitters in hilly or urban scenarios. Different technologies are available:

AoA – using the angle of arrival of an emitter. With two direction finding (DF) receivers in LoS (line of sight) positions, the geo-location of an emitter can be determined.

TDoA – using the time difference of arrival of radio waves, the geo-location of emitters can be determined. Typically, this approach is used in mobile scenarios.

Both of the technologies have their advantages and disadvantages for certain scenarios. Therefore we propose the combination of both for improvement of geo-locating more flexible to the specific environment:

Hybrid approach which combines the TDoA and AoA functionalities.

Depending on the scenario, the best-suited approach may be chosen. With this approach, also multi-functional usage is possible.

Example for AoA geo-location

AOA This approach uses traditional direction finding (DF) technology. For a more effective coverage of the spectrum, we use wideband direction finding technology.

Strengths:

Excellent accuracy through full parallel architecture and individual system calibration

Only two sensors are required

High bandwidth, scanning mode

This technique requires LoS environment, but some multipath effects and co-channel interference issues can be resolved by our software solution SRDF (super resolution DF).

TDOA This approach uses the propagation information of radio signals and their arrival times at different sensors.

Strengths:

More robust to reflections

Compact, simple sensors, easy temporally installation on vehicles for tactical use

TDoA sensor as multi-functional sensor with monitoring capabilities

This technique is especially recommended for tactical and mobile applications, especially in difficult radio frequency environment.

Example for TDoA geo-location

GEO-LOCATION OF RADIO EMITTERS

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HYBRID SOLUTION This solution combines both the strengths of the AoA and the TDoA technology in one approach.

All the strengths that are shown by both approaches are valid in the hybrid approach.

These strengths are provided additionally:

Situational picture generated by wideband-scanning AoA system can be used for cueing the TDoA sensors

Situation dependent data fusion is available now.

Sensors are available in different sizes depending on their usage in either semi-mobile or mobile scenarios (cars).

In practise, sensors can be used for AoA and TDoA depending on the current situation and needs (multi-functional sensors).

During a mission, the sensors can deploy in the area of interest to receive at their optimum position (urban scenarios, moving emitters).

Set of receivers for mobile usage

Sketch of a typical scenario using the hybrid approach

REFERENCES AoA based direction finding systems have been delivered for many years in a large variety of installations and sizes on different platforms.

The first TDoA based system was successfully installed in 2012 for mobile geo-location in urban and hilly scenarios.

The first hybrid geo-location system was successfully installed in 2016.

New techniques like SRDF (super resolution direction finding) and ADBF (adaptive digital beam forming) are also available. These features can be ordered as (mainly) software upgrade to all of our interferometric DF systems.

We have references in the naval domain as well as for shelter-based, vehicle-based, and static installations.

Set of receivers for semi-mobile usage

Saab Medav Technologies GmbH Gräfenberger Str. 32-34, 91080 Uttenreuth, Germany Phone +49 9131 583-0 Fax: +49 9131 583-11 info-smt@saabgroup.com www.saab.com www.medav.de

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