Tiger Wideband DF and Beamforming System

Antenna Array

The Tiger Antenna Array consists of a set of compact active antenna elements arranged in a circular pattern. Each active element consists of a novel discone antenna that produces a flat VSWR and response across the entire operating frequency region (30 MHz - 6 GHz).

Each antenna element is fitted with a novel pre-amp that accomoodates for antenna factor and produces a flat response across the entire operating frequency region. The antenna pre-amp consists of a series of cascaded amplifier stages, and this allows the Tiger to be tailored for a variety of different cable lengths. A separate signal conditioning section at the receiver end of the cable allows further gain management and also allows distribution of element signals to other systems.

The Tiger antenna array also includes a novel technique for the mitigation of super-structure related reflection issues if the array is deployed on a vehicle, ship, aircraft or other scenario where near field reflections would cause issues.

The Tiger array is a compact array (~ 0.75m in diameter and 19 cms high) and is suitable for either fixed or mobile deployment.

Each Tiger array is equipped with an electronic compass and level, as well as a GPS antenna.

The figure above shows a typical Tiger deployment which consists of the antenna array, a signal conditioning and distribution unit, a set of coherent receivers and a processing/data recording unit.

The Tiger system is capable of distributing a variety of data products including element and/or beamformed signals and DF results. Signals can be distributed as RF or digital IF. Digital IF distributions are via VITA-49 streams over TCP/IP. The Tiger includes a built in Moriarty module for all signal distribution, command and control and data recording functions. DF results are distributed in TNG compatible JICD 4.2 format.

Tiger Software

The Tiger system includes a scalable, configurable software component. The Tiger system software can be hosted on a variety of computing platforms including monolithic servers as well as clustered systems using a number of different processing elements (e.g. an OpenVPX system).

The scalable nature allows Tiger to process signals with different instantaneous bandwidths. The default maximum instantaneous bandwidth is 80 MHz. The system can also be deployed for 40, 20 and 10 MHz, with no changes in the signal collection hardware, or system software.

Beamforming

Tiger includes a sophisticated frequency domain beamformer with weights optimized for SNR enhancement. Tiger can produce two types of beams, either beams steered in a single direction or beams where various parts of the processed spectrum are pointed in different directions. This allows two different collection modes. In the first case the beam produces spatial filetering for a particular direction. In the second case the beam produces enhanced collection in specific directions.

Tiger is capable of beam forming with the receivers in either stare or scan mode.

DF

The Tiger system software includes two different DF techniques, a phase correlation interferometer and a super-resolution DoA solver. In a given deployment either one or both can be used. The normal constraint is the available computational resources. The super-resolution method also allow separation of mutliple targets operating at the same frequency.

The Tiger DF engine is a continuous wide-band DF system capable of acquiring a line of bearing on every target that meets certain user-definable criteria such as signal strength, bandwidth, SNR, signal masks etc. The DF system is not constrained by signal bandwidth or modulation type, and no apriori signal characteristics are required. The system can detect and perform DF on frequency hopper signals with hop rates in excess of 1 kHz. The ability to record signal data allows a user to go back and reconstruct the signal from an agile frequency target.