High Fidelity Modeling and Simulation

ISL’s team consists of creative scientists and engineers with both theoretical and experimental expertise in the areas of physics, geophysics, oceanography, signal processing theory and application, nonlinear modeling, electro optics, and optical communications. Current work includes research and development of electric field detection sensor systems, electromagnetic performance prediction modeling, deep underwater gravity technology, modeling of factional network dynamics, modeling and hardware implementation of neurobiologically inspired networks, and long wave infrared chemical sensing technology. Salt Water Test Tank, EMI Screen Room, Prototyping Facilities.

High Fidelity RF Sensor Modeling and Simulation

ISL provides a wide range of simulation and modeling services for analyzing RF sensors including radar and ELINT. ISL’s expertise and modeling tools are used to provide our customers with a cost-effective means of predicting real-world system performance without the need for costly hardware prototyping and data collection campaigns.

ISL’s tools accurately model the effects of site-specific terrain, land cover, background/civilian targets, sensor-platform interactions and errors in the receive chain, and sensor motion (flexing, vibration, etc.). Thus, they are capable of providing the rigorous physics-based characterization of all the real-world effects that must be considered when designing and testing sensor signal processing algorithms.

RFView is an advanced cloud-based site-specific radio frequency simulation and analysis environment. The simulation environment is built on ISL’s industry-leading Splatter, Clutter, and Target Signal (SCATS) RF phenomenology engine. SCATS has successfully supported numerous advanced development projects for DARPA, Army, Navy, Air Force and other classified customers since 1989. It was one of the earliest site-specific radio frequency (RF) phenomenology analysis tools to provide an accurate characterization of complex RF environments. Uses of the model include system analysis, test planning, high-fidelity synthetic data generation, and signal processing algorithm development. The model provides characterization of target returns, direct path signal, ground scattered signal (clutter for radar), direct path signals from interferers, and ground scattered interference signals (hot clutter, splatter, or terrain-scattered interference).

ISL is currently developing the RFView web-based interface.We plan to launch this new capability in the coming months. The new interface will allow our customers to easily access the SCATS capability to support their specific project needs.

Under the Knowledge-Aided Sensor Signal Processing and Expert Reasoning (KASSPER) program ISL used the SCATS model to deliver high-fidelity simulated radar data sets to support the needs of our DARPA/AFRL customer. The data sets were used by government and industry organizations to develop and validate advanced adaptive processing algorithms that improve GMTI radar performance in stressing environments. Numerous non-ISL open literature papers have reported results using these data sets.

Scats 3
Scats 4

Designing RF systems for military operations in urban terrain (MOUT) requires site-specific models of built-up areas. ISL has used the Wireless Insite REMCOM model together with ISL’s own high-fidelity modeling tools for urban sensing and geolocation applications. This model, extensively use by the cellular phone community for urban coverage analysis, incorporates ray tracing and uniform theory of diffraction and a site-specific city data base to make predictions of fast and slow fading, delay spread of signal multipath as well as specific calculations of individual multipath signals. Since future DoD RF Systems will likely have requirements driven by military operations in urban terrain (MOUT), such a modeling capability is an essential component of advanced RF system design and analysis.  

System Concept Development and Analysis

System concept development and analysis at ISL is based on a strong physics-based domain expertise in propagation, electromagnetic analysis, and other relevant phenomenology. This enables solutions that account for the real-world environment in which the system will operate as well as realistic hardware limitations. All aspects of ISL development (including algorithm development and implementation and modeling and simulation) are accomplished within this systems framework resulting in a more robust solution set for our customers.

Electromagnetic Performance Prediction Modeling

ISL has a suite of proprietary models for the scattering and propagation of electromagnetic fields. The core model is our multi-layer harmonic dipole propagation model. This model allows for the propagation of the electromagnetic fields of any Hertzian dipole (horizontal or vertical, electric or magnetic) in a medium consisting of an arbitrary number of layers of arbitrary conductivity. Thus, it is well suited to handle propagation from the lithosphere through a layered seabed, ocean, and earth-ionosphere waveguide as well as scattering from select targets. The model is readily extensible to linear or areal distributed dipoles. Time-dependent problems are solved by Fourier analysis; the propagation code is used to develop a transfer function and the time series at the sensor is reconstructed from that and the time-dependent source. For more complex environments (beyond plane parallel layers), we use a suite of fully three-dimensional harmonic electromagnetic geophysics codes. These are likewise applied to time-dependent problems using Fourier analysis.

The electromagnetic propagation codes are augmented by several noise models, which together provide a complete testbed for performance analysis. The noise models include two geomagnetic noise models (based on empirical electric and magnetic field data), hydrodynamic noise models for surface and internal waves, and sensor noise models for electric and magnetic field sensors.

Neurobiologically Inspired Networks

ISL has developed a novel, computationally efficient approach enabling the replication of the signal processing and control functions involved in complex neurobiological networks. Processing of sensory information and generation of control commands in the network is done with spikes produced by the neurons interacting through the synapses. The key element of our approach is the use of new phenomenological models of neurons and synapses derived in the form of a simple discrete-time algorithms (map-based models). These models are capable of replicating the important spike pattern characteristics of specific neurons, dynamics of synapses and the spatio-temporal patterns of network activity. We have demonstrated that our approach to the modeling of the lamprey Central Pattern Generator network enables real-time simulations of neuronal activity that controls swimming of biomimetic robot using a commercial floating-point DSP chip.

Advanced Algorithm Development & Implementation 

ISL prototypes advanced signal processing, simulation, and other systems engineering analyses in Matlab® and other environments. This development is conducted in a Matlab toolbox framework complete with configuration management and documentation. The software can be reused between projects or delivered to customers. As a part of the development, functions are implemented in compiled-code languages and used in Matlab via the Matlab External (MEX) interface. These MEX functions provide an environment for continuously testing both the Matlab and compiled-code implementations and facilitates the transition of the software to embedded signal processing applications. Applications include surface, airborne, and space-based sensors.