Post on 03-Apr-2018
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Co-site interference analysis
Marli Strydom CST AG
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
The Cosite Scenario Victim Rx trying to “hear” desired signal from remote Tx At the same time, local emitters are transmitting Emitters can interfere with desired signal reception
= Cosite Interference
Undesired Emitters Victim Rx
Desired Signal
THE GOAL: predict the potential for cosite interference
for all Rx’s in the scenario.
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Multiple RF systems co-located in a common environment Diverse system characteristics
Frequency bands (10 KHz to 40+ GHz) Power levels Modulation types
Multiple EMI coupling paths Antenna coupling Cable coupling Circuit coupling
The Co-Site Problem
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Mechanisms for Cosite Interference There are many mechanisms for coupling
between the Tx’s and the Rx: Antennas Cables Enclosures Conducted vs. Radiated
Coupling can be direct between a Tx and Rx…
Or it can be more complex… Or even devious! (e.g., rusty bolt effect) Non-linear interactions generate additional
spectral components (Intermodulation)
Emitter signal spectra contain both narrowband (NB) and broadband (BB) signal components
Signals in-band and out-of-band must be considered
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Many methods to achieve EMC Antenna placement, type Decreased transmit power levels Adding filters Replacing defective hardware Frequency planning
The Conceptual Solution: Cosite EMI
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Availability of input data – varying types and fidelities Cosite evaluation usually cannot wait on high-fidelity system data Data management and cosite models must allow incremental refinements Result post-processing is critical for identifying and mitigating cosite EMI
problems.
Predicting Cosite EMI The biggest challenge in making useful cosite EMI predictions lies in managing all of the input data, models, output data, and results.
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
EMIT
EMIT provides an approach to data management and simulation for cosite EMI predictions.
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Antenna models Aircraft geometry (CAD) RF component models Radio emissions and
susceptibility models
Inputs for an EMIT Analysis
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Co-Site Interference Workflow
Antenna synthesis Antenna coupling Co-site EMI
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Predator Co-Site Analysis
UHF blade 320 MHz
VHF blade 30-100 MHz
GPS elliptical patch 1.575 GHz
IFF2 monopole 1020-1100 MHz
IFF1 monopole 1020-1100 MHz
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Broadband Multi-Port Coupling
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Installed Patterns
60 MHz 320 MHz 1.06 GHz 1.06 GHz 1.575 GHz
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Delcross EMIT Co-Site Tool Tx Emissions
Rx Vulnerability Component Characteristics
Antenna Coupling
Software framework for managing system performance data,
simulating intra-system EMI effects and mitigating EMI issues
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Emit is a system management tool Multi-fidelity quality inputs can be used EMI prediction can start at early level of project As input fidelity increases, so do the EMI prediction
Conclusion
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
Multi-Fidelity Coupling Models
Constant Coupling - constant Path Loss - free-space path loss
(distance) Path Loss + Gain - computed from the
path loss and the antenna gain in the direction between antennas.
S-Parameters - wideband coupling from user-supplied S-parameters (from measurements or CST STUDIO SUITE)
(dB
)
Fixed Value
Path Loss
Path Loss & GainS-Parameters
CST – COMPUTER SIMULATION TECHNOLOGY | www.cst.com
EMIT Library EMIT Library currently provides multiple models of
‘typical’ radios of interest to military and commercial users
Each model is notated with specific details of the system
Representative models for outboard components are also provided
The Library content will continue to be enhanced and updated
Users can create and maintain their own databases of systems and components in custom libraries
Libraries can be exported for sharing with other users