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Systems Concepts Research Applied to Radar Design


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Module: [LIBR_02]_SIGE XIII_SCR Applied to Radar Design
Subject: Systems Concepts Research Applied to Radar Design
Article by Antonio Sallum Librelato and Osamu Saotome, presented and published during the XIII SIGE. ITA, 27 a 30 de setembro de 2011.


Principles of SCR
Motivations for SCR Applied for Radar Systems
Phases of the SCR







Published in: Technology
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Systems Concepts Research Applied to Radar Design

  1. 1. ISSN: 1983 7402 ITA, 27 a 30 de setembro de 2011 Systems Concepts Research Applied to Radar Design Antonio Sallum Librelato1 and Osamu Saotome2 1 EThICS Engineering - Rua Prof. Maria Lima Cesar, 181, Ap. 12 - CEP 12216-141 - São José dos Campos - SP - Brasil 2 Instituto Tecnológico de Aeronáutica - Praça Marechal Eduardo Gomes, 50 – Vila das Acácias – São José dos Campos – SP - Brasil Abstract  Radar systems are usually based on complex Motivations for SCR Applied for Radar Systems:and critical technologies, and demand solutions to attend The project of radar systems, as many other complex anddemanding operational, functional and performance critical systems, is submitted to challenging factors presentedrequirements, under restrictions of costs and submitted to by the current environment, as suggested by [2]. Theseharch environments. To create new radar systems, or even factors are the main motivations to adopt the SCR method, asto upgrade existing radars, it is recommended to execute the follow, in the case of radar systems:concept phase of the project life cycle. The Systems • Increasing radar systems complexities, due to:Concepts Research (SCR) method was structured by one of More applications and interests on informationthe authors1, and is appropriate to obtain the most adequate about targets: polarimetry, multi-mode, multi-radar system concept to attend the needs and requirements. target, anti-jamming, countermeasure. The objective of this article is to describe the phases, New systems and circuits solutions: MIMO, multi-steps and tasks of the SCR, applied for the definition of a radar, phased-array (digital beamforming),generic radar system, considering the most prominent compact systems.characteristics of radar systems and their operational • Evolving radar technologies changes. as:environments. Solid-state analog components, permitting to Keywords  research, assurance, radar. implement new “all solid-state” radars and phased- array antennas. I. INTRODUCTION Digital converters and processors, permitting to increase radar signal and data processing The references [1], [2], and [3] consider the Systems capabilities, to digitally implement radar functionsConcept phase to be executed before the Systems nearer to the antenna, and to reduce the number ofDevelopment phase, and the reference [4] presents the and products assurance technologies to be applied The Software-Defined Radio (SDR) technologyduring all life cycle of the project. The reference [5] method, and method, applied to radar systems. [13] [14]for radar systems analysis, focus on radar requirements, [15]systems architecture and performance parameters, to be • Extended systems life cycles, demanding for:defined before the radar system development. Higher reliability, availability and durable Those are the main elements that inspired the creation of solutions.the SCR method, with the addition and integration of the Reduced life cycle assurance technologies. • Shorter technologies life cycles, creating demands for: Systems upgrading in shorter periods. Principles of SCR: More versatile solutions. The Systems Concepts Research (SCR) method • Constantly changing requirements, creating:comprises a series of interactive tasks. It will require Necessity of intense efforts to understand thespecialized knowledge and skills on management and problem to be solved and to collect and analyze theengineering of systems, requirements, risks, product requirements.assurance, costs and project planning and product Necessity of being ready to easily modify thedevelopment. Depending on the specific conditions of solutions during the life cycle.procurement and supply of systems, the work share between • More emphasis on “systems” (versus components),client and manufacturer (or supplier) will vary. Anyway, the driving to:complete composition of tasks is practically the same. Consider the System Of Systems (SOS) and The SCR method brings great benefits on obtaining the system concept as part of the project, since thebest solution for the needs, reduction of time and costs, beginning.increase on the system assurance, performance and cost- Define the concept from top (SOS, system) toeffectiveness, and better satisfaction of customers, users and down (units, modules, parts), as an integrated line-producers. of-thinking engineering.A. S. Librelato,, Tel +55-12-39418277. O. Saotome,, Tel +55-12- 39475818.
  2. 2. ISSN: 1983 7402 ITA, 27 a 30 de setembro de 2011 • Higher overall radar life-cycle costs, driving to: • Investigations should be done to define why and how Use systems and products assurance techniques, a radar system will satisfy the needs. applied during the project, to create solutions with • What are the evidences of the needs? reduced acquisition and support costs. • Operational objectives and goals. Reduce hardware and increase software solutions. • Restrictions and suppositions: • Increasing demand for mitigation and control of Restrictions and suppositions to be imposed to the uncertainty and hazard risks during the project, radar system, its characteristics, operations and mainly when based on new and not well mature project, like type of radar, frequency bands, and technologies, to obtain higher availability, integrity transmitted power, sometimes may be known since and safety. the beginning of the project. There is a consensus that, by using a methodology like the • Costs and schedule:SCR, it is possible to obtain a cost-effectiveness balance Costs (life cycle costs, unitary sales costs) andbetween the economic (cost and return on investment) and schedule are usually assessed at this moment.technical (performance and assurance) factors. [1] [2] [3] [4] • Owners, operators, users, actors, responsible, and other interested persons and organizations: Phases of the SCR: Concerning the ownership of the SOS and future The SCR method here applied consists of four steps: radar system, it is necessary to define who are the • NRA - Needs and Requirements Analysis owners, operators, users, and other interested • SCE - Systems Concepts Exploration persons and organizations, to well define • SCD - System Concept Definition responsibilities and authorities for requirements, • SRAA - Systems Risks and Assurance Analysis restrictions, and suppositions and other definitions The details of each step and tasks, applied for a generic and eventual modifications.radar system, are presented in the following. Institutions that will approve, qualify or certificate the radar system shall be defined. II. NEEDS AND REQUIREMENTS ANALYSIS FOR A RADAR SYSTEM NRA3. OPERATIONAL ANALYSIS Mission, profiles and scenarios: [5] It starts with the description of the context of the problem The details of missions, operations and functionalto be solved by using the radar system. architectures, interfaces, and environments of the radar During this step of SCR, it is highly recommended the system will be defined according to the following tasks:intense interaction and understanding between the client and • Obtain a quantitative statement of the mission of thedeveloper specialists. radar system, with: Operational boundaries and limits. NRA1. VISION OF PROBLEM Purpose and applications of the radar system. • The problem of the SOS: Requirements for the primary functions of Usually, the radar will be part of a wider system, surveillance and tracking. the SOS - System Of Systems, composed of Additional functions of detection and acquisition communications, remote control and operation, of targets. data and image processing and other the like Eventual multifunction and dedication to more systems. than one mission. The existing problem of the SOS that is intended Distinct profiles and scenarios of the mission, to be solved by the use of the radar system shall be associated with modes of operation. understood. Additional related functions, as self-testing, • Motivation and context of operations: training, and other special tasks. What are the operational objectives and goals to be Top-level radar system states requirements, considered? covering transportation, storage, disassembling, What are the actors and responsible for the radar reassembling, and others states. system operation? Deployment and usage conditions: The context of operations may be more complex • Determine the conditions of operational deployment than the radar system solely, but certainly it will be and usage of the radar system: based on targets detection and ranging, using radio Permanently fixed installation. signals. Temporary fixed installation, being transported (by • The problem of the radar system: roadway, waterway or airway) from one site to Looks for a radar system that will be operational, another. functional, feasible, and cost-effective, according Mobile installation (ground, air, water, and space to the needs. vehicles). • Determine the type of radar system and application: NRA2. NEEDS ANALYSIS Short range, long range coverage.
  3. 3. ISSN: 1983 7402 ITA, 27 a 30 de setembro de 2011 Sensing, surveillance, tracking. statistical signal fluctuation for the targets. [5] [6] [7] Radar transmit-receive techniques (monostatic, [8] bistatic, MIMO). • Characterize what will be considered as clutter,Operational concepts: depending on what is considered as targets of interest• Indicate the types and steps of the future operations of and on the operational environment. the radar system, in all their extent and details. • Define the required performance of clutter and• Define the repartition and relationship of the interference processing by the radar system. parameters and operational states between the SOS • Determine if target tracks history will be required. [6] elements. Number of objects:Operational environments: • Clarify how many simultaneous objects (targets) the• Describe and quantify the space and time radar system shall process, by surveillance, tracking, environmental conditions prevailing during the radar and processing, considering the timing required for system manufacturing, transportation, operation and those operations. maintenance, considering natural and man-made Threats: sources. • Classify and characterize the expected environment ofRadar system architecture: threats, jammers and other kind of man-made• Present the top-level composition and architecture of interference for the radar system operation, according the SOS, as well as the composition and architecture to their natures and origins. of the radar system as part of the SOS. Radar frequency:• Describe the basic identification of radar system and • The frequencies of operation are extremely influent subsystems elements and specification of the and decisive on the project of radar systems. performance requirements and their relationship with • Sometimes, the desired mission and operational the radar system functions. concept determine the frequency band to be adopted• Present the main physical requirements by the future radar [5] [6] [7] [8]. Then, it is only characterization of the radar system. necessary to know the particular conditionsInterfaces and interoperability: (requirements) about the range of values of the• Specify the requirements for the internal and external frequencies and about their selection and variations interfaces and interoperability conditions for system according to mission and operations profiles. and subsystems elements. • If the frequency of operation is not pre-defined, it will• Examine and describe the special interfaces of the be necessary to define it as a function of other radar system elements and the operational requirements and the scope of the system. The environment conditions. frequencies permitted to be used by radar systems areOperational surveillance coverage: established by international, regional and national• Define the space and time coverage dimensions for the regulations. operational surveillance of the radar. • The choice of the radar frequency bands is affected• Determine the required limits of range, elevation, mainly by: azimuth and eight from the radar point of view. The radar specific applications.Targets, target cross section, and target models: The region of the world where the radar system• Define and quantify the types, complexities and space will be operated. and time occurrence and distributions of targets to be The permitted frequency bands by standards and detected, considering: regulations. Punctual targets: aircrafts, missiles, vessels, • The radar operation frequency mainly affects: ground vehicles, and other similar. The effects on the propagation and attenuation of Surface targets: ground (soil, vegetation), sea the radar signals on the atmosphere. surface. The backscattering radar cross section of targets, Volumetric targets: natural tropospheric structures clutter and other objects. (clouds, precipitations, air turbulences), smoke, The backscattering power received from targets dust, sand, particles, and clusters of insects or and clutter. birds, ionospheric layers. The antenna radiation diagram, main and• Characterize the speed limits, the minimum separation secondary lobes and gain. among targets, clusters of targets and targets The Doppler frequency as a function of the radial behaviors and attitudes relative to the radar. velocity of detected targets.• Describe and quantify the radar cross sections of the The sampling decorrelation time of targets. targets. The Doppler radar dilemma.• Establish models of targets, including microphysical Processing resources: characteristics of the targets and their backscattering • Describe the types and requirements characteristics of response according to the polarization of the incident the signal and data processing resources of the radar radiofrequency signals, and the Swerling classes of system.
  4. 4. ISSN: 1983 7402 ITA, 27 a 30 de setembro de 2011System assurance requirements: Ambiguity: the extent to which the accuracy• Consider, quantify and allocate to the radar system parameters can be measured without ambiguity or elements, each of the system and product assurance the difficulty encountered in resolving any requirements, considered all the life cycle of the radar ambiguity. system, operations and environments, comprising: Resolution: degree to which two or more targets Risks and Cost-Effectiveness. may be separated in one or more spatial Configuration Management. coordinates, in radial velocity or acceleration. Rights and Penalties of Assurance and Warranties. Discrimination: the ability to detect or to track a Software Assurance. target echo in the presence of environmental Quality Assurance. echoes (clutter). Reliability Assurance. Immunity to threat: the capacity to sustain the Maintainability. operations when submitted to electronic Safety. countermeasure or jamming menaces. Security. Immunity to electromagnetic interference: the Human Factors. capacity to sustain the operations when submitted Supportability and Logistics. to friendly radiofrequency interference. Sustainability. Functional simulation: Others, the like. • Create a functional model of the radar system and Verification and Validation. subsystems.• The radar system qualification, acceptance and • Create a realistic measurement error model. certification conditions and procedures must be also • Analyze the functioning with the model. included. • Include the performance characteristics in the modelSystem life cycle and cost elements: and analyze their effectiveness.• The main life cycle elements are to be established, concerning: NRA5. FEASIBILITY DEFINITIONS Date desired to start using the system. Evaluation of radar systems currently available solutions: Expected duration of the useful life. • Collect data about current radar systems, similar to the Cycles of operation, maintenance, revision and radar system under analysis. upgrading of the system. • Assess the details about the used technologies. Total cost of ownership (total cost of acquisition Comparison of radar solutions and radar requirements: plus the total cost of operation). • Analyze and compare the specifications of the existing Number of radar systems to be deployed. solutions with the requirements for the new radar Logistic support organization. system. Evaluation of feasibility of radar systems functionalNRA4. FUNCTIONAL ANALYSIS concepts:Radar system functional concepts: [5] • Evaluate if the technologies of the current solutions• Define the functional modes and parameters, their will permit to obtain the required functions and repartition and relationship between the SOS performances. elements. • Describe the needs for other technologies to attend the• Establish the role of the radar system on the SOS functional concepts. context.Functional requirements: NRA6. NEEDS VALIDATION• Describe the functions of the radar system and • Verify the evidences of the needs. subsystems. • Analyze the viability of needs attendance.Functional allocation to radar subsystems: • Validate the needs and systems concepts relationship.• Allocate the functional requirements to the radar system and subsystems. NRA7. OPERATIONAL REQUIREMENTSFunctional radar performance requirements: SYNTHESIS• Establish the main criteria for measuring the quality of • Elicit, analyze and validate all radar system performance of the radar system, in adverse operational requirements and constraints. environments, as [7]: Reliability of detection: maximum detection range III. SYSTEMS CONCEPTS EXPLORATION and probability or percentage of time that the FOR A RADAR SYSTEM desires targets will be detected. Accuracy, measured with respect to target Taking the NRA results into account, it is necessary a parameter estimates: target range, angular detailed revision and analysis to consolidate the requirements coordinates, range and angular rates and and constraints, and to prepare a complete and integrated accelerations. functional and performance model to be used as a
  5. 5. ISSN: 1983 7402 ITA, 27 a 30 de setembro de 2011background, and to generate various alternatives of radar Evaluate the expected range of noise temperaturesystem concepts. from the antenna and other radiofrequency elements of the receiving circuit. SCE1. OPERATIONAL REQUIREMENTS Evaluate the best available technologies to provideANALYSIS receiver front-end elements (amplifiers, filters, • Critical analysis and revision of the radar system protections) in the radar system frequency bands, operational objectives. with minimum inherent noise factors, to be • Detailed revision and analysis of the radar system considered in the models. operational concept and requirements: Based on the previous evaluations, calculate the With diagrams and models. system noise temperature. Consolidating them in a complete non ambiguous • Create a model of the MDS - minimum detectable and consistent list, using, if possible, appropriate signal for the receiving front-end, considering: tools. Frequency bandwidth and form factor of the • Feasibility analysis of the radar system operational receiver filter. requirements: Frequency bandwidth of the receiver signal, after Verify how each of the radar system operational filtering. requirements could be executed, considering Minimum SNR - signal-to-noise ratio at the output modes, constraints and functions. of the receiver. If any inconsistency arises, turn back to the NRA The Boltzmann´s constant. step to better understand the concepts and Calculate the minimum value of the received radar requirements and to remove the inconsistency. signal at the receiver input, capable to be processed and detected by the subsequent radar SCE2. PERFORMANCE REQUIREMENTS receiver channel circuits.FORMULATION Transmitter performance analysis: [5] [7] [8] • Derivation of radar subsystems functions and • Create a model for the analysis of the performance of performance requirements: the radar during transmission, considering: Consistently with each function and mode of Radar frequencies of operation. operation of the radar system, based on the results Peak power. of the previous analysis and reviews of NRA. Modulations. • Formulation of radar system and subsystems Average power. performance characteristics: PRF - pulse repetition frequency. Develop functional and performance radar models Pulsewidths. to evaluate the theoretical and practical viability of Bandwidths. accomplishment of the functional performance, by: Antenna performance analysis: [5] [7] [8] Using the radar equation and other relation • Create a model for the representation and analysis of among the characteristics already established. the performance of the antenna, considering: Exploring different radar parameters and Antenna technology, format (reflector, phased features. array, aperture, beam forming) and dimensions. • Derivation and formulation of radar system and Antenna radiation diagram (main lobe, sidelobes, subsystems performance characteristics. nulls, boresight, and gain). General system architecture Antenna beamwidth (pencil beam, fan beam, multi • Before exploring the complete solutions of the radar beam). system, it is recommended to explore the radiofrequency front-end of the system, as a basis for SCE3. IMPLEMENTATION CONCEPTS the other radar elements. EXPLORATION • The principles and techniques of SDR - software- • Assessment and analysis of radar technologies and defined radio apply also to software-defined radar. systems possibilities: Besides elimination of hardware elements (cost Before describing specific complete radar systems, reduction, greater reliability, etc), it gives much more the available technologies of hardware and flexibility, increase functionalities, and permit software usual for those types of systems must be adaptation to environments and missions. assessed and evaluated. This will give an updated Receiver performance analysis [5] [6] [7] [8] [9] [10] [11] view of the possibilities, inspire innovations and • Create a model of the internal and external losses. reinforce the knowledge of systems architecture. • Create a model of the noise temperature of the Elements of the radiofrequency front-end: receiving front-end of the radar, considering: Based on the previous analysis about radar type, Expected noise temperature environment, frequency, space resolution, radiation diagram, comprising the natural and man-made noise mobility, coverage, etc., the type and general sources external to the system. dimensions of the antenna and antenna-transceiver coupling circuits can be selected.
  6. 6. ISSN: 1983 7402 ITA, 27 a 30 de setembro de 2011 Based on the receiver performance analysis, • Description, classification and qualification of each describe alternatives of receiver front-end (LNA, radar system alternative. filter, COHO, mixer), and analyze the • Synthesis of the radar system alternatives performance characteristics (gain, dynamic range, MDS, SNR, requirements. band pass, IF, etc) of each solution. Considering the radar frequency, antenna gain and IV. SYSTEM CONCEPT DEFINITION FOR A diagram, space coverage, targets, threats, RADAR SYSTEM interferences and atmospheric effects, and losses, estimate the minimum transmitter output peak SCD1. PERFORMANCE REQUIREMENTS power. ANALYSIS Describe the alternatives of transmitter • Analysis and refinement of performance and technologies (solid state, tubes, etc) and solutions functional requirements of the radar system concept (oscillator, linear amplifier, etc), and analyze their alternatives. characteristics. Define the transmission modulation techniques, SCD2. FUNCTIONAL ANALYSIS AND considering the peak and medium power, PRF, FORMULATION detection performance, etc. • Definition and simulation of the functional Examine the characteristics of the transmitter components of the radar system concept alternatives. driving signal: frequency, power level, • Modeling and demonstrations with prototypes of the synchronism signals, etc. radar system concept alternatives. Define the characteristics of duplexer, antenna coupler, RF line, power supplies and control SCD3. IMPLEMENTATION CONCEPT elements. SELECTION Elements of the digital processing subsystem: • Selection of the preferred radar system concept. Up and down converters circuits. ADC/DCA circuits. SCD4. CONCEPT VALIDATION AND DSP, CPU, FPGA, memories, interfaces. DESCRIPTION Software modules with radar functions and signal • Modeling of selected radar system concept and its processing based on SDR techniques and practices. environment. [12] • Functional and architectonic specifications of the Elements of the visualization and networking subsystem: selected radar system concept. Computers, servers, network interfaces, data • Selected radar system concept validation and storage technologies, human-systems interface. description. Software for data processing, product generation and visualization, radar networking, local and remote control and operation. SCD5. SYSTEM DEVELOPMENT PLANNING • Formulation of alternatives of radar implementation • Planning for the life cycle of the selected radar system concept: concepts: Planning for the development. Considering the technologies and the functional and performance analysis, create alternatives of Planning for the production. systems concepts possible to be implemented. Planning for the support and logistics. Planning for the use. • Execution of radar elements proof-of-concepts Planning for the discard and substitution. experiments: When necessary, construct models or physical V. SYSTEMS RISKS AND ASSURANCE elements to be submitted to tests and proof-of- ANALYSIS FOR A RADAR SYSTEM concept evaluation. • Evaluation of exequibility of radar system SRAA1. SRAA DURING NRA alternatives. • Classification of risks of hazards and uncertainties. • Evaluation of the performance and the cost- • Definition of analysis criteria. effectiveness characteristics of each radar system • Assessment and evaluation of the potential risks for alternative. the project, the system, and the operations. SCE4. PERFORMANCE REQUIREMENTS • Evaluation of the risks derived if the radar problemVALIDATION will not be solved. • Definition, integration and validation of the radar • Assessment, limits characterization, and evaluation of system performance characteristics. the main system assurance requirements, comprising: Configuration management, verification and SCE5. PERFORMANCE REQUIREMENTS validation, software assurance.SYNTHESIS
  7. 7. ISSN: 1983 7402 ITA, 27 a 30 de setembro de 2011 Quality, reliability, maintainability, safety, It was also possible to demonstrate how to integrate the security, human factors, supportability and risks, cost-effectiveness and assurance analysis to each step logistics, sustainability, and other analogous. of the SCR for a radar system concept. • Preliminary evaluation and analysis of the TCO - The sequence of tasks to select and define the most Total Cost of Ownership perceived by the market. appropriate radar system concept was demonstrated. • Go-No Go decision. REFERENCES SRAA2. SRAA DURING SCE • Evaluation and comparison of risks and system [1] A. Kossiakoff; W. N. Sweet. Systems Engineering - Principles and Practice. Hoboken, NJ: John Wiley, 2003. assurance parameters of each alternative of system [2] S. Blanchard. System Engineering Management. 4th ed. concept. Hoboken, NJ: John Wiley, 2008. • Assessment of the availability and disclosure of parts [3] S. Wasson. System Analysis, Design, and Development - and technologies from foreign suppliers. Concepts, Principles and Practices. Hoboken, NJ: John Wiley, • Analysis and evaluation of each trade-off solutions: 2006. [4] G. Raheja; A. Allocco. Assurance Technologies Principles and • Analysis of viability of accomplishment of the Practices. 2nd ed. Hoboken, NJ: John Wiley, 2006. assurance requirements and cost-effectiveness [5] J. Bogush, Jr. Radar and the Atmosphere. Norwood, MA: Artech balance. House, 1989. • Go-No Go decision. [6] M. L. Skolnik. Introduction to Radar Systems. 2nd ed. Tokyo, • Recommendations for the mitigation and control of Japan: McGraw-Hill Kogakusha, 1981. risks and for provisioning of systems assurance and [7] F. E. Nathanson. Radar Design Principles - Signal Processing and the Environment. 2nd ed. Raleigh, NC: SciTech Pub, 1999. cost-effectiveness. [8] M. Skolnik, ed. Radar Handbook. 3rd ed. USA: McGraw-Hill, 2008. SRAA3. SRAA DURING SCD [9] M. Carpentier. Radars - Bases Modernes 4e ed. Paris: Mason, • Detailed analysis, description and recommendation for 1981. mitigation and control of risks, system assurance and [10] L. V. Blake "NRL Report 5668 - Antenna and receiver-system cost-effectiveness elements of the selected radar noise-temperature calculation". U. S. Naval Research Laboratory, system concept. September 19, 1961. [11] M. Schwartz. Transmissão de informação, modulação e ruído. 2. • Final Go-No Go decision. Ed. Rio de Janeiro: Guanabara Dois, 1979. [12] M. A. Richards. Fundamentals of Radar Signal Processing. USA: If the final decision is to proceed with the radar system McGraw-Hill, 2005.development, the results obtained during the SCR phase shall [13] I. Müürsepp.” Software Radar”, in ELECTRONICS ANDbe documented and transferred to the next phase of ELECTRICAL ENGINEERING, 2008. No. 4(84).Development of Systems and Products (DSP). [14] Mark Frankford. “Software-Defined Radar for MIMO Applications - Documentation Series V”. The Ohio State University. Available at ftp://esl.eng.ohio- VI. CONCLUSIONS Accessed at 31/05/2011. [15] Lee K. Patton. “A GNU Radio Based Software-Defined Radar”. The example of application of the Systems Concepts Master Thesis. Department of Electrical Engineering, WrightResearch (SCR) method to the case of a generic radar system State University, 2007.concept was performed and resulted on a careful and >>>>>> = <<<<<<complete analysis of the problem, the needs and theoperational, functional and performance requirements.