Claudia User Manual
Contents
1. Australian Government Department of Defence Defence Science and Technology Organisation Claudia User Manual Daniel Finch Nick Lioutas and Ross Kyprianou Electronic Warfare and Radar Division Defence Science and Technology Organisation DSTO GD 0554 ABSTRACT This document is the user manual for version 1 0 of the generic maritime radar performance model Claudia Claudia computes the target detection performance of radars in maritime environments APPROVED FOR PUBLIC RELEASE DSTO GD 0554 Published by DSTO Defence Science and Technology Organisation PO Box 1500 Edinburgh South Australia 5111 Australia Telephone 08 8259 5555 Facsimile 08 8259 6567 Commonwealth of Australia 2008 AR No AR 014 326 October 2008 APPROVED FOR PUBLIC RELEASE DSTO GD 0554 Claudia User Manual Executive Summary The EWRD Microwave Radar Branch has undertaken to establish a flexible framework for radar modelling to maximise code reusability The framework is focussed on the parametric modelling of maritime radars and provides the ability to develop a complete system from individual components to conduct performance evaluation of maritime radar systems iii DSTO GD 0554 lv DSTO GD 0554 Authors Daniel Finch Electronic Warfare and Radar Division Daniel Finch works in radar modelling and analysis in EWRD DSTO He joined DSTO in 2003 after completing degrees in Mathematics and El2. Gr is the transmit antenna gain see 3 3 2 27 Gr is the receive antenna gain see 3 3 2 21 A is the transmitter wavelength a is the target radar cross section see 3 5 2 5 PCR is the pulse compression ratio see 3 3 2 18 Lr is the RF loss between the final power amplifier stage and the antenna see 3 3 2 29 LR is the RF loss between antenna and input of radar receiver see 3 3 2 22 Lgs is the beamshape loss see 3 3 2 4 Lsp is the total signal processing losses see 3 3 2 26 and K isthe 2 way path factor see 6 2 This equation is based on the standard radar range equation 7 Note the propagation term K includes the range dependence 6 2 Propagation Claudia uses a propagation path factor K in its calculations This factor is equivalent to the propagation factor divided by the path length and is given by o f ka for free space propagaction 6 ka kr for multi path propagation The terms kg and k correspond to the contributions due to the direct and reflected paths and are given by ds V exp 2i7Dg A 7 Da V LAtma hon Vopsprdexp 2inD X 8 D Latm DSTO GD 0554 where Vi is the voltage gain of radiation pattern for direct ray Vo is the voltage gain of radiation pattern for reflected ray Da is the slant range for direct ray D is the slant ranges for reflected ray Lam is the 1 way atmospheric attenuation due to clear weather and rain for direct ray LaAtm is the 1
3. Platform Environment Configuration and Scenario Calculate signal to interference ratio get_signal_to_interference_ratio Parameter gt al NonCoherentIntegration Calculate Pd video_integration Calculate Pd binary_integration Return the probability of detection Figure 9 Flow chart of get_detection_probability 24 DSTO GD 0554 Input details of Radar Target Platform Environment Configuration and Scenario Calculate the propagation paths angles get_ray_paths Returns a struct with details of propagation angles to target and surface Calculate the rain attenuation coefficient get_rain_attenuation_coeff volume clutter power get_volume_clutter_power Calculate the target power get_target_return surface clutter power get_surface_clultter_power Calculate the effective clutter distribution shape parameter Combine individual power returns into a signal to interference ratio Return the shape parameter and gt signal to interference ratio Figure 10 Flow chart of get_signal_to_interference_ratio 25 DSTO GD 0554 26 6 Radar Range Equation This section provides a general description of the radar range equation used by Claudia to evaluate the detection performance of a maritime radar 6 1 Target The target return power is given as g PrGrGRMPCRoK 4r 3LrLrLgsLsp where Pr is the peak transmit power see 3 3 2 30
4. Accepted values for Sea Water Temperature are in the range 0 to 40 C inclusive 3 6 2 7 WaveDirection WaveDirection 7 is the direction of wave motion relative to true north It is specified in degrees and can assume any floating point value from 0 to 360 WaveDirection is used with the antenna look direction look see 3 3 2 1 to determine the relative look direction reg as Orel 180 Otook E w 4 13 DSTO GD 0554 14 where all angles are in degrees The relative look direction is one of the parameters used to calculate the mean sea clutter reflectivity 3 7 The Scenario File The scenario file includes the values for parameters describing the characteristics of the radar s region of operation The scenario file is named by convention scn_name xml where name is anything descriptive e g scn_Southern Winter xml A typical listing for the scenario file is provided below 3 7 1 Sample Scenario File Listing lt Scenario gt lt Season value Winter gt lt Latitude value Mid gt lt Scenario gt 3 7 2 Description of Parameters 3 7 2 1 Latitude Latitude can be one of three values i e Low Mid or High where e Low corresponds to latitudes less than 22 e Mid means latitudes between 22 and 45 e High is for latitudes greater than 45 Latitude is used together with Season see 3 7 2 2 to determine the water vapour density absolute temperature and dry air pressur
5. lt this is a comment gt lt child2 key1 valuei gt lt root gt Elements are enclosed in opening and closing tags As shown above the opening tag begins with the angled bracket lt and is followed by a tag name any number of paired attribute names e g keyl and attribute values e g valuel and finally an angled bracket gt The closing tag is constructed with the angled bracket tag name and the closing angled bracket gt In the case of empty elements it is possible combine the opening and closing tags e g child2 above Note that tag names are case sensitive and must not contain spaces As shown XML syntax requires the attribute names and their corresponding values be separated by an and attribute values be enclosed by double quotes Attribute names are not quoted XML files may also contain any number of comment lines The comments are enclosed within an opening tag of lt and closing tag gt as shown above Comment lines can be inserted anywhere within the XML except within the opening and closing tags of elements 3 2 Claudia XML Elements and Conventions The root element of each file has the same name as the component represented in the file e g lt Radar gt for a Radar component All parameters of this component are DSTO GD 0554 then entered as child elements with the two attributes value and units Order of the parameters w
6. Heading is the azimuth heading of the radar platform relative to true north It is specified in degrees and can assume any floating point value from 0 to 360 inclusive Heading is not used in this version of the radar model and should always be set to NaN 3 4 2 2 Height Height is the height of the radar antenna above sea level specified in metres Claudia uses temperature pressure and water vapour pressure profiles 4 to compute the atmospheric attenuation in clear weather These profiles extend to an altitude of 30000 m hence Height can be set to any floating point value between 0 and 30000 inclusive Height may be set to NaN in which case a value for Height is calculated such that it provides the radar with a clear line of sight to the radar s MaximumDisplayRange see 3 3 2 12 3 4 2 3 Speed Speed represents the speed of the radar platform and is specified in metres per second Speed is not used in the current version of the radar model and is should therefore be set to NaN DSTO GD 0554 3 5 The Target File The target file includes the values for the parameters describing the characteristics of the radar target In the current version of the radar model the target is represented as a single point scatterer with a constant radar cross section at a specified height above sea level The target file is named by convention tgt_name xml where name is anything de scriptive e g tgt_patrolboat xml A typical listing for the targe
7. allows mathematical expressions to be valid values for example expressions such as sin 3 pi 2 that can be evaluated by MATLAB Claudia allows each input parameter to be entered in a number of different units These parameter values are converted to the corresponding SI unit internally in the software For example range specified in nautical miles is converted into metres Exceptions occur where non SI units are standard expressions for specific equations 5 2 Processing This section describes the processing steps performed when Claudia is executed As an example the following steps are executed in order for the run function find detection range 1 The input parameters are read from XML files and are used to create MATLAB data structures These structures correspond to Claudia s components i e the radar platform target environment scenario and configuration 21 DSTO GD 0554 2 Processing of the input values occurs so that the value of each parameter is converted to the units required by Claudia In addition parameter values required by Claudia but entered as NaN by the user e g BeamShapeLoss are computed from other related parameters 3 The maximum ground range is calculated and the current ground range set to the maximum range 4 The signal to clutter plus noise or signal to interference ratio and the resultant probability of detection is determined at the current ground range 5 If the probability of d
8. integrated and the N pulse bursts are non coherently integrated N is equivalent to NoPulseBursts and Neon is equivalent to NoPulsesPerBurst see 3 3 2 15 NoPulseBursts can be set to the following values e an integer greater or equal to 1 e NaN in which case the number of non coherent integrated pulses is calculated from the number of pulses received between the 3dB beamwidth points for the azimuth scanning radar antenna as given by PRF x0 N Nawet gt 3 where Q is the radar scan rate see 3 3 2 25 Burst 1 Burst N 1 2 Si Ncoh 1 2 m Ncoh Figure 1 Dwell consisting of N bursts each with Neon pulses 3 3 2 15 NoPulsesPerBurst NoPulsesPerBurst is the integer number of pulses that occur within a pulse burst NoPulsesPerBurst is equivalent to the number of pulses co herently integrated and is related to CoherentIntegrationGain by Equation 1 3 3 2 16 Polarisation Polarisation of the radar radiation can be set to H V or C to indicate horizontal vertical or circular antenna polarisation respectively Polarisation is used in the radar model to determine i the 1 way atmospheric attenuation due to rain ii the mean sea clutter reflectivity iii the shape parameter for the amplitude distribution of sea clutter and iv the specular reflection coefficient for a smooth sea surface 3 3 2 17 PRE PREF is the pulse repe
9. way atmospheric attenuation due to clear weather and rain for reflected ray d is the divergence factor due to spherical reflecting surface PF is the specular reflection coefficient for smooth plane surface and Ps is the rough surface reflection coefficient This equation is derived from the common definition for the propagation factor as found in 7 6 3 Signal to Interference Ratio The signal to interference ratio SIR is given by PARE E a Luc S SIR Pm Ge Psc Ise Pue Luc y is the receiver thermal noise power see 6 6 is the coherent integration gain see 3 3 2 9 is the sea clutter return power see 6 4 is the rain clutter return power see 6 5 is the surface clutter improvement factor for sea clutter see 3 3 2 7 and is the volume clutter improvement factor for rain clutter see 3 3 2 8 This equation assumes the clutter decorrelation time is greater than or equal to the coherent integration time Thermal noise is assumed to decorrelate from one pulse to the next 6 4 S urface Clutter The calculation of the received surface clutter power Pe is based on equations from 7 and is given as where Asc o0 Vsc BE PrGTGrA Asco Vso 10 47 LrLe D L Atma b is the area of clutter cell is the mean sea clutter reflectivity is the voltage gain of radiation pattern for a target height of zero 27 DSTO GD 0554 28 6 5 Volume Clutter Pye is de
10. 3 6 2 Description of Parameters e e 12 3 7 The Scenario File 4 14 3 7 1 Sample Scenario File Listing 14 3 7 2 Description of Parameters e 14 3 8 The Configuration File 0 o e 15 3 8 1 Sample Configuration File Listing 15 3 8 2 Description of Parameters a 15 Running Claudia 15 4 1 System Requirements oaoa 15 4 2 Installing the Software e e ee 16 43 RunmnsClalidia iia o a a A A dog Ae Foe A 16 4 4 Claudia Outputs s sersa 0444 24 8 ER a a 17 4 4 1 find_detectionrange 0 p aa oeoa p g ee eee 17 vii DSTO GD 0554 viii 4 4 2 plot_detection_probability o 4 4 3 find detection probability o e AAA plot PAIC e 4 4 e a ata o ee Oe eS AAS cploterange rcs ra A A A a MANO plotreguited Tese to a a la A a 5 Software Design Bik introduction 14 E Oe A A at EE O 2 Processing se raa A ee EE RA A ee e a 5 3 Functional Description 2 0 2 0 0 o 6 Radar Range Equation Gel Sabet ok a ele a ea Te a E gaa Ow ae Gee Soe Sra OT oe ee 6 2 Propagation sae sae aeoe eee ee RO ae eee e 6 3 Signal to Interference Ratio 2 0 o 6 4 Surface Clutter prego ease eek ee OY ee A ek E 6 5 Volume Glitters a ce eo elon ete Ra ae 6 6 ROS 6 7 Probability of Detection 2 0 0 0 0 e 7 Planned Enhancemen
11. AVEAT PRIVACY MARKING DOCUMENT CONTROL DATA 2 TITLE 3 SECURITY CLASSIFICATION Claudia User Manual Document U Title U Abstract U 4 AUTHORS 5 CORPORATE AUTHOR Daniel Finch Nick Lioutas and Ross Kyprianou Defence Science and Technology Organisation PO Box 1500 Edinburgh South Australia 5111 Australia 6a DSTO NUMBER 6b AR NUMBER 6c TYPE OF REPORT 7 DOCUMENT DATE DSTO GD 0554 AR 014 326 General Document October 2008 8 FILE NUMBER 9 TASK NUMBER 10 SPONSOR 11 No OF PAGES 12 No OF REFS 2008 1100798 1 DMS15 CEWRD 31 9 13 URL OF ELECTRONIC VERSION 14 RELEASE AUTHORITY http www dsto defence gov au corporate Chief Electronic Warfare and Radar Division reports DSTO GD 0554 pdf 15 SECONDARY RELEASE STATEMENT OF THIS DOCUMENT Approved For Public Release OVERSEAS ENQUIRIES OUTSIDE STATED LIMITATIONS SHOULD BE REFERRED THROUGH DOCUMENT EXCHANGE PO BOX 1500 EDINBURGH SOUTH AUSTRALIA 5111 16 DELIBERATE ANNOUNCEMENT No Limitations 17 CITATION IN OTHER DOCUMENTS No Limitations 18 DSTO RESEARCH LIBRARY THESAURUS Maritime environments Modelling Performance evaluation Target detection User manuals 19 ABSTRACT This document is the user manual for version 1 0 of the generic maritime radar performance model Claudia Claudia computes the target detection performance of radars in maritime environments Page classification UNCLASSIFIED
12. Height is the height of the target scattering centre above sea level and may be specified in metres kilometres or feet Height can be set to any floating point value between 0 and 30000 metres inclusive 3 5 2 5 RCS RCS is the radar cross section of the target specified in square metres and is assumed to be constant over all aspect angles 3 5 2 6 Speed Speed is the speed of the target in metres per second Speed is not used in this version of the model and as such is set to NaN 3 6 The Environment File The environment file includes the values for parameters describing the characteristics of the radar s operating environment The environment file is named by convention env_name xml where name is anything descriptive e g env_MediumSeaState xml A typical listing for the environment file is provided below 3 6 1 Sample Environment File Listing lt Environment gt lt SeaState value 0 gt lt RainRate value 0 units mm hr gt lt WaveDirection value 0 units deg gt lt SeaWaterTemperature value 15 units c gt lt CloudHeight value 5000 units m gt lt RainStartRange value 0 units m gt lt RainStopRange value 60000 units m gt lt Environment gt 3 6 2 Description of Parameters Paremeters for the environment component are listed below in alphabetical order 3 6 2 1 CloudHeight CloudHeight is the maximum height at which rain can be present Its value is specified in metres or kilometres DS
13. S specified in the input file is shown as the dashed red line 19 20 DSTO GD 0554 Required RCS dB m Required RCS vs Range yor Y T T T T YO V Pd 0 5 Pd 0 9 15 L t L 0 2000 4000 6000 8000 10000 12000 14000 Range m Figure 6 Example output for run function plot_required_rcs DSTO GD 0554 5 Software Design 5 1 Introduction MATLAB has been chosen as the programming language for the design of Claudia for the following reasons e it is a good prototyping language and therefore lends itself to developing software quickly in an iterative manner e it is suitable for implementing models of a mathematical nature e graphical user interfaces are simple to develop e there is readily available knowledge in the language The software design uses a functional programming approach The design also aimed to be flexible so that individual models e g GIT for sea clutter could be easily replaced with more precise or higher level models The XML format is selected to store user inputs for Claudia because it is an open industry accepted W3C recommended standard The XML format of the input files sup ports the following features e it is self documenting e it can include descriptive comments e it is a hierarchical structure that supports representing multiple sets of parameters such as those associated with different operating modes for the radar e it
14. TO GD 0554 3 6 2 2 RainRate RainRate is the rain rate in millimetres per hour The radar model assumes a uniform rain rate within the rain cell bounded by the ground RainStartRange RainStopRange and CloudHeight as shown in Figure 2 RainRate is used to calculate the atmospheric attenuation due to the presence of rain and the rain clutter reflectivity at the target range if the rain cell extends to and beyond the target range 3 6 2 3 RainStartRange RainStartRange specifies the ground range from the plat form to the start of the rain cell see Figure 2 Its value may be specified in meters kilometres or nautical miles 3 6 2 4 RainStopRange RainStopRange specifies the ground range from the plat form to end of the rain cell see Figure 2 Its value may be specified in metres kilometres or nautical miles 1yb19eHpno 9 rain cell RainStartRange gt RainStopRange Figure 2 Use of a rain cell 3 6 2 5 SeaState SeaState can take on any value from 0 to 6 If a SeaState of 0 is specified the radar model will convert this to a small value i e 0 0001 to avoid division by zero SeaState is used to calculate the rough surface reflection coefficient and mean clutter reflectivity for sea clutter 3 6 2 6 SeaWaterTemperature SeaWaterTemperature is specified in degrees Cel sius and is used to calculate the complex dielectric constant and hence the specular reflec tion coefficient for a smooth sea surface
15. ave the default file extension of xml appended and therefore do not require this extension to be added in the argument list 4 4 Claudia Outputs Claudia has six run functions Each of these will produce a graphical plot of results and or data stored as a variable in the MATLAB workspace These six run functions are detailed below 4 4 1 find detection range This function will find the maximum ground range for the target that corresponds to a specified probability of detection The range will be given as a multiple of 50m independent of radar resolution No plots are produced 4 4 2 plot_detection probability This function will plot the probability of detection for the target between the maximum ground range and the radar in steps of 50 metres The maximum ground range is the end of the propagation interference region This function will produce a plot of the probability of detection against range An example is shown in Figure 3 4 4 3 find_detection_probability This function may be used to quickly calculate the probability of detection for a target at a user designated ground range No plots are produced 17 DSTO GD 0554 18 0 8 4 07 A l 0 6 4 0 57 4 Pd 0 47 7 0 3F 4 0 27 al 0 17 4 0 We 1 L L fi L 0 2000 4000 6000 8000 10000 12000 14000 Range m Figure 3 Example output for run function plot_detection_probability 4 4 4 plot_pd_rcs This func
16. calculations The design is such that new methods can be added easily as required This document is a description and user guide for operating Claudia version 1 0 It describes software installation setting up the input files and running the model Included in this document is a functional description to assist with a more informed use of the software and a description of the equations on which the model is based 2 Claudia Capabilities This section outlines Claudia s current capabilities regarding calculation of the detec tion performance of maritime radars However Claudia is in reality a modelling frame work so the following attributes are not necessarily limiting These capabilities are sum marised as follows e Coherent pre detection and non coherent post detection video or binary inte gration of pulses and pulse bursts DSTO GD 0554 six Ability to evaluate detection thresholds and probability of detection for surface clut ter with variable amplitude distributions and a Rayleigh distribution of noise and volume clutter Detection thresholds and probabilities of detection can be calculated for targets with Swerling case 0 1 2 3 and 4 radar cross section fluctuations The target is represented as a point scatterer with a specified radar cross section at a specified height above sea level The Georgia Institute of Technology GIT sea clutter model 1 is used to compute the mean sea clutter reflectivity in the f
17. e profiles as a function of height These profiles are then used to calculate the atmospheric attenuation for clear weather using the procudure from 6 For Mid and High latitudes there are distinct water vapour density absolute temper ature and dry air pressure profiles for the two Season options Summer and Winter For Low latitudes there are no seasonal variations and a single profile is used for vapour density temperature and air pressure for both Summer and Winter A comprehensive description of water vapour density absolute temperature and dry air pressure profiles is provided in 4 All of the profiles used in Claudia are valid up to an altitude of 30000 m 3 7 2 2 Season Season can be one of two values i e Summer or Winter Season is used together with Latitude see 3 7 2 1 to determine the water vapour density absolute temperature and dry air pressure profiles as a function of height These profiles are then used to calculate the atmospheric attenuation for clear weather DSTO GD 0554 3 8 The Configuration File The configuration file includes parameters that influence the radar s detection perfor mance but are not included in any of the above files The configuration file is named by convention cfg_ name xml where name is anything descriptive e g cfg Multipath xml A typical listing for the configuration file is provided below 3 8 1 Sample Configuration File Listing lt Configuration g
18. ectrical Engineering at the University of Wollongong Nick Lioutas Electronic Warfare and Radar Division Nick Lioutas currently works in Electronic Warfare and Radar Division DSTO His work involves the analysis and modelling of radar system performance He completed a BSc Hons degree at the University of Adelaide in 1981 Ross Kyprianou Electronic Warfare and Radar Division Ross Kyprianou currently works in EWRD in the area of sea clutter modelling after graduating from the University of Ade laide in 1985 with a Bachelor of Science and a Post Graduate Diploma in Computer Science in 1987 DSTO GD 0554 vi DSTO GD 0554 Contents Introduction 1 Claudia Capabilities 1 Input Files 3 Ol troduction 345 4 a eS Bee ee y Spe A 3 Solid XM Syntax seg en nh eae OA eee oO ecb tae ere i eee et 3 3 2 Claudia XML Elements and Conventions 3 3 3 The Radar File us eee ee eee e ee eS 4 3 3 1 Sample Radar File Listing 5 3 3 2 Description of Parameters e 6 o4 The PlatiormFHile cons tii a oe ie Pama He dog Ae Foe ona A 10 3 4 1 Sample Platform File Listing 10 3 4 2 Description of Parameters 0 0 0 0002 eee 10 3 5 Fhe Target Hilado 11 3 5 1 Sample Target File Listing aooaa a 11 3 5 2 Description of Parameters e 11 3 6 The Environment File e 12 3 6 1 Sample Environment File Listing 12
19. et to 1 0 CIF Surface is dimensionless 3 3 2 8 CIFVolume CIF Volume is the clutter improvement factor for volume clutter due to MTI and or doppler processing If neither MTI nor doppler processing is used for volume clutter suppression CIF Volume should be set to 1 0 CIF Volume is dimensionless DSTO GD 0554 3 3 2 9 CoherentIntegrationGain CoherentIntegrationGain Geon is the gain ob tained from the coherent integration or sum of pulses within a pulse burst and is speci fied in decibells The user can determine an appropriate value for CoherentIntegrationGain from the number of pulses within a pulse burst as Geach 10log 0 Neon 1 where Neon is NoPulsesPerBurst see 3 3 2 15 CoherentIntegrationGain can be dependent on the operating mode of the radar If the operating mode does not integrate pulses coherently the value of CoherentIntegrationGain should be set to 0 dB Only one of CoherentIntegrationGain and CoherentIntegrationTime Teon is required thus one of these parameters should be set to a valid numeric value and the other to NaN The coherent gain Ge used in calculations given as G Geoh when Teon NaN 2 10logip teonPRF otherwise 3 3 2 10 CoherentIntegrationTime CoherentIntegrationTime Teon is the observa tion time during which pulses are coherently integrated and is specified in seconds As discussed in paragraph 3 3 2 9 this parameter should be set to NaN if CoherentIntegra tionGa
20. etection is less than the user required probability the ground range is decremented and the previous step is repeated Otherwise execution stops and the current ground range is returned to the workspace as the result 5 3 Functional Description This section provides a graphical description of the core software modules that comprise the radar model The behaviour of the main functions are illustrated as Unified Modelling Language UML activity diagrams The UML symbols and conventions used in the graphical description are shown in Figure 7 C gt Activity lt gt Decision Note gt Transition Synchronisation Initial state Final state Figure 7 UML activity symbols Figure 8 shows the function find_detection_range one of the six run functions de scribed in Section 4 4 Figure 9 shows the function get_detection_probability This function calculates the probability of detection for the current radar target geometry Figure 10 highlights the core operations performed in get_signal_to_interference_ratio 22 DSTO GD 0554 Calculate maximum range get_ground_range Maximum detection range is the end of the propagation interference region dependent on frequency and heights decrement the currentRange Does Pd exceed user required value Return currentRange gt Figure 8 Flow chart of find_detection_range 23 DSTO GD 0554 Input details of the Radar Target
21. fined as Puc PrGrGrA Vpn 1 11 am ErLEr DiLatm where LAtm is the 1 way atmospheric attenuation due to clear weather and rain for slant range n is the rain clutter reflectivity and Vp is the rain cell beam pattern i e the rain cell volume with correction due to gaussian shaped beam The calculation of the volume clutter power is derived from equations found in 7 The term V is calculated based on the dimensions of the rain cell fig 2 defined by the user 6 6 Noise The thermal noise power P is calculated as Py kB FnT ret Bn 12 where kg is the Boltzmann constant 1 38x10 23 W Hz k En is the noise figure of the radar receiver see 3 3 2 24 Bn is the noise bandwidth of the radar receiver see 3 3 2 23 Tref is the reference noise temperature which is set to 290K 6 7 Probability of Detection The calculation of the probability of detection from the SIR are based on e the Meyer and Mayer 8 formula for video integration e Shnidman 9 formula for binary integration for all relevant Swerling cases 7 Planned Enhancements The following enhancements have been planned for future versions of this radar model e Representing the radar target as a cluster of distributed scatterers in addition to the current representation of the target as a single point scatterer e Assessing the impact on detection performance of radar propagation in an evapora tion duct e Calculatio
22. in has been set 3 3 2 11 ElevationBeamwidth ElevationBeamwidth is the average of the transmit and receive antenna 3 dB one way beamwidth in elevation ElevationBeamwidth may be entered in degrees or radians 3 3 2 12 MaximumDisplayRange MaximumDisplayRange is the maximum display range for the radar s operating mode and may be specified in metres kilometres nautical miles or feet MaximumDisplayRange is used only when the height of the platform is not specified see 3 4 2 2 and may be set to NaN at other times 3 3 2 13 NonCoherentIntegration NonCoherentIntegration is the method for the non coherent integration of the pulses The two options are video or binary If video integration is used the parameters BinaryM see 3 3 2 5 and BinaryN see 3 3 2 6 should be set to NaN binary integration requires at least BinaryM pulses out of BinaryN avail able pulses to equal or exceed the single pulse threshold to declare a detection 3 3 2 14 NoPulseBursts Within an observation dwell the radar transmits and re ceives a waveform consisting of Nawe pulses The dwell is constructed as N pulse bursts with each burst consisting of Neon pulses Hence the number of pulses per dwell is given by Nawei N x Neon as shown in Figure 1 This division of the dwell allows the radar DSTO GD 0554 system to provide a combination of coherent and non coherent pulse integration process ing The Neon pulses within each burst are coherently
23. ion The modelling outcomes from Claudia are presented to the user via one of the following outputs detection probability of a target at a specified range detection range of a target for a given probability of detection a plot of probability of detection against detection range a plot of the minimum required RCS versus range so that a user defined detection probability is reached a plot of detection range against a predefined set of RCS values a plot of detection probability against RCS at a user defined range DSTO GD 0554 3 Input Files 3 1 Introduction This section describes the format and parameters of the six components that drive the radar model Each component is defined in a separate input file using the XML syntax for the reasons outlined in Section 5 The components are named Radar Platform Target Environment Scenario and Configuration 3 1 1 XML Syntax A brief outline of the EXtensible Markup Language XML syntax is provided below More information on the XML syntax is available from computing texts or online tutorials such as W3Schools 5 XML is a method of expressing data in a hierarchical tree structure The top of the tree is the root element under which child elements are placed All elements can have subelements child elements This structure is demonstrated below lt root gt lt child1 gt lt subchild gt lt subchild gt lt child1 gt
24. ithin the file is not important Parameter names are case sensitive however inputs for value and units are not Parameters that are dimensionless may either exclude the units attribute or set the unit to NA The exception to this is parameters that are commonly expressed in decibels in which case the units are set to dB or absolute Parameters that require character or string inputs should include single quotes e g value binary It is possible to enter a valid MATLAB expression as the value of a parameter e g value sin 3 pi 2 All parameters for the component must be included in the input file however the value attribute may be set as NaN MATLAB s IEEE representation of not a number in the following two cases e the parameter is optional in which case a default value will be used e the parameter is not required for calculations the parameter is reserved for a future version of the software and not used in the current version the parameter is a member of a subset of parameters exactly one of which is required the parameter is not required for the processing options selected 3 3 The Radar File The radar file includes the parameter names and values for describing the radar s trans mitter receiver antenna and signal processing components A typical listing is provided in Section 3 3 1 The structure of the radar file may be divided into modes to describe rada
25. l be negative This parameter is used in the calculation of the antenna s voltage gain 3 3 2 3 AzimuthBeamwidth AzimuthBeamwidth is the average of the transmit and receive antenna one way 3 dB beamwidth in azimuth The value may be entered in degrees or radians 3 3 2 4 BeamShapeLoss BeamShapeLoss is the loss resulting from the non uniform gain within the 3dB beamwidth of the antenna as it scans past the target If BeamShapeLoss is set to NaN it is calculated from the number of pulses integrated within the 3dB beamwidth of the antenna Otherwise it can be input as a user defined value in dB 3 3 2 5 BinaryM BinaryM is the number of pulses that must equal or exceed the single pulse threshold to declare a detection using binary integration BinaryM should be set to an integer value between 1 and BinaryN see 3 3 2 6 inclusive when NonCoher entIntegration see 3 3 2 13 is set to binary BinaryM is dimensionless 3 3 2 6 BinaryN This is the total number of available pulses in the binary integration process When NonCoherentIntegration see 3 3 2 13 is set to binary BinaryN should be set to an integer value greater or equal to BinaryM see 3 3 2 5 Otherwise it should be set to NaN BinaryN is dimensionless 3 3 2 7 CIFSurface ClIFSurface is the clutter improvement factor for surface clutter due to MTI and or doppler processing If neither MTI nor doppler processing is used for surface clutter suppression CIFSurface should be s
26. l working folder as required using a text editor so that the values in these xml files describe the radar platform target environment scenario and configuration the user wants to model 2 Start MATLAB and set the current working directory to the location of the xml files this avoids the need to enter the full path of the files at the next step 3 Execute the desired Claudia run function within MATLAB The run functions for Claudia have a common input argument format As an example we consider the function find_detection_range m We run this function by entering the following command at the MATLAB command line detectionRange find_detection_range rdr_example A tgt_example env_example plt_example scn_example cfg_example 0 5 16 DSTO GD 0554 The arguments are 1 The filename of the radar component without the xml extension e g rdr_example 2 The name of the radar mode to use e g A If modes are not specified in the radar component this input should be an empty string 3 The filename of the target component 4 The filename of the environment component 5 The platform component s filename 6 The filename of the scenario component 7 The configuration component s filename 8 Any additional run function dependent arguments In this example the required probability of detection 0 5 The input file names such as rdr_example will h
27. n of improvement factors for the suppression of surface and volume clutter DSTO GD 0554 References M M Horst F B Dyer and M Tuley Radar sea clutter model International Conference on Antennas and Propagation IEE Part II pp 6 10 London UK 1978 ITU Specific attenuation model for rain for use in prediction methods Recommenda tion ITU R P 838 1 F E Nathanson Radar Design Principles Signal Processing and the Environment 2nd Edition SciTech Publishing 1999 ITU Reference standard atmospheres Recommendation ITU R P 853 3 http www w3schools com xml XML tutorial ITU Attenuation of atmospheric gases Recommendation ITU R P 676 5 pp 1 7 L V Blake Radar Range Performance Analysis Artech House 1986 D P Meyer and H A Mayer Radar Target Detection Academic Press Inc 1973 D Shnidman Binary integration for swerling target fluctuations IEEE Trans Aero Elec Sys Vol 34 pp 1043 1053 1998 29 DSTO GD 0554 30 DSTO GD 0554 Appendix A Parameter Summary The following tables provide a summary of the parameter inputs for the six input files Each table shows the parameter name and valid units as entered in the xml files and the symbol used for the parameter within this document numeric inputs only Parameter Valid units Symbol AntennaLookDirection deg rad Olook AntennaTilt deg rad Plook AzimuthBeamwidth deg 03 BeamShapeLoss dB Lbs BinaryM NA My Binar
28. n the operating mode of the radar 3 3 2 26 TotalSignalProcessingLosses TotalSignalProcessingLosses represents the total sum of losses contributed by signal processes such as range straddling pulse com pression CFAR collapsing filter mismatching The user evaluates or estimates the total sum of these contributions and enters this sum as the parameter value in dB 3 3 2 27 TxAntennaGain TxAntennaGain is the gain of the transmit antenna spec ified in dB 3 3 2 28 TxFrequency TxFrequency is the transmitter frequency specified in hertz It can represent the mean operating frequency of the transmitter 3 3 2 29 TxLineLoss TxLineLoss is the RF loss between the final power amplifier stage and the antenna measured in dB 3 3 2 30 TxPeakPower TxPeakPower is the peak transmitter power specified in watts or kilowatts DSTO GD 0554 10 3 4 The Platform File The platform file includes the parameters that describe the radar platform s dynamics A typical listing for the platform file is provided below The suggested convention for the filename is plt_name xml where name is anything descriptive e g plt_lowaltitude xml 3 4 1 Sample Platform File Listing lt Platform gt lt Heading value NaN units deg gt lt Height value 30 units m gt lt Speed value NaN units m s gt lt Platform gt 3 4 2 Description of Parameters Parameters for the platform component are listed below in alphabetical order 3 4 2 1 Heading
29. ows or UNIX environments Disk space requirements are minimal i e less than 5 MB Claudia requires a small number of functions from the MATLAB statistics toolbox 15 DSTO GD 0554 4 2 Installing the Software Claudia is distributed as a single zip file A separate install script is available that will guide the user through the install process To use the install function change the MATLAB current directory to the folder where these files are located then execute claudia install m The user will be prompted during the install process for preferred locations of files and folders To manually install Claudia follow the following steps 1 Extract the claudia zip file into a suitable directory eg matlab toolbox A Claudia subfolder will be created automatically 2 Using the MATLAB pathtool add the following folders to the MATLAB path claudia claudia runmodules claudia system claudia gui claudia progress 3 At the MATLAB command prompt enter docroot to find the location of document directory This will usually be matlab help Create a new folder called Claudia under the document directory Move the contents of the folder claudia help to this new folder This will ensure commands such as doc claudia function correctly 4 3 Running Claudia Claudia is run directly from the MATLAB command line To run Claudia perform the following in sequence 1 Edit the sample xml files in a loca
30. r parameters that pertain to the radar s various operating modes This is achieved using a Mode element having a value attribute corresponding to the mode s name When using modes parameters that are common to all modes are entered directly below the Radar tag and those for the specific mode are entered as child elements of the mode This structure is demonstrated in the sample file listing The radar file is named by convention rdr_radarname xml where radarname is the name of the radar being described e g rdr_aps115 xml but this convention is not en forced DSTO GD 0554 3 3 1 Sample Radar File Listing lt Radar gt lt TxPeakPower value 143000 units W gt lt TxFrequency value 9 05e9 units Hz gt lt TxLineLoss value 3 0 units dB gt lt AntennaTilt value 0 5 units deg gt lt RadomeLoss value 1 units dB gt lt TxAntennaGain value 30 units dB gt lt RxAntennaGain value 30 units dB gt lt AzimuthBeamwidth value 2 5 units deg gt lt ElevationBeamwidth value 9 9 units deg gt lt Polarisation value H gt lt RxNoiseFigure value 9 5 units dB gt lt RxLineLoss value 3 0 units dB gt lt NonCoherentIntegration value binary gt lt BinaryN value 7 gt lt BinaryM value 3 gt lt AntennaLookDirection value 30 units deg gt lt PulseCompressionRatio value 1 0 gt lt CoherentIntegrationGain value 0 units dB gt lt To
31. requency range 1 100 GHz Radar propagation may be set as either free space i e direct path only or multi path i e direct and reflected path Both the free and multi path propagation models use a modified earth radius effective earth radius factor of 4 3 to account for the refraction of the radar signals by the troposphere The maximum range of the target cannot exceed the maximum range of the interference region Beyond the interference region it is assumed that multi path propagation is not valid The Gaussian function is used to define the main lobe pattern of the radar antenna The impact of rain attenuation and reflectivity on detection performance is calcu lated Rain attenuation calculations use the ITU recommendation 2 This algo rithm is limited to horizontal and vertical polarisations and transmitter frequencies in the range 1 400 GHz Rain reflectivity is computed for transmitter frequencies in the range 3 140 GHz and rain rates up to 16 mm hr using tables from Nathanson 3 Water vapour density absolute temperature and dry air pressure profiles are calcu lated using the ITU recommendation 4 as a function of height operating latitude and the season of the year These values are used to calculate the clear weather atmospheric attenuation A uniform sea surface having the same sea state and wave direction at all locations is assumed The region of rain is represented as a rectangular cell of finite dimens
32. t lt PropagationType value Free gt lt PFA value 1e 6 gt lt Configuration gt 3 8 2 Description of Parameters 3 8 2 1 PFA PFA is the output probability of false alarm after non coherent integra tion PFA is used with e NoPulseBursts to calculate the detection threshold when NonCoherentIntegration see 3 3 2 13 is set to video e BinaryM and BinaryN to calculate the single pulse detection threshold when Non CoherentIntegration is set to binary 3 8 2 2 PropagationType PropagationType is specified as Free for free space i e direct path only radar propagation or Multi for multi path i e direct and reflected path radar propagation When Free is selected the influence of reflection and scattering off the sea surface and divergence factor due to a spherical reflecting surface are not taken into account in the calculation of the pattern propagation factor The multi path propagation model uses scattering due to sea surface roughness and dispersion caused by the sea surface curvature to evaluate the pattern propagation factor due to the interference of the direct signals and signals reflected by the sea surface The multi path radar propagation model is valid in the zone known as the interference region 4 Running Claudia 4 1 System Requirements To run Claudia MATLAB 7 0 or above must be installed on the user s computer The software can be run with MATLAB installed in the Wind
33. t file is provided below 3 5 1 Sample Target File Listing lt Target gt lt FluctuationModel value 1 gt lt RCS value 3 0 units m2 gt lt Length value NaN units m gt lt Height value 1 5 units m gt lt Speed value NaN units m s gt lt Heading value NaN units deg gt lt Target gt 3 5 2 Description of Parameters Paremeters are listed in alphabetical order 3 5 2 1 FluctuationModel FluctuationModel is the target fluctuation model and as sumes a value of 0 1 2 3 or 4 that corresponds to non fluctuating Marcum and Swerling case 1 2 3 or 4 respectively The characteristics of the four Swerling cases are summarised in Table 1 The Rayleigh distribution is used to represent targets composed of many inde pendent scatters the Chi square with four degrees of freedom is used for targets of one large scatter plus many small independent scatters Density function Fluctuation rate slow rapid Rayleigh 1 2 Chi square 3 4 Table 1 Summary of Swerling targets 3 5 2 2 Length Length is the target length in metres Length is not used in this version of the model and as such is set to NaN 11 DSTO GD 0554 12 3 5 2 3 Heading Heading is the target heading relative to true north It is specified in degrees and can assume any floating point value from 0 to 360 inclusive Heading is not used in this version of the model and is therefore set to NaN 3 5 2 4 Height
34. talSignalProcessingLosses value 1 0 units dB gt lt NoPulseBursts value NaN gt lt NoPulsesPerBurst value NaN gt lt CoherentIntegrationTime value NaN units s gt lt CIFSurface value 1 0 gt lt CIFVolume value 1 0 gt lt BeamShapeLoss value NaN units dB gt lt Mode value A gt lt PRF value 1600 units Hz gt lt ScanRate value 12 units rpm gt lt PulseWidth value 0 5e 6 units s gt lt MaximumDisplayRange value 64 1852 units m gt lt RxNoiseBandwidth value 2 0e6 units Hz gt lt Mode gt lt Mode value B gt lt PRF value 400 units Hz gt lt ScanRate value 6 units rpm gt lt PulseWidth value 2 5e 6 units s gt lt MaximumDisplayRange value 128 1852 units m gt lt RxNoiseBandwidth value 0 4e6 units Hz gt lt Mode gt lt Radar gt DSTO GD 0554 3 3 2 Description of Parameters There are thirty parameters for the radar file these are listed in alphabetical order below 3 3 2 1 AntennaLookDirection AntennaLookDirection is the azimuth look direc tion of the radar antenna and is specified in degrees or radians clockwise from true north The target is also assumed to be on this bearing 3 3 2 2 AntennaTilt This is the elevation angle of the radar antenna bore sight axis with respect to the horizontal AntennaTilt is specified in degrees below the horizontal i e if the bore sight axis is tilted above the horizontal AntennaTilt wil
35. tion will produce a plot of the detection probability for a target at a user designated ground range against target RCS values between 0 1 and 100 m The x axis RCS is presented in a log scale as shown in Figure 4 The user entered ground range may be a vector in which case multiple plots on the same axes are produced Values for the ground range must be within the propagation interference region 1 T Range 20000 Range 7000 0 8F 4 3 S 0 67 4 o a 2 o 0 4F 7 oO D Q 0 2 F 4 1 L 107 10 10 10 Res m Figure 4 Example output for run function plot_pd_rcs DSTO GD 0554 4 4 5 plot_range_rcs This function will produce a plot for a user defined detection probability of the max imum detection range against target RCS RCS values are between 0 1 and 100 m The input required detection probability may be a vector An example plot is shown in Figure 5 14000 Pdii0 5 12000 Pd 0 9 10000 F 3 8000 F g 6000 F 7 Detection range m 4000 F J 2000 F 4 0 L L L L i 10 5 0 5 10 15 20 Res dB m Figure 5 Example output for run function plot_range_rcs 4 4 6 plot_required_rcs This function will produce a plot of the minimum RCS required to reach the user defined detection probability for a target at ground ranges within the propagation inter ference region An example plot is shown in Figure 6 The target RC
36. tition frequency of the transmitter in hertz The PREF is used to determine the maximum unambiguous range of the radar and may be used to determine the number of pulse bursts see 3 3 2 14 3 3 2 18 PulseCompressionRatio PulseCompressionRatio is the ratio of the trans mitted pulse width see 3 3 2 19 to the compressed pulse width This value may be used in the calculation of the receiver noise bandwidth see 3 3 2 23 PulseCompressionRatio is dimensionless DSTO GD 0554 3 3 2 19 PulseWidth PulseWidth is the width of the transmitted uncompressed pulses in seconds 3 3 2 20 RadomeLoss RadomeLoss is the 1 way radome loss specified in dB 3 3 2 21 RxAntennaGain RxAntennaGain is the gain of the receive antenna speci fied in dB 3 3 2 22 RxLineLoss RxLineLoss is the RF loss between the antenna and input of the radar receiver specified in dB 3 3 2 23 RxNoiseBandwidth RxNoiseBandwidth is the noise bandwidth of the radar receiver and is specified in hertz This parameter may be set to NaN in which case the noise bandwidth is calculated as the reciprocal of the compressed pulse width see 3 3 2 18 3 3 2 24 RxNoiseFigure RxNoiseFigure is the noise figure of the radar receiver spec ified in dB RxNoiseFigure and RxNoiseBandwidth see 3 3 2 23 are used in the model to calculate the noise power of the receiver 3 3 2 25 ScanRate ScanRate is the scan rate of the antenna specified in rotations per minute rpm ScanRate can be dependent o
37. ts References Appendix A Parameter Summary 21 21 21 22 26 26 26 27 27 28 28 28 28 29 31 DSTO GD 0554 1 Introduction EWRD s Microwave Radar MR Branch has undertaken to establish a flexible frame work for radar modelling to maximise code re usability Claudia is based on a software model previously generated within MR Branch and is focussed on the parametric mod elling of ship borne surface search and airborne maritime radars The framework also provides the ability to develop a complete system from individual user developed compo nents to conduct performance evaluation of maritime radar systems Claudia computes the detection performance of a maritime radar within its operat ing environment against designated targets It is written in the MATLAB programming language and is comprised of a number of software modules and data structures each representing different components of the modelled scene and detection process All soft ware modules are designed to be easily interchangeable when more precise or higher level components are developed The model inputs are divided into six components Each component is defined by a number of user defined parameters which are readily modifiable The components are e the radar e radar platform dynamics e a target e the operating environment e scenario e configuration The software has six pre defined methods of presenting results from detection perfor mance
38. yN NA No CIFSurface dB Loc CIF Volume dB y CoherentIntegrationGain dB Goh CoherentIntegrationTime s Toh ElevationBeamwidth deg rad 3 Maximum DisplayRange m km n mile Rmax NonCoherentIntegration NA NoPulseBursts NA N NoPulsesPerBurst NA Neoh Polarisation NA PRE Hz PRF PulseCompressionRatio dB absolute PCR PulseWidth S T RadomeLoss dB Lrad RxAntennaGain dB Gr RxLineLoss dB LR RxNoiseBandwidth Hz B RxNoiseFigure dB En ScanRate rpm Q TotalSignalProcessingLoss dB Lsp TxAntennaGain dB Gr TxFrequency Hz f TxLineLoss dB Lr TxPeakPower W kW Pr Table A1 Parameters for Radar 31 DSTO GD 0554 Parameter Valid units Symbol Heading deg Height m hp Speed m s Table A2 Parameters for Platform Parameter Valid units Symbol FluctuationModel NA Heading deg Height m het Length m RCS m2 o Speed m s Table A3 Parameters for Target Parameter Valid units Symbol CloudHeight m hr RainRate mm hr ie SeaState NA Ss Sea Water Tempreature C To RainStartRange m Tmin RainStopRange m Emar WaveDirection deg Y Table A4 Parameters for Environment Parameter Valid units Symbol Latitude NA Season NA Table A5 Parameters for Scenario Parameter Valid units Symbol PFA NA Pfa PropagationType NA Table A6 Parameters for Configuration 32 Page classification UNCLASSIFIED DEFENCE SCIENCE AND TECHNOLOGY ORGANISATION 1 C
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