Web Base Satellite Tracking System
Contents
1. Software Lifecycle Processes with additional focus on quality assurance activities according to the IEEE Std 730 Software Quality Assurance Plans 2 The software design architecture applies the David Parnas principle of separation of concerns which divides software functions based on the I O responsibilities regarding telescope control web camera control database interface and user interface among others 3 The implementation method uses object oriented technologies including the latest available version of Java and design patterns of which one was created in this project Virtual Singleton Pattern 4 The testing process relies on following IEEE Standards 8 and focuses on performance measurements with respect to computational accuracy and server s robustness 5 Tools developed during this project which include a new communication protocol a new design pattern perl package for dumping SQL database contents and Java package for command and communication with external devices using serial port are made available for the public and may serve general population of designers The beta version has been released It can be accessed from satnet fgcu edu and by making prior email arrangement with team members Full testing is still being pursued and was conducted successfully during the FGCU Research Day Student Poster Competition where the Team won first price www fgcu edu orsp Further work is needed to fix minor bug2. data the SLAM to communicate with the telescope and the NTP Client to access precise time information time keeping for calculating satellite positions is handled by the NTP Client synchronized with an NTP server and providing time to the Telescope Controller network connectivity other than Internet is provided by an External Interface for future expansion webcam broadcast is provided by a public domain version of the QuickTime software 2 2 1 User Interface Design The basic appearance of satnet fgcu edu website is shown in Figure 3 From there the use can register and log on to satellite tracking functions which is illustrated in Figures 4 and 5 respectively Iel htp satnet fgcu edu Java Client What is SAT NET Tracking ISS ZARY The objective of the SAT NET Satellite g ie Acquisition amp Tracking with Network Azimuth 75 36 Enabled Telescope project is to develop x A o N software providing Internet connectivity Elevation 50 10 pas to a telescope allowing satellite tracking Range 10249 90 SAT NET can be used by organizations to X enhance safety of their air space and Latitude 6 89 N track intruding vehicles It will also allow Longitude 26 13 E users around the world to view track and learn about satellites from a Java enabled Altitude 358 83 km web browser Connected by the Internet Internet the system allows for expandability so Velocity 7 69 kps that ma
3. project which allowed for various optimizations They are listed in Table 3 along with the criteria taken into account Table 3 Design Decisions and Optimization Design Decision Criterion Disadvantage Use open source software Portability Java sacrifies speed and ease of Linux Java MySQL UML access to hardware Linux tends to cause difficulty in configuring UML notation and tools are an overkill for simpler system Follow the principle of Modularity May cause undesired over separation of concerns simplification for bigger systems Apply quality assurance at each development stage Various SRS clarity completeness correctness consistency traceability testability Design cohesion coupling Code readability structuredness Extremely time consuming but very productive New Text based Internet Protocol Ease of implementation Yet another protocol New Virtual Singleton Design Pattern for Main Module Implementation Simplicity Less robust than regular Singleton Pattern when reused full implementation would require a friend feature Use of UDC Time Accuracy and simplicity Leads to confusion within the project Manually manage version control as opposed to CVS Simplifies development Causes confusion especially during module integration and testing 2 2 4 Tools Developed There were four new tools developed in this project
4. to have several maintenance tasks such as downloading and parsing TLE files maintain the database and so forth Also reading and parsing the configuration file is the responsibility of BOSS The MADAM is the heart of the satellite tracking This is where all the calculations are done and the data is then forwarded to the user via the RUIN and WRACK Data is also sent to SLAM to move the telescope to point at the satellite It is composed of three threads e TelescopeController Thread As the name implies this thread is responsible for sending freshly calculated azimuth and elevation for the satellite currently being tracked The thread uses a simplified set of calculations since only azimuth and elevation is needed SLAMs receiveCoords method is then called with azimuth and elevation As soon as receiveCoords returns after the telescope is done moving the calculations are repeated This goes on continuously RUITelemetry Thread This thread is responsible for supplying the user with accurate telemetry data That means that it is a continuous thread that calculates a full set of data azimuth elevation range longitude latitude altitude velocity orbit number visibility score SLAM error number calculation model SDP4 SGP4 SDP8 and SGP8 future options footprintl Visibility status visible in sunlight eclipsed sun azimuth and sun elevation will most likely be added to the telemetry object sometime in the future The RUITeleme
5. 2 2 5 1 Testing of MADAM Computational Accuracy An extensive test was conducted on MADAM consisted of collecting a number of predictions from SAT NET and comparing it to the baseline program PREDICT 2 The latest available TLE file from http www qsl net kd2bd predict tle was used for both programs The predictions were set to start at UNIX time 1082426819 Tue Apr 20 02 06 59 UTC 2004 and calculate for every 5 minutes for 24 hours The results were written to text files for later analysis This analysis proved to be very good news as the only differences seem to be caused by slight differences in rounding The largest difference we saw was for the range In some cases this was off by 0 01 km 10 m and as mentioned is most likely caused by rounding Either way when the range is in excess of 40 000 km 10 meters is not bad Due to the amount of data collected we only present here graphs for azimuth and latitude which show typical behavioral patterns 2 OSCAR 10 Azimuth plot 400 00 350 00 300 00 250 00 SATNET PREDICT ees 200 00 Deg 150 00 100 00 50 00 0 10000 20000 30000 40000 50000 60000 70000 80000 90000 100000 Seconds since start time UNIX Time 1082426819 Figure 11 Azimuth Test for SATNET compared to PREDICT OSCAR 10 Latitude plot 30 00 20 00 10 00 SATNET 0 00 PREDICT Degrees 10 00 20 00 30 00 S
6. AK does not implement its own user interface instead using the WRAKControl class for that purpose As special method is written as dictated by the ActionListener interface to which all buttons in the various user interface components ultimately report It is implemented as a large switch statement with a separate case for each supported event Corresponding events are split into internal generated by user interaction with user interface elements created by one of the WRAK classes and external generated by the WRAKComm module in response to messages from the server events In this report only external events are presented see Table 2 2 2 2 2 RUIN Remote User Interaction Negotiator Design RUIN is the server element of the SAT NET software It is tasked with accepting connections from clients authenticating clients and responding to commands and requests from clients The design of RUIN is intended to be maximally scalable care was taken to minimize per client resource allocations Most notably RUIN makes use of the Java s newest I O facilities the NIO package to ensure that the number of threads is constant regardless of client load efficient use of Java s previous I O facilities often required one thread for each connection RUIN contains three threads of execution The first the acceptor thread is tasked with listening for incoming socket connections When a connection occurs the acceptor thread instantiates a Connection o
7. OOM and time NTPC getCurrentTracked updatePredictions Vvalidate doom ntpe NTPC slam ruin madam getJulian SatelliteElements getGregorian MADAM E E commonCalculations fullCalculations predictVisiblePasses SLAM ore eel recelveCoords getErrorNum PortOperations Figure 7 SAT NET Class Diagram Detailed designs of respective classes are discussed in the following subsections only partially due to space limitations 2 2 2 1 Java Applet Design A Java applet named WRAK is the core of the SAT NET remote interface It is responsible for coordinating the various user interface elements and communicating with the RUIN Remote User Interaction Negotiator module residing in the SAT NET server WRAK is entirely event driven receiving both local events generated by the various user interface elements and remote events originating with the server It communicates with the server by sending similar events messages to the RUIN State is enforced through the dynamic display hiding and enabling disabling of user interface elements The bulk of WRAK s functionality is controlled by the Java event model the main WRAK class is an implementation of the ActionListener interface and is registered to listen to pertinent UI elements WRAK also receives events from WRAKComm the networking module Once instantiated WRAKComm launches a new thread to receive information from
8. SAT NET Satellite Acquisition amp Tracking with Network Enabled Telescope Florida Gulf Cost University Fort Myers Florida USA http satnet fgcu edu Florida Gulf Coast University Team Members Dustin Felton dgfelton eagle fgcu edu Sean Kerwin spkerwin eagle fgcu edu Anders Petersen ahpeters eagle fgcu edu Ray Rhode rarhode eagle fgcu edu Project Mentor Janusz Zalewski Ph D zalewski fgcu edu Mentor Assistant Andrew White aswhite eagle fgcu edu Abstract As the population of the world grows and tends much more to travel we are becoming increasingly dependent on communication navigational aide and weather forecasting As such protection of the infrastructure of these ends becomes irrevocably more important as well The SAT NET system is a means to help in making such protection a reality SAT NET allows for distributed monitoring of communication satellites and other orbiting bodies thus giving anyone with a computer and Internet connection the ability to monitor these increasingly important resources This report documents our experiences in implementing this vision It quantifies efforts of the Project Team in creating SAT NET with respect to requirements specification design implementation and testing and summarizes the project status for today 1 The design methodology applied draws significantly from the IEEE Std 1074 1997 Developing Software Life Cycle Processes and its counterpart ISO IEC Publication 12207
9. abase which are illustrated in Figure 9 Specifics of each field are omitted due to report space limitations Email A ffilia tio n BannedUntil City Country DOB FirstName Is Superuser LastName Latitude Longitude NumTries Occupation Reason ZipCode Sate fite ID is V erified i passw ord registeredDate verificationKey predictions Satellite ID AOS LOS OrbitNumber se eeeeee UserID Start end ID BSTAR Eccentric ity Epoch Inclination IsBeingTracked Is Permanent Is V is ible MeanAnomaly MeanMotion MeanMotionFirstDerivative MeanMotionSecondDerivative Name Perigee RAAN RevolutionNumber Figure 9 Entity Relationship Diagram for DOOM 2 2 2 5 SLAM Design The SLAM module provides serial communications with the telescope to and from the server This is the module which allows the server and indirectly the user to control and operate the telescope SLAM uses the standard DB9 pin serial 232 port on the computer to link with the telescope and issues the commands in A Synchronous mode The module accepts input from the Telescope Control module MADAM These inputs are the current azimuth and elevation and the predicted azimuth and elevation after 5 seconds and the current Right Ascension and Declination of the satellite The module is composed of two classes Slam and PortOperations A brief description of module s functionality provided below public void recieveCoords doub
10. bject a nested class within RUIN and adds it to a vector member containing all current connections Each connection object maintains a buffer of outgoing data which is written to that connection s socket as its write buffer frees space This writing is accomplished by the second thread the I O service thread The I O service thread is also charged with reading data from sockets as it becomes available parsing the data into RIP packets using the RIPUtils class and handling them appropriately The final thread maintains a packet representing a list of the currently visible celestial objects because this list is request by clients quite frequently it is more efficient for it to be done once in a separate thread of execution than to be done many times as clients enquire RUIN communicates only with the MADAM and DOOM modules The MADAM module periodically calls RUIN s sendTelemetry method which is used to inform clients of the currently tracked satellite s position and DOOM module is called by RUIN to validate user credentials determine visible objects and retrieve and store information about reservations 2 2 2 3 BOSS and MADAM As the name implies BOSS is the module in charge It creates and handles all the instances of all the other modules All communication between the other modules goes via BOSS to ensure that there only is one instance of a module thereby creating a virtual Singleton design pattern In addition BOSS is intended
11. e that is currently being tracked The SAT NET software shall allow all users to view the currently available schedule for the satellites being tracked The SAT NET software shall allow automatic booking of satellite tracking time for regular users within available time for the telescope 2 1 2 Non functional requirements 24 25 26 27 28 29 30 31 Safety The SAT NET software shall take precautions against rotating the telescope too far to cause damage to power cables running from the base of the telescope to the side motor Security The User Interface shall be required to verify to the server it is a valid instance of the interface before it is allowed to send or receive any information Security User information sent by the User Interface to the server shall be encrypted before being sent to prevent the interception of personal and login information and upon receipt by the server the information shall be decrypted for verification Security All passwords shall be at least six characters long and must contain at least one digit and one letter Security In case a user has failed to login to an account five successive times the SAT NET software shall have the account locked for one hour during which even if the correct password is entered the user cannot login Security Passwords sent to the server by the client during authentication shall be transmitted only in an enciphered form such that potential i
12. econds since start time UNIX Time 1082426819 Figure 12 Latitude Test for SATNET compared to PREDICT 2 2 5 2 Testing Robustness of the Server RUIN DOOM Combination The second performance test focused on testing the speed of response latency in case of increasing load due to access from multiple numbers of client Multiple calls to RUIN were executed through its RIP protocol emulating the actual SAT NET events The time in milliseconds was recorded it takes RUIN to call DOOM and DOOM to return the results back This procedure was repeated for increasing number of clients from 1 to 10 all making simultaneous requests Additionally artificial resource consumption on the server was added to test the effect of spurious activities The resulting graph is shown in Figure 13 Service latency for increasing number of users 3500 3000 2500 2000 1 user 1500 2 users 5 users 1000 10 users 500 0 500 Time ms Request Number Figure 13 Testing SATNET Robustness Service Latency vs Number of Users 3 Summary The project was completed successfully and the beta version has been released It can be accessed from satnet fgcu edu and by making prior email arrangement with team members Full testing is still being pursued and was conducted successfully during the FGCU Research Day Student Poster Competition where the Team won first price www fgcu edu orsp Further work is needed to fix
13. es to reserve control time for the SAT NET system they may do so by clicking the Reserve Control Time button on the control pane This will lead to the appearance of the reservation window Figure 6 The user may select a date and time by manipulating the popup buttons at the top of the window as these values are altered the time bar across the middle of the window will update correspondingly The blue section of the bar represents the time the user is currently attempting to reserve while red sections show times for which reservations already exist If the user were to alter the value of the Duration popup to two hours the blue box would overlap the rightmost red section The overlap would be colored in purple to indicate a conflict and the Request Reservation button would be disabled until the conflict was removed SKORS Reservation Reservation Date February A 20 ES 2004 A Friday Reservation Time 10 RA 00 x AM xs f US Eastern E 10 00 Duration 1 Hour Figure 6 Requesting a Reservation to Control the Telescope at a Future Date and Time 2 2 2 Class Design The overall structure of SAT NET software as derived from the System Architecture of Figure 2 is illustrated in a class diagram shown in Figure 6 It represents the relationships between a main class BOSS and other classes controlling respectively the telescope SLAM computations MADAM user interface RUIN database access D
14. glish Faculty 3 Post development a Report Preparation MS Word Final Report b Beta Release JDK 1 4 2 Code beta version c S W Modifications UML diagrams amp Code production JDK 1 4 2 version d User Training HTML Web documents 1 3 Technical Innovations 1 Remote operation of a telescope for satellite tracking via the Internet Satellite tracking is a rather standard operation in scientific community but thus far no system has enabled a telescope with Internet accessibility SAT NET is the first to make this integration Visual satellite tracking with a real time video feed Real time satellite tracking is available but on a text only basis SAT NET will allow visual tracking of a satellite in real time Potential to track a satellite through the entirety of its orbit SAT NET will allow for tracking of a satellite around the globe utilizing multiple SAT NET stations Exapandibility allowing SAT NET s inclusion as module of a larger system Modularity of the SAT NET software and its open network protocol permits its use by a system with full scale functions of greater importance such as air traffic control system or satellite ground control station 2 Implementation and Engineering Considerations The SAT NET has two functioning modes a User Mode and a View Mode The User Mode logs a user into the system allows them to schedule time when they can control the telescope and allows the user to take control of the telesc
15. le azimuth double elevation Whenever a new object of the Slam class is created it performs the following actions in the respective order The actions it takes determine if any action is needed and if so what action and then preforms that action Partial functions include the following e Saves the time at invocation in member variable startTime e Calls function ChangeState with no arguments changing variable state to end the current thread moving the telescope if there is one e Calls function GetTelecsopePosition with no arguments stores the values in TeleAz and TeleEl e Determines if the telescope is already moving and or not and if the module is active or not and moves the telescope if it is not moving is it is active e Calls function SendCommand with 1 argument which is the command for current telescope Azimuth ReceiveCoords db1 db1 db1 db1 db1 db1 Az E1 AZN EIN Ra Dec Is Telescope Done Moving calculateRate db1 db1 pos posn TelescopeDone db1 db1 azkate elRate CheckSafety db1 db1 azRate elRate getTelescopePos str SendCommandwaitforPound pecs eae telePos Is it Safe To Move the Telescope NO Update Telescope Position Figure 10 Details of SLAM Design basic flowchart and structure chart 2 2 3 Major Design Decisions and Optimizations There were several major design decisions taken during the course of this
16. ler Dennison T Linux Talon and Astronomy Linux J No 117 January 2004 4 Boshart B Satellite Tracker Atwood Ontario 2003 http www heavenscape com 5 SatTrack Real Time Orbit Simulation Program http www amsat org amsat 6 Fauerbach M PhD College of Arts and Sciences Florida Gulf Coast University Ft Myers Florida January 2004 7 Johnson R PhD Florida Space Institute UCF Orlando Fla February 2004 8 IEEE Software Engineering Standards Collection 2003 Edition CD ROM IEEE New York 2003 9 Meade Instruments Corporation Irvine Calif 2004 http www meade com 10 SAT NET Project Website Florida Gulf Coast University Ft Myers Florida 2004 http itech fgcu edu faculty zalewski COP493 1 COP493 1 projects html 11 Celestrak Center for Space Standards and Innovation Malvern Penn http www celestrak com NORAD documentation spacetrk pdf 12 Rusin D Mathematical Sciences Northern Illinois University DeKalb Illinois http www math niu edu rusin Appendix Definitions amp Acronyms Authentication the process whereby a client is verified to represent a registered user and thus upgraded to a logged in client Client the remote software used to interface with the SAT NET server via the internet Note This is not necessarily the official SAT NET Client software SAT NET is designed to support alternate clients so long as they support the protocol Coordinates latit
17. minor bugs and coordinate operation of the webcam with telescope control software We consider the outcome of this project to be important in three aspects technical societal and personal for team members Technical The primary goal of this project was the production of a functioning implementation of the SAT NET system Specifically we intended to produce a web site at which users may remotely control FGCU s telescope and observe the results Our intention is to leave this system in place allowing for global access to this important educational resource Societal Secondly we aimed to open source the SAT NET software so that it is can be easily downloaded and operated by any organization with the appropriate hardware SAT NET s wide adoption would represent a significantly broader realization of its potential societal benefits especially in improving safety of the air space and in education of the younger generation Personal Thirdly we hope to win the competition and not only further educational and research possibilities but increase our own understanding of software development engineering teamwork and professional challenges While being technically innovative the SAT NET project will benefit society in several different ways In addition to its primary purpose which is enhancing safety of air space it will provide global access for non scientists to scientific experiments over the Internet as well as address the issue of technol
18. nterceptors would be unable to determine the deciphered form Note The enciphering process should be dependant upon a pseudo random seed generated by the server so as to prevent simple playback for a recorded authentication exchange Performance Accuracy of satellite position computations azimuth elevation latitude longitude and range shall be better than 0 01 Performance Responsiveness of SAT NET server shall not degrade more than 5 per each 10 clients requesting service simultaneously 2 2 Software Design Description Overall system architecture is presented in Figure 2 in a form of a context diagram It includes all external devices telescope web camera database server and Internet access to clients and time server NTP From the architectural standpoint two major components in the SAT NET software were distinguished the Satellite Tracker playing the role of a SAT NET Server which runs on a server machine and is responsible for telescope interaction and the Remote User Interface which runs as an applet within any browser and handles all human interaction These two main components are built out of separate modules each of which performs specific functions of the SAT NET software Webcam Broadcast Telescope Webcam Electronics Remote User Interface Satellite Tracker NTP Client accessing tme Services using NTP protocol Serial Line Access Module handle com munica
19. ny servers can be set up Footprint 4182 17 km permitting to view a satellite or other space object utilizing multiple site Orbit 30965 locations as it moves across air space or SAT NET Server makes an entire orbit around the Earth Modsi She As show in the picture the basic implementation of SAT NET is simple A user using a Java enabled web browser connects through the Internet onto the SAT NET server The server then relays commands to the telescope and tracks the satellite Simultaneously a web camera sends the real time image back to the user for viewing 2004 FGCU SAT NET Site Policy Contact Us Figure 3 Main Webpage for the Satellite Tracking Upon browsing to the main SAT NET interface page the user is presented with Figure 3 The left half of the page referred to as the control pane is the SAT NET Java client applet while the right half is the live video stream coming from the telescope The telemetry data on the upper half of the control pane will be continually updated to reflect the current focus of the telescope Upon clicking the Log In button the user will be presented with the Log In dialog box If the credentials entered are valid the Log In dialog box will close and the control pane will update The status message in the upper right hand corner will change from Not Logged In to Logged In If the user is logged in with special credentials e g as an adminis
20. ode and affiliation 6 The SAT NET software shall allow users to request their passwords to be emailed to the address they provide 7 The SAT NET Software shall allow clients to connect to the server and view telemetry relating to the satellite currently being tracked 8 The SAT NET software shall allow scheduled access for controlled tracking of the satellite based on logon procedures and after logon on prioritizing users and first come first served principle 9 The SAT NET Software shall allow connected clients to request authentication if the credentials sent correspond to a registered user who is not currently banned the request shall be granted and the client shall become a logged in client otherwise the authentication request shall be denied 10 The SAT NET Software shall grant control privileges to a single logged in client at a time allowing that client to select a new target for the software to track 11 The SAT NET Software shall allow logged in clients to view a list of currently visible satellites 12 The SAT NET Software shall allow logged in clients to request a reservation of time at a future date during which they will have control over the software which shall be granted if and only if the requested time period is of duration within specified tolerances does not conflict with any preexisting reservations and does not exceed a specified per user per day time 13 The SAT NET Software shall allow logged in clients
21. ogical underdevelopment in countries without the means to provide such educational and scientific tools to the population In particular the project will 1 Provide students at all levels Intermediate School High School College Students etc with access to experimentation using scientific equipment such as a telescope which will result in popularization of Science 2 Reduce the cost of science education by allowing expensive scientific equipment to be shared by schools rather than requiring each school to purchase the equipment or go without the resource 3 Allow for an exchange of knowledge and research which extends throughout the globe to countries of minimal industrial development and world industrial powers alike Project costs are divided into Development Cost which is incurred only during development and Implementation Cost which is related to every implementation They did not exceed the limit set by rules of this Competition Development Cost Satellite Tracking Software for Research 50 00 Null Modem Cable 15 00 Total Development Cost 65 00 Implementation Cost Serial Cable For Connection with Telescope 26 00 Web Camera for Telescope 150 00 Total Implementation Cost 176 00 Total Cost 241 00 4 References 1 Kidder T The Soul of a New Machine Little Brown Boston Mass 1981 2 Magliacone J A Tracking Satellites with PREDICT Linux J No 75 July 2000 3 Steid
22. ogy Design methodology follows the logic of IEEE Std 1074 1997 Developing Software Life Cycle Processes and its counterpart ISO IEC Publication 12207 Software Lifecycle Processes with additional focus on quality assurance activities according to the IEEE Std 730 Software Quality Assurance Plans all involving pre development development and post development activities conducted with object oriented technologies as presented in Table 1 Table 1 Processes and Activities in Design Methodology adopted from IEEE Std 1074 8 Processes and Activities Support Tool Deliverable Quality Assurance 1 Pre development a Mental Preparation Kidder s book 1 Internal discussion b Domain Knowledge Consulting Record in minutes Acquisition experts 2 7 c Team Organization Organizational Assignment of theory responsibilities d Feasibility Study IEEE Standards Preliminary design Collection 8 decisions 2 Development a Software UML Uses Case S W Requirements Walkthrough wrt clarity Requirements Diagrams Specification completeness correctness consistency traceability testability b Software Design UML Class and S W Design Design Review wrt Sequence Diag Description coupling amp cohesion c Coding JDK 1 4 2 Code Code Inspection d Testing Test Execution Test Plan and Test Test Review Report e Documentation MS Word User Manual En
23. ope The View Mode allows all viewers to watch a real time video stream of a web camera attached to the telescope The operation of the SAT NET software is defined in the Software Requirements Specification Section 2 1 below The Design Description is presented in Section 2 2 followed by the list of major design decisions and tools developed Sections 2 3 and 2 4 respectively Test results are presented in Section 2 5 2 1 Software Requirements Specification Software requirements have been derived with help of Use Case diagrams which are not shown here for the lack of space For better clarity the requirements are split into Functional Requirements and Non functional Requirements safety security and performance 2 1 1 Functional Requirements 1 The SAT NET software shall allow free access to satellite viewing for anyone on the Internet from a computer equipped with a Java enabled browser 2 The SAT NET software shall allow scheduled access from the Internet to telescope control with registration and verification for regular users 3 The SAT NET software shall allow registration based on valid email addresses and only for email addresses not previously used 4 The SAT NET software shall require the following data for user registration first name last name date of birth email address 5 The SAT NET software shall allow entering optional data such as occupation reason for registering latitude longitude country city zip c
24. s and coordinate operation of the webcam with telescope control software 1 System Overview 1 1 Technical Requirements The objective of the SAT NET Satellite Acquisition amp Tracking with Network Enabled Telescope project is to develop software providing Internet connectivity to a telescope allowing satellite tracking 9 SAT NET can be used by organizations to enhance safety of their air space and track intruding vehicles It also allows users around the world to view track and learn about satellites from a Java enabled web browser Connected by the Internet the system allows for expandability so that many servers can be set up to view a satellite or other space object utilizing multiple site locations as it moves across air space or makes an entire orbit around the Earth Satellite Telescop gt gt 3 SAT NET Server Figure 1 SAT NET Overview As shown in Figure 1 the basic implementation of SAT NET is simple A user using a Java enabled web browser connects through the Internet onto the SAT NET server The server then relays commands to the telescope and tracks the satellite Simultaneously a web camera sends the real time image back to the user for viewing Specific functional requirements are listed in Section 2 1 Performance requirements include accuracy of computations of satellite positions and server robustness to increasing load They are defined in Section 2 2 1 2 Design Methodol
25. the server Information received is parsed and if it represents a known event relayed to WRAK Table 2 Externally Generated Network WRAK Events Event Name Handling KREMOTE CONNECTED Enable log in button Set status display to Not Logged In KREMOTE FAILED Disable all buttons Display alert Construct retry thread and start KREMOTE DROPPED Disable all buttons Display alert KREMOTE LOGIN YES Change status display Enable request control button Enable reservation button Enable logout button Dispose WRAKLogin kKREMOTE LOGIN NO Call WRAKLogin credentials WereInvalid kREMOTE LOGOUT Enable log in button Disable request control button Disable reservation button Disable logout button Set status display to Not Logged In kREMOTE TELEMETRY Call WRAKControl updateTelemetry kREMOTE_CONTROL_YES Instantiate new WRAK Targeting kREMOTE CONTROL NO Display alert Enable request control button RIN ejeje n BW DN RJR In BR WN RIN ejN ejN Re kREMOTE VISIBLE Call WRAK VisibleDataModel updateList The main class of the WRAK applet WRAK is created automatically by the web browser and is tasked with responding to all remote and local events Unlike most subclasses of Applet or JApplet WR
26. tion with telescope RUIN DOOM External Interface Video Stream handles all user handles all databasq module CORBA Interaction interaction SQI Database Figure 2 System Architecture Context Diagram Telescope Controller calculate satellite positions Java applet The basic software architecture of SAT NET is based on the principle of separation of concerns Which divides software functions based on the following I O responsibilities user interface equipment control database access network connectivity precise time keeping webcam control and internal computations Accordingly these functions have been mapped on their respective modules as follows user interface is handled by a Java Applet executing within a browser passing login telescope scheduling and other information to the Remote User Interaction Negotiator RUIN module which has access to the database manager equipment control telescope is handled by Serial Line Access Module SLAM receiving commands from the computational module Telescope Controller database interface is handled by the Database Object Operations Manager DOOM module which take relevant data from the Java Applet and provide these data upon request to the computational module Telescope Controller computations are concentrated in the Telescope Controller which is responsible for calculating satellite positions and interacting with the Database module to receive and send
27. to view the time and duration of current reservations 14 15 16 17 18 19 20 21 22 23 The SAT NET Software shall allow logged in clients to request control at any time which shall be granted if either a the client has a reservation for the current time b no client currently has control or c the client currently in control does not have a reservation and has been in control for longer than a specified duration otherwise the client s request shall be denied The SAT NET software shall allow a superuser access to telescope control with preemption of other users The SAT NET software shall allow superuser assign rights to users administer user accounts and overwrite schedules The SAT NET Software shall allow logged in superuser clients to request control at any time which shall be granted if control is not currently granted to a superuser client otherwise the superuser client s request shall be denied The SAT NET software shall provide access to explanation of site policies on the front page of the Satellite Tracker website The SAT NET software shall provide guidelines explaining the principles of operation of the satellite tracker accessible from the Satellite Tracker website The User Interface shall allow a regular user to preselect a satellite with predefined Keplerian elements or enter their own Keplerian elements The SAT NET software shall allow all users to view the data from the satellit
28. trator or priority user that status would be reflected in this message as well AAA SAT NET lt gt e http satnet fgcu edu Account register php OO Go E QA Calendar MacCentral Apple eBay Newsy VG Dagbladet TPPy Lokalty VersionTracker Airpics Forums My Yahoo gt SAT NET J S a v SAT NE M About the Project Account Contact Us Download Java Client Account Register Required Info Tracking ISS ZARYA First name Azimuth 37 10 Last name Elevation 50 98 Email 7 1 Range 10370 53 Latitude 35 47 N Date of birth Day I Month ie Year P Longitude 2 30 E Altitude 358 46 km Velocity 7 70 kps Footprint 4180 10 km Country United States Orbit 30965 Zip Code Model SGP4 Optional Info City Longitude Latitude Affiliated with Occupation Reason for registering Register Reset form Figure 4 SAT NET User Registration Page ONO Satelite Tracker Ul Mockup e hy file Users skerwin Desktop SatUl build satui html Satellite Tracker Not Logged In Tracking Something Azimuth 337 074 deg Elevation 23 621 deg ponn sen 690 Log In Range Velocity Latitude Please enter your name and password Longitude User Name Altitude Password sstst S A Figure 5 Logging in to SAT NET to Access the Scheduling and Control Features If the user wish
29. try thread will call the outputTelemetry method in the RUIN at the end of the iteration e Prediction Thread The prediction thread will only run every 24 hours or so specific times can be entered in the configuration file It is recommend that this is scheduled for times when the server has a light load as it may require significant resources and time depending on the number of satellites in the database It will loop through all the satellite in the database and try to calculate when each of these satellites will be visible during the next 7 can be changed in the configuration file days When a visible pass required score can be set in the configuration file is found DOOMs updatePredictions method is called with SatelliteID OrbitNumber AOSTime and LOSTime as the parameters For all three threads there is a common set of calculations that calculate azimuth elevation and range The specifics of the calculations depend on whether or not the satellite is considered a deep space satellite A deep space satellite is defined as a satellite with a period time of one orbit of more than 225 minutes First the satellites position in a Earth Centered Inertial ECI coordinate system is calculated based on the data given in in TLE files These calculations are quite complex and are explained in detail in 11 Second the ECI position of the ground station where the telescope is located is calculated with special care taken to adj
30. ude longitude elevation from Horizon azimuth altitude and velocity Footprint the geographic region on the earth underneath a satellite which is in the appropriate range to receive that satellite s information Keplerian Elements a coordinate set derived from Kepler s equations for celestial bodies Logged In Client a client which has completed the authentication procedure verifying that the current operator of the client corresponds to a registered user NTP Network Time Protocol Priority User a user who is allowed to control the telescope and has assigned priority to do so Regular User a user who can control the telescope only if there are no priority users currently controlling it RUI Remote User Interface SAT NET Satellite Acquisition amp Tracking with Network Enabled Telescope SDP Simplified Deep Space Perturbations SGP Simplified General Perturbations Superuser a user in charge of administrative functions for the Software TLE two line element User superuser priority user regular user or viewer Valid Email An address of the form username domain ext which is capable of receiving and responding to emails Viewer a user who is allowed to receive images and data from Satellite Tracker but not allowed to control the telescope
31. ust as the Earth is not a perfect sphere 11 Third the difference between these to ECI coordinate sets is used to calculate azimuth elevation and range 11 This is needed to determine if the satellite could be visible MADAMs implementation is based on the one used by PREDICT but a description of the mathematics used to determine this can be found at 12 RUI Telemetry Thread Get Satinto trom space Yes No Calculate azimuth elevation and range using SDP4 Calculate azimuth elevation and range using SGP4 Calculate latitude longitude and altitude Send all calculated data to RUIN Prediction Thread Start prediction Get Satinto from database fta Find AOS Acquisition of signal tor pass Calculate telemetry and increment time reference for the calculation with x Depends on the elevation and altitude of the satellite for ISS approx 75 seconds Sum up visibility score Ts visibility score greater than oF equal to 227 Update Predictions table in database satellite ID orbit number AOS time LOS time No Find LOS Loss of signal for pass and go to next pass Last satellite Sleep for 24 hours Figure 8 Telemetry and Prediction Threads 2 2 2 4 DOOM Design DOOM which stands for Database Object Operations Manager is a passive class designed to respond to requests for database access It operates on a number of fields in an SQL dat
32. where a tool is understood as a vehicle assisting in performing a primary software function during development and operation They are listed in Table 4 and the details can be found on project website 10 Table 4 Description of Four Tools Developed in This Project Tool Name Function Virtual Singleton Design Pattern Extension of a Singleton pattern to make it thread safe and enable parameter passing Remote Interaction Protocol RIP Meta protocol an additional transport stream than can layer atop TCP to provide increased convenience in implementing basic networking functionality Database Backup Tool Perl script that connects to the MySQL database using the perl DBI interface to cycle through all the database and dump its contents Java Serial Link Tool Communicates with the serial port devices allowing issuing all commands it receives to the serial device as strings 2 2 5 Software Testing Testing for this project has been accomplished in the following phases preparation of test plans for each module addressing specific requirements functional testing of each module according to requirements 1 23 safety and security testing according to requirements 24 29 and performance testing according to requirements 30 31 For the lack of space in this report we are only including results of performance testing Results of other tests are made available from the project website 10
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