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Basic Scenario Testing

Basic Scenario Testing. Agenda. Introduction to SimGEN Overview of SimGEN Starting and stopping scenarios Modifying the scenario start time and duration Loading almanacs for updating the constellation Using quick-look to display, log and plot data Adjusting satellite signal power

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Basic Scenario Testing

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  1. Basic Scenario Testing

  2. Agenda • Introduction to SimGEN • Overview of SimGEN • Starting and stopping scenarios • Modifying the scenario start time and duration • Loading almanacs for updating the constellation • Using quick-look to display, log and plot data • Adjusting satellite signal power • Automating testing with User Action Files • Additional SimGEN Information

  3. Agenda • Introduction to SimGEN • Overview of SimGEN • Starting and stopping scenarios • Modifying the scenario start time and duration • Loading almanacs for updating the constellation • Using quick-look to display, log and plot data • Adjusting satellite signal power • Automating testing with User Action Files • Additional SimGEN Information

  4. SimGEN for Windows • SimGEN is a the primary interface software for Spirent’s broad range of Satellite Navigation Simulators • SimGEN also provides the control of the simulator hardware via a proprietary interface over the Ethernet for the GSS8000 simulators, IEEE for GSS7700 simulators and USB for GSS6560 simulators • Through the user interface or remotely, SimGEN enables the specification, development and execution of simulations • The simulations are saved as Scenarios, which are constructed of a set of source files for customizing and manipulating various settings in the simulation

  5. Starting SimGEN • SimGEN is preinstalled on all SimGEN PCs • Starting SimGEN can be performed by either: • Desktop Icon • Start Menu • Note: Also in the Start Menu under SimGEN are various applications and documents • Antenna Pattern editor • Documents (SimGEN, SimREMOTE, Hardware User Manuals) • Software release notes • TCP/IP String send utility • Firmware backup utility

  6. Starting SimGEN (cont.) • Starting SimGEN begins with the view to the right • This window allows the user to select the desired scenario to use for the simulation • By default, the scenario shown after starting SimGEN is the last successful scenario used • Should SimGEN be closed improperly, then the previous successfully closed scenario will be displayed

  7. SimGEN Main Window • The overview of the SimGEN Main Window and its features is shown below Menu Bar Toolbar Vehicle Dials Date and Time Power Levels Skyplot Scenario ContentsWindow Ground Track MessageWindow Status Bar

  8. Start Time • Define when the scenario starts • Specify the scenario duration to define when the scenario stops • Options • Define various input/output features for streaming truth data, barometric, RTCM and NMEA data • Automating testing with User Action Files • Advanced scenario and signal control with User Command Files • Specify Leap Second rollovers • Capture desired log, plot and display source files • Atmosphere • Define the troposphere and ionosphere models • Specify switching of models for various space applications • Vehicle Motion • Use SimGEN’s models or customer generated trajectories for defining the vehicle motion during the simulation Scenario Contents Window • The scenario contents window contains all of the scenario source files for defining the simulation

  9. GPS Constellation • Specify the desired satellites, frequencies, codes and navigation data • Designate orbital and clock errors • Assign different navigation data uploads • Use a different satellite transmission pattern • Advanced manipulation of satellite ephemeris, navigation data, and atmosphere delays • Vehicle Options • Clock G-sensitivity, INS models for inertial aiding, obscurations and multipath models • Aiding offsets file for defining a GPS receiver aiding sensor location, such as an inertial sensor • Vehicle Antenna • Specify the signal types received, such as L1 and L2, GLONASS, interference, etc. • Define the antenna lever arm to offset the antenna from the center of gravity • Apply antenna gain and phase patterns to the antenna and use antenna switching to switch between patterns and lever arms Scenario Contents Window (cont.) • The scenario contents window contains all of the scenario source files for defining the simulation

  10. Editing Scenario Source Files • The source files can be edited for modifying them for each scenario • Editing the source files use the standard Windows™ protocol • Double-click the file in the scenario contents window • Or press the EDIT button at the foot of the scenario contents window

  11. Saving Scenario Source Files • The user can save the edited source files to unique filenames • Changes to the source files are overwritten unless a new filename is specified • Unless “shared”, the files get saved in the current scenario folder • “Shared” files get saved in the Shared folder for use by more than one scenario • If a shared file is edited it will change the file for all of the other scenarios that access it as well

  12. Scenario File Hierarchy • Systems are normally shipped with the example scenarios under the default location: • C:\Program Files\Spirent Communications\SimGEN\Scenarios • Each scenario is stored in its own folder (taking the same name as the scenario) under a common parent folder • Scenarios under a common parent folder may share common files from a folder named “shared” • The organization of the shared folder and scenarios is described below Shared Folder for shared files User Generated Scenarios Pre-installed scenarios

  13. Selecting Scenario Source Files • The user also has the option of selecting existing source files for use in the current scenario • The top shows the files in the current scenario folder • The middle shows the files in other scenario folders adjacent to the current scenario folder • The bottom shows the shared files in the “shared” folder • Steps for selecting new source files are described to the right (steps 1-5)

  14. Saves the current scenario and source files to the current scenario folder Defining and Saving Scenarios • Users can generate New scenarios or copy and edit existing scenarios for defining and saving scenarios for testing • Starting with a New scenario, the user can specify a name which will create a new scenario folder using the default source files for the All Defaults scenario and the current date • Thus if the default files are modified, then the updated default files will be used when New scenarios are created • Or the user can save existing scenarios with different names to copy the files to a new scenario folder for editing

  15. Run Button Starting a Scenario • To start a scenario, press the run button on the tool bar • The scenario will then start on the next internal 1PPS (if set to internal trigger) • After the scenario has started, the Status bar will then update with a Running indicator that will start to flash to show that the scenario is running

  16. Stopping a Scenario • There are several ways to stop a scenario • By default, the Scenario will automatically stop when the predefined scenario duration has been reached • It can also be stopped prior to the duration end manually with the halt button on the tool bar • After stopping a scenario, the user will be prompted to rewind the scenario and save any selected files Halt Button

  17. Agenda • Introduction to SimGEN • Overview of SimGEN • Starting and stopping scenarios • Modifying the scenario start time and duration • Loading almanacs for updating the constellation • Using quick-look to display, log and plot data • Adjusting satellite signal power • Automating testing with User Action Files • Additional SimGEN Information

  18. SimGEN Time Specification • When the time is set in SimGEN it determines a few important characteristics, such as the visible constellation • The almanac and ephemeris that describes the satellite positions at any given time and date is based on a reference time and is predicted forwards and backwards from that time • The date and time can be specified in Cartesian calendar format or by using GPS time Referemce: http://www.barnabu.co.uk/the-gps-spider/

  19. GPS Time Overview • The very first epoch of GPST occurred at 00:00:00 UTC, on 6th Jan 1980 • GPST is defined in weeks containing 604,800 seconds • Each week begins at midnight every Saturday • Each week with GPS is numbered from 0 to 1023 (1024 weeks). • After 1024 weeks, a GPS week rollover occurs, with the GPS week starting again from 0. The following are the current GPS week rollovers: • Roll over 0 = 6th Jan 1980 to 15th Aug 1999 • Roll over 1 = 22nd Aug 1999 to 31st Mar 2019 *Current* • Specifying the current rollover is not supported in the Legacy navigation data, only the modernized (L2C, L5, M) navigation data messages • Thus, legacy GPS receivers may have to make an assumption for the current rollover • Z-count is the fundamental GPS time unit • It is a 29-bit binary number, of which the 10 most significant bits give the binary representation of the GPS week number, and the 19 least significant bits give the time-of-week (TOW) count in units of 1.5 seconds

  20. Today's Date Select the Cartesian date and Time Number of times the week numbers have rolled over the 1024 limit GPS week number Time of week in 1.5s Z-count epochs Time of week in 1s epochs Set the scenario duration (24 days maximum) to automatically stop the scenario SimGEN Time Specification (cont.) • The user can easily modify the scenario start date and time from the Scenario Contents Window • Modifying the time is performed by double-clicking on ‘Start time’ or highlighting Start Time and pressing the ‘Edit’ button

  21. SimGEN Time Specification (cont.) • When OK is pressed, notice that the visible constellation changes according to the stored almanac in the GPS Constellation source file

  22. Time Travel • SimGEN easily allows users to simulate dates in the future or past • Replicate conditions experienced in the past • Check if receivers are likely to fail at the next GPS week roll-over date • Proving a receiver cold start is genuine by testing its ability to acquire and track far into the future with an unexpected constellation, date and time • Unless using SimGEN’s default almanac of 24 GPS ideal orbits, then propagating YUMA or other almanac files too far in the future or past may produce unrealistic orbits • This can be mitigated by: • Setting the Eccentricities to zero for all satellites (makes the orbits perfectly circular) • Setting the Root Semi-Major Axis to the same value, for instance 5153.7008109998 √meters (allows the orbits to be propagated at the same rate)

  23. Agenda • Introduction to SimGEN • Overview of SimGEN • Starting and stopping scenarios • Modifying the scenario start time and duration • Loading almanacs for updating the constellation • Using quick-look to display, log and plot data • Adjusting satellite signal power • Automating testing with User Action Files • Additional SimGEN Information

  24. Almanacs • Almanacs define the relative orbits for each satellite in the constellation • Common parameters include the orbit radius information, orbit inclination, eccentricity, etc. • Almanacs can be obtained from the U.S. Coast Guard website • www.navcen.uscg.gov/gps/almanacs.htm • A common almanac is the YUMA almanac • The YUMA almanac defines: • Which satellites are in the constellation • The orbital parameters for each satellite • The satellites clock and health information Referemce: http://www.barnabu.co.uk/the-gps-spider/

  25. Loading Almanacs in SimGEN • The GPS constellation used in the scenario is defined in the GPS constellation > Signal Sources File shown below • Can be opened by double-clicking the source file or using the Edit button at the bottom

  26. Loading Almanacs in SimGEN (cont.) • Loading almanac files is supported under Motion > Orbits as shown below • SimGEN supports • YUMA Format Almanacs • SEM Format (System Effectiveness Model) • RINEX Format (Receiver Independent Exchange) Select saved almanac file for loading

  27. YUMA Impact in SimGEN • SimGEN uses the loaded YUMA to: • Update the almanac and ephemeris information in the navigation data • Model the satellite orbits • Update the health for each satellite in the navigation data • Model the clock Af0 and Af1 terms on the RF • Include the Af0 and Af1 terms in the navigation data

  28. Agenda • Introduction to SimGEN • Overview of SimGEN • Starting and stopping scenarios • Modifying the scenario start time and duration • Loading almanacs for updating the constellation • Using quick-look to display, log and plot data • Adjusting satellite signal power • Automating testing with User Action Files • Additional SimGEN Information

  29. Quick-Look Data • When testing, it may be necessary to view, plot or log certain sets of truth data for the simulated vehicle or satellites • Displaying the vehicle truth position for real-time comparison with the receiver’s • Plotting the vehicle speed or pseudorange ramp error for visually observing the time series events • Logging just simulation time and latitude, longitude and altitude may be useful for a certain post-processing applications • SimGEN’s “Quick Look” provides the user the capability of logging, displaying and plotting customized data during the test • The Quick Look is located on the Scenario Toolbar as shown below DATA LOGGING DATA PLOT DATA DISPLAY

  30. Quick-Look Data • The Quick-look data for logging, displaying and plotting is available before or during a simulation by pressing the buttons on the Scenario Toolbar • Each quick-look option displays a window that permits the user to Add the desired data as shown below Note: Must enable Logging On if data is to be logged

  31. Quick-Look Data (cont.) • The parametric data available for plotting, displaying and logging is summarized below • Time: Time into run, GPS time, TOW, Z-count week, etc • Vehicle: Vehicle motion data, e.g. ECEF or geodetic position, velocity, etc • Antenna: Antenna motion data, dependent upon the lever arm • Transmitter: SV (e.g. GPS, SBAS) or other signal source (e.g. LAAS, Interference) position and velocity data • Signal: Data relevant to the selected transmitter type, e.g. GPS Tx allows pseudorange, atmospheric delay, signal level, etc. Interference only has signal level selections • UUT: External device position, velocity data, etc. Such as receiver NMEA input into SimGEN

  32. Quick-Look Data (cont.) • All three options make available the same parametric data • Data Plots will show in real-time the changing simulation values vs. time into run as a graph on the screen as shown below • Data Display will show the ‘current’ real-time simulation values as it changes during scenario as shown below • Data Logging will create a csv file of the specified simulation values vs. time into run as shown below

  33. Saving Quick-Look Files • The user can save the selected plot, display and logging parameters for automatic loading with the scenario or to be reused in other scenarios • Saving the specified values are performed by using “Save all” as shown below on each Quick-Look window • “Data Plots” • saved with .qlp file extension • “Data Display” • saved with .qld file extension • “Data Logging” • saved with .qll file extension

  34. Modifying Quick-Look Data Logging • The saved quick-look source files can be automatically loaded with the scenario if defined in the “Data display and logging file” in the SimGEN Scenario Contents Window • This file permits additional user specifications for quick-look data logging as well • Logging rate of data in milliseconds. Logging rate must be equal to or less than the simulation iteration rate • Specify a filename and location (default is called “post_proc.csv” and saved to scenario folder)

  35. Additional Quick-Look Options • The On times menu allows the user to specify continuous or user-defined discontinuous data logging time periods throughout the test for logging only desired ‘events’ for instance • The Automatic Loading menu permits the user to add the save quick-look display, plots and logging source files so that they are automatically loaded when the scenario is opened

  36. Agenda • Introduction to SimGEN • Overview of SimGEN • Starting and stopping scenarios • Modifying the scenario start time and duration • Loading almanacs for updating the constellation • Using quick-look to display, log and plot data • Adjusting satellite signal power • Automating testing with User Action Files • Additional SimGEN Information

  37. Adjusting Satellite Signal Power • It is often useful to have control of the satellite signal power during simulation testing • For instance this provides the benefit of: • Configuring all of the satellites for a nominal transmission power level • Compensation for signal loss from couplers or transmission lines • Providing the desired carrier-to-noise (C/No) at the receiver • Sensitivity testing for determining when the receiver can acquire or track satellites at various power levels • Modeling black-outs or loss of signal

  38. Adjusting Satellite Signal Power (cont.) • The Signal Power menu shown to the right allows the user to define power offsets for each signal, code and satellite • The Global Offset is used for specifying the nominal reference power level for each satellite • Useful for defining the necessary signal power to provide the desired C/No at the receiver • Can easily be applied to satellites using the All button

  39. Adjusting Satellite Signal Power (cont.) • Signal power levels can be adjusted in real-time within SimGEN • Useful for reacquisition testing or if the C/No is observed to be too low/high at the receiver after the test has started for instance • Accessing this for each satellite can be performed by: • Double-clicking the Signal Powers menu or.. • Using the shortcut on the Toolbar • Moving the channel sliders adjusts the signal power for each satellite on each signal generator channel • Satellites can be turned “off” by checking Signal Off • If All channels is selected then each action is applied to all satellites

  40. Agenda • Introduction to SimGEN • Overview of SimGEN • Starting and stopping scenarios • Modifying the scenario start time and duration • Loading almanacs for updating the constellation • Using quick-look to display, log and plot data • Adjusting satellite signal power • Automating testing with User Action Files • Additional SimGEN Information

  41. Automating Testing • Some test requirements may benefit from automated signal modifications or logging of user signal adjustments during the test so that they can be repeated • Stepping the power level down for sensitivity testing • Adding various multipath signals to test the performance threshold • Turning signal levels On/Off for Time To First Fix (TTFF) testing • SimGEN provides ‘User Action Files’ to support these unique test requirements

  42. User Actions File • SimGEN’s User Actions files allow a sequential list of actions to be pre-defined that will then be executed at specified times once the scenario is running • User Actions can be scripted prior to the start of the simulation or.. • Generated during the simulation by logging the user’s actions for post simulation editing or replaying • If logging user’s action’s during the simulation, then logging of the user’s actions must be enabled prior to running the simulation • The user must specify a filename for the recorded actions file • The user will be prompted to save the logged user’s actions at the end of the simulation

  43. User Actions File Editor • Either using recorded actions or creating a new User Actions file, SimGEN provides a User Actions File Editor to script a time ordered list of actions to be performed during the simulation shown below • Actions can be edited or created for the entire scenario duration with an unlimited number of commands supported • After scripting the commands, the user can check the order of commands using the Check All function under Tools shown below

  44. User Actions File Editor (cont.) • The User Actions file supports modifying the following: • Power level modifications including power off/on • Power mode changes from absolute to relative • Apply Pseudorange ramps for modeling range errors • Switch Land Mobile Multipath environments • Addition of multipath signals • Ground Reflector • Fixed offset • Doppler offset • Vertical Plane • Timer Card Pulse – transmit a timing marker pulses at pre-defined times from an optional PCI timer card in the SimGEN PC • Can be used to reset the receiver, or… • Commanding events for other test equipment • Reflection Pattern • Legendre • Polynomial • Sinusoidal • Embedded Multipath (GSS8000 only)

  45. Agenda • Introduction to SimGEN • Overview of SimGEN • Starting and stopping scenarios • Loading almanacs for updating the constellation • Modifying the scenario start time and duration • Using quick-look to display, log and plot data • Adjusting satellite signal power • Automating testing with User Action Files • Additional SimGEN Information

  46. Message Reporting • SimGEN displays and logs various messages for information and debugging purposes for each SimGEN session (from open to close) • Messages can be displayed in real-time or logged and saved to a file • Enabling and manipulation of message reporting is available under Options -> Message Reporting • Messages are time-stamped relative to time-into-run • Users can disable pop-up windows and report additional details which can aid in debugging and communicating problems with Spirent’s customer support

  47. Message Window • Default window layout places message window in bottom right-hand corner of SimGEN • Use ‘envelope’ icon to enable/disable • Message window color-codes the 6 message types • Debug = Grey • Hardware = Dark Red • Information = Green • Warning = Blue • Error = Red • Fatal = Red • Click on top, left icon to clear messages

  48. Message_log File • Saved with default name “Message_log.txt” • Depending on how SimGEN is launched, file saved to following locations • Double-click SimGEN application icon or SimGEN application shortcut • File saved to SimGEN root folder C:\Program Files\Spirent Communications\SimGEN • Double-click scenario file (.scn file) • File saved to scenario root folder • If opening many scenarios as part of same ‘session’ all messages saved to the same Message_log.txt file • If wishing to save a Message_log.txt file • Message_log files are overwritten when a new SimGEN ‘session’ is started • Move or rename files that need to be saved

  49. Turbo mode • Permits the user to run a scenario at 40x real-time • Applies only when SimGEN is running in ‘No Hardware’ mode, thus no RF will be output from the signal generator • Useful for processing truth data for long scenarios or to get truth data quickly after running a test • Control the Turbo mode speed is performed by the slider on the menu bar Enable Turbo Mode Turbo Slider Speed

  50. Scenario Description File • This is an optional text-only file in each scenario • Allows users to include additional information about the scenario • Can be used for any purpose, such as storing notes, revision control, who created the scenario, purpose of the test, etc. • This file can be edited and saved within SimGEN

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