Basic Scenario Testing

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Dec 11, 2013 (4 years and 21 days ago)

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PROPRIETARY AND CONFIDENTIAL

Basic Scenario Testing

‹#›

PROPRIETARY AND CONFIDENTIAL

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

‹#›

PROPRIETARY AND CONFIDENTIAL

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


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PROPRIETARY AND CONFIDENTIAL

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


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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

SimGEN Main Window


The overview of the SimGEN Main Window and its features is
shown below

Scenario
Contents

Window

Ground Track

Message

Window

Toolbar

Skyplot

Vehicle
Dials

Power
Levels

Date and
Time

Status Bar

Menu Bar

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PROPRIETARY AND CONFIDENTIAL

Scenario Contents Window


The scenario contents window
contains all of the scenario source
files for defining the simulation

Start Time



Define when the scenario starts



Specify the scenario duration to
define when the scenario stops

Atmosphere



Define the troposphere and
ionosphere models



Specify switching of models
for various space applications

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

Vehicle Motion



Use SimGEN’s models or customer
generated trajectories for defining the
vehicle motion during the simulation

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PROPRIETARY AND CONFIDENTIAL

Scenario Contents Window (cont.)


The scenario contents window
contains all of the scenario source
files for defining the simulation

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

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

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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


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PROPRIETARY AND CONFIDENTIAL

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

C:\Program Files\Spirent
Communications\SIMGEN\
Scenarios
Example 2
User Scenario
Example 1
User Scenario
Shared
Shared Folder

for shared files

Pre
-
installed scenarios

User Generated

Scenarios

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PROPRIETARY AND CONFIDENTIAL

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)


1

2

3

5

4

Select file location

Click on
Select

Highlight chosen file

Choose Select, Copy
or Share

Chosen file will be
added to scenario at
location specified in
Step (1)


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PROPRIETARY AND CONFIDENTIAL

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

Saves the current
scenario and
source files to the
current scenario
folder

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PROPRIETARY AND CONFIDENTIAL

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

Run Button



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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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


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PROPRIETARY AND CONFIDENTIAL

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/

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PROPRIETARY AND CONFIDENTIAL


The very first epoch of GPST occurred at 00:00:00 UTC, on 6
th

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 = 6
th

Jan 1980 to 15
th

Aug 1999


Roll over 1 = 22
nd

Aug 1999 to 31
st

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

GPS Time Overview

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PROPRIETARY AND CONFIDENTIAL

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

Select the Cartesian
date and Time

Time of week in 1s epochs

GPS week number

Number of times the week
numbers have rolled over
the 1024 limit

Time of week in 1.5s
Z
-
count epochs

Set the scenario duration (24 days
maximum) to automatically stop the
scenario

Today's Date

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PROPRIETARY AND CONFIDENTIAL


When OK is pressed, notice that the
visible constellation changes
according to the stored almanac in
the GPS Constellation source file

SimGEN Time Specification (cont.)

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PROPRIETARY AND CONFIDENTIAL

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)

‹#›

PROPRIETARY AND CONFIDENTIAL

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


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PROPRIETARY AND CONFIDENTIAL

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/

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

‹#›

PROPRIETARY AND CONFIDENTIAL

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


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PROPRIETARY AND CONFIDENTIAL

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 PLOT

DATA DISPLAY

DATA
LOGGING

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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


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PROPRIETARY AND CONFIDENTIAL

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)

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PROPRIETARY AND CONFIDENTIAL

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

‹#›

PROPRIETARY AND CONFIDENTIAL

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


‹#›

PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

‹#›

PROPRIETARY AND CONFIDENTIAL

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


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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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)

‹#›

PROPRIETARY AND CONFIDENTIAL

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


‹#›

PROPRIETARY AND CONFIDENTIAL

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

‹#›

PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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

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PROPRIETARY AND CONFIDENTIAL

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