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Testing

4 -12

4.1.7

Measuring Time to First Fix (TTFF) and Position Accuracy

TTFF and position accuracy measurements are important parameters in GPS receiver

testing. In many GPS applications, the time it takes for the receiver to return its actual

location can significantly affect the receiver’s usability. In addition, the accuracy with

which a receiver returns its reported location is important.
For a receiver to obtain a position fix, it must download the almanac and ephemeris

information from the satellite through a navigation message. Because it takes 30 seconds

for a receiver to download an entire GPS frame, a “cold start” TTFF condition can take

anywhere from 30 to 60 seconds.
Signal strength also is a factor in correlation lock time and hence TTFF.

Fig. 4-4 TTFF vs. Signal Strength

Many receivers specify several TTFF conditions, including Acquisition (cold and warm

start), Reacquisition (hot start) and Positional Accuracy.

Содержание 87339

Страница 1: ...GPSG 1000 GPS Galileo Positional Simulator Operation Manual...

Страница 2: ...rved No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without the prior p...

Страница 3: ...must be used with this equipment when interfacing with the RS 232 and Ethernet For continued EMC compliance all external cables must be shielded and 3 meters or less in length NOMENCLATURE STATEMENT I...

Страница 4: ...ii THIS PAGE INTENTIONALLY LEFT BLANK...

Страница 5: ...ion of Conformity Certificate included with the Unit should remain with the Unit VIAVI Solutions recommends the operator reproduce a copy of the Declaration of Conformity Certificate to be stored with...

Страница 6: ...iv THIS PAGE INTENTIONALLY LEFT BLANK...

Страница 7: ...al conditions specified in the performance data CASE COVER OR PANEL REMOVAL Opening the Case Assembly exposes the operator to electrical hazards that may result in electrical shock or equipment damage...

Страница 8: ...pment USE RECOMMENDED FUSES ONLY Use only fuses specifically recommended for the equipment at the specified current and voltage ratings Refer to Performance Specifications for fuse requirements and sp...

Страница 9: ...OMESTIC WASTE OR DISPATCH THEM BY POST THEY SHOULD BE SEPARATELY AND SECURELY PACKED AND CLEARLY IDENTIFIED TO SHOW THE NATURE OF THE HAZARD AND THEN DISPOSED OF IN A SAFE MANNER BY AN AUTHORIZED TOXI...

Страница 10: ...G IS COMMENSURATE WITH THE CURRENT REQUIREMENTS OF THIS EQUIPMENT TX PORT MAXIMUM REVERSE POWER 100 mW RX LEVEL MUST NOT EXCEED 20 dBM This equipment contains components sensitive to damage by Electro...

Страница 11: ...On and Power Off procedures Provides functional description of Graphic User Interface GUI components Provides instructions for defining Test Set parameters CHAPTER 3 TEST SET FUNCTIONS Provides functi...

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Страница 13: ...ps to unpack the Test Set STEP PROCEDURE 1 Cut and remove sealing tape on top of the shipping container Open shipping container and remove top packing mold 2 Grasp the Test Set firmly while restrainin...

Страница 14: ...tems as well as purchased options Report all discrepancies to VIAVI Solutions Contact Standard Items VIAVI Solutions Customer Service Department 10200 West York Street Wichita Kansas 67215 Telephone 8...

Страница 15: ...xiii Transit Case 88493 1 Coax Cable 50ft 90114 1 GPSG Antenna Coupler 87636 1 Shot Bag 88753 1 RX Antenna 90113 1 ITEM PART NUMBER QTY...

Страница 16: ...ry Charger 87040 1 Antenna Coupler Placement Pole Kit Pole and D Ring 90106 1 Kit CPLR Dual GPS Antenna System 91136 1 Kit CPLR Triple GPS Antenna System 91137 1 Maintenance Manual 89023 1 GPS Receive...

Страница 17: ...ing Battery Cradle 2 2 Installation 2 3 Ventilation Requirements 2 3 Bench Top Installation 2 3 Controls and Connectors 2 4 Front Panel Controls 2 4 Rear Panel Controls and Connectors 2 6 Operating Pr...

Страница 18: ...Window 3 27 Maintenance Function Window 3 29 Calibration Function Window 3 30 Diagnostics Function Window 3 31 File Almanacs Function Window 3 32 File Routes Function Window 3 34 File Settings Functio...

Страница 19: ...nction Windows 5 7 System Function Windows 5 10 Chapter 6 Principles of Operation 6 1 Principles of Operation 6 1 GPSG 1000 6 1 GPS System 6 2 SPS Standard Positioning Service 6 6 Position Calculation...

Страница 20: ...ogy B 1 Appendix C Exporting Editing and Importing Waypoints C 1 Appendix D Exported and Imported File Formats D 1 Appendix E Recording and Playing Trajectory Routes E 1 Appendix F GPSG 1000 USB Memor...

Страница 21: ...Galileo Static 3 2 Simulation Function Window SBAS Static 3 2 Setup Simulation Window 3 5 Setup Motion Window 3 12 Setup Channels Window 3 13 Setup I O Window 3 14 SV PRN Selection Function Window 3...

Страница 22: ...on Date Time 5 17 GPS System Segments 6 2 GPS Satellite 6 3 GPS Satellite Orbital Planes 6 3 GPS SV Block Schematic 6 4 GPS SV Signal Data Structure 6 4 GPS Monitor Stations 6 5 GPS Navigation Data 6...

Страница 23: ...oint Edit Screen C 2 Waypoint Edit Waypoint Data Screen C 2 New Waypoint List C 3 File Waypoints Screen C 3 Waypoint Export Successful C 4 File Waypoints Screen C 5 USB Import Warning Pop up C 6 Waypo...

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Страница 25: ...11 TTFF Values for Four Simulations at Different UTC 4 16 Horizontal Accuracy for Various UTC Simulations 4 17 PS Positional Error Sources 6 18 RAIM Alarms 6 23 Galileo Signals 6 30 SNC SNR and C N0 6...

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Страница 27: ...ature Cross Reference List Type of Manual Operation Manual Equipment Name Model Number GPSG 1000 GPS Galileo Positional Simulator Equipment use Satellite constellation simulator for testing GPS and Ga...

Страница 28: ...ides users with the following standard capabilities Selectable single carrier Twelve channel configuration GPS Signals Simulated L1 L1C L2C L5 Galileo Signals Simulated E1 E5 E5a E5b Simultaneous GPS...

Страница 29: ...inuously utilizing the DC power supply The internal battery is equipped to power the GPSG 1000 for four hours of continuous use 2 2 2 AC Power Requirements The DC Power Supply supplied with the GPSG 1...

Страница 30: ...g yellow Trickle charge during extremely low voltage on the battery Battery Charging flashing green Charge in progress Battery Fully Charged green Battery Temperature Extreme blue Temperature 0 C or 4...

Страница 31: ...ment on or close to other equipment that is hot 2 3 2 Bench Top Installation The Test Set can be positioned in flat or tilted position by utilizing the built in screen cover stand when used in a bench...

Страница 32: ...and is not yet able to indicate status on the display during initial OS and application load Off Standby orange Unit is off but power is supplied to the power supply from the AC power supply Off w o E...

Страница 33: ...ely low voltage on the battery Battery Charging flashing green Charge in progress Battery Fully Charged green Battery Temperature Extreme blue Temperature 0o C or 45o C can t charge battery Battery Er...

Страница 34: ...PS Tx Coupler RF output for connection to Antenna Coupler REF In 10MHz The 10MHz In 5V p p Max Connector is a BNC connection used to connect the Test Set to an external frequency standard providing a...

Страница 35: ...CEDURE 1 Press On Off Button on Front Panel to power on Test Set 2 The Power Up window is displayed when the unit is first powered on or after Factory Defaults have been restored 2 5 2 Power OFF Test...

Страница 36: ...cal scrolling menu located at the left side of the User Interface The Launch Bar provides access to the Function Icons as shown in Fig 2 4 The menu must be opened to access the Function Icons The Laun...

Страница 37: ...t Set Fig 2 6 Function Keys 2 6 4 Function Windows Function Windows provide visual access to the Test Set s control parameters and displayed data Fig 2 7 Function Window Function How to Opening Closin...

Страница 38: ...ive State Maximizes Function Window and opens Status Bars Minimizes Function Window and closes Status Bars Selects the next tab left or right Displays a gray background when no additional tabs are ava...

Страница 39: ...Numeric Keypad allows the user to enter a specific numeric value A value is entered by pressing the numbers on the keypad The value is enabled pressing the unit of measurement on the Numeric Keypad Fi...

Страница 40: ...Data Slew Bar Fig 2 9 Data Slew Bar 2 7 4 Drop down Menus Drop down Menus are used to list pre defined variables Selecting a Drop down Menu opens the list of variables available for that field The va...

Страница 41: ...cating that the field is locked and may not be edited or accessed The altitude field shown is locked due to the fact that a simulation is running or the simulation mode has been set to dynamic mode Th...

Страница 42: ...ns 3 2 TEST SET FUNCTIONS 3 2 1 Simulation Function Window The Simulation Function Window is used to display the selected GPS Galileo and SBAS SV PRN s Visible SV s carrier and PVT position velocity a...

Страница 43: ...ntry Latitude entered in decimal format Example 37o39 0000N 37 degrees 39 0000 minutes North Sign N or S NOTE This field is locked when SIMULATION DYNAMIC or TRAJECTORY Longitude Incremental Data Entr...

Страница 44: ...S and Carrier selections in Setup NOTE The GPS Services and Galileo Services are displayed in the Services field GNSS System GPS Carrier L1 GPS Services C A Pseudo P Y Carrier L1 no P y GPS Services C...

Страница 45: ...Displays name of ending waypoint when running a dynamic simulation dependent on Name entered on the Route Edit page Distance To Go Displays the Distance To Go from the current simulated position to th...

Страница 46: ...SS Allocation dual mode settings on the Setup Channels Window Carrier Drop down menu provides selection of carrier carrier is dependent on GNSS selection in Setup Drop Down Selections GPS L1 L1C L2 L2...

Страница 47: ...ing to the receiver antenna On When connecting directly to the receiver bypassing the antenna LNA NOTE Automatically set to OFF when RF PORT COUPLER Automatically set to ON when RF PORT DIRECT NOTE Us...

Страница 48: ...ation dates are within a period starting approximately 60 days before the leap second event The appropriate message content is updated within two hours after the leap second event RF Level Numeric Pad...

Страница 49: ...its used during dynamic simulation mode will be based on the item chosen in the drop down selection menu The values of the velocity and acceleration can be viewed using the Motion tab on the Setup Mot...

Страница 50: ...f sight component This situation typically occurs in urban environments and during propagation through the atmosphere Shadowing simulates the effect of occasionally losing the line of sight signal due...

Страница 51: ...1 9 dB Rice factor 40 s mean time in state Blocked bad state 5 9 dB Rice factor 10 s mean time in state 5 dB attenuation Fading bandwidth 0 5 Hz Shadowing bandwidth 1 Hz Shadowing variation 2 dB 1 Lan...

Страница 52: ...view of the sky PEDESTRIAN Representative of a pedestrian in an urban environment LAND Representative of a land vehicle in a rural environment AERONAUTIACAL Representative of the environment experienc...

Страница 53: ...2 Maximum Normal Acceleration Numeric Pad Normal Acceleration entered in either feet second 2 with a maximum of 328 083 ft s 2 or in meters second 2 with a maximum of 100 m s 2 Maximum Velocity Numeri...

Страница 54: ...2 12 Ch SV s Only used during GPS Galileo dual mode simulation Galileo SV s Numeric Pad Sets the total number of Galileo SV s available for simulation Range 1 6 6 Ch or 1 12 12 Ch SV s Total GPS Galil...

Страница 55: ...to determine the loss value to enter in this control component Direct Cable Numeric Pad Direct RF coax cable loss in dB Range 0 to 12 dB NOTE If using the optional GPS Receiver Termination Kit see the...

Страница 56: ...ermine the accuracy of the positional simulation SV s which are currently being use are displayed in green text and SV s which are available for use but not currently being used are displayed in white...

Страница 57: ...1 Hz increments NOTE Doppler shift for each SV is applied dynamically throughout the simulation run time This parameter introduces a step change in Doppler used for RAIM testing Amp Offset Numeric Pad...

Страница 58: ...Not displayed for Galileo SV s GAL Integrity Allows selection of CONNECTED or DISCONNECTED Carried in Galileo Nav Data Only displayed in Galileo SV s NOTE Not displayed for GPS SV s Cancel Cancel para...

Страница 59: ...ute Validates the current route to let the user know if there are any route errors When Validate Route is pressed the route is checked and if no errors are found no error message is displayed however...

Страница 60: ...t from the route Edit Opens the Route Edit Window to edit the selected waypoint Move Up Moves the highlighted waypoint up in the list of waypoints Move Down Moves the highlighted waypoint down in the...

Страница 61: ...ints Fig 3 11 Route Edit Stored Window Control Component Description Sorted By Drop down selections Code Name City Country Latitude Longitude and Altitude Cancel Closes the Route Edit Stored Window an...

Страница 62: ...tes East Sign E or W Altitude Numeric Pad Altitude 0 to 100 000 ft in 1 ft steps or 0 to 18 288 M in 1 M steps Turn Radius Numeric Pad Turn Radius 3 281 to 328 084 ft in 001 ft steps or 1 to 100 000 m...

Страница 63: ...e Rate 5 905 ft min in 001 ft min steps or 1800 m min in 001 m min steps Cancel Closes the Route Edit Edit Window and returns to the Route Window Done Closes the Route Edit Edit Window and returns to...

Страница 64: ...Window so that a new waypoint may be created Delete Deletes selected waypoint NOTE Allow approximately 15 seconds for the selected waypoint to be deleted after pressing Delete NOTE Permanent waypoints...

Страница 65: ...untry Displays Waypoint Country Latitude Displays Waypoint Latitude in decimal format Example 37o 39 0000N 37 degrees 39 0000 minutes North Sign N or S Longitude Displays Waypoint Longitude in decimal...

Страница 66: ...n be selected from a table to be edited on the Waypoint Edit Edit Window Fig 3 14 Waypoint Edit Window Control Component Description Sorted by Drop down selections Code Name City Country Latitude Long...

Страница 67: ...point Name City Alpha Numeric Pad Enter or change waypoint City Country Alpha Numeric Pad Enter or change waypoint Country Latitude Incremental Data Entry Enter or change waypoint Latitude in decimal...

Страница 68: ...ch would then allow the receiver under test to hot start Fig 3 16 GPS Receiver Window Control Component Description GPS Receiver Selects internal GPS receiver Load Almanac from GPS Rx Loads almanac fr...

Страница 69: ...N 37 degrees 39 0000 minutes North Sign N or S Longitude Waypoint Longitude in decimal format Example 97o26 0000E 97 degrees 26 0000 minutes East Sign E or W Altitude Displays Altitude as determined b...

Страница 70: ...Maintenance Function Window Selecting the Maintenance icon from the Launch Bar Menu will display the Maintenance sub menu The Maintenance sub menu contains the Calibration and Diagnostics icons Fig 3...

Страница 71: ...menu will display the Calibration Password Entry Window The Calibration Function Window is password protected Contact VIAVI Solutions for the default password Enter the password to open the Calibrati...

Страница 72: ...31 3 2 17 Diagnostics Function Window Selecting Diagnostics from the Maintenance sub menu will display the Diagnostics Function Window See Chapter 5 Maintenance for details Fig 3 19 Diagnostics Functi...

Страница 73: ...file name will be displayed in the Current Almanac File Window Manage Almanacs Opens the Manage Almanacs Window Press Save to save the Current Almanac File to the Almanac file list To delete a saved A...

Страница 74: ...Testing 3 33 Display Component Description Current Almanac File Displays the file name of the Almanac file currently used for GPS simulations...

Страница 75: ...he Current Route File Window Manage Routes Opens the Manage Routes Window Press Save to save the Current Route File to the Route file list To delete a saved Route file select Route file from list and...

Страница 76: ...ile Window Manage Settings Opens the Manage Settings Window Press Save to save the Current Settings File to the Settings file list To delete a saved Settings file select Settings file from list and pr...

Страница 77: ...anage Trajectory Opens the Manage Trajectory Window Press Save to save the Current Trajectory File to the trajectory file list To delete a saved trajectory file select NMEA file from list and press De...

Страница 78: ...in GDT format on the unit The data loaded onto the unit during the conversion of the Kml file can be played as a trajectory simulation Load Route Opens the Load Kml Window Select a Kml file and press...

Страница 79: ...ion Current Settings File Displays the file name of the Kml file currently used to setup the unit Maximum Velocity 0 to 1118 Mph or 0 to 1800 Km h Conversion Sampling Rate 1 2 4 or 5 Hz Minimum Turnin...

Страница 80: ...25 Waypoint Window Control Component Description Clear Settings Deletes all user entered waypoints stored in the unit Import from USB Copies user entered waypoints from a USB drive to the internal st...

Страница 81: ...Window Selecting the System icon from the Launch Bar Menu will display the System sub menu The System sub menu contains the Options System Configuration and System Update icons See Chapter 5 Maintenan...

Страница 82: ...ft of the aircraft under test GPS antenna top fuselage 2 Place the Shot Bag weight over the center section of the GPS Antenna Coupler 3 Connect the 50 ft RF Coax Cable to the GPSG 1000 Coupler TX TNC...

Страница 83: ...e Clock Internal RF Output RF Level When setting the output level of GPS generated signal a setting of 115 to 120 dB should be adequate for most receivers When directly connecting to a receiver the no...

Страница 84: ...and perhaps a series inductor between the signal line and the ground Such a device may need to be custom built depending on the receiver requirements NOTE It is recommended that the receiver under te...

Страница 85: ...Start Time Clock User Date For optional entry of date Time For optional entry of time RF Output RF Level When setting the output level of GPS generated signal a setting of 115 to 20 dB should be adequ...

Страница 86: ...TX Port NOTE Some receivers sense current draw on the DC supply to their active antenna If there is no current drawn they may assume that no antenna is connected In such cases the current draw must b...

Страница 87: ...ional entry of date Time For optional entry of time RF Output RF Level When setting the output level of GPS generated signal a setting of 115 to 120 dB should be adequate for most receivers When direc...

Страница 88: ...mulation if the user intends to match the SV constellation simulated by the GPSG 1000 to that of the SV constellation in view by the receiver at the time of the recording NOTE Most GPS receivers expec...

Страница 89: ...ion The NMEA 183 protocol supports six basic sentences and each provides a different data type Refer to table 4 1 The first word in each sentence is the three letter data type Table 4 1 Basic NMEA 183...

Страница 90: ...a Coupler Installation procedure Section 4 1 1 If directly connecting GPSG 1000 to GPS receiver under test proceed to step 2 2 Perform Setup procedure Section 4 1 2 3 Select Launch Bar tab to display...

Страница 91: ...n to close the Function Window On the Setup Simulation Function Window Select PRN Signal drop down menu Select VARIABLE to ensure the relative SV signal levels are set proportional to the respective p...

Страница 92: ...OTE It is important that a given receiver is first characterized by measuring the acquisition sensitivity to ensure that receiver self interference e g spurs or digitization noise does not adversely e...

Страница 93: ...s reported location is important For a receiver to obtain a position fix it must download the almanac and ephemeris information from the satellite through a navigation message Because it takes 30 seco...

Страница 94: ...Coupler perform Antenna Coupler Installation procedure Section 4 1 1 If directly connecting GPSG 1000 to GPS receiver under test proceed to step 2 2 Perform Setup procedure Section 4 1 2 3 Ensure GPS...

Страница 95: ...ctly connecting GPSG 1000 to GPS receiver under test proceed to step 2 2 Perform Setup procedure Section 4 1 2 3 Ensure GPS receiver is in warm start mode i e no ephemeris in memory or receiver has no...

Страница 96: ...under test proceed to step 2 2 Perform Setup procedure Section 4 1 2 3 Select Launch Bar tab to display launch bar Select SV PRN function key to display the SV PRN Function Window The GPS SV s in view...

Страница 97: ...y determined or user selected satellites available in that location at that time thereby providing a means to verify receiver positional accuracy under variable conditions NOTE As GPS and Galileo time...

Страница 98: ...ttain is highly dependent on the available satellites that it has to lock to Whilst a receiver s accuracy will vary over the course of several hours when satellites change the positional repeatability...

Страница 99: ...ranges Due to the SV orbital plane inclination of 55 deg positions in temperate latitudes the equator and polar regions Temperate latitudes exhibit SV azimuths that range in an arc either side of 90...

Страница 100: ...acement Perform the following steps to replace battery STEP PROCEDURE 1 Verify the GPSG 1000 is OFF and not connected to AC power via the AC Adapter 2 Place the GPSG 1000 on a flat surface lower side...

Страница 101: ...btain the latest software update zip file from VIAVI Solutions 2 Insert a USB memory device into the PC and copy the zip file to the root directory of the USB memory device 3 Remove any Instrument dir...

Страница 102: ...d in the STATUS window 11 Select Install Software The update will start and the progress screen appears 12 When all RPM files have been installed a pop up will be displayed instructing the operator to...

Страница 103: ...he power button to turn on the GPSG 1000 During the boot process two text files will be created on the USB Memory Device Fig 2 5 One file is called gps1000rs232 txt and the other file is called gps100...

Страница 104: ...6 Open the Launch Bar by touching the light gray bar located on the left side of the User Interface and scroll down to the System function key STEP PROCEDURE 17 Touch the System function key to open t...

Страница 105: ...memory device VIAVI Solutions P N 67325 under the directory name of Instrument almanacs plus almanac file name Instrument almanacs week617 alm 3 Power up the GPSG 1000 4 Select System then select Syst...

Страница 106: ...aintenance Function Windows Selecting the Maintenance icon from the Launch Bar Menu will display the Maintenance sub menu The Maintenance sub menu contains the Calibration and Diagnostics icons Fig 5...

Страница 107: ...ription Password Alpha Numeric Pad Enter password to open the Calibration Function Window NOTE Contact VIAVI Solutions for the default password Cancel Closes the Calibration Password Window OK After t...

Страница 108: ...ics output enabled output is modulated GPS signal and simulation is locked Frequency Drop down selections 1176 45 MHz 1207 14 MHz 1227 60 MHz 1278 75 MHz or 1575 42 MHz Amplitude Numeric pad Power in...

Страница 109: ...7 System Function Windows Selecting the System icon from the Launch Bar Menu will display the System sub menu The System sub menu contains the Options System Configuration and System Update icons Fig...

Страница 110: ...NOTE Factory use only Install License Installs Option License files that have been copied to the internal memory Remove License Removes Option License files NOTE This will permanently remove installed...

Страница 111: ...on Status Display Component Description Operating Time Displays the total operating time in hrs mins secs since power up Memory Available Displays memory available to software resources in GB MB or KB...

Страница 112: ...cessor temperature in degrees Celsius Digital Board Temperature Displays the current PXI digital board temperature in degrees Celsius Control Component Description Format SD Formats the internal SD me...

Страница 113: ...splays digital board firmware version number Digital Board Application Firmware Version Displays digital board application firmware version number Upconverter Card ID Displays upconverter card ID numb...

Страница 114: ...ys Slot 1 CPLD version number Slot 1 FPGA Version Displays Slot 1 FPGA version number Slot 1 Board Revision Displays Slot 1 Board Revision number Power Supply Version Displays power supply version num...

Страница 115: ...mat 255 255 255 0 example Gateway Numeric pad Gateway entry in the format 10 101 0 1 example NOTE This field is only active when Network Mode DHCP DNS Server Connection specific Domain Name Server suf...

Страница 116: ...5 12 System Configuration Date Time Control Component Description Time Numeric pad Time entry in the 24 Hour format HH MM SS Date Numeric pad Date entry in the format MM DD YYYY NOTE The unit time an...

Страница 117: ...Testing 5 18 THIS PAGE INTENTIONALLY LEFT BLANK...

Страница 118: ...terval of 4 hours this being the update rate supported by both GPS and Galileo The GPSG 1000 generates in real time the positions of all simulated Satellites i e positions are not be pre computed for...

Страница 119: ...and process GPS signals is affordable and reliable and does not require atomic clocks or antenna arrays For the GPS user the system is passive and requires a receiver only without the requirement to...

Страница 120: ...tellites varies from 31 13 degrees to 119 98 degrees Each plane exhibits a different angular spacing for the satellites resident to it A computer model determines the satellite spacing to accommodate...

Страница 121: ...n inadequate satellite coverage Fig 6 4 GPS SV Block Schematic Fig 6 5 GPS SV Signal Data Structure Each GPS satellite transmits a unique signature assigned to it on the same carrier frequency This si...

Страница 122: ...nnas Fig 6 6 GPS Monitor Stations The objective of the GPS control segment is Maintain each of the satellites in its proper orbit through infrequent small commanded maneuvers Make corrections and adju...

Страница 123: ...code approximately 2 35 1014 bits in length 235 000 000 000 000 bits and each satellite repeatedly transmits its assigned segment of the master code 6 1 4 Position Calculation Position calculations co...

Страница 124: ...wn in Fig 6 8 Almanac data is typically updated every 24 hours Data for a few weeks is also provided in case of a delay in update Once a receiver has an almanac loaded in its memory it can be used for...

Страница 125: ...nformation found in the data stream clock corrections ionospheric model UTC data are used to resolve potential sources of GPS position errors 6 1 4 B Code and Frequency Correlation The power of the re...

Страница 126: ...ried without achieving correlation the receiver local oscillator frequency is offset to the next value and the process is repeated The reason for this frequency offset is because satellites and receiv...

Страница 127: ...Principals of Operation 6 10 Fig 6 12 GPS Code Correlation Process Fig 6 13 GPS Nav Data Recover by Moduo 2 Addition...

Страница 128: ...ese satellites is equipped with onboard atomic clocks In order to make them even more accurate they are regularly adjusted or synchronized from various control points on Earth GPS satellites transmit...

Страница 129: ...ver word HOW immediately follows the telemetry word in each subframe The handover word is 17 bits in length a range of values from 0 to 131071 can be represented using 17 bits and contains within its...

Страница 130: ...ult an incorrect distance is measured that is known as a pseudorange Fig 6 16 GPS Pseudo Range 6 1 4 D Obtain Satellite Positions GPS receivers download an almanac into memory which defines where in t...

Страница 131: ...e distance D despite having an imprecise receiver clock using the following formula D t1 t2 x c S 2 Fig 6 17 GPS Pseudo Range In this example two pseudo ranges were employed to determine a position in...

Страница 132: ...where on a circle Fig 6 18 Triangulation using one known point Distance to two points is known desired position is in one of two locations Fig 6 19 Triangulation using two known point Distance to thre...

Страница 133: ...ift disparity can introduce 0 to 2 5 meters of positional error and measurement noise can introduce 0 to 10 meters of positional error Receiver Clock Inaccuracies and Rounding Errors Despite the synch...

Страница 134: ...at a shallow angle hence a thicker band has to be traversed Two methods can be used to correct for Ionospheric delays Once the receiver s approximate location is known a mathematical model can be use...

Страница 135: ...offset with International Atomic Time TAI TAI GPS 19 seconds Periodic corrections are performed on the on board clocks to correct relativistic effects and keep them synchronized with ground clocks The...

Страница 136: ...of triangulation The precision of the computations by triangulation depends on the constellation of all satellites of which the signals are taken into account four or more As the number and position o...

Страница 137: ...ailability through the integration of external information into the calculation process SBAS Satellite Based Augmentation System and RAIM Receiver Autonomous Integrity Monitoring System are GNSS augme...

Страница 138: ...Principals of Operation 6 21 All SBAS satellites support the same protocols and therefore can support seamless augmentation from one region to another Fig 6 26 SBAS Coverage...

Страница 139: ...hich supports differential GPS designed to supplement the GPS system by reporting then improving on the reliability and accuracy of those signals MSAS for aviation use was commissioned on September 27...

Страница 140: ...orm RAIM computations is dependent upon the number of satellites in view their geometry and the mask angle which is dependent upon the ability of the antenna to track satellites near the horizon and a...

Страница 141: ...ating every 20 ms The CL code is 767 250 bits long repeating every 1500 ms Each signal is transmitted at 511 500 bits per second bit s however they are multiplexed together to form a 1 023 000 bit s s...

Страница 142: ...PS week number is now represented as 13 bits or 8192 weeks and only repeats every 157 0 years meaning the next return to zero won t occur until the year 2137 This is longer compared to the L1 NAV mess...

Страница 143: ...ed signal will be called the L5 Data signal The L5 quadrature phase Q5 carrier has no data and will be called the L5 Pilot signal L5 Frequency information Broadcast on the L5 frequency 1176 45 MHz 10...

Страница 144: ...specific region i e several hundred kilometers in diameter and increase the local signal strength by 20 dB 10X voltage field strength 100X power A side effect of having two antennas is that the GPS s...

Страница 145: ...itial test satellites were launched GIOVE A in 2005 and GIOVE B in 2008 to validate the basic Galileo space segment Four In Orbit Validation IOV satellites are scheduled to be launched in the 2010 to...

Страница 146: ...lileo system consists of five main services OS Open Service Free to air and for use by the mass market Simple timing and positioning down to 1 meter CS Commercial Service Encrypted Higher data rate im...

Страница 147: ...eiver consists mainly of thermal noise but also background and inter modulation noise Most of the single influences are constant or can be assumed to be constant in the order of measurement accuracy S...

Страница 148: ...ed for 1 millisecond resulting in an effective 1 kHz bandwidth Converting SNC to SNR Normally SNR Signal to Noise Ratio is expressed as a power ratio on a logarithmic scale instead of an amplitude rat...

Страница 149: ...hen extracting the navigation data from the GPS signals and reduced carrier and code tracking loop jitter Reduced carrier and code tracking loop jitter in turn results in less noisy range measurements...

Страница 150: ...you can measure the receivers noise figure by applying the following formula N figure 174dBm Hz SVpower C N0 For example 174 0 dBm 136 1 dBm 30 0 dB Hz 7 9 dB Rounding C N0 Receivers that support the...

Страница 151: ...ower level of 136 1 dBm produces a C N0 ratio of 30 0 dB Hz Table 6 6 Correlation of RF Power Level and Receiver C N0 RF Power Level Receiver C N0 135 6 dBm 31 dB Hz 135 7 dBm 31 dB Hz 135 8 dBm 30 dB...

Страница 152: ...udo P Y L2C 1227 600 MHz L5 1176 450 MHz New Civil SOL Galileo Carriers E1 L1 1575 420MHz PRS OS CS SOL pseudo G NAVL E5a 1191 795 MHz OS F NAV E5b 1207 140 MHz OS CS SOL I NAV Accuracy Same as Master...

Страница 153: ...500 b s NOTE Long random codes simulated Primary Code length 767 250 bits Modulation QPSK L5 Code Code Rate 10 230 Mc s Primary Code length 10 230 bits Modulation QPSK Galileo Codes From Open Service...

Страница 154: ...rchannel Code Phase Alignment 0 02 m RSS Interchannel Carrier Phase Alignment 0 265mm RSS 7 2 MASTER OSCILLATOR Frequency 10 MHz nominal see note Temperature Stability 0 05 ppm Aging Rate 0 3 ppm yr 2...

Страница 155: ...15 5 lbs 7 kg 7 7 ENVIRONMENTAL Test Set Certifications Operational Temperature 20 to 55 C Storage Temperature 51 to 71 C when no battery is installed Operational Humidity MIL PRF 28800F Class 2 Stor...

Страница 156: ...nal AC to DC Converter Use Indoors Altitude 10 000 m Operating Temperature 0 to 40 C Storage Temperature 20 to 71 C Transit Case Certifications Drop Test FED STD 101C Method 5007 1 Paragraph 6 3 Proce...

Страница 157: ...Principals of Operation 7 6 THIS PAGE INTENTIONALLY LEFT BLANK...

Страница 158: ...1 Pin Out Diagram Pin Number Signal Type Signal Type Function 1 Data Transmit Ethernet TX 2 Data Transmit Ethernet TX 3 Data Receive Ethernet RX 4 NC NC 5 NC NC 6 Data Receive Ethernet RX 7 NC NC 8 NC...

Страница 159: ...t Diagram Pin Number Signal Type Signal Type Function 1 Power VCC USB Power 2 Data Data USB Data 3 Data Data USB Data 4 GND GND Ground Pin Number Signal Type Signal Type Function 1 Power VCC USB Power...

Страница 160: ...429 Channel 1 RX B 3 NC NC 4 DATA ARINC 429 Out A ARINC 429 Channel 1 TX A 5 DATA ARINC 429 Out B ARINC 429 Channel 1 TX B 6 NC NC 7 Control RS232 CTS RS 232 Clear to Send 8 DATA RS232 TX1 RS 232 Tran...

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Страница 162: ...r in the measurement model used for data processing if high accuracy is sought There are several sources of biases with varying characteristics such as magnitude periodicity satellite or receiver depe...

Страница 163: ...equence Channel A single satellites signal on a single frequency Code Phase GPS measurements based on the C A Code The term is sometimes restricted to the C A or P Code pseudo range measurement when e...

Страница 164: ...nsmitter and receiver Dual Frequency Refers to the instrumentation that can make measurements on both L Band frequencies or to the measurements themselves e g L1 and L2 pseudo range or carrier phase m...

Страница 165: ...hs or so to keep UTC approximately synchronized with the earth s rotational period with respect to the sun GPST has no leap seconds At the integer second level GPST matched UTC in 1980 but because of...

Страница 166: ...ter than in the Zenith direction The Delay is largely eliminated in Relative or Differential Positioning however the residual Ionospheric Delay increases as the baseline length increases and may be a...

Страница 167: ...B 6 THIS PAGE INTENTIONALLY LEFT BLANK...

Страница 168: ...file CSV which can be shared among GPSG 1000 units using the waypoint export and import functions It is important to note that importing a custom waypoint file from another GPSG 1000 will result in th...

Страница 169: ...creen On the Waypoint Edit Screen select one of the lines from the table For this exercise we will select ANC line 7 Once you have highlighted the line select Next The data from the selected line will...

Страница 170: ...to open the file screen first click on the main menu at the left side of the touchscreen and select the File button On the file screen open the Waypoint tab To export the custom waypoints plug a compa...

Страница 171: ...g code in column D Column J is added to the end of each Waypoint entry and set to 0 forcing a comma at the end of each row of the output file Column A A unique name the user assigns to each user Waypo...

Страница 172: ...g is complete save the file to the USB flash drive in the same directory location and with the same name from which it was originally opened Importing Waypoints Importing waypoints is done through the...

Страница 173: ...the USB will overwrite the existing waypoints on the system Press Yes to continue Figure C 8 Fig C 8 USB Import Warning Pop up A green popup box will appear and confirm when the import has been comple...

Страница 174: ...nctions provided to the user through the UI the user cannot further manipulate the files while they are contained within the unit The user can however export the files to a USB drive where they can be...

Страница 175: ...suitable to convert recorded routes from a GPS receiver in to Kml files for simulation in the GPSG 1000 Recorded routes should be loaded to the GPSG 1000 as Nmea Files for playback The compiled gdt fi...

Страница 176: ...0 09 154 82 290113 A 79 The sentence structure for each position sentence GGA Essential fix data which provide 3D location and accuracy data GPGGA 150923 000 3856 4506 N 09445 2627 W 1 07 1 1 332 2 M...

Страница 177: ...nd SNR for up to 4 satellites per sentence 75 Checksum data always begins with RMC NMEA has its own version of essential gps pvt position velocity time data It is called RMC The Recommended Minimum wh...

Страница 178: ...8 20028888888889 Altitude 1524 TargetSpeed 53 64466666666667 TurningCircleRadius 131 3646919714563 Waypoint Longitude 78 83963333333332 MaxAcceleration 9 800000000000001 MaxClimbRate 3 048 Name RIVKE...

Страница 179: ...climb or descent rate that the body in motion is allowed to achieve as it travels from the current waypoint to the next The climb descent rate is expressed in m s Name is followed by the text indicat...

Страница 180: ...trian LateralAcceleration 2 94 Velocity 10 72896 LongitudinalAcceleration 2 94 Automobile LateralAcceleration 9 800000000000001 Velocity 89 408 LongitudinalAcceleration 9 800000000000001 Marine Latera...

Страница 181: ...n D Unique code to each user Waypoint GPSG 1000 can sort Waypoints by this code Column E CAO Code A four character code designating each airport around the world In this case the Waypoint is not an ai...

Страница 182: ...X and playback the file for simulation Files saved from other GPS receivers may have nmea file extension When transferred to the GPSG 1000 for playback they must be renamed with mne file extension See...

Страница 183: ...the lower portion of the Main Menu select GPS RX Figure E 2 Fig E 2 Main Menus Lower Section The GPS RX page will display the current GPS position fix and the visible satellite Figure E3 Fig E 3 GPS...

Страница 184: ...GPS RX Page with 3d Fix Press the Record Trajectory button to start recording The GPSG 1000 will continue to record until the Stop Recording button is pressed Note the Current Date Time field the time...

Страница 185: ...d To load the new Trajectory File for playback select File from the Main Menu and then Trajectory from the tabs at the top of the page Press the Load button and select the new nme file press Open Figu...

Страница 186: ...Power Level to simulate the actual recorded S N For this feature to work the simulation must be played back with the same Almanac with which the recording was made If the Trajectory File is played wi...

Страница 187: ...E 6 The Simulation will run until the end of the Trajectory File Figure E 10 Fig E 10 Trajectory Simulation Complete...

Страница 188: ...matting The GPSG 1000 requires a USB Memory Device to be formatted as FAT32 or FAT16 only It is also recommended that users have a dedicated USB Memory Device for the GPSG 1000 so that the directory s...

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Страница 190: ...r and Shot Bag supplied with the GPSG 1000 3 Ensure the Connector Termination is in place on the open GPSG Splitter connector 4 For Coupler Loss and Cable Loss values to enter in the GPSG 1000 I O set...

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Страница 192: ...tween the GPSG Splitter and three GPSG 1000 Antenna Couplers Use the GPSG 1000 Antenna Coupler and Shot Bag supplied with the GPSG 1000 3 Enter Coupler Loss and Cable Loss values into in the GPSG 1000...

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Страница 194: ...e content of the GPSG 1000 optional kit is not required if using the GPSG 1000 RF coupler to transmit GPS data to the antenna of the GPS receiver under test GPSG Dual Antenna Coupler Kit Connection ST...

Страница 195: ...I 2 THIS PAGE INTENTIONALLY LEFT BLANK...

Страница 196: ...eplacement 5 1 O Operating Procedures 2 7 Power Off Test Set 2 7 Power On Test Set 2 7 P Power Requirements 2 1 Battery Recharging 2 2 General 2 1 Principles of Operation 6 1 Galileo System 6 28 GPS R...

Страница 197: ...Waypoint Edit Window 3 26 Waypoint Edit Stored Window 3 25 Waypoint Edit Window 5 8 5 9 Waypoint Function Window 3 15 3 23 Testing GPS Galileo Receivers Antenna Coupler Installation 4 1 5 5 GPS Recei...

Страница 198: ...VI Solutions North America 1 844 GO VIAVI 1 844 468 4284 Latin America 52 55 5543 6644 EMEA 49 7121 862273 APAC 1 512 201 6534 All Other Regions viavisolutions com contacts 88037 Rev D0 May 2020 Engli...

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