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2050

 

User Guide

 

Glossary 

.yym files

 see meteorological files (where yy = two digit year data was collected). 

.yyn files

 see navigation files (where yy = two digit year data was collected). 

.yyo files

 see observation files (where yy = two digit year data was collected). 

almanac files a

n almanac file contains orbit information, clock corrections, and atmospheric delay 

parameters for all satellites tracked. It is transmitted to a receiver from a satellite and is used by 
mission planning software. 

alt

 see 

altitude

altitude

 vertical distance above the 

ellipsoid

 or 

geoid

. It is always stored as height above 

ellipsoid

 in 

the 

GPS

 receiver but can be displayed as height above 

ellipsoid

 (HAE) or height above 

mean sea 

level

 (

MSL

). 

antenna phase center (APC) 

The point in an antenna where the 

GPS

 signal from the satellites is 

received. The height above ground of the APC must be measured accurately to ensure accurate 

GPS

 readings. The APC height can be calculated by adding the height to an easily measured point, 

such as the base of the antenna mount, to the known distance between this point and the APC. 

APC

 see 

antenna phase center or phase center

Autonomous positioning (

GPS

)  

a mode of operation in which a 

GPS

 receiver computes 

position

 

fixes in real time from satellite data alone, without reference to data supplied by a 

reference station 

or orbital clock corrections. 

Autonomous positioning

 is typically the least precise positioning 

procedure a 

GPS

 receiver can perform, yielding 

position

 fixes that are precise to 100 meters with 

Selective Availability on, and 30 meters with S/A off. 

azimuth

 the 

azimuth

 of a line is its direction as given by the angle between the 

meridian

 and the line 

measured in a clockwise direction from the north branch of the 

meridian

base station

 see 

reference station

baud rate (

bits per second

)

 the number of bits sent or received each second. For example, a 

baud 

rate

 of 9600 means there is a data flow of 9600 bits each second. One character roughly equals 10 

bits. 

bits per second

 see 

baud rate 

bps 

see 

baud rate

  

BSW

 

(British Standard Whitworth)

 a type of coarse screw thread. A 5/8” diameter 

BSW

 is the 

standard mount for survey instruments. 

C/A code

 see 

Coarse Acquisition code

CAN BUS 

a balanced (differential) 2-wire interface that uses an asynchronous transmission 

scheme. Often used for communications in vehicular applications.  

channel

 a 

channel

 of a 

GPS

 receiver consists of the circuitry necessary to receive the signal for a 

single 

GPS

 satellite. 

 Glossary-61 

Содержание 2050

Страница 1: ... u id e e e i id d u u G G r r e e s s U U t t c c u u d d o o r r P P S S P P G G 0 0 5 5 2 2 0 v v a a N N C C Ver 1 0e August 2004 C C Technologies Inc GPS Services Group 730 E Kaliste Saloom Road Lafayette LA 70508 U S A http www cctechnol com ...

Страница 2: ...1 2 ...

Страница 3: ...t 21 Maintenance 21 External Power Source 21 Safety First 22 Appendix A GPS Sensor Technical Specifications 23 2050G and 2050M 23 LED Display Functions Default 25 Appendix B GPS Antenna Technical Specifications 27 L1 L L2 GPS Antenna 27 Appendix C Global corrected GPS GcGPS 29 Description 29 How to Access the C Nav StarFire Service 32 Appendix D NMEA Data Output Message Formats 37 D 1 ALM NMEA Sen...

Страница 4: ...Operation is subject to the following two conditions 1 this device may not cause harmful interference and 2 this device must accept any interference received including interference that may cause undesired operation User Notice NAVCOM C C SHALL NOT BE RESPONSIBLE FOR ANY INACCURACIES ERRORS OR OMISSIONS IN INFORMATION CONTAINED HEREIN INCLUDING BUT NOT LIMITED TO INFORMATION OBTAINED FROM THIRD PA...

Страница 5: ...red or altered outside the NavCom Technology Inc production facility unless authorized in writing by NavCom Technology Inc THIS PROVISION IS EXPRESSLY ACCEPTED BY THE BUYER IN LIEU OF ANY OR ALL OTHER AGREEMENTS STATEMENTS OR REPRESENTATIONS EXPRESSED OR IMPLIED IN FACT OR IN LAW INCLUDING THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE AND OF ALL DUTIES OR LIABILITI...

Страница 6: ...rational parameters of the 2050 GPS Sensor COCOM Limits The U S Department of Commerce requires that all exportable GPS products contain performance limitations so that they cannot be used in a manner that could threaten the security of the United States The following limitations are implemented on the C Nav 2050 GPS Receiver Immediate access to satellite measurements and navigation results is dis...

Страница 7: ...of your system the actual receiver parameters of operation and the exact type make and configuration of your computer and navigation software in use If you have received error messages please specify the exact wording If you need to send a data file along with your inquiry please compress the file using PKZIP or WINZIP Software and name the file with the extension ZIP Use one of the following meth...

Страница 8: ......

Страница 9: ...al Real Time Gypsy RTG and regional Wide area Correction Transform WCT solutions Additionally the unit can accept corrections for DGPS WAAS EGNOS assuring seamless position output The 2050G is packaged for mobility It can be used for Geographical Information System GIS aerial and hydrographic surveying and post processed dual frequency surveys The GPS sensor can be carried in a backpack with the a...

Страница 10: ...to 70 000 feet Note Although rated to 70K feet the standard survey antenna is not designed for aircraft installations Controller The 2050 GPS sensor is designed for use with an external Controller Solution connected via one of the two COM ports normally Com2 Port B This may be accomplished using an IBM compatible PC Tablet PC or Personal Digital Assistant PDA and a software program which implement...

Страница 11: ...01 12 LEMO 4 Pin External Power Cable C C P N 4250005 10 LEMO 7 Pin to DB9S Data Communications Cable C C P N 4250003 6 Dual Data Interface Cable Not Shown C C P N 4250004 0 CD Rom C C P N 6250001 xx containing User Guide software utilities STARUTIL etc 2050 User s Guide Hard Copy Not Shown C C P N 5250001 xx Ruggedized Travel Case Not Shown C C P N 3250004 0 Figure 1 2050 Supplied Equipment 3 ...

Страница 12: ... base station Thus saving time and capital expenditure Regional Wide area Correction Transform WCT is also available from the StarFire correction service where applicable Positioning Flexibility The 2050 is capable of using two internal Satellite Based Augmentation System SBAS channels that provide Wide Area Augmentation System WAAS or European Geostationary Navigation Overlay Service EGNOS code c...

Страница 13: ... improved real time positioning Independent tests have proven the NCT 2000D to be the best receiver when facing various multipath environments Rugged Design The rugged design of the 2050 system components provides protection against the harsh environments common to areas such as construction sites offshore vessels and mines Units have been tested to conform to MIL STD 810F for low pressure solar r...

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Страница 15: ...ed together inside the 2050 GPS sensor Pins 3 and 4 are connected together inside the GPS sensor C C P N 4250005 10 is a 3m 10ft unterminated power cable fitted with a LEMO plug type Mfr P N FGG 1K 304 CLAC50Z and red strain relief is suitable for supplying power to the 2050 GPS sensor This cable is supplied with the 2050 series of GPS sensors The GPS sensor is protected from reverse polarity by a...

Страница 16: ...two 7 pin female LEMO connector communication ports located at the bottom front of the GPS sensor as shown in Figure 2 labeled COM1 and COM2 Each conforms to the EIA RS232 standard with data speeds between 1200 bps and 115 2kbps The pin outs for these connectors are described in Table 2 An interface data cable C C P N 4250003 6 is supplied with the 2050 for easy startup The cable construction is d...

Страница 17: ...2050 User Guide Figure 2 2050 Front View Figure 3 2050M Only Back View 2 9 ...

Страница 18: ... off I O switch and a quick view of the status of the 2050 GPS sensor corrections source type and StarFire signal strength Each of the three indicators has three LEDs which depict status as detailed in the following tables To power the unit on or off the on off I O switch must be depressed for more than 3 seconds During power up of the GPS sensor all LEDs will be on for a period of 3 5 seconds 2 1...

Страница 19: ... factory default configuration Rover Mode is discussed LINK Status Command Mode Repeating Red to Amber to Green indicates Searching StarFire signal Strong Signal Strength from StarFire Medium Signal Strength StarFire Weak Signal Strength StarFire Table 3 Link Light Indication Base LEDs BASE Status The BASE LEDs are not utilized in the 2050 GPS sensor Table 4 Base station Indication 2 11 ...

Страница 20: ...y better than 100ns The 1 PPS is 50 Ohm TTL level By using the appropriate NCT proprietary command the 1PPS pulse width is user configurable between 0 01 and 0 50 seconds with the default width set to 0 10 seconds The delay default is set to 0 0 seconds from the GPS zero second mark and is configurable between 0 0 seconds and 0 999 seconds This precise pulse can be used for a variety of time mark ...

Страница 21: ...S time tagging such as aerial photography The action of a camera s aperture could send a pulse to the Event port of the 2050M and have it output position information relative to the time the photograph was taken It requires input impedance of 50 Ohms a minimum High Level Input of 2 5V and a minimum Low Level Input of 1 2V The propagation delay is less than 100nsec The Event Input latch can be conf...

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Страница 23: ...ge and will void the equipment warranty There should be an unobstructed view of the sky above a 7 degree elevation mask for optimum GPS satellite visibility Any obstructions above the horizon should be mapped using a compass and clinometer and used in satellite prediction software with a recent satellite almanac to assess the impact on satellite visibility at that location Potential sources of int...

Страница 24: ...e 7 SF 2050 Base Plate Dimensions The 2050 can be installed in a backpack for mobile surveying applications The sensor should not be placed in a confined space or where it may be exposed to excessive heat moisture or humidity Note There are no user serviceable parts inside the 2050 GPS sensor Undoing the four screws which secure the front end plate and the four securing the rear end plate will voi...

Страница 25: ...1 LEMO 7 Pin connector allows the input of external Radio IALA correction data messages plus the output of 2050 position data messages to your system interface at one and the same time Figure 8 Communication Port Connections Note By factory default COM 2 is designated as the control port for the 2050 COM 1 can be designated as the control port by using the appropriate NCT proprietary commands Alth...

Страница 26: ...his is suitable for connecting the 2050 GPS sensor to the Tri Mode antenna In line L Band RF amplifiers C C P N 3250002 T suitable for all GPS frequencies may be used to increase the length of the antenna cable but care should be exercised that tracking performance is not degraded due to multiple connections noise from the amplifier and possible ingress of moisture and dust Note The antenna cable ...

Страница 27: ... 19 2k Baud This baud rate can be changed to accommodate faster data rates Refer to Appendix D for NMEA detailed information The standard factory configuration for the 2050 allows for the basic operation of the system The Control Port factory default for NCT Proprietary Message Blocks output is described in Table 7 These message blocks afford the novice or seasoned GPS user the best opportunity to...

Страница 28: ...of satellites being tracked and the number and identity of satellites used in solution PDOP and the satellite PRN B0 Raw Measurement Data Raw Measurement Data Block that contains the GPS Week GPS Time of Week Time Slew Indicator and Status Information included is Channel Status CA Pseudorange L1 Phase P1 CA Pseudorange P2 CA Pseudorange and L1 Phase This data stream is repeated for any additional ...

Страница 29: ...The 2050 equipment can be cleaned using a new lint free cloth that may be moistened with pure alcohol Connectors must be inspected and if necessary cleaned before use Always use the provided connector protective caps to minimize moisture and dirt ingress Cables should be regularly inspected for kinks and cuts as these may cause interference and equipment failure Damp equipment must be dried at a t...

Страница 30: ...nside the 2050 GPS sensor Accessing the inside of the equipment will void the equipment warranty Care should be taken to ensure that the 2050 does not come into contact with electrical power installations the unit is securely fastened and there is protection against electromagnetic discharge in accordance with local regulations The GPS sensor has been tested in accordance with FCC regulations for ...

Страница 31: ...cquisition of satellite broadcast corrections Rugged and lightweight package for mobile applications Accepts external DGPS input in RTCM v2 2 or CMR format L1 L2 full wavelength carrier tracking C A P1 P2 code tracking User programmable output rates Minimal data latency 2 separate WAAS EGNOS channels Superior interference suppression Patented multipath rejection Supports NMEA 0183 v3 1 messages Se...

Страница 32: ...z User programmable output rates PVT 1Hz 2Hz 5Hz Standard 10Hz 25Hz Optional Raw data 1Hz 2Hz 5Hz Standard 10Hz 25Hz 50Hz Optional Data Latency PVT 20 ms at all nav rates Raw data 20 ms at all rates Time to first fix Cold Start Satellite Acquisition 60seconds typical Satellite Reacquisition 1 second Dynamics Acceleration up to 6g Speed 300 m s Altitude 60 000 ft 1PPS Accuracy 2050M Only 12 5ns Rel...

Страница 33: ...rietary Data PVT Raw Measurement Satellite Messages Nav Quality Receiver Commands NMEA Messages Output Only ALM GGA GLL GSA GST GSV RMC VTG ZDA Code Corrections RTCM 1 or 9 Satellite Based Aumentation Systems StarFire LED Display Functions Default Link StarFire Signal Strength Default Base Station N A in 2050 ROVER GPS Position Quality Satellite Based Augmentation System Signals WAAS EGNOS MSAS et...

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Страница 35: ...marsat L Band 1217 1237 MHz GPS L2 Polarization Right Hand Circular RHCP Finish Fluid resistant Ultem UV stable Cable Connector TNC Female Pre Amplifier 39dB gain 2 Input Voltage 4 2 to 15 0 VDC Impedance 50 Ohms VSWR 2 0 1 Band Rejection 20 dB 250MHz Power Handling 1 Watt Operating Temp 55 C to 85 C Altitude 70 000 Note An optional aircraft mount antenna also rated to 70 000 feet is also availabl...

Страница 36: ...r Guide Designed to DO 160D Standard Figure 9 Tri Mode Antenna Dimensions Note In order to achieve the greatest level of accuracy the absolute phase center values must be incorporated into your processing B 28 ...

Страница 37: ...unprecedented decimeter accuracy Because the Wide Area Differential GPS corrections are broadcast via Inmarsat geo stationary communication satellites the user needs no local reference stations or post processing to get this exceptional accuracy Furthermore the same accuracy is available virtually any where on the earth s surface on land or sea from 75 N to 75 S latitude due to the worldwide cover...

Страница 38: ...rietary differential processing techniques used to generate real time precise orbits and clock correction data for each satellite in the GPS constellation This proprietary Wide Area DGPS WADGPS algorithm is optimized for a dual frequency system in which dual frequency ionospheric measurements are available at both the reference receivers and the user receivers It is the use of dual frequency recei...

Страница 39: ...s Centers each receiving all of the reference site inputs and each with redundant communications links to the uplink Land Earth Stations LES The Land Earth Stations are equipped with two complete and continuously operating sets of uplink equipment arbitrated by an automatic fail over switch Finally a comprehensive team of support engineers maintains round the clock monitoring and control of the sy...

Страница 40: ... subscription will provide an encrypted keyword which is specific to the Serial Number of the C Nav or StarFire receiver L Band Module LBM to be authorized This is entered into the receiver using the provided Controller Solution The only piece of equipment needed to use the system is a C Nav or StarFire receiver There are a variety of receivers configured for different applications C Nav or StarFi...

Страница 41: ...T SERVICE DESCRIPTION REGION North Central America South America Northern Europe and Mediterranean Black Sea Africa Middle East and South East Asia Asia Australia New Zealand and Western Pacific Other Please Check One I We are requesting a C Nav 2050 18 Word Authorization Code FILE in accordance with above pecifications I We are requesting a C Nav 2050 18 Word Deactivation Code FILE in accordance ...

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Страница 45: ...electrical signal requirements data transmission protocol timing and specific sentence formats for up to 38 4K baud for a serial interface data bus NMEA 0183 sentences are ASCII text information with each field or parameter separated by a comma i e comma delimited text format The following outlines the format of the NMEA sentence structure The basic format for an NMEA 0183 sentence or message is A...

Страница 46: ...ctronic Chart Display Information System ECDIS GL GLONASS Receiver GN Global Navigation Satellite System GNSS GP Global Positioning System GPS HC Heading Sensors Compass Magnetic HE Heading Sensors Gyro North Seeking HN Heading Sensors Gyro Non north Seeking II Integrated Instrumentation IN Integrated Navigation VM Velocity Sensor Speed Log Water Magnetic VW Velocity Sensor Speed Log Water Mechani...

Страница 47: ...roceeded by the comma character The checksum field is preceded by the asterisk character and is the 8 bit exclusive OR no start or stop bits of all characters in the sentence including the comma character delimiters between but not including the dollar character and asterisk character delimiters The hexadecimal values of the result are converted to two ASCII characters 0 9 A F for transmission The...

Страница 48: ...Description 1 Total Number of messages 2 Message Number 3 Satellite PRN Number 01 thru 32 4 GPS Week Number 5 SV Health bits 17 thru 24 of each almanac page 00 healthy 6 Eccentricity e 7 Almanac Reference Time toa 8 Inclination Angle sigma i 9 Rate of Right Ascension OMEGADOT 10 Root of Semi Major Axis root A 11 Argument of Perigee OMEGA 12 Longitude of Ascention Node OMEGA 0 13 Mean Anomaly M0 14...

Страница 49: ... S Corrected Fix 3 PPS Mode Fix Valid 4 RTK Mode FIXED Integers 5 RTK Mode Floating Integers 6 Estimated dead reckoning Mode 7 Manual Input Mode 8 Simulator Mode 7 Number of GPS Satellites SVs used in solution fix 8 Horizontal Dilution of Precision HDOP 9 C Nav GPS Receiver antenna altitude reference to Mean Sea Level MSL see Field 11 below 10 Altitude units M indicates meters 11 WGS 84 Geoidal Se...

Страница 50: ...ual freq 6 reserved 06 StarFire RTG single freq no Tide Adjustment 7 reserved 07 reserved 8 reserved 08 reserved 9 Forced to unknown frequency ie Manual selection 09 reserved 10 DGPS RTCM type 1 or 9 Dual Freq 11 StarFire RTG dual freq no Tide Adjustment 12 Code base Nav Single Frequency NCT Format Proprietary see I F Control Document 13 Code base Nav Single Frequency RTCM 18 19 14 Code base Nav S...

Страница 51: ...escription 1 Latitude in DDMM mmmmm format 5 decimal places 2 Direction of Latitude N North S South 3 Longitude in DDMM mmmmm format 5 decimal places 4 Direction of Longitude E East W West 5 UTC time of position fix in HHMMSS ss format 6 Fixed text A character shows that the data is valid otherwise null 7 Check Sum hexadecimal representation followed by CRLF terminator pair Table D 5 GLL Sentence ...

Страница 52: ...r PRN numbers which range from 1 to 32 b S B A S WAAS EGNOS etc has reserved numbers which range from 33 to 64 to identify their PRN identification which actually range from 120 to 138 Therefor an offset from NMEA S B A S SV ID to PRN number is 87 Thus an ENOS PRN number of 120 minus 87 yields a NMEA SV ID of 33 c The numbers 65 to 96 are reserved for GLONNASS satellites GLONASS satellites are ide...

Страница 53: ...ror in meters 8 Standard Deviation of altitude error in meters 9 Check Sum hexadecimal representation followed by CRLF terminator pair Table D 7 GST Sentence Fields The C Nav 2050 GPS Receiver uses a conventional weighted least squares algorithm for its position solution The results of the weighted least squares solution are reported directly to the external interfaces with no additional filtering...

Страница 54: ...ma value can be approximated to an area of probability in which 95 of the horizontal position measurements will lie by multiplying by 2 447 References National Marine Electronics Association NMEA 0183 Standard for Interfacing Marine Electronic Devices Version 2 1 October 15 1995 UKOOA Guidelines For The Use of Differential GPS in Offshore Surveying Appendix C equation 1 25 UKOOA Guidelines For The...

Страница 55: ...never the C Nav GPS Receiver suspects something is in error or wrong 3 Latitude in DDMM mmmmm format 5 decimal places 4 Direction of Latitude N North S South 5 Longitude in DDMM mmmmm format 5 decimal places 6 Direction of Longitude E East W West 7 Speed Over Ground SOG in nautical miles per hour knots 8 Course Over Ground COG in degrees from True North 9 UTC Date in DDMMYY format 10 Magnetic Vari...

Страница 56: ...orth 3 Course over Ground COG in degrees from Magnetic North null value 4 Letter M to indicate course is relative to Magnetic North 5 Speed over Ground SOG in nautical miles per hour knots 6 Letter N to indicate that the speed over ground is in knots 7 Speed over Ground SOG in kilometers per hour km hr 8 Letter K to indicate that the speed over ground is in km hr 9 Letter D to indicate a different...

Страница 57: ...umber and the local time zone minutes Example GPZDA 124215 02 06 2004 00 00 4B FIELD Description 1 UTC time in HHMMSS ss format 2 UTC Day 3 UTC Month 4 UTC Year 5 Local Time Zone Number for East Longitude 6 Local Time Zone Minutes 7 Check Sum hexadecimal representation followed by CRLF terminator pair Table D 10 ZDA Sentence Fields C 49 ...

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Страница 59: ...equency Name RTG WCT SBAS Geo stationary Position 1545 545 MHz LBM Channel 41090 Americas YES YES NO 98 Deg West 1545 545 MHz LBM Channel 41090 Far East YES YES NO 109 Deg East 1545 540 MHz LBM Channel 41080 Europe Africa YES YES NO 25 Deg East GPS L1 PRN 122 AOR W NO NO WAAS 54 Deg West GPS L1 PRN 134 POR NO NO WAAS 178 Deg East GPS L1 PRN 120 AOR E NO NO EGNOS 15 5 Deg West GPS L1 PRN 124 ARTEMI...

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Страница 61: ...tion the RAW binary data to a log file and directory and enable the logging SCHEDULE Use a logging file name of serialnumber dat 4 When running the STARUTIL program continually in this scheduled logging mode then every day a new data file will be created in the selected logging directory folder 5 Every few days you can purge any old unwanted data logging files to save disk space The RAW binary dat...

Страница 62: ...2050 User Guide C 54 ...

Страница 63: ...2050 User Guide Enter a filename using the actual C Nav 2050 Serial Number with an extension of dat C 55 ...

Страница 64: ...2050 User Guide C 56 ...

Страница 65: ...2050 User Guide C 57 ...

Страница 66: ...2050 User Guide This correction age is setup for C Nav RTG corrections Set to a lower value if using External RTCM correction input mode C 58 ...

Страница 67: ...2050 User Guide Select the NMEA data output baud rate required for your Nav or DP system This is the Com1 auxillary RS 232 connection on the front of the C Nav 2050 unit C 59 ...

Страница 68: ...2050 User Guide Connect to MS Windows computer running the STARUTIL application Port B Connect to Nav or DP system for NMEA Data Messages Port A External 3rd party correction input option C 60 ...

Страница 69: ...us positioning GPS a mode of operation in which a GPS receiver computes position fixes in real time from satellite data alone without reference to data supplied by a reference station or orbital clock corrections Autonomous positioning is typically the least precise positioning procedure a GPS receiver can perform yielding position fixes that are precise to 100 meters with Selective Availability o...

Страница 70: ...ns based on the actual and observed ranges to the satellites being tracked The coordinates of the unknown location can be computed with sub meter level precision by applying these corrections to the satellite data received by the rover Dilution of Precision DOP a class of measures of the magnitude of error in GPS position fixes due to the orientation of the GPS satellites with respect to the GPS r...

Страница 71: ... management and development planning GIS software is used to display edit query and analyze all the graphical objects and their associated information Global Positioning System GPS geometrically there can only be one point in space which is the correct distance from each of four known points GPS measures the distance from a point to at least four satellites from a constellation of 24 NAVSTAR satel...

Страница 72: ...s that make up the RINEX file format Where YY indicates the last two digits of the year the data was collected A meteorological file contains atmospheric information MSL see Mean sea level multipath error a positioning error resulting from interference between radio waves that has traveled between the transmitter and the receiver by two paths of different electrical lengths navigation YYn files on...

Страница 73: ...ber sequence from 1 32 prn Lower Case see Pseudorandom Noise Protected code see P code Proprietary commands those messages sent to and received from GPS equipment produced by NavCom Technology Inc own copyrighted binary language pseudo random noise prn a sequence of data that appears to be randomly distributed but can be exactly reproduced Each GPS satellite transmits a unique PRN in its signals G...

Страница 74: ...e the navigation YYn file and the meteorological YYm files where YY indicates the last two digits of the year the data was collected rover any mobile GPS receiver and field computer collecting data in the field A roving receiver s position can be differentially corrected relative to a stationary reference GPS receiver or by using GPS orbit and clock corrections from a SBAS such as StarFire roving ...

Страница 75: ...ellite Universal Time Coordinated UTC a time standard maintained by the US Naval Observatory based on local solar mean time at the Greenwich meridian GPS time is based on UTC UTC see Universal time coordinated WAAS Wide Area Augmentation System a set of corrections for the GPS satellites which are valid for the Americas region They incorporate satellite orbit and clock corrections WADGPS Wide Area...

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