Satellites

Satellite Constellations

Your Global Positioning System receiver (GPSr) must utilize information transmitted from one or more of the following GPS satellite constellations to accurately and precisely calculate your current position. Which systems are used and the number of satellite signals available will impact performance.

GPS

The Global Positioning System is a space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites. The original concept for a Defense Navigation Satellite System (DNSS) in September 1973 was later named Navstar (NAVigation System using Timing And Ranging), then Navstar-GPS to identify the constellation of Navstar satellites, and eventually shortened simply to GPS. Achieving initial operational capability (IOC) in December 1993, Full Operational Capability (FOC) was declared by Air Force Space Command (AFSPC) in April 1995. The highest quality signals were reserved for military use, and the signal available for civilian use was intentionally degraded. Selective Availability was discontinued on May 2, 2000, allowing users to receive a non-degraded signal globally. GPS is maintained by the United States government and is freely accessible to anyone with a GPS receiver.

GLONASS

The GLObal NAvigation Satellite System is a space-based satellite navigation system operated by the Russian Aerospace Defence Forces. It both complements and provides an alternative to the United States' Global Positioning System (GPS) and is the only alternative navigational system in operation with global coverage and comparable precision. GLONASS initially achieved Full Operational Capability (FOC) in December, 1995. Financial difficulties crippled the Russian space program, leaving them with only 6 operational satellites by 2001. In 2010, GLONASS had achieved 100% coverage of Russia's territory, and by October 2011, the full orbital constellation of 24 satellites was restored, enabling full global coverage.

GALILEO

Galileo is the global navigation satellite system (GNSS) that is being created by the European Union (EU) through the European GNSS Agency (GSA), headquartered in Prague in the Czech Republic, with two ground operations centres, Oberpfaffenhofen near Munich in Germany and Fucino in Italy. The project is named after the Italian astronomer Galileo Galilei. Galileo is intended to provide an independent high-precision positioning system so European nations do not have to rely on the Russian GLONASS, Chinese BeiDou or US GPS systems. The first Galileo test satellite, the GIOVE-A, was launched 28 December 2005, while the first satellite to be part of the operational system was launched on 21 October 2011. As of July 2018, 26 of the planned 30 active satellites were in orbit. Galileo started offering Early Operational Capability (EOC) on 15 December 2016, providing initial services with a weak signal, and is expected to reach Full Operational Capability (FOC) in 2019.


 

GBAS

The Ground Based Augmentation System (also referred to as Local Area Augmentation System in U.S.) is intended primarily to support precision aviation approach operations. GBAS information is transmitted using VHF signals Garmin GPSMAP receivers are not equipped to receive.

SBAS

A Satellite Based Augmentation System supports wide-area or regional augmentation through the use of additional satellite-broadcast messages.

WAAS

The Wide Area Augmentation System is a satellite based augmentation system (SBAS) jointly developed by the United States Department of Transportation (DOT) and the Federal Aviation Administration (FAA). WAAS was commissioned for use on July 10, 2003.

EGNOS

The European Geostationary Navigation Overlay Service is a satellite based augmentation system (SBAS) developed by the European Space Agency, the European Commission, and EUROCONTROL. EGNOS operations were initiated in July 2005. An EGNOS Data Access Service was made available in July 2012.

MSAS

The Multi-functional Satellite Augmentation System is a Japanese satellite based augmentation system (SBAS) commissioned on September 27, 2007.

GAGAN

The GPS Aided Geo Augmented Navigation is a regional satellite based augmentation system (SBAS) implemented by the government of India. GAGAN is scheduled to be fully operational in early 2014.

Satellite Identification

Have you ever considered what the numbers assigned to each GPS satellite on your Garmin GPSr represent, or how they are determined?

PRN

Global positioning systems use a form of spread-spectrum or code-division multiple access (CDMA) communications where each signal source is modulated by a PRN (pseudo-random noise) code. The PRN code (along with other encoded sub codes) dithers the L1 carrier (or the coarse-acquisition carrier) of the signal. All receivers listen on the same L1 frequency, but they sort out the satellite signals by demodulating them according to their PRN encoding.

NMEA

Garmin GPS receivers employing the NMEA 0183 specification assign each GPS satellite signal a unique NMEA identification number based on the satellite PRN number (GPS) or slot number (GLONASS):
PRN
Standard Assignment
NMEA
Garmin Assignment
Garmin NMEA Conversion
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01-32
GPS
01-32
GPS
NMEA = PRN
33-63
GPS
33-63
SBAS
NMEA = SBAS PRN - 87
64-96
GBAS
65-88
GLONASS
NMEA = GLONASS Slot Number + 64
97-119
GBAS





120-158
SBAS





159-210
Future GNSS







Satellite Tracking
PRN NMEA System Identification Note
         
01 01 GPS SVN 63 (Navstar 66) USA-232  
02 02 GPS SVN 61 (Navstar 56) USA-180  
03 03 GPS SVN 69 (Navstar 72) USA-258  
04 04 GPS SVN 34 (Navstar 35) USA-96 Decommissioned 03NOV15
05 05 GPS SVN 50 (Navstar 64) USA-206 (IIR-3) (IIR-21)
06 06 GPS SVN 67 (Navstar 70) USA-251  
07 07 GPS SVN 48 (Navstar 62) USA-201 (IIR-19)
08 08 GPS SVN 72 (Navstar 74) USA-262  
09 09 GPS SVN 68 (Navstar 71) USA-256  
10 10 GPS SVN 73 (Navstar 75) USA-265  
11 11 GPS SVN 46 (Navstar 46) USA-145  
12 12 GPS SVN 58 (Navstar 59) USA-192 (IIR-16)
13 13 GPS SVN 43 (Navstar 43) USA-132  
14 14 GPS SVN 41 (Navstar 49) USA-154  
15 15 GPS SVN 55 (Navstar 60) USA-196 (IIR-17)
16 16 GPS SVN 56 (Navstar 51) USA-166  
17 17 GPS SVN 53 (Navstar 57) USA-183  
18 18 GPS SVN 54 (Navstar 50) USA-156 Retired 05MAR18
19 19 GPS SVN 59 (Navstar 54) USA-177  
20 20 GPS SVN 51 (Navstar 47) USA-150  
21 21 GPS SVN 45 (Navstar 52) USA-168  
22 22 GPS SVN 47 (Navstar 53) USA-175  
23 23 GPS SVN 60 (Navstar 55) USA-178  
24 24 GPS SVN 65 (Navstar 67) USA-239  
25 25 GPS SVN 62 (Navstar 65) USA-213 First to broadcast operational L5 signal
26 26 GPS SVN 71 (Navstar 73) USA-260  
27 27 GPS SVN 66 (Navstar 68) USA-242 Launched 15MAY13, Enabled 21JUN13
28 28 GPS SVN 44 (Navstar 48) USA-151  
29 29 GPS SVN 57 (Navstar 61) USA-199 (IIR-18)
30 30 GPS SVN 64 (Navstar 69) USA-248 (GPS 2F-5)
31 31 GPS SVN 52 (Navstar 58) USA-190 (IIR-15)
32 32 GPS SVN 70 (Navstar 76) USA-266  
         
PRN NMEA System Identification Note
         
120 33 EGNOS Inmarsat 3-F2 (AOR-E)  
121 34 SBAS Inmarsat 3-F5 (EMEA) (SBAS backup)
122 35 WAAS Inmarsat 3-F4 (AOR-W) Ceased WAAS transmissions 31JUL07
124 37 EGNOS ARTEMIS  
126 39 EGNOS Inmarsat 4-F2 (IOR-W)  
127 40 GAGAN GSAT-8  
128 41 GAGAN GSAT-10  
129 42 MSAS MTSAT-1R (Himawari 6)
131 44 EGNOS Inmarsat 3-F1 (IOR)  
133 46 WAAS Inmarsat 4-F3  
134 47 WAAS Inmarsat 3-F3 (POR) Ceased WAAS transmissions 31JUL07
135 48 WAAS Galaxy 15  
137 50 MSAS MTSAT-2 (Himawari 7)
138 51 WAAS Anik F1-R  
         
Slot NMEA System Identification Note
         
01 65 GLONASS 730 (COSMOS 2456)  
02 66 GLONASS 747 (COSMOS 2485)  
03 67 GLONASS 744 (COSMOS 2476)  
04 68 GLONASS 742 (COSMOS 2474)  
05 69 GLONASS 734 (COSMOS 2458)  
06 70 GLONASS 733 (COSMOS 2457)  
07 71 GLONASS 745 (COSMOS 2477)  
08 72 GLONASS 743 (COSMOS 2475)  
09 73 GLONASS 736 (COSMOS 2464)  
10 74 GLONASS 717 (COSMOS 2426)  
11 75 GLONASS 723 (COSMOS 2436)  
12 76 GLONASS 737 (COSMOS 2465)  
13 77 GLONASS 721 (COSMOS 2434)  
14 78 GLONASS 715 (COSMOS 2424)  
15 79 GLONASS 716 (COSMOS 2425)  
16 80 GLONASS 738 (COSMOS 2466)  
17 81 GLONASS 714 (COSMOS 2419)  
18 82 GLONASS 754 (COSMOS 2491)  
19 83 GLONASS 720 (COSMOS 2433)  
20 84 GLONASS 719 (COSMOS 2432)  
21 85 GLONASS 755 (COSMOS 2500)  
22 86 GLONASS 731 (COSMOS 2459)  
23 87 GLONASS 732 (COSMOS 2460)  
24 88 GLONASS 735 (COSMOS 2461)  
         
PRN NMEA System Identification Note
         
E01   GALILEO GALILEO 13 (26A)  
E02   GALILEO GALILEO 14 (26B)  
E03   GALILEO GALILEO 16 (26C)  
E04   GALILEO GALILEO 17 (26D)  
E05   GALILEO GALILEO 18 (26E)  
E06   GALILEO    
E07   GALILEO GALILEO 15 (267)  
E08   GALILEO GALILEO 11 (268)  
E09   GALILEO GALILEO 12 (269)  
E10   GALILEO    
E11   GALILEO GALILEO-PFM  
E12   GALILEO GALILEO-FM2  
E13   GALILEO GALILEO 24 (2C0)  
E14   GALILEO GALILEO 6 (262)  
E15   GALILEO GALILEO 25 (2C1)  
E16   GALILEO    
E17   GALILEO    
E18   GALILEO GALILEO 5 (261)  
E19   GALILEO GALILEO-FM3  
E20   GALILEO GALILEO-FM4 Payload power problem 27MAY14 - No E1, E5, or E6 transmission.
E21   GALILEO GALILEO 19 (2C5)  
E22   GALILEO GSAT0204 Removed from active service 08DEC17 for constellation management purposes.
E23   GALILEO    
E24   GALILEO GALILEO 9 (205)  
E25   GALILEO GALILEO 20 (2C6)  
E26   GALILEO GSAT0203  
E27   GALILEO GALILEO 21 (2C7)  
E28   GALILEO    
E29   GALILEO    
E30   GALILEO GALILEO 10 (206)  
E31   GALILEO GALILEO 22 (2C8)  
E32   GALILEO    
E33   GALILEO GALILEO 26 (2C2)  
E34   GALILEO    
E35   GALILEO    
E36   GALILEO GALILEO 23 (2C9)  
         


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