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Satellite Constellations
Your Global Positioning System receiver (GPSr) must
utilize information transmitted from one or more satellite constellations to accurately and precisely calculate your current position. Which systems are used and the number of satellite signals available will impact
device performance and accuracy.
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.Iridium
Iridium is the only mobile voice and data satellite communications network that spans the entire globe. It is comprised of six polar orbiting planes, each containing 11 crosslinked satellites totaling 66 in the operational constellation, creating a web of coverage around the Earth. Iridium enables connections between people, organizations and assets to and from anywhere, in real time.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 most handheld Garmin GPS 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 satellites transmit differential correction data to improve the accuracy of positions derived from US GPS satellite signals while providing users with GPS signal reliability information.
- 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.
- MSAS uses two Multi-functional Transport Satellites (MTSAT) and a network of ground stations to augment GPS signals over Japan.
GAGAN
- The GPS Aided Geo Augmented Navigation is a regional satellite based augmentation system (SBAS) implemented by the government of India.
- GAGAN consists of 3 geostationary satellites, 15 reference stations, 3 uplink stations and 2 control centers.
- GAGAN is compatible with other SBAS systems (WAAS, EGNOS, MSAS).
- The final satellite in the constellation was launched November 10, 2015.
SDCM
- The Russian System for Differential Corrections and Monitoring is an integral component of GLONASS.
- SDCM differentiates itself from other SBAS systems by performing integrity monitoring of both GPS and GLONASS satellites.
SNAS
- China is currently in the process of developing their Satellite Navigation Augmentation System under the BeiDou program.
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
- Most global positioning systems use a form of spread-spectrum or code-division multiple access (CDMA) communications where each signal source is modulated by a pseudo-random noise (PRN) 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, GALILEO, SBAS) 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 |
|||||||
| 64-96 |
GBAS |
65-88 |
GLONASS |
NMEA = GLONASS Slot Number + 64 |
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| 97-119 |
GBAS |
|
||||||
| 120-138 |
SBAS |
33-51 |
SBAS |
NMEA = SBAS PRN - 87 |
||||
| 139-158 |
SBAS Expansion/Testing |
52-71 |
SBAS |
NMEA = SBAS PRN - 87 |
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| 159-210 |
Future GNSS |
|||||||
| E01-E36 | GALILEO | 01-36 | GALILEO | NMEA = PRN (no "E" prefix) |
Satellite Tracking
- Track individual GPS, GLONASS and GALILEO satellites or...
- Choose a satellite from the list below to view current status, location and other detailed information.
- Compare current satellite locations against the Satellite page on your GPSr.
| PRN | NMEA | System | NORAD | Identification | Notes |
| 01 | 01 | GPS | 37753 | SVN 63 (Navstar 66) USA-232 | |
| 02 | 02 | GPS | 28474 | SVN 61 (Navstar 56) USA-180 | |
| 03 | 03 | GPS | 40294 | SVN 69 (Navstar 72) USA-258 | |
| 04 | 04 | GPS | 43873 | SVN 74 (Navstar 77) USA-289 | First to broadcast operational L1C signal |
| 05 | 05 | GPS | 35752 | SVN 50 (Navstar 64) USA-206 | (IIR-3) (IIR-21) |
| 06 | 06 | GPS | 39741 | SVN 67 (Navstar 70) USA-251 | |
| 07 | 07 | GPS | 32711 | SVN 48 (Navstar 62) USA-201 | (IIR-19) |
| 08 | 08 | GPS | 40740 | SVN 72 (Navstar 74) USA-262 | |
| 09 | 09 | GPS | 40105 | SVN 68 (Navstar 71) USA-256 | |
| 10 | 10 | GPS | 41019 | SVN 73 (Navstar 75) USA-265 | |
| 11 | 11 | GPS | 25933 | SVN 46 (Navstar 46) USA-145 | |
| 12 | 12 | GPS | 29601 | SVN 58 (Navstar 59) USA-192 | (IIR-16) |
| 13 | 13 | GPS | 24876 | SVN 43 (Navstar 43) USA-132 | |
| 14 | 14 | GPS | 26605 | SVN 41 (Navstar 49) USA-154 | |
| 15 | 15 | GPS | 32260 | SVN 55 (Navstar 60) USA-196 | (IIR-17) |
| 16 | 16 | GPS | 27663 | SVN 56 (Navstar 51) USA-166 | |
| 17 | 17 | GPS | 28874 | SVN 53 (Navstar 57) USA-183 | |
| 18 | 18 | GPS | 22877 | SVN 34 (Navstar 35) USA-96 | |
| 19 | 19 | GPS | 28190 | SVN 59 (Navstar 54) USA-177 | |
| 20 | 20 | GPS | 26360 | SVN 51 (Navstar 47) USA-150 | |
| 21 | 21 | GPS | 27704 | SVN 45 (Navstar 52) USA-168 | |
| 22 | 22 | GPS | 28129 | SVN 47 (Navstar 53) USA-175 | |
| 23 | 23 | GPS | 28361 | SVN 60 (Navstar 55) USA-178 | |
| 24 | 24 | GPS | 38833 | SVN 65 (Navstar 67) USA-239 | |
| 25 | 25 | GPS | 36585 | SVN 62 (Navstar 65) USA-213 | First to broadcast operational L5 signal |
| 26 | 26 | GPS | 40534 | SVN 71 (Navstar 73) USA-260 | |
| 27 | 27 | GPS | 39166 | SVN 66 (Navstar 68) USA-242 | Launched 15MAY13, Enabled 21JUN13 |
| 28 | 28 | GPS | 26407 | SVN 44 (Navstar 48) USA-151 | |
| 29 | 29 | GPS | 32384 | SVN 57 (Navstar 61) USA-199 | (IIR-18) |
| 30 | 30 | GPS | 39533 | SVN 64 (Navstar 69) USA-248 | (GPS 2F-5) |
| 31 | 31 | GPS | 29486 | SVN 52 (Navstar 58) USA-190 | (IIR-15) |
| 32 | 32 | GPS | 41328 | SVN 70 (Navstar 76) USA-266 | |
| PRN | NMEA | System | NORAD | Identification | Notes |
| 120 | 33 | SBAS | 24307 | Inmarsat 3-F2 (AOR-E) | (174 W) |
| 121 | 34 | SBAS | 25153 | Inmarsat 3-F5 (EMEA) | (25 E) (APR 2024) |
| 122 | 35 | AUS-NZ | 28628 | Inmarsat 4-F1 | (143.5 E) (JAN 2019) |
| 123 | 36 | EGNOS | 39617 | Astra 5B | (31.5 E) (NOV 2021) |
| 124 | 37 | SBAS | 26863 | ARTEMIS | (76.8 E) (APR 2024) |
| 125 | 38 | SDCM | 37951 | Luch-5A | (16 W) (DEC 2021) |
| 126 | 39 | EGNOS | 28899 | Inmarsat 4-F2 (IOR-W) | (63.9 E) (APR 2019) |
| 127 | 40 | GAGAN | 37605 | GSAT-8 | (55 E) (SEP 2020) |
| 128 | 41 | GAGAN | 38779 | GSAT-10 | (83 E) (SEP 2020) |
| 129 | 42 | MSAS | 28622 | MTSAT-1R | (148 E) (JAN 2020) (Himawari 6) |
| 130 | 43 | SNAS | BDSBAS (G6) | (80 E) (OCT 2020) | |
| 131 | 44 | WAAS | 41589 | Eutelsat 117 West B | (117 W) (MAR 2028) |
| 132 | 45 | GAGAN | 41028 | GSAT-15 | (93.5 E) (NOV 2025) |
| 133 | 46 | WAAS | 33278 | Inmarsat 4-F3 | (98 W) (OCT 2029) |
| 134 | 47 | KAAS | 40882 | Inmarsat 5-F3 | (178 E) (JUN 2021) |
| 135 | 48 | WAAS | 28884 | Galaxy 15 | (133 W) (JUL 2019) |
| 136 | 49 | EGNOS | 38652 | SES 5 | (5 E) (NOV 2021) (a.k.a. Sirius 5 or Astra 4B) |
| 137 | 50 | MSAS | 28937 | MTSAT-2 | (145 E) (JAN 2020) (Himawari 7) |
| 138 | 51 | WAAS | 28868 | Anik F1-R | (107.3 W) (JUL 2022) |
| Slot | NMEA | System | NORAD | Identification | Notes |
| 01 | 65 | GLONASS | 36111 | 730 (COSMOS 2456) | GN 65 |
| 02 | 66 | GLONASS | 39155 | 747 (COSMOS 2485) | GN 66 |
| 03 | 67 | GLONASS | 37867 | 744 (COSMOS 2476) | GN 67 |
| 04 | 68 | GLONASS | 37829 | 742 (COSMOS 2474) | GN 68 |
| 05 | 69 | GLONASS | 43508 | 756 (COSMOS 2527) | GN 69 |
| 06 | 70 | GLONASS | 36112 | 733 (COSMOS 2457) | GN 70 |
| 07 | 71 | GLONASS | 37868 | 745 (COSMOS 2477) | GN 71 |
| 08 | 72 | GLONASS | 37869 | 743 (COSMOS 2475) | GN 72 |
| 09 | 73 | GLONASS | 40315 | 702 (COSMOS 2501) | GN 73 |
| 10 | 74 | GLONASS | 29671 | 717 (COSMOS 2426) | GN 74 |
| 11 | 75 | GLONASS | 41554 | 753 (COSMOS 2516) | GN 75 |
| 12 | 76 | GLONASS | 44299 | 758 (COSMOS 2534) | GN 76 |
| 13 | 77 | GLONASS | 32393 | 721 (COSMOS 2434) | GN 77 |
| 14 | 78 | GLONASS | 42939 | 752 (COSMOS 2522) | GN 78 |
| 15 | 79 | GLONASS | 43687 | 757 (COSMOS 2529) | GN 79 |
| 16 | 80 | GLONASS | 37139 | 736 (COSMOS 2464) | GN 80 |
| 17 | 81 | GLONASS | 41330 | 751 (COSMOS 2514) | GN 81 |
| 18 | 82 | GLONASS | 39620 | 754 (COSMOS 2492) | GN 82 |
| 19 | 83 | GLONASS | 32275 | 720 (COSMOS 2433) | GN 83 |
| 20 | 84 | GLONASS | 32276 | 719 (COSMOS 2432) | GN 84 |
| 21 | 85 | GLONASS | 40001 | 755 (COSMOS 2500) | GN 85 |
| 22 | 86 | GLONASS | 36400 | 731 (COSMOS 2459) | GN 86 |
| 23 | 87 | GLONASS | 36402 | 732 (COSMOS 2460) | GN 87 |
| 24 | 88 | GLONASS | 36401 | 735 (COSMOS 2461) | GN 88 |
| PRN | NMEA | System | NORAD | Identification | Notes |
| E01 | 01 | GALILEO | 41550 | GALILEO 13 (26A) | |
| E02 | 02 | GALILEO | 41549 | GALILEO 14 (26B) | |
| E03 | 03 | GALILEO | 41860 | GALILEO 16 (26C) | |
| E04 | 04 | GALILEO | 41861 | GALILEO 17 (26D) | |
| E05 | 05 | GALILEO | 41862 | GALILEO 18 (26E) | |
| E06 | 06 | GALILEO | |||
| E07 | 07 | GALILEO | 41859 | GALILEO 15 (267) | |
| E08 | 08 | GALILEO | 41174 | GALILEO 11 (268) | |
| E09 | 09 | GALILEO | 41175 | GALILEO 12 (269) | |
| E10 | 10 | GALILEO | |||
| E11 | 11 | GALILEO | 37846 | GALILEO-PFM | |
| E12 | 12 | GALILEO | 37847 | GALILEO-FM2 | |
| E13 | 13 | GALILEO | 43567 | GALILEO 24 (2C0) | |
| E14 | 14 | GALILEO | 40129 | GALILEO 6 (262) | |
| E15 | 15 | GALILEO | 43564 | GALILEO 25 (2C1) | |
| E16 | 16 | GALILEO | |||
| E17 | 17 | GALILEO | |||
| E18 | 18 | GALILEO | 40128 | GALILEO 5 (261) | |
| E19 | 19 | GALILEO | 38857 | GALILEO-FM3 | |
| E20 | 20 | GALILEO | 38858 | GALILEO-FM4 | Payload power problem 27MAY14 |
| E21 | 21 | GALILEO | 43055 | GALILEO 19 (2C5) | |
| E22 | 22 | GALILEO | 40545 | GSAT0204 | Removed from active service 08DEC17 |
| E23 | 23 | GALILEO | |||
| E24 | 24 | GALILEO | 40889 | GALILEO 9 (205) | |
| E25 | 25 | GALILEO | 43056 | GALILEO 20 (2C6) | |
| E26 | 26 | GALILEO | 40544 | GSAT0203 | |
| E27 | 27 | GALILEO | 43057 | GALILEO 21 (2C7) | |
| E28 | 28 | GALILEO | |||
| E29 | 29 | GALILEO | |||
| E30 | 30 | GALILEO | 40890 | GALILEO 10 (206) | |
| E31 | 31 | GALILEO | 43058 | GALILEO 22 (2C8) | |
| E32 | 32 | GALILEO | |||
| E33 | 33 | GALILEO | 43565 | GALILEO 26 (2C2) | |
| E34 | 34 | GALILEO | |||
| E35 | 35 | GALILEO | |||
| E36 | 36 | GALILEO | 43566 | GALILEO 23 (2C9) |
What's Up?
- Have you ever wondered what satellites and other low orbit objects are flying over you right now?
- View all available GPS satellites positioned at minimum 20° above the horizon for your current location.
- View all available SBAS satellites positioned at minimum 20° above the horizon for your current location.
- View all available GLONASS satellites poitioned at minimum 20° above the horizon for your current location.
- View all available GALILEO satellites poitioned at minimum 20° above the horizon for your current location.
- View all satellites positioned at minimum 60° above the horizon (directly overhead) for your current location.
- View current GPS, GLONASS and GALILEO constellation status reports.