GPS Ground Segment - Revision history

Gema.Cueto: Updated reference ICD/SDD links

2026-04-17T12:12:45Z

Updated reference ICD/SDD links

← Older revision		Revision as of 12:12, 17 April 2026
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	*Passive tracking of the satellites.		*Passive tracking of the satellites.

	The Ground Segment is comprised of four major subsystems:<ref name="GPS SPS PS">[https://www.gps.gov/~~technical~~/ps/2020-SPS-performance-standard.pdf GPS Standard Positioning Service (SPS) Performance Standard, 5th Edition, April 2020]</ref>		The Ground Segment is comprised of four major subsystems:<ref name="GPS SPS PS">[https://www.gps.gov/sites/default/files/2025-07/2020-SPS-performance-standard.pdf GPS Standard Positioning Service (SPS) Performance Standard, 5th Edition, April 2020]</ref>
	*Master Control Station (MCS)		*Master Control Station (MCS)
	*Alternate Master Control Station		*Alternate Master Control Station

Gema.Cueto at 07:19, 5 November 2020

2020-11-05T07:19:52Z

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	\|Title={{PAGENAME}}		\|Title={{PAGENAME}}
	}}		}}

	The GPS Ground Segment (also referred to as Control Segment or Operational Control System) is the responsible for the proper operation of the GPS system.		The GPS Ground Segment (also referred to as Control Segment or Operational Control System) is the responsible for the proper operation of the GPS system.

	The GPS Control Segment consists of a global network of ground facilities that track the GPS satellites, monitor their transmissions, perform analysis, and send commands and data to the constellation<ref name=GPS_GS>[https://www.gps.gov/systems/gps/control/ GPS Ground Segment information in GPS official website]</ref>.		The GPS Control Segment consists of a global network of ground facilities that track the GPS satellites, monitor their transmissions, perform analysis, and send commands and data to the constellation<ref name=GPS_GS>[https://www.gps.gov/systems/gps/control/ GPS Ground Segment information in GPS official website]</ref>.


	==Introduction==		==Introduction==

Gema.Cueto: /* Introduction */

2020-11-05T07:19:09Z

Introduction

← Older revision		Revision as of 07:19, 5 November 2020
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	*Passive tracking of the satellites.		*Passive tracking of the satellites.

	The Ground Segment is comprised of four major subsystems:<ref name="GPS SPS PS">[~~http~~://www.gps.gov/technical/ps/~~2007~~-~~PPS~~-performance-standard.pdf GPS Standard Positioning Service (SPS) Performance Standard, ~~4th~~ Edition, ~~September 2008~~]</ref>		The Ground Segment is comprised of four major subsystems:<ref name="GPS SPS PS">[https://www.gps.gov/technical/ps/2020-SPS-performance-standard.pdf GPS Standard Positioning Service (SPS) Performance Standard, 5th Edition, April 2020]</ref>
	*Master Control Station (MCS)		*Master Control Station (MCS)
	*Alternate Master Control Station		*Alternate Master Control Station

Gema.Cueto: /* Notes */

2020-11-05T07:16:42Z

Notes

← Older revision		Revision as of 07:16, 5 November 2020
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	==Notes==		==Notes==
	<references group="footnotes"/>		<references group="footnotes"/>
			This article contains some verbatim paragraphs taken from U.S. governmental web pages. Please see the References section.

	==References==		==References==
	<references/>		<references/>

Gema.Cueto: /* Control Segment Modernization */

2020-11-05T07:16:12Z

Control Segment Modernization

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 As part of the GPS modernization program, the Air Force has continuously upgraded the GPS control segment for many years. The ground upgrades are necessary to command and control the newer GPS satellites and to enhance cybersecurity.
 The Next Generation Operational Control System (OCX) is the future version of the GPS control segment. OCX will command all modernized (GPS III) and legacy GPS satellites, manage all civil and military navigation signals, and provide improved cybersecurity and resilience for the next generation of GPS operations. It will consist of<ref name="OCX">[https://www.gps.gov/systems/gps/control/OCX/ Next Generation Operational Control System (OCX) in GPS official website]</ref>:
 ==Notes==

Gema.Cueto: /* The Ground Antennas */

2020-11-05T07:14:10Z

The Ground Antennas

← Older revision		Revision as of 07:14, 5 November 2020
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	In addition, 7 Air Force Satellite Control Network (AFSCN) remote tracking stations are part of the Ground Antennas.		In addition, 7 Air Force Satellite Control Network (AFSCN) remote tracking stations are part of the Ground Antennas.

			==Control Segment Modernization==
			As part of the GPS modernization program, the Air Force has continuously upgraded the GPS control segment for many years. The ground upgrades are necessary to command and control the newer GPS satellites and to enhance cybersecurity.
			The Next Generation Operational Control System (OCX) is the future version of the GPS control segment. OCX will command all modernized (GPS III) and legacy GPS satellites, manage all civil and military navigation signals, and provide improved cybersecurity and resilience for the next generation of GPS operations. It will consist of<ref name="OCX">[https://www.gps.gov/systems/gps/control/OCX/ Next Generation Operational Control System (OCX) in GPS official website]</ref>:

	==Notes==		==Notes==

Gema.Cueto: /* The Ground Antennas */

2020-11-05T07:10:23Z

The Ground Antennas

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	[[File:GPS_infrastructure.png‎\|GPS infrastructure in the world\|200px\|right\|thumb]]		[[File:GPS_infrastructure.png‎\|GPS infrastructure in the world\|200px\|right\|thumb]]

	The Ground Antennas ~~uplink~~ data to the satellites via S-~~band radio signals. These data includes ephemerides~~ and ~~clock correction information transmitted within the Navigation Message, as well as command telemetry from the MCS~~.		The main functions of the Ground Antennas are:
			*Send commands, navigation data uploads, and processor program loads to the satellites.
			*Collect telemetry.
			*Communicate via S-Band and perform S-Band ranging to provide anomaly resolution and early orbit support.

	This information can be uploaded to each satellite three times per day, i.e., every 8 hours; nevertheless, it is usually updated just once a day.		This information can be uploaded to each satellite three times per day, i.e., every 8 hours; nevertheless, it is usually updated just once a day.
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	*Kwajalein		*Kwajalein

			In addition, 7 Air Force Satellite Control Network (AFSCN) remote tracking stations are part of the Ground Antennas.

	==Notes==		==Notes==

Gema.Cueto: /* The Monitor Stations */

2020-11-05T07:08:03Z

The Monitor Stations

← Older revision		Revision as of 07:08, 5 November 2020
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	==The Monitor Stations==		==The Monitor Stations==
	They are distributed around the world and equipped with atomic clocks standards and GPS receivers to continuously collect GPS data for all the satellites in view from their locations. The collected data is sent to the Master Control Station where it is processed to estimate satellite orbits (ephemerides) and clock errors, among other parameters, and to generate the Navigation Message.		They are distributed around the world and equipped with atomic clocks standards and GPS receivers to continuously collect GPS data for all the satellites in view from their locations. The collected data is sent to the Master Control Station where it is processed to estimate satellite orbits (ephemerides) and clock errors, among other parameters, and to generate the Navigation Message. They also collect navigation signals, range/carrier measurements and atmospheric data.

	Prior to the modernization program, the Monitor Stations network comprised five sites located in<ref name="GNSS-Book "/>:		Prior to the modernization program, the Monitor Stations network comprised five sites located in<ref name="GNSS-Book "/>:
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	*Wellington (New Zealand).		*Wellington (New Zealand).

	With this configuration, each satellite is seen from at least three monitor stations,<ref name="GNSS-Book ">J. Sanz Subirana, JM. Juan Zornoza and M. Hernández-Pajares, ''Global Navigation Satellite Systems: Volume I: Fundamentals and Algorithms''</ref> which allows computing more precise orbits and ephemeris data, therefore improving system accuracy.		Currently the network is composed by 16 stations, 6 from the Air Force plus 10 from the NGA (National Geospatial-Intelligence Agency). With this configuration, each satellite is seen from at least three monitor stations,<ref name="GNSS-Book ">J. Sanz Subirana, JM. Juan Zornoza and M. Hernández-Pajares, ''Global Navigation Satellite Systems: Volume I: Fundamentals and Algorithms''</ref> which allows computing more precise orbits and ephemeris data, therefore improving system accuracy.

	==The Ground Antennas==		==The Ground Antennas==

Gema.Cueto: /* The Master Control Station */

2020-11-05T07:06:43Z

The Master Control Station

← Older revision		Revision as of 07:06, 5 November 2020
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	==The Master Control Station==		==The Master Control Station==
	Located at Colorado Springs, the Master Control Station (MCS) is the central control node for the GPS satellite constellation. The MCS is responsible for all aspects of constellation command and control, ~~to include~~:<ref name="GPS SPS PS"/>		Located at Colorado Springs, the Master Control Station (MCS) is the central control node for the GPS satellite constellation. It is backed up by a fully operational alternate master control station. The MCS is responsible for all aspects of constellation command and control, including:<ref name="GPS SPS PS"/>
			*Provides command and control of the GPS constellation.
			*Uses global monitor station data to compute the precise locations of the satellites.
			*Generates navigation messages for upload to the satellites.
			*Monitors satellite broadcast and system integrity to ensure constellation health and accuracy.
	*Routine satellite bus and payload status monitoring.		*Routine satellite bus and payload status monitoring.
	*~~Satellite~~ maintenance and anomaly resolution.		*Performs satellite maintenance and anomaly resolution, including repositioning satellites to maintain optimal constellation.
	*Monitoring and management of ~~Precise Positioning Service (PPS)~~ Signal-In-Space (SIS) performance ~~in support of~~ all performance standards.		*Currently uses separate systems (AEP and LADO) to control operational and non-operational satellites.
			*Monitoring and management of GPS Signal-In-Space (SIS) performance to comply with all performance standards (SPS PS and PPS PS).
	*Navigation message data upload operations as required to sustain performance in accordance with accuracy and integrity performance standards.		*Navigation message data upload operations as required to sustain performance in accordance with accuracy and integrity performance standards.
	*Detecting and responding to ~~PPS~~ SIS failures.		*Detecting and responding to GPS SIS failures.

	==The Monitor Stations==		==The Monitor Stations==

Gema.Cueto: /* Introduction */

2020-11-05T07:02:44Z

Introduction

← Older revision		Revision as of 07:02, 5 November 2020
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	==Introduction==		==Introduction==
	[[File:GPS ground segment.png\|GPS Operational Control System\|~~300px~~\|thumb\|right]]		[[File:GPS ground segment.png\|GPS Operational Control System\|250px\|thumb\|right]]
	[[File:GPSGroundSegment.png \| GPS Control ~~System~~<ref name=GPS_GS></ref>\|~~300px~~\|thumb\|right]]		[[File:GPSGroundSegment.png \| GPS Control Segment<ref name=GPS_GS></ref>\|250px\|thumb\|right]]

	The Ground Segment, also referred to as Control Segment or Operational Control System, OCS, is the responsible for the proper operation of the GPS system. The main tasks performed by the CS are the following:		The Ground Segment, also referred to as Control Segment or Operational Control System, OCS, is the responsible for the proper operation of the GPS system. The main tasks performed by the CS are the following: