GPS Signal Plan - Revision history

Gema.Cueto: Updated reference ICD/SDD links

2026-04-17T12:55:54Z

Updated reference ICD/SDD links

← Older revision		Revision as of 12:55, 17 April 2026
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	The information presented in this NAVIPEDIA’s article is an extract of the PhD work performed by Dr. Jose Ángel Ávila Rodríguez in the FAF University of Munich as part of his Doctoral Thesis “On Generalized Signal Waveforms for Satellite Navigation” presented in June 2008, Munich (Germany)		The information presented in this NAVIPEDIA’s article is an extract of the PhD work performed by Dr. Jose Ángel Ávila Rodríguez in the FAF University of Munich as part of his Doctoral Thesis “On Generalized Signal Waveforms for Satellite Navigation” presented in June 2008, Munich (Germany)

	The information of this article is regularly updated in line with the GPS modernization plan updates. Applicable GPS ICD documents can be found in https://~~www~~.gps.gov/technical/icwg/		The information of this article is regularly updated in line with the GPS modernization plan updates. Applicable GPS ICD documents can be found in https://archive.gps.gov/technical/icwg/
	[[Category:GNSS Signals]]		[[Category:GNSS Signals]]
	[[Category:GPS]]		[[Category:GPS]]
	[[Category:GPS Signal Structure]]		[[Category:GPS Signal Structure]]

Gema.Cueto at 10:40, 16 April 2026

2026-04-16T10:40:42Z

← Older revision		Revision as of 10:40, 16 April 2026
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	* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, [[GNSS Authentication and encryption \| authentication]], and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.		* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, [[GNSS Authentication and encryption \| authentication]], and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.

	* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800~~] Revision G,~~ "Navstar GPS Space Segment/User Segment L1C Interfaces".</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to [[GNSS Authentication and encryption \| authenticate]] the location of a GPS receiver to another party.		* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[https://archive.gps.gov/technical/icwg/IRN-IS-800J-003.pdf GPS ICD-800 "Navstar GPS Space Segment/User Segment L1C Interfaces"]</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to [[GNSS Authentication and encryption \| authenticate]] the location of a GPS receiver to another party.


	For more details on the code generation refer to the [GPS ICD 200]<ref name="GPS_SIS_ICD_200">[GPS ICD-200~~] Revision L,~~ "Navstar GPS Space Segment/User Segment Interfaces".</ref> and [GPS ICD-800]<ref name="GPS_SIS_ICD_800"></ref>. Finally, the technical characteristics of the existing GPS signals in the L1 band are summarized in the following Table 1.		For more details on the code generation refer to the [GPS ICD 200]<ref name="GPS_SIS_ICD_200">[https://archive.gps.gov/technical/icwg/IRN-IS-200N-003.pdf GPS ICD-200 "Navstar GPS Space Segment/User Segment Interfaces"]</ref> and [GPS ICD-800]<ref name="GPS_SIS_ICD_800"></ref>. Finally, the technical characteristics of the existing GPS signals in the L1 band are summarized in the following Table 1.

	::::[[File:Chapter_2_Table_1.png\|none\|thumb\|520px\|'''''Table 1:''''' GPS L1 signal technical characteristics.]]		::::[[File:Chapter_2_Table_1.png\|none\|thumb\|520px\|'''''Table 1:''''' GPS L1 signal technical characteristics.]]
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	The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.		The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.

	The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705~~] Revision G,~~ "Navstar GPS Space Segment/User Segment L5 Interfaces" </ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.		The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[https://archive.gps.gov/technical/icwg/IRN-IS-705J-003.pdf GPS ICD-705 "Navstar GPS Space Segment/User Segment L5 Interfaces"]</ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.

Gema.Cueto: /* GPS L1 Band */

2021-01-29T12:05:24Z

GPS L1 Band

← Older revision		Revision as of 12:05, 29 January 2021
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	* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, [[GNSS Authentication and encryption \| authentication]], and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.		* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, [[GNSS Authentication and encryption \| authentication]], and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.

	* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800] Revision G, "Navstar GPS Space Segment/User Segment L1C Interfaces".</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to authenticate the location of a GPS receiver to another party.		* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800] Revision G, "Navstar GPS Space Segment/User Segment L1C Interfaces".</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to [[GNSS Authentication and encryption \| authenticate]] the location of a GPS receiver to another party.

Gema.Cueto: /* GPS L1 Band */

2021-01-29T11:34:27Z

GPS L1 Band

← Older revision		Revision as of 11:34, 29 January 2021
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	* The P Code is the precision signal and is coded by the precision code. Moreover the Y-Code is used in place of the P-code whenever the Anti-Spoofing (A/S) mode of operation is activated as described in the ICDs 203, 224 and 225. The PRN P-code for SV number i is a ranging code, Pi(t), 7 days long at a chipping rate of 10.23 Mbps. The 7 day sequence is the Modulo-2 sum of two sub-sequences referred to as <math>X_1</math> and <math>X_{2i}</math> with 15,345,000 chips and 15,345,037 chips, respectively. The <math>X_{2i}</math> sequence is an <math>X_2</math> sequence selectively delayed by 1 to 37 chips allowing the basic code generation technique to produce a set of 37 mutually exclusive P-code sequences 7 days long.		* The P Code is the precision signal and is coded by the precision code. Moreover the Y-Code is used in place of the P-code whenever the Anti-Spoofing (A/S) mode of operation is activated as described in the ICDs 203, 224 and 225. The PRN P-code for SV number i is a ranging code, Pi(t), 7 days long at a chipping rate of 10.23 Mbps. The 7 day sequence is the Modulo-2 sum of two sub-sequences referred to as <math>X_1</math> and <math>X_{2i}</math> with 15,345,000 chips and 15,345,037 chips, respectively. The <math>X_{2i}</math> sequence is an <math>X_2</math> sequence selectively delayed by 1 to 37 chips allowing the basic code generation technique to produce a set of 37 mutually exclusive P-code sequences 7 days long.

	* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, authentication, and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.		* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, [[GNSS Authentication and encryption \| authentication]], and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.

	* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800] Revision G, "Navstar GPS Space Segment/User Segment L1C Interfaces".</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to authenticate the location of a GPS receiver to another party.		* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800] Revision G, "Navstar GPS Space Segment/User Segment L1C Interfaces".</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to authenticate the location of a GPS receiver to another party.

Gema.Cueto at 08:54, 14 December 2020

2020-12-14T08:54:15Z

← Older revision		Revision as of 08:54, 14 December 2020
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	The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.		The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.

	The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705] Revision B, "Navstar GPS Space Segment/User Segment L5 Interfaces" </ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.		The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705] Revision G, "Navstar GPS Space Segment/User Segment L5 Interfaces" </ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.

Gema.Cueto at 11:30, 11 December 2020

2020-12-11T11:30:30Z

← Older revision		Revision as of 11:30, 11 December 2020
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	* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, authentication, and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.		* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, authentication, and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.

	* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800~~, 2011~~] ~~IS-GPS-800~~ Revision G.</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to authenticate the location of a GPS receiver to another party.		* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800] Revision G, "Navstar GPS Space Segment/User Segment L1C Interfaces".</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to authenticate the location of a GPS receiver to another party.


	For more details on the code generation refer to the [GPS ICD 200]<ref name="GPS_SIS_ICD_200">[GPS ICD-200~~, 2011~~] ~~IS-GPS-200~~ Revision L.</ref> and [GPS ICD-800]<ref name="GPS_SIS_ICD_800"></ref>. Finally, the technical characteristics of the existing GPS signals in the L1 band are summarized in the following Table 1.		For more details on the code generation refer to the [GPS ICD 200]<ref name="GPS_SIS_ICD_200">[GPS ICD-200] Revision L, "Navstar GPS Space Segment/User Segment Interfaces".</ref> and [GPS ICD-800]<ref name="GPS_SIS_ICD_800"></ref>. Finally, the technical characteristics of the existing GPS signals in the L1 band are summarized in the following Table 1.

	::::[[File:Chapter_2_Table_1.png\|none\|thumb\|520px\|'''''Table 1:''''' GPS L1 signal technical characteristics.]]		::::[[File:Chapter_2_Table_1.png\|none\|thumb\|520px\|'''''Table 1:''''' GPS L1 signal technical characteristics.]]
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	The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.		The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.

	The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705] Revision B, "Navstar GPS Space Segment/User Segment L5 Interfaces. " </ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.		The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705] Revision B, "Navstar GPS Space Segment/User Segment L5 Interfaces" </ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.

Gema.Cueto at 11:28, 11 December 2020

2020-12-11T11:28:20Z

← Older revision		Revision as of 11:28, 11 December 2020
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	The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.		The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.

	The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705~~, 2011~~] ~~IS-GPS-705~~ Revision B </ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.		The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705] Revision B, "Navstar GPS Space Segment/User Segment L5 Interfaces. " </ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.

Gema.Cueto: /* GPS L1 Band */

2020-12-10T16:06:04Z

GPS L1 Band

← Older revision		Revision as of 16:06, 10 December 2020
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	== GPS L1 Band ==		== GPS L1 Band ==

	The GPS L1 band (1575.42 MHz) has turned to be the most important band for navigation purposes. Indeed most of the applications in the world nowadays are based on the signals transmitted at this frequency. ~~Four~~ signals are transmitted at the moment by GPS in L1: C/A Code, P(Y) Code,M-Code and the new L1C signal, which is in the process of being fielded as L2C and L5. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future, all of ~~them~~ modulated in the L1 RF carrier frequency~~. We describe all of them~~ in the next lines:		The GPS L1 band (1575.42 MHz) has turned to be the most important band for navigation purposes. Indeed most of the applications in the world nowadays are based on the signals transmitted at this frequency. Three signals are transmitted at the moment by GPS in L1: C/A Code, P(Y) Code,M-Code and the new L1C signal, which is in the process of being fielded as L2C and L5. The legacy civil signal, called L1 C/A or C/A at L1, will continue broadcasting in the future. We describe all of these signals modulated in the L1 RF carrier frequency in the next lines:

	* The Coarse/Acquisition (C/A) code signal was primarily thought for acquisition of the P (or Y) code and has become nowadays the most important signal for mass market applications. The PRN C/A Code for SV ID number i is a Gold code, <math>G_i (t) </math>, of 1 millisecond in length at a chipping rate of 1.023 Mbps. The <math>G_i (t) </math> sequence is a linear pattern generated by the Modulo-2 addition of two subsequences, <math>G_1</math> and <math>G_{1i}</math>, each of them being a 1023 chip long linear pattern. The epochs of the Gold code are synchronized with the <math>X_1</math> epochs of the P-code.		* The Coarse/Acquisition (C/A) code signal was primarily thought for acquisition of the P (or Y) code and has become nowadays the most important signal for mass market applications. The PRN C/A Code for SV ID number i is a Gold code, <math>G_i (t) </math>, of 1 millisecond in length at a chipping rate of 1.023 Mbps. The <math>G_i (t) </math> sequence is a linear pattern generated by the Modulo-2 addition of two subsequences, <math>G_1</math> and <math>G_{1i}</math>, each of them being a 1023 chip long linear pattern. The epochs of the Gold code are synchronized with the <math>X_1</math> epochs of the P-code.

Gema.Cueto at 16:05, 10 December 2020

2020-12-10T16:05:10Z

← Older revision		Revision as of 16:05, 10 December 2020
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	* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, authentication, and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.		* The modernized military signal (M-Code) is designed exclusively for military use and is intended to eventually replace the P(Y) code [E. D. Kaplan and C. Hegarty, 2006]<ref>[E. D. Kaplan and C. Hegarty, 2006] E. D. Kaplan and C. Hegarty, Understanding GPS: Principles and Applications-2nd Edition, Chapter 4.</ref>. The M-Code provides better jamming resistance than the P(Y) signal, primarily through enabling transmission at much higher power without interference with C/A code or P(Y) code receivers [B.C. Barker et al., 2000]<ref>[B.C. Barker et al., 2000] B.C. Barker, J.W. Betz, J.E. Clark, J.T. Correia, J.T. Gillis, S. Lazar, Lt. K. A. Rehborn, J.R. Straton, III, ARINC, Overview of the GPS M-Code Signal, Proceedings of the National Technical Meeting of the Institute of Navigation, ION-NTM 2000, 26-28 January 2000, Anaheim, California, USA.</ref>. Moreover, the M-Code provides more robust signal acquisition than is achieved today, while offering better security in terms of exclusivity, authentication, and confidentiality, along with streamlined key distribution. In other aspects, the M-Code signal provides much better performance than the P(Y) Code and more flexibility.

	* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800, 2011] IS-GPS-800 Revision G~~, IS-IRN-800B-001, Navstar GPS Space Segment/User Segment L1C Interfaces, 21 September 2011~~.</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to authenticate the location of a GPS receiver to another party.		* The new L1 Civil signal (L1C), defined in the [GPS ICD-800]<ref name="GPS_SIS_ICD_800">[GPS ICD-800, 2011] IS-GPS-800 Revision G.</ref>, has been designed for interoperability with Galileo E1. It is compatible with current L1 signal but broadcast at a higher power level and includes advanced design for enhanced performance. It consists of two main components; one denoted <math>L1C_P</math> to represent the pilot signal, consisting of a time-multiplexing of BOC(1,1) and BOC(6,1), thus without any data message, and <math>L1C_D</math>, with a pure BOC(1,1), for the data channel. This is spread by a ranging code and modulated by a data message. The pilot channel <math>L1C_P</math> is also modulated by an SV unique overlay secondary code, <math>L1C_O</math>. An enhancement to this L1C signal is being analysed, which is called CHIMERA (Chips Message Robust Authentication). This technique consists on adding encrypted watermarks to the L1C signal that not only let users know when a signal is being spoofed but also makes it possible to authenticate the location of a GPS receiver to another party.


	For more details on the code generation refer to the [GPS ICD 200]<ref name="GPS_SIS_ICD_200">[GPS ICD-200, 2011] IS-GPS-200 Revision L~~, IS-IRN-200F-001, Navstar GPS Space Segment/User Segment Interfaces, 21 September 2011~~.</ref> and [GPS ICD-800]<ref name="GPS_SIS_ICD_800"></ref>. Finally, the technical characteristics of the existing GPS signals in the L1 band are summarized in the following Table 1.		For more details on the code generation refer to the [GPS ICD 200]<ref name="GPS_SIS_ICD_200">[GPS ICD-200, 2011] IS-GPS-200 Revision L.</ref> and [GPS ICD-800]<ref name="GPS_SIS_ICD_800"></ref>. Finally, the technical characteristics of the existing GPS signals in the L1 band are summarized in the following Table 1.

	::::[[File:Chapter_2_Table_1.png\|none\|thumb\|520px\|'''''Table 1:''''' GPS L1 signal technical characteristics.]]		::::[[File:Chapter_2_Table_1.png\|none\|thumb\|520px\|'''''Table 1:''''' GPS L1 signal technical characteristics.]]
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	The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.		The L5 signal consists of two carrier components that are in phase quadrature with each other. Each carrier component is bi-phase shift key (BPSK) modulated by a separate bit train. One bit train is module-2 sum of the I5-code, NAV data, and synchronization sequence while the other is the Q5-code with no NAV data, but with another synchronization sequence. For a particular SV, all transmitted signal elements (carriers, codes, synchronization sequence and data) are coherently and derived from the same on-board frequency source.

	The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705, 2011] IS-GPS-705 Revision B~~, IS-IRN-705B-001, Navstar GPS Space Segment/User Segment L5 Interfaces, 21 September 2011.~~</ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.		The L5 data channel and the L5 pilot channel are the two carrier frequencies. Moreover, two PRN ranging codes are transmitted on L5. The PRN L5-codes for SV number i are independent, but time synchronized ranging codes ,<math>X_I^i(t) </math> and <math> X_Q^i(t) </math>, of 1 millisecond in length at a chipping rate of 10.23 Mbps [GPS ICD-705]<ref name="GPS_SIS_ICD_705">[GPS ICD-705, 2011] IS-GPS-705 Revision B </ref>. For each code, the 1-millisecond sequences are the modulo-2 sum of two sub-sequences referred to as XA and XBi with lengths of 8,190 chips and 8,191 chips respectively, which restart to generate the 10,230 chip code. The XBi sequence is selectively delayed, thereby allowing the basic code generation technique to produce the different satellite codes.

Gema.Cueto: /* GPS L1 Band */

2020-12-10T16:02:22Z

GPS L1 Band

← Older revision		Revision as of 16:02, 10 December 2020
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	Of all the signals above, the C/A Code is the best known as most of the receivers that have been built until today are based on it. The C/A Code was open from the very beginning to all users, although until May <~~math~~>1^st</~~math~~>, 2000 an artificial degradation was introduced by means of the Select Availability (SA) mechanism which added an intentional distortion to degrade the positioning quality of the signal to non-desired users. As we have already mentioned, the C/A Code was thought to be an aid for the P(Y) Code (to realize a Coarse Acquisition). The M-Code is the last military signal that has been introduced in GPS.		Of all the signals above, the C/A Code is the best known as most of the receivers that have been built until today are based on it. The C/A Code was open from the very beginning to all users, although until May 1<sup>st</sup>, 2000 an artificial degradation was introduced by means of the Select Availability (SA) mechanism which added an intentional distortion to degrade the positioning quality of the signal to non-desired users. As we have already mentioned, the C/A Code was thought to be an aid for the P(Y) Code (to realize a Coarse Acquisition). The M-Code is the last military signal that has been introduced in GPS.

	For a long time different signal structures for the M-Code were under consideration [J.W. Betz, 2001] <ref>[J.W. Betz, 2001a] J.W. Betz, Binary Offset Carrier Modulations for Radionavigation, NAVIGATION: Journal of The Institute of Navigation Vol. 48, No. 4, Winter 2001/02</ref>being the Manchester code signals (BPSK) and the binary offset carrier (BOC) signals the two favored candidates. Both solutions result from the modulation of a non-return to zero (NRZ) pseudo random noise spreading code by a square-wave sub-carrier. While the Manchester code has a spreading code of rate equal to that of the square-wave, the BOC signal does not necessarily have to be so, being the only constraint that the rate of the spreading code must be less than the sub-carrier frequency.		For a long time different signal structures for the M-Code were under consideration [J.W. Betz, 2001] <ref>[J.W. Betz, 2001a] J.W. Betz, Binary Offset Carrier Modulations for Radionavigation, NAVIGATION: Journal of The Institute of Navigation Vol. 48, No. 4, Winter 2001/02</ref>being the Manchester code signals (BPSK) and the binary offset carrier (BOC) signals the two favored candidates. Both solutions result from the modulation of a non-return to zero (NRZ) pseudo random noise spreading code by a square-wave sub-carrier. While the Manchester code has a spreading code of rate equal to that of the square-wave, the BOC signal does not necessarily have to be so, being the only constraint that the rate of the spreading code must be less than the sub-carrier frequency.