Galileo Navigation Message - Revision history

Gema.Cueto at 11:03, 16 April 2026

2026-04-16T11:03:25Z

Natalia.Castrillo at 07:41, 26 August 2025

2025-08-26T07:41:11Z

← Older revision		Revision as of 07:41, 26 August 2025
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	The I/NAV message structures for the E1B and E5b-I signals use the same page layout since the service provided on these frequencies is a dual frequency service, using frequency diversity. Only page sequencing is different, with page swapping between both components in order to allow a fast reception of the data by a dual frequency receiver. However, the frame is designed to allow receivers to work also with a single frequency.		The I/NAV message structures for the E1B and E5b-I signals use the same page layout since the service provided on these frequencies is a dual frequency service, using frequency diversity. Only page sequencing is different, with page swapping between both components in order to allow a fast reception of the data by a dual frequency receiver. However, the frame is designed to allow receivers to work also with a single frequency.

	Each frame of the I/NAV message has a duration of 720 seconds and it is composed by 24 sub-frames. In turn, each sub-frame has a duration of 30 seconds and it is composed by 20 pages with a duration of 2 seconds. The page itself is composed by 3 fields:		Each frame of the I/NAV message has a duration of 720 seconds and it is composed by 24 sub-frames. In turn, each sub-frame has a duration of 30 seconds and it is composed by 15 pages with a duration of 2 seconds. The page itself is composed by 3 fields:
	* Synchronisation pattern: has a length of 10 bits and is always 0101100000 being its purpose to allow the receiver to achieve synchronisation to the page boundary;		* Synchronisation pattern: has a length of 10 bits and is always 0101100000 being its purpose to allow the receiver to achieve synchronisation to the page boundary;
	* I/NAV page part: has a length of 114 bits and it is the interleaved FEC encoded part of the page where the navigation data is conveyed.		* I/NAV page part: has a length of 114 bits and it is the interleaved FEC encoded part of the page where the navigation data is conveyed.

Gema.Cueto: /* Notes */

2021-06-04T11:14:32Z

Notes

← Older revision		Revision as of 11:14, 4 June 2021
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	==Notes==		==Notes==
	<references group="footnotes"/>		<references group="footnotes"/>

	The information from this article has been updated by GMV based on the applicable Galileo OS Signal-In-Space Interface Control Document (ICD).		The information from this article has been updated by GMV based on the applicable Galileo OS Signal-In-Space Interface Control Document (ICD).

Gema.Cueto at 09:51, 17 May 2021

2021-05-17T09:51:57Z

← Older revision		Revision as of 09:51, 17 May 2021
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	[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.		[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.

	The Galileo OS ICD released in January 2021 introduces new features in parts of I/NAV message transmitted on the Galileo E1-B signal component which were previously marked as spare or reserved. This means that these improvements will provide full backwards compatibility. The new features are:		The Galileo OS ICD released in January 2021 <ref name = "GAL SIS ICD"/> introduces new features in parts of I/NAV message transmitted on the Galileo E1-B signal component which were previously marked as spare or reserved. This means that these improvements will provide full backwards compatibility. The new features are:
	* Reduced Clock and Ephemeris Data (RedCED);		* Reduced Clock and Ephemeris Data (RedCED);
	* Reed-Solomon Outer Forward Error Correction Data (FEC2);		* Reed-Solomon Outer Forward Error Correction Data (FEC2);

Gema.Cueto: /* I/NAV Structure */

2021-05-17T09:48:02Z

I/NAV Structure

← Older revision		Revision as of 09:48, 17 May 2021
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	[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.		[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.

	The Galileo OS ICD released in January 2021 ~~announced the introduction of~~ new features in parts of I/NAV message transmitted on the Galileo E1-B signal component which were previously marked as spare or reserved. This means that these improvements will provide full backwards compatibility. The new features are:		The Galileo OS ICD released in January 2021 introduces new features in parts of I/NAV message transmitted on the Galileo E1-B signal component which were previously marked as spare or reserved. This means that these improvements will provide full backwards compatibility. The new features are:
	* Reduced Clock and Ephemeris Data (RedCED);		* Reduced Clock and Ephemeris Data (RedCED);
	* Reed-Solomon Outer Forward Error Correction Data (FEC2);		* Reed-Solomon Outer Forward Error Correction Data (FEC2);

Gema.Cueto: /* I/NAV Structure */

2021-05-17T09:41:13Z

I/NAV Structure

← Older revision		Revision as of 09:41, 17 May 2021
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	The I/NAV message structures for the E1B and E5b-I signals use the same page layout since the service provided on these frequencies is a dual frequency service, using frequency diversity. Only page sequencing is different, with page swapping between both components in order to allow a fast reception of the data by a dual frequency receiver. However, the frame is designed to allow receivers to work also with a single frequency.		The I/NAV message structures for the E1B and E5b-I signals use the same page layout since the service provided on these frequencies is a dual frequency service, using frequency diversity. Only page sequencing is different, with page swapping between both components in order to allow a fast reception of the data by a dual frequency receiver. However, the frame is designed to allow receivers to work also with a single frequency.

	Each frame of the I/NAV message has a duration of 720 seconds and it is composed by 24 sub-frames. In turn, each sub-frame has a duration of 30 seconds and it is composed by 15 pages with a duration of 2 seconds. The page itself is composed by 3 fields:		Each frame of the I/NAV message has a duration of 720 seconds and it is composed by 24 sub-frames. In turn, each sub-frame has a duration of 30 seconds and it is composed by 20 pages with a duration of 2 seconds. The page itself is composed by 3 fields:
	* Synchronisation pattern: has a length of 10 bits and is always 0101100000 being its purpose to allow the receiver to achieve synchronisation to the page boundary;		* Synchronisation pattern: has a length of 10 bits and is always 0101100000 being its purpose to allow the receiver to achieve synchronisation to the page boundary;
	* I/NAV page part: has a length of 114 bits and it is the interleaved FEC encoded part of the page where the navigation data is conveyed.		* I/NAV page part: has a length of 114 bits and it is the interleaved FEC encoded part of the page where the navigation data is conveyed.

Gema.Cueto at 09:32, 17 May 2021

2021-05-17T09:32:34Z

← Older revision		Revision as of 09:32, 17 May 2021
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	* For bit/byte ordering, the most significant bit/byte is transmitted first.		* For bit/byte ordering, the most significant bit/byte is transmitted first.

	According with the current published ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf OS SIS ICD]</ref> both F/NAV and I/NAV navigation messages are called super-frame and broadcast as a sequence of frames that are composed of several sub-frames which in turn is composed by several pages.		According with the current published ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> both F/NAV and I/NAV navigation messages are called super-frame and broadcast as a sequence of frames that are composed of several sub-frames which in turn is composed by several pages.

	[[File:Galileo_Navigation_Message_Structure.png \|none\|thumb\|400px]]		[[File:Galileo_Navigation_Message_Structure.png \|none\|thumb\|400px]]
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	* Alert pages: having a duration of 1 second transmitted in two parts of duration 1 second each at the same epoch over the E1B and E5b-I components. Again, the first part of the page is denoted ‘even’ and the second one is denoted ‘odd’. This transmission is repeated at the next epoch but switching the two parts between the components.		* Alert pages: having a duration of 1 second transmitted in two parts of duration 1 second each at the same epoch over the E1B and E5b-I components. Again, the first part of the page is denoted ‘even’ and the second one is denoted ‘odd’. This transmission is repeated at the next epoch but switching the two parts between the components.

	Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.		Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.

	[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.		[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.

Gema.Cueto at 09:30, 17 May 2021

2021-05-17T09:30:47Z

Gema.Cueto: /* I/NAV Structure */

2021-01-29T11:22:26Z

I/NAV Structure

← Older revision		Revision as of 11:22, 29 January 2021
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	Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SIS-ICD.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SIS-ICD.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.		Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SIS-ICD.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SIS-ICD.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.

	[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA capability will be added in the Reserved 1 40 bits in E1 I/NAV message.		[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.

	The Galileo OS ICD released in January 2021 announced the introduction of new features in parts of I/NAV message transmitted on the Galileo E1-B signal component which were previously marked as spare or reserved. This means that these improvements will provide full backwards compatibility. The new features are:		The Galileo OS ICD released in January 2021 announced the introduction of new features in parts of I/NAV message transmitted on the Galileo E1-B signal component which were previously marked as spare or reserved. This means that these improvements will provide full backwards compatibility. The new features are:

Gema.Cueto: /* I/NAV Structure */

2021-01-29T11:21:56Z

I/NAV Structure

← Older revision		Revision as of 11:21, 29 January 2021
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	Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SIS-ICD.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SIS-ICD.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.		Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SIS-ICD.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/system/files/galileo_documents/Galileo-OS-SIS-ICD.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.

	Galileo OS-NMA capability will be added in the Reserved 1 40 bits in E1 I/NAV message.		[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA capability will be added in the Reserved 1 40 bits in E1 I/NAV message.

	The Galileo OS ICD released in January 2021 announced the introduction of new features in parts of I/NAV message transmitted on the Galileo E1-B signal component which were previously marked as spare or reserved. This means that these improvements will provide full backwards compatibility. The new features are:		The Galileo OS ICD released in January 2021 announced the introduction of new features in parts of I/NAV message transmitted on the Galileo E1-B signal component which were previously marked as spare or reserved. This means that these improvements will provide full backwards compatibility. The new features are:

← Older revision		Revision as of 11:03, 16 April 2026
Line 10:		Line 10:
	The G/NAV navigation message does not belong to the public domain and the C/NAV is not yet defined. Please note that the formerly Commercial Service is now known as High Accuracy Service.		The G/NAV navigation message does not belong to the public domain and the C/NAV is not yet defined. Please note that the formerly Commercial Service is now known as High Accuracy Service.

	The details of the Galileo Signal Status are provided in the Galileo OS SIS Interface Control Document (ICD). <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> No other ICD documents have been published to date.		The details of the Galileo Signal Status are provided in the Galileo OS SIS Interface Control Document (ICD). <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.2.pdf Galileo OS SIS ICD]</ref> No other ICD documents have been published to date.

	== General Structure and Contents ==		== General Structure and Contents ==
	The Galileo Signal-In-Space data channels transmit different messages type according to the general contents identified in the following table. The F/NAV types of message correspond to the OS and the I/NAV types of messages correspond to both OS and CS (current High Accuracy Service). The following table indicates the signal component associated to each navigation message type. Let us also note that the Return Link Message from Galileo SAR service is provided as part of I/NAV data.		The Galileo Signal-In-Space data channels transmit different messages type according to the general contents identified in the following table. The F/NAV types of message correspond to the OS and the I/NAV types of messages correspond to both OS and CS (current High Accuracy Service). The following table indicates the signal component associated to each navigation message type. Let us also note that the Return Link Message from Galileo SAR service is provided as part of I/NAV data.

	[[File:Message_types.png \|none\|thumb\|400px\| Source: Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> ]]		[[File:Message_types.png \|none\|thumb\|400px\| Source: Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.2.pdf Galileo OS SIS ICD]</ref> ]]

	The complete navigation message data are transmitted on each data component as a sequence of frames. A frame is composed of several sub-frames, and each sub-frame is composed of several pages. The page is the basic structure for building the navigation message.		The complete navigation message data are transmitted on each data component as a sequence of frames. A frame is composed of several sub-frames, and each sub-frame is composed of several pages. The page is the basic structure for building the navigation message.
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	* For bit/byte ordering, the most significant bit/byte is transmitted first.		* For bit/byte ordering, the most significant bit/byte is transmitted first.

	According with the current published ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> both F/NAV and I/NAV navigation messages are called super-frame and broadcast as a sequence of frames that are composed of several sub-frames which in turn is composed by several pages.		According with the current published ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.2.pdf Galileo OS SIS ICD]</ref> both F/NAV and I/NAV navigation messages are called super-frame and broadcast as a sequence of frames that are composed of several sub-frames which in turn is composed by several pages.

	[[File:Galileo_Navigation_Message_Structure.png \|none\|thumb\|400px]]		[[File:Galileo_Navigation_Message_Structure.png \|none\|thumb\|400px]]
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	The Page Type field identifies the broadcast page which allows the user-receivers to react accordingly and grants the possibility of changing the pages sequencing, while keeping backward compatibility. The CRC is used as the most inner mechanism of errors detection because it is computed only on the Page Type and Navigation Data fields.		The Page Type field identifies the broadcast page which allows the user-receivers to react accordingly and grants the possibility of changing the pages sequencing, while keeping backward compatibility. The CRC is used as the most inner mechanism of errors detection because it is computed only on the Page Type and Navigation Data fields.

	Please refer to the Galileo OS SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the F/NAV Frame layout and page contents.		Please refer to the Galileo OS SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.2.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the F/NAV Frame layout and page contents.

	== I/NAV Structure ==		== I/NAV Structure ==
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	* Alert pages: having a duration of 1 second transmitted in two parts of duration 1 second each at the same epoch over the E1B and E5b-I components. Again, the first part of the page is denoted ‘even’ and the second one is denoted ‘odd’. This transmission is repeated at the next epoch but switching the two parts between the components.		* Alert pages: having a duration of 1 second transmitted in two parts of duration 1 second each at the same epoch over the E1B and E5b-I components. Again, the first part of the page is denoted ‘even’ and the second one is denoted ‘odd’. This transmission is repeated at the next epoch but switching the two parts between the components.

	Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.		Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.2.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.2.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.

	[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.		[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.
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	As a result of these technical solutions, users will experience an improvement of the Galileo E1 Open Service performance in terms of Robustness and Timeliness; a significant Time To First Fix Improvement in challenging environments addressing both unassisted and assisted GNSS; backward compatibility guaranteed (no impact on legacy or non-participative receivers) and low complexity implementation within OS receivers.		As a result of these technical solutions, users will experience an improvement of the Galileo E1 Open Service performance in terms of Robustness and Timeliness; a significant Time To First Fix Improvement in challenging environments addressing both unassisted and assisted GNSS; backward compatibility guaranteed (no impact on legacy or non-participative receivers) and low complexity implementation within OS receivers.

	The Galileo system is set to begin transmitting these new I/NAV capabilities by 2023. <ref>[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo ~~Open Service Signal-in-Space Interface Control Document, v2.0~~]</ref>		The Galileo system is set to begin transmitting these new I/NAV capabilities by 2023. <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.2.pdf Galileo OS SIS ICD]</ref>

	==Notes==		==Notes==

← Older revision		Revision as of 09:30, 17 May 2021
Line 10:		Line 10:
	The G/NAV navigation message does not belong to the public domain and the C/NAV is not yet defined. Please note that the formerly Commercial Service is now known as High Accuracy Service.		The G/NAV navigation message does not belong to the public domain and the C/NAV is not yet defined. Please note that the formerly Commercial Service is now known as High Accuracy Service.

	The details of the Galileo Signal Status are provided in the Galileo OS SIS Interface Control Document (ICD). <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/~~system~~/files/~~galileo_documents~~/~~Galileo-OS-SIS-ICD~~.pdf Galileo OS SIS ICD]</ref> No other ICD documents have been published to date.		The details of the Galileo Signal Status are provided in the Galileo OS SIS Interface Control Document (ICD). <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> No other ICD documents have been published to date.

	== General Structure and Contents ==		== General Structure and Contents ==
	The Galileo Signal-In-Space data channels transmit different messages type according to the general contents identified in the following table. The F/NAV types of message correspond to the OS and the I/NAV types of messages correspond to both OS and CS (current High Accuracy Service). The following table indicates the signal component associated to each navigation message type. Let us also note that the Return Link Message from Galileo SAR service is provided as part of I/NAV data.		The Galileo Signal-In-Space data channels transmit different messages type according to the general contents identified in the following table. The F/NAV types of message correspond to the OS and the I/NAV types of messages correspond to both OS and CS (current High Accuracy Service). The following table indicates the signal component associated to each navigation message type. Let us also note that the Return Link Message from Galileo SAR service is provided as part of I/NAV data.

	[[File:Message_types.png \|none\|thumb\|400px\| Source: Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/~~system~~/files/~~galileo_documents~~/~~Galileo-OS-SIS-ICD~~.pdf Galileo OS SIS ICD]</ref> ]]		[[File:Message_types.png \|none\|thumb\|400px\| Source: Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> ]]

	The complete navigation message data are transmitted on each data component as a sequence of frames. A frame is composed of several sub-frames, and each sub-frame is composed of several pages. The page is the basic structure for building the navigation message.		The complete navigation message data are transmitted on each data component as a sequence of frames. A frame is composed of several sub-frames, and each sub-frame is composed of several pages. The page is the basic structure for building the navigation message.
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	* For bit/byte ordering, the most significant bit/byte is transmitted first.		* For bit/byte ordering, the most significant bit/byte is transmitted first.

	According with the current published ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/~~system~~/files/~~galileo_documents~~/~~Galileo-OS-SIS-ICD~~.pdf ~~Galileo~~ OS SIS ICD]</ref> both F/NAV and I/NAV navigation messages are called super-frame and broadcast as a sequence of frames that are composed of several sub-frames which in turn is composed by several pages.		According with the current published ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf OS SIS ICD]</ref> both F/NAV and I/NAV navigation messages are called super-frame and broadcast as a sequence of frames that are composed of several sub-frames which in turn is composed by several pages.

	[[File:Galileo_Navigation_Message_Structure.png \|none\|thumb\|400px]]		[[File:Galileo_Navigation_Message_Structure.png \|none\|thumb\|400px]]
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	The Page Type field identifies the broadcast page which allows the user-receivers to react accordingly and grants the possibility of changing the pages sequencing, while keeping backward compatibility. The CRC is used as the most inner mechanism of errors detection because it is computed only on the Page Type and Navigation Data fields.		The Page Type field identifies the broadcast page which allows the user-receivers to react accordingly and grants the possibility of changing the pages sequencing, while keeping backward compatibility. The CRC is used as the most inner mechanism of errors detection because it is computed only on the Page Type and Navigation Data fields.

	Please refer to the Galileo OS SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/~~system~~/files/~~galileo_documents~~/~~Galileo-OS-SIS-ICD~~.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the F/NAV Frame layout and page contents.		Please refer to the Galileo OS SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> for detailed analysis on the F/NAV Frame layout and page contents.

	== I/NAV Structure ==		== I/NAV Structure ==
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	* Alert pages: having a duration of 1 second transmitted in two parts of duration 1 second each at the same epoch over the E1B and E5b-I components. Again, the first part of the page is denoted ‘even’ and the second one is denoted ‘odd’. This transmission is repeated at the next epoch but switching the two parts between the components.		* Alert pages: having a duration of 1 second transmitted in two parts of duration 1 second each at the same epoch over the E1B and E5b-I components. Again, the first part of the page is denoted ‘even’ and the second one is denoted ‘odd’. This transmission is repeated at the next epoch but switching the two parts between the components.

	Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/~~system~~/files/~~galileo_documents~~/~~Galileo-OS-SIS-ICD~~.pdf ~~Galileo~~ OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/~~system~~/files/~~galileo_documents~~/~~Galileo-OS-SIS-ICD~~.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.		Please refer to the Galileo OS SIS ICD <ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf OS SIS ICD]</ref> for detailed analysis on the I/NAV Frame layout and page contents. Let us remark that the [[Galileo Search and Rescue Service\|Galileo Search and Rescue (SAR)]] Return Link Message (RLM) is transmitted only in the E1-B component. The SAR field structure for the E1-B component in nominal mode is formatted according to the values stated in the Galileo SIS ICD<ref name = "GAL SIS ICD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo OS SIS ICD]</ref> and the Galileo SAR Service Definition Document<ref name="SAR SDD">[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo-SAR-SDD.pdf Galileo SAR Service Definition Document]</ref>.

	[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.		[[Galileo Open Service Navigation Message Authentication \| Galileo OS-NMA]] capability will be added in the Reserved 1 40 bits in E1 I/NAV message.
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	As a result of these technical solutions, users will experience an improvement of the Galileo E1 Open Service performance in terms of Robustness and Timeliness; a significant Time To First Fix Improvement in challenging environments addressing both unassisted and assisted GNSS; backward compatibility guaranteed (no impact on legacy or non-participative receivers) and low complexity implementation within OS receivers.		As a result of these technical solutions, users will experience an improvement of the Galileo E1 Open Service performance in terms of Robustness and Timeliness; a significant Time To First Fix Improvement in challenging environments addressing both unassisted and assisted GNSS; backward compatibility guaranteed (no impact on legacy or non-participative receivers) and low complexity implementation within OS receivers.

	The Galileo system is set to begin transmitting these new I/NAV capabilities by 2023. <ref>[https://www.gsc-europa.eu/~~news~~/~~updated-galileo-os-sis-icd-now-available~~ Galileo Open Service Signal-in-Space Interface Control Document, v2.0]</ref>		The Galileo system is set to begin transmitting these new I/NAV capabilities by 2023. <ref>[https://www.gsc-europa.eu/sites/default/files/sites/all/files/Galileo_OS_SIS_ICD_v2.0.pdf Galileo Open Service Signal-in-Space Interface Control Document, v2.0]</ref>

	==Notes==		==Notes==