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Klobuchar Ionospheric Model

Jalbert — Wed, 17 Jun 2026 07:03:39 GMT

Fixed typo error in point 5: Changed latitude to longitude.

← Older revision		Revision as of 07:03, 17 June 2026
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	:<math>		:<math>
	t' = (43200 \cdot \~~lambda~~ + t_{\text{GPS}}) \mod 86400		t' = (43200 \cdot \lambda_I + t_{\text{GPS}}) \mod 86400
	</math>		</math>

	:where:		:where:
	:* <math>t_{\text{GPS}}</math> is the '''GPS time in seconds of the week''' (0 to 604800 s).		:* <math>t_{\text{GPS}}</math> is the '''GPS time in seconds of the week''' (0 to 604800 s).
	:* <math>\~~lambda~~</math> is the geodetic ~~latitude~~ of the ionospheric pierce point (in semicircles).		:* <math>\lambda_I</math> is the geodetic longitude of the ionospheric pierce point (in semicircles).
	:* The '''modulo operation ensures''' that <math>t'</math> remains within a 24-hour cycle, which is required for the Klobuchar model to correctly compute the ionospheric delay.		:* The '''modulo operation ensures''' that <math>t'</math> remains within a 24-hour cycle, which is required for the Klobuchar model to correctly compute the ionospheric delay.

GPS Navigation Message

Jalbert — Mon, 01 Jun 2026 08:31:33 GMT

Small fix in LNAV sub-frames 4 and 5.

← Older revision		Revision as of 08:31, 1 June 2026
(One intermediate revision by the same user not shown)
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	* Sub-frame 5: contains data from the almanac and the constellation status. It allows to quickly identify the satellite from which the signal comes. A total of 25 frames are needed to complete the almanac.		* Sub-frame 5: contains data from the almanac and the constellation status. It allows to quickly identify the satellite from which the signal comes. A total of 25 frames are needed to complete the almanac.
	Sub-frames 1, 2 and 3 are transmitted with each frame (i.e., they are repeated every 30 seconds). Sub-frames 4 and 5 contain different pages (25 pages each) of the navigation message (see figure 1). Thence, the transmission of the full navigation message takes 25 × 30 seconds = 12.5 minutes.		Sub-frames 1, 2 and 3 are transmitted with each frame (i.e., they are repeated every 30 seconds). Sub-frames 4 and 5 contain different pages (25 pages each) of the navigation message (see figure 1). Thence, the transmission of the full navigation message takes 25 × 30 seconds = 12.5 minutes.
	The content of sub-frames 4 and 5 ~~is common for all~~ satellites. ~~Thence~~, the ~~almanac~~ data ~~for all in orbit satellites~~ can ~~be obtained from a single tracked satellite~~.		The content of sub-frames 4 and 5 can be different between satellites. Furthermore, within the GPS LNAV navigation data structure, these subframes can differ depending on whether the PRN numbers belong to the lower set (1–32) or the upper set (33–63).

	Further information on the LNAV message can be found in IS-GPS-200 ICD document <ref name="GPS ICD 200">[https://archive.gps.gov/technical/icwg/IS-GPS-200N.pdf GPS ICD-200 Revision N, "Navstar GPS Space Segment/Navigation User Segment Interfaces"]</ref>.		Further information on the LNAV message can be found in IS-GPS-200 ICD document <ref name="GPS ICD 200">[https://archive.gps.gov/technical/icwg/IS-GPS-200N.pdf GPS ICD-200 Revision N, "Navstar GPS Space Segment/Navigation User Segment Interfaces"]</ref>.

BeiDou Signal Plan

Dgarcia — Fri, 29 May 2026 14:16:05 GMT

@@ Line 196: / Line 196: @@
 |-
 | Received Power Levels on Ground || -156 dBW for MEO and -158 dBW for IGSO satellites (measured at the output of a 0 dBi RHCP user receiving antenna when the satellites are above a 5-degree elevation angle)
 |-
 | Signal Multiplexing Mode || Code Division Multiple Access (CDMA)

NAVIC

Jalbert — Thu, 21 May 2026 15:06:04 GMT

Fixed errors in IRNSS Space Segment point

← Older revision		Revision as of 15:06, 21 May 2026
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	==IRNSS Architecture==		==IRNSS Architecture==

	IRNSS has 7 satellites complemented with the appropriate ground infrastructure as a minimum<ref name=IRNSS_ICD>[https://www.~~unoosa~~.~~org/pdf/icg~~/~~2013/icg-8/5~~.~~pdf~~ ~~Indian Regional Navigation Satellite System Program,~~ Indian Space Research Organisation HQ]</ref>.		IRNSS has 7 satellites complemented with the appropriate ground infrastructure as a minimum<ref name=IRNSS_ICD>[https://www.isro.gov.in/SatelliteNavigationServices.html Indian Space Research Organisation, Department of Space, Satellite Navigation Services]</ref>.
	As it is traditional in GNSS systems, the architecture is described next in three different segments: the space segment, the ground segment and the user segment.		As it is traditional in GNSS systems, the architecture is described next in three different segments: the space segment, the ground segment and the user segment.

	*The '''IRNSS Space Segment''': 3 of the 7 satellites are geostationary orbit (GEOs) and they are located at 32.5º East, 83º East and ~~131~~.5º East longitude<ref name=IRNSS_ICD/>. There are 4 ~~geostationary~~ satellites (GSO) in orbits of 24,000 km apogee and 250 km perigee inclined at 29 degrees. Two of the GSOs cross the equator at 55º East and the other two at 111.75º East (two satellites in each plane)<ref name=IRNSS_ICD/>. The life span of the GEOs is 9.5 years and 11 years in the case of the GSOs.<ref>[https://www.jagranjosh.com/general-knowledge/irnss-1606397318-1 What is the Indian Regional Navigation Satellite System (IRNSS-NavIC)? in Jagran Josh website]</ref> The Constellation Design Considerations have been mainly:		*The '''IRNSS Space Segment''': 3 of the 7 satellites are geostationary orbit (GEOs) and they are located at 32.5º East, 83º East and 129.5º East longitude<ref name=IRNSS_ICD/>. There are 4 geosynchronous satellites (GSO) in orbits of 24,000 km apogee and 250 km perigee inclined at 29 degrees. Two of the GSOs cross the equator at 55º East and the other two at 111.75º East (two satellites in each plane)<ref name=IRNSS_ICD/>. The life span of the GEOs is 9.5 years and 11 years in the case of the GSOs.<ref>[https://www.jagranjosh.com/general-knowledge/irnss-1606397318-1 What is the Indian Regional Navigation Satellite System (IRNSS-NavIC)? in Jagran Josh website]</ref> The Constellation Design Considerations have been mainly:
	** Minimizing the Maximum DOP		** Minimizing the Maximum DOP
	** Minimum number of satellites		** Minimum number of satellites