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{{Article Infobox2 | {{Article Infobox2 | ||
|Category=GLONASS | |Category=GLONASS | ||
|Authors=GMV | |Authors=GMV | ||
|Level=Basic | |Level=Basic | ||
Line 7: | Line 6: | ||
|Logo=GMV | |Logo=GMV | ||
}} | }} | ||
Equivalent to the Standard Positioning Service (SPS) and the Precise Positioning Service (PPS) of [[:Category:GPS|GPS]], [[:Category:GLONASS|GLONASS]] provides a standard precision (SP) navigation signal and a high precision (HP) navigation signal | Equivalent to the Standard Positioning Service (SPS) and the Precise Positioning Service (PPS) of [[:Category:GPS|GPS]], [[:Category:GLONASS|GLONASS]] provides a standard precision (SP) navigation signal and a high precision (HP) navigation signal, also referred to as Channel of Standard Accuracy (CSA) and Channel of High Accuracy (CHA), respectively. | ||
However, as in GPS there is Standard Positioning Service Performance and the Precise Positioning Standard, in [[:Category:GLONASS|GLONASS]] there is no document specifying the performances provided by each service. According to Sergey Revnivykh, the deputy head of the GLONASS Mission Control Center, a GLONASS performance document will be released in the 2012-2013 time frame.<ref>[http://www.gpsworld.com | However, as in GPS there is Standard Positioning Service Performance and the Precise Positioning Standard, in [[:Category:GLONASS|GLONASS]] there is no document specifying the performances provided by each service. According to Sergey Revnivykh, the deputy head of the GLONASS Mission Control Center, a GLONASS performance document will be released in the 2012-2013 time frame.<ref>[http://www.gpsworld.com GLONASS Update Delves into Constellation Details, GPSWorld]</ref> | ||
It has been stated<ref>"A Review of GLONASS" Miller, 2000</ref> that at peak efficiency, the SP signal offers horizontal positioning accuracy within 5–10 meters, vertical positioning within 15 meters, a velocity vector measuring within 10 cm/s, and timing within 200 ns. However these specifications are outdated, based on the performances provided by [[:Category:GLONASS|GLONASS]] in the year 2000, before starting the Modernization Plan. | It has been stated<ref>"A Review of GLONASS" Miller, 2000</ref> that at peak efficiency, the SP signal offers horizontal positioning accuracy within 5–10 meters, vertical positioning within 15 meters, a velocity vector measuring within 10 cm/s, and timing within 200 ns. However these specifications are outdated, based on the performances provided by [[:Category:GLONASS|GLONASS]] in the year 2000, before starting the Modernization Plan. | ||
Line 16: | Line 15: | ||
==GLONASS Availability== | ==GLONASS Availability== | ||
The low number of operational satellites in the constellation (in 2001 there were only seven satellites) along with a ground segment limited to Russian territory, have been the main reasons of [[:Category:GLONASS|GLONASS]] poor availability performance. The modernization of the [[GLONASS Ground Segment|Ground Segment]], including new monitoring stations (some of them outside Russia) and especially the increase of the number of satellites in the constellation (in the present, [[:Category:GLONASS|GLONASS]] constellation consists of | The low number of operational satellites in the constellation (in 2001 there were only seven satellites) along with a ground segment limited to Russian territory, have been the main reasons of [[:Category:GLONASS|GLONASS]] poor availability performance. The modernization of the [[GLONASS Ground Segment|Ground Segment]], including new monitoring stations (some of them outside Russia) and especially the increase of the number of satellites in the constellation (in the present, [[:Category:GLONASS|GLONASS]] constellation consists of 31 satellites in orbit although only 23 of them are operational), have led to almost worldwide coverage and 100% availability in the Russian territory. | ||
The table included below shows the increasing of the number of satellites and the availability performance (calculated as the percentage of time during which the condition PDOP | The table included below shows the increasing of the number of satellites and the availability performance (calculated as the percentage of time during which the condition PDOP <= 6 is valid at mask angles >= 5 deg) from the beginning of 2007 to beginning 2012.<ref>[http://www.glonass-center.ru/en/archive/ Information-Analytical Centre, Archive]</ref> | ||
{| class="wikitable" | {| class="wikitable" | ||
!rowspan="1"|Date | !rowspan="1"|Date | ||
Line 25: | Line 24: | ||
!rowspan="1" Width = "150px"|Integral Availability on Russian territory | !rowspan="1" Width = "150px"|Integral Availability on Russian territory | ||
|- | |- | ||
!align="center"|2012/01/23 | |||
|align="center"|23 | |align="center"|23 | ||
|align="center"|99. | |align="center"|99.9 % | ||
|align="center"|100 % | |||
|- | |||
!align="center"|2012/01/01 | |||
|align="center"|24 | |||
|align="center"|100 % | |||
|align="center"|100 % | |align="center"|100 % | ||
|- | |- | ||
!align="center"|2011/01/01 | |||
|align="center"|22 | |align="center"|22 | ||
|align="center"|99 % | |align="center"|99 % | ||
|align="center"|100 % | |align="center"|100 % | ||
|- | |- | ||
!align="center"|2010/01/01 | |||
|align="center"|15 | |align="center"|15 | ||
|align="center"|73.6 % | |align="center"|73.6 % | ||
|align="center"|85.3 % | |align="center"|85.3 % | ||
|- | |- | ||
!align="center"|2009/01/01 | |||
|align="center"|16 | |align="center"|16 | ||
|align="center"|87.4 % | |align="center"|87.4 % | ||
|align="center"|96.6 % | |align="center"|96.6 % | ||
|- | |- | ||
!align="center"|2008/01/01 | |||
|align="center"|12 | |align="center"|12 | ||
|align="center"|48 % | |align="center"|48 % | ||
|align="center"|57.6 % | |align="center"|57.6 % | ||
|- | |- | ||
!align="center"|2007/01/01 | |||
|align="center"|9 | |align="center"|9 | ||
|align="center"|19.2 % | |align="center"|19.2 % | ||
Line 56: | Line 60: | ||
|} | |} | ||
==GLONASS | According to the table above, in January 23 2012 there were 31 [[:Category:GLONASS|GLONASS]] satellites in orbit, being 23 of them in operational status. The following figure presents the corresponding worldwide Availability Performance (calculated as the percentage of time during which the condition [[Positioning Error|PDOP]] = 6 is valid for a masking angle of 5 degrees). | ||
::::[[File:GLONASSavailability.jpg|none|thumb|500px|'''''Figure 1:''''' Integral availability of GLONASS navigation (PDOP=6) during the 24 hours period (masking angle =5 deg) Date: 23.01.2012]] | |||
The improvements carried out on the space, ground-based and user equipment segments have paid off, | |||
==GLONASS Accuracy== | |||
In the beginning of the century, one of the main objectives of the [[:Category:GLONASS|GLONASS]] program was to ensure performances similar to [[:Category:GPS|GPS]] by the end of 2011. GLONASS traditional poorer performance was the culmination of several factors, such as, poor on board atomic clocks or less accuracy in GLONASS broadcast ephemeris.<ref name="GlonassFuture_InsideGNSS">[http://www.insidegnss.com/ Russia Dwells on Glonass Future, InsideGNSS]</ref> | |||
The improvements carried out on the space, ground-based and user equipment segments have paid off, having recovered [[:Category:GLONASS|GLONASS]]. As it is shown in the figure below, in 2006 GLONASS accuracy at 1 sigma was in the order of 35 m, and in 2011 the accuracy of GLONASS reached less than 3 meters, hence similar to the GPS one. | |||
[[File:GLONASS_AccuracyEvolution.jpg|500px||'''''Figure 2:''''' GLONASS Accuracy Improvement|centre|thumb]] | |||
==GLONASS Accuracy Comparison== | |||
With regard to [[:Category:GLONASS|GLONASS]] accuracy, according to the Russian System of Differentional Correction and Monitoring (SDCM)<ref name="SDCM"/>, as of 23 January 2012, [[:Category:GLONASS|GLONASS]] horizontal precision is in the order of 4-7 m whereas the vertical error is in the order of 10-15 meters: | |||
{| class="wikitable" | |||
!rowspan="2"|Station | |||
!colspan="3"|GLONASS Error of navigation def. (p=0,95) | |||
!rowspan="2"|Mean number of NSV | |||
|- | |||
!latitude (m) | |||
!longitude (m) | |||
!altitude (m) | |||
|- | |||
|Bellinsgauzen | |||
|align="center"|4.80 | |||
|align="center"|5.23 | |||
|align="center"|11.44 | |||
|align="center"|8 | |||
|- | |||
|Gelendzhik | |||
|align="center"|5.60 | |||
|align="center"|6.28 | |||
|align="center"|14.08 | |||
|align="center"|8 | |||
|- | |||
|Irkutsk | |||
|align="center"|6.35 | |||
|align="center"|6.39 | |||
|align="center"|10.52 | |||
|align="center"|8 | |||
|- | |||
|Kamchatka | |||
|align="center"|5.73 | |||
|align="center"|5.25 | |||
|align="center"|12.72 | |||
|align="center"|8 | |||
|} | |||
Analyzing the accuracy obtained with GPS in the same stations it can be derived that GLONASS is slightly less accurate than GPS. In the same way, the mean number of GLONASS satellites in view is lower than GPS: | |||
{| class="wikitable" | |||
!rowspan="2"|Station | |||
!colspan="3"|GPS Error of navigation def. (p=0,95) | |||
!rowspan="2"|Mean number of NSV | |||
|- | |||
!latitude (m) | |||
!longitude (m) | |||
!altitude (m) | |||
|- | |||
|Bellinsgauzen | |||
|align="center"|2.74 | |||
|align="center"|2.70 | |||
|align="center"|8.09 | |||
|align="center"|11 | |||
|- | |||
|Gelendzhik | |||
|align="center"|2.46 | |||
|align="center"|2.09 | |||
|align="center"|5.62 | |||
|align="center"|10 | |||
|- | |||
|Irkutsk | |||
|align="center"|2.32 | |||
|align="center"|2.02 | |||
|align="center"|5.16 | |||
|align="center"|10 | |||
|- | |||
|Kamchatka | |||
|align="center"|3.13 | |||
|align="center"|2.05 | |||
|align="center"|6.10 | |||
|align="center"|10 | |||
|} | |||
==Combined Services Performances== | ==Combined Services Performances== | ||
By combining GLONASS with other GNSS systems, such as GPS, | By combining GLONASS with other GNSS systems, such as GPS, Galileo, BeiDou, SBAS and GBAS, improved performance in the following domains can be expected: | ||
*[[Availability]]: Using as an example GLONASS in combination with GPS, the number of operational satellites will increase from 8-9 satellites to 18-19 (as it is shown in the table below). This is especially important in urban canyon environments, where the presence of large buildings leads to frequent shadowing of signal | *[[Availability]]: Using as an example GLONASS in combination with GPS, the number of operational satellites will increase from 8-9 satellites to 18-19 (as it is shown in the table below). This is especially important in urban canyon environments, where the presence of large buildings leads to frequent shadowing of signal. | ||
*Position [[Accuracy]]: Allied to an increased availability in restricted environments (urban) is a better geometry of spacecraft or enhanced positioning performance. | *Position [[Accuracy]]: Allied to an increased availability in restricted environments (urban) is a better geometry of spacecraft or enhanced positioning performance. | ||
*[[Integrity]]: GNSS based integrity systems and techniques, such as SBAS, RAIM and GBAS, would benefit from the addition of new constellations, including GLONASS, in terms of lower achievable protection levels and/or integrity risk. | *[[Integrity]]: GNSS based integrity systems and techniques, such as SBAS, RAIM and GBAS, would benefit from the addition of new constellations, including GLONASS, in terms of lower achievable protection levels and/or integrity risk. | ||
*Redundancy: | *Redundancy: Safety of Life applications require a full backup solution to be protected in the situation where the primary system fails. The combination of independent systems will lead to the required level of redundancy. | ||
The following table depicts a comparison example of the navigation error (at 95% probability) provided by GLONASS only solution and GLONASS in combination with GPS, as well as the number of satellites in view in four different reference stations:<ref>[http://www.sdcm.ru/smglo/stparam?version=eng&repdate&site=extern Precision of GLONASS/GPS Navigation Definitions, SDCM]</ref> | |||
{|class="wikitable" | {|class="wikitable" | ||
Line 90: | Line 170: | ||
!GLONASS+GPS | !GLONASS+GPS | ||
|- | |- | ||
!Bellinsgauzen | |||
|align="center"| | |align="center"|4.80 | ||
|align="center"| | |align="center"|2.69 | ||
|align="center"|5. | |align="center"|5.23 | ||
|align="center"|2. | |align="center"|2.29 | ||
|align="center"| | |align="center"|11.44 | ||
|align="center"| | |align="center"|6.26 | ||
|align="center"|8 | |align="center"|8 | ||
|align="center"|19 | |align="center"|19 | ||
|- | |- | ||
|Irkutsk | !Gelendzhik | ||
|align="center"| | |align="center"|5.60 | ||
|align="center"| | |align="center"|2.83 | ||
|align="center"| | |align="center"|6.28 | ||
|align="center"|2. | |align="center"|2.60 | ||
|align="center"|10. | |align="center"|14.08 | ||
|align="center"|5. | |align="center"|6.86 | ||
|align="center"|8 | |||
|align="center"|18 | |||
|- | |||
!Irkutsk | |||
|align="center"|6.35 | |||
|align="center"|3.08 | |||
|align="center"|6.39 | |||
|align="center"|2.86 | |||
|align="center"|10.52 | |||
|align="center"|5.98 | |||
|align="center"|8 | |align="center"|8 | ||
|align="center"|19 | |align="center"|19 | ||
|- | |- | ||
!Kamchatka | |||
|align="center"| | |align="center"|5.73 | ||
|align="center"|3. | |align="center"|3.03 | ||
|align="center"|5. | |align="center"|5.25 | ||
|align="center"|2. | |align="center"|2.40 | ||
|align="center"|12. | |align="center"|12.72 | ||
|align="center"|6.07 | |||
|align="center"|8 | |||
|align="center"| | |||
|align="center"| | |||
|align="center"|18 | |align="center"|18 | ||
|} | |} |
Latest revision as of 17:21, 22 June 2018
GLONASS | |
---|---|
Title | GLONASS Performances |
Author(s) | GMV |
Level | Basic |
Year of Publication | 2011 |
Equivalent to the Standard Positioning Service (SPS) and the Precise Positioning Service (PPS) of GPS, GLONASS provides a standard precision (SP) navigation signal and a high precision (HP) navigation signal, also referred to as Channel of Standard Accuracy (CSA) and Channel of High Accuracy (CHA), respectively.
However, as in GPS there is Standard Positioning Service Performance and the Precise Positioning Standard, in GLONASS there is no document specifying the performances provided by each service. According to Sergey Revnivykh, the deputy head of the GLONASS Mission Control Center, a GLONASS performance document will be released in the 2012-2013 time frame.[1]
It has been stated[2] that at peak efficiency, the SP signal offers horizontal positioning accuracy within 5–10 meters, vertical positioning within 15 meters, a velocity vector measuring within 10 cm/s, and timing within 200 ns. However these specifications are outdated, based on the performances provided by GLONASS in the year 2000, before starting the Modernization Plan.
Currently, accuracy comparisons provided by the Russian System of Differential Correction and Monitoring,[3] show that GLONASS is slightly less accurate than GPS.
GLONASS Availability
The low number of operational satellites in the constellation (in 2001 there were only seven satellites) along with a ground segment limited to Russian territory, have been the main reasons of GLONASS poor availability performance. The modernization of the Ground Segment, including new monitoring stations (some of them outside Russia) and especially the increase of the number of satellites in the constellation (in the present, GLONASS constellation consists of 31 satellites in orbit although only 23 of them are operational), have led to almost worldwide coverage and 100% availability in the Russian territory.
The table included below shows the increasing of the number of satellites and the availability performance (calculated as the percentage of time during which the condition PDOP <= 6 is valid at mask angles >= 5 deg) from the beginning of 2007 to beginning 2012.[4]
Date | Operational Satellites in constellation | Integral Availability Global | Integral Availability on Russian territory |
---|---|---|---|
2012/01/23 | 23 | 99.9 % | 100 % |
2012/01/01 | 24 | 100 % | 100 % |
2011/01/01 | 22 | 99 % | 100 % |
2010/01/01 | 15 | 73.6 % | 85.3 % |
2009/01/01 | 16 | 87.4 % | 96.6 % |
2008/01/01 | 12 | 48 % | 57.6 % |
2007/01/01 | 9 | 19.2 % | 26.3 % |
According to the table above, in January 23 2012 there were 31 GLONASS satellites in orbit, being 23 of them in operational status. The following figure presents the corresponding worldwide Availability Performance (calculated as the percentage of time during which the condition PDOP = 6 is valid for a masking angle of 5 degrees).
GLONASS Accuracy
In the beginning of the century, one of the main objectives of the GLONASS program was to ensure performances similar to GPS by the end of 2011. GLONASS traditional poorer performance was the culmination of several factors, such as, poor on board atomic clocks or less accuracy in GLONASS broadcast ephemeris.[5] The improvements carried out on the space, ground-based and user equipment segments have paid off, having recovered GLONASS. As it is shown in the figure below, in 2006 GLONASS accuracy at 1 sigma was in the order of 35 m, and in 2011 the accuracy of GLONASS reached less than 3 meters, hence similar to the GPS one.
GLONASS Accuracy Comparison
With regard to GLONASS accuracy, according to the Russian System of Differentional Correction and Monitoring (SDCM)[3], as of 23 January 2012, GLONASS horizontal precision is in the order of 4-7 m whereas the vertical error is in the order of 10-15 meters:
Station | GLONASS Error of navigation def. (p=0,95) | Mean number of NSV | ||
---|---|---|---|---|
latitude (m) | longitude (m) | altitude (m) | ||
Bellinsgauzen | 4.80 | 5.23 | 11.44 | 8 |
Gelendzhik | 5.60 | 6.28 | 14.08 | 8 |
Irkutsk | 6.35 | 6.39 | 10.52 | 8 |
Kamchatka | 5.73 | 5.25 | 12.72 | 8 |
Analyzing the accuracy obtained with GPS in the same stations it can be derived that GLONASS is slightly less accurate than GPS. In the same way, the mean number of GLONASS satellites in view is lower than GPS:
Station | GPS Error of navigation def. (p=0,95) | Mean number of NSV | ||
---|---|---|---|---|
latitude (m) | longitude (m) | altitude (m) | ||
Bellinsgauzen | 2.74 | 2.70 | 8.09 | 11 |
Gelendzhik | 2.46 | 2.09 | 5.62 | 10 |
Irkutsk | 2.32 | 2.02 | 5.16 | 10 |
Kamchatka | 3.13 | 2.05 | 6.10 | 10 |
Combined Services Performances
By combining GLONASS with other GNSS systems, such as GPS, Galileo, BeiDou, SBAS and GBAS, improved performance in the following domains can be expected:
- Availability: Using as an example GLONASS in combination with GPS, the number of operational satellites will increase from 8-9 satellites to 18-19 (as it is shown in the table below). This is especially important in urban canyon environments, where the presence of large buildings leads to frequent shadowing of signal.
- Position Accuracy: Allied to an increased availability in restricted environments (urban) is a better geometry of spacecraft or enhanced positioning performance.
- Integrity: GNSS based integrity systems and techniques, such as SBAS, RAIM and GBAS, would benefit from the addition of new constellations, including GLONASS, in terms of lower achievable protection levels and/or integrity risk.
- Redundancy: Safety of Life applications require a full backup solution to be protected in the situation where the primary system fails. The combination of independent systems will lead to the required level of redundancy.
The following table depicts a comparison example of the navigation error (at 95% probability) provided by GLONASS only solution and GLONASS in combination with GPS, as well as the number of satellites in view in four different reference stations:[6]
Station | Error of navigation def. (p=0,95) | Mean number of NSV | ||||||
---|---|---|---|---|---|---|---|---|
latitude (m) | longitude (m) | altitude (m) | ||||||
GLONASS | GLONASS+GPS | GLONASS | GLONASS+GPS | GLONASS | GLONASS+GPS | GLONASS | GLONASS+GPS | |
Bellinsgauzen | 4.80 | 2.69 | 5.23 | 2.29 | 11.44 | 6.26 | 8 | 19 |
Gelendzhik | 5.60 | 2.83 | 6.28 | 2.60 | 14.08 | 6.86 | 8 | 18 |
Irkutsk | 6.35 | 3.08 | 6.39 | 2.86 | 10.52 | 5.98 | 8 | 19 |
Kamchatka | 5.73 | 3.03 | 5.25 | 2.40 | 12.72 | 6.07 | 8 | 18 |
Notes
References
- ^ GLONASS Update Delves into Constellation Details, GPSWorld
- ^ "A Review of GLONASS" Miller, 2000
- ^ a b Russian System of Differentional Correction and Monitoring
- ^ Information-Analytical Centre, Archive
- ^ Russia Dwells on Glonass Future, InsideGNSS
- ^ Precision of GLONASS/GPS Navigation Definitions, SDCM