Singh said the decisions were being taken at the Air Force headquarters and by Isro. He, however, confirmed that the IAF will soon be migrating to the indigenised version of GPS, using Isro's Indian Regional Navigation Satellite System (IRNSS).
Chandigarh: PEC University of Technology will working with institutions to collect data for the Indian Regional Navigation Satellite System (IRNSS) programme of ISRO, named as NAVIC (acronym for NAVigation using Indian Constellation)
The college will receive four receivers soon which will be used in research and teaching methods. Besides this, the college will work on small projects and the performance of these will be examined for a year.
PEC has signed a memorandum of understanding with SAC, which has additionally roped in various other technical institutes from the country for the IRNSS data collection exercise using SAC-developed IRNSS ground receiver.
The onboard atomic clocks that drive the satellite-navigation signals on Europe's Galileo network have been failing at an alarming rate.Across the 18 satellites now in orbit, nine clocks have stopped operating.Three are traditional rubidium devices; six are the more precise hydrogen maser instruments that were designed to give Galileo superior performance to the American GPS network.
Esa is also in contact with the Indian space agency which is using the same clocks in its sat-nav system. So far, the Indians have not experienced the same failures.
Most of the maser failures (5) have occurred on the satellites that were originally sent into orbit to validate the system, whereas all three rubidium stoppages are on the spacecraft that were subsequently launched to fill out the network.
It appears the rubidium failures "all seem to have a consistent signature, linked to probable short circuits, and possibly a particular test procedure performed on the ground".
The maser clock failures are said to be better understood, with two likely causes, the second of which has caused most grief.The Esa statement said this second scenario was "related to the fact that when some healthy [hydrogen maser] clocks are turned off for long periods, they do not restart due to a change in clock characteristics".
Galileo satellites experiencing multiple clock failuresQuoteThe onboard atomic clocks that drive the satellite-navigation signals on Europe's Galileo network have been failing at an alarming rate.Across the 18 satellites now in orbit, nine clocks have stopped operating.Three are traditional rubidium devices; six are the more precise hydrogen maser instruments that were designed to give Galileo superior performance to the American GPS network.QuoteEsa is also in contact with the Indian space agency which is using the same clocks in its sat-nav system. So far, the Indians have not experienced the same failures.QuoteMost of the maser failures (5) have occurred on the satellites that were originally sent into orbit to validate the system, whereas all three rubidium stoppages are on the spacecraft that were subsequently launched to fill out the network.QuoteIt appears the rubidium failures "all seem to have a consistent signature, linked to probable short circuits, and possibly a particular test procedure performed on the ground".QuoteThe maser clock failures are said to be better understood, with two likely causes, the second of which has caused most grief.The Esa statement said this second scenario was "related to the fact that when some healthy [hydrogen maser] clocks are turned off for long periods, they do not restart due to a change in clock characteristics".
Quote from: vyoma on 01/18/2017 05:54 pmGalileo satellites experiencing multiple clock failuresQuoteThe onboard atomic clocks that drive the satellite-navigation signals on Europe's Galileo network have been failing at an alarming rate.Across the 18 satellites now in orbit, nine clocks have stopped operating.Three are traditional rubidium devices; six are the more precise hydrogen maser instruments that were designed to give Galileo superior performance to the American GPS network.QuoteEsa is also in contact with the Indian space agency which is using the same clocks in its sat-nav system. So far, the Indians have not experienced the same failures.QuoteMost of the maser failures (5) have occurred on the satellites that were originally sent into orbit to validate the system, whereas all three rubidium stoppages are on the spacecraft that were subsequently launched to fill out the network.QuoteIt appears the rubidium failures "all seem to have a consistent signature, linked to probable short circuits, and possibly a particular test procedure performed on the ground".QuoteThe maser clock failures are said to be better understood, with two likely causes, the second of which has caused most grief.The Esa statement said this second scenario was "related to the fact that when some healthy [hydrogen maser] clocks are turned off for long periods, they do not restart due to a change in clock characteristics".There you go !!. One of the IRNSS satellite has developed a problem !!.It seems India is using Spectratime-built atomic clocks as is the case with Chinahttp://www.ndtv.com/india-news/indias-swadeshi-gps-develops-a-problem-but-remains-functional-1652638
Does this indicate the problem was likely with the clocks themselves, and not due to test procedures or associated instruments?
India's Swadeshi GPS Develops A Problem, But Remains Functional"The on-board atomic clock has developed a problem and we are trying to revive it," said Dr. Kiran Kumar, Chairman of ISRO or the Indian Space Research Organization, to NDTV.
“It is not a development issue with the clocks,” Benedicto said. “It is not a fundamental part of the unit that is failing.They were not bound to fail. But in certain conditions where you have certain parameters going in the wrong direction together, it could cause the unit to fail. You have to be particularly unlucky and have all the failure parameters drifting in a specific direction.""
. In the framework of the IRNSS program, each satellite will have four SpectraTime Rubidium atomic clocks on board to reach a stability of less than 10 billionths of a second per day. « To give a point of comparison, our clocks are 10 million times more precise than a watch made of quartz" », says Pascal Rochat, Chief Executive Officer of SpectraTime.
In the NavIC, a constellation of seven satellites, one of the three crucial rubidium timekeepers on IRNSS-1A spacecraft failed six months ago. The other two followed subsequently.
A. S. Kiran Kumar, Chairman of the Indian Space Research Organisation, confirmed the glitch in the clocks but clarified that the satellite was otherwise all right, and the rest of the satellites were performing its core function of providing accurate position, navigation and time. However, without its clocks, the IRNSS-1A “will give a coarse value. It will not be used for computation. Messages from it will still be used.”
“There are some anomalies in the atomic clock system on board. We are trying to restart it. Right now we are working out a mechanism for operating it,” he told The Hindu.“The problem is only with the clock system of one spacecraft. The signals are all coming, we are getting the messages, everything else is working and being used, except the stability portion which is linked to the clock,” he said. A minimum of four working satellites was sufficient to realise the full use of the navigation system”.
NavIC has 21 atomic clocks on seven spacecraft. “How would the other clocks fare? Would ISRO reconsider the supplier of its atomic clocks? Such questions are not easy to answer. Generally any [space] hardware is an issue. We have to find ways of going around it,” he said.
The troubled IRNSS-1A spacecraft was put in space in July 2013 and has an expected life span of 10 years.
2010: First RAFS rubidium clocks flying & operating on the COMPASS/Baidu satellites2011: Prime Swiss supplier of the PHM maser & RAFS rubidium clocks for Galileo's 14 satellites2012: Prime Swiss supplier of 29 space RAFS rubidium clocks for the IRNS (Indian Regional Navigation System)2015: Prime Swiss supplier of all PHM maser & RAFS rubidium clocks for the first 22 Galileo satellites
I hope ISRO, ESA and Spectratime figure out the issue, and if possible recalibrate/reconfigure atomic clock hardware on other satellites to avoid further failures.Even Chinese COMPASS and DFH satellites are using Spectratime Rubidium clocks, not sure if they've hit similar snags?!
Alarming !! All three clocks have failed – one primary and two backups Replacement satellite 1H plannedhttps://thewire.in/103934/atomic-clock-rubidium-irnss/
Quote from: chota on 01/30/2017 05:00 amAlarming !! All three clocks have failed – one primary and two backups Replacement satellite 1H plannedhttps://thewire.in/103934/atomic-clock-rubidium-irnss/Would be really interesting to know how those clocks are faring in CNSA's satellites. Anyway, IRNSS-1H is going to to be built same hardware, not sure if it really helps in the long run.
India will launch one of its back up navigation satellites this year as a replacement to IRNSS-1A satellite, whose three atomic clocks have failed, an official of the Indian space agency said on Monday.The official denied the existence of similar problems with the rubidium atomic clocks in another navigation satellite."The atomic clocks have failed in only one satellite. We will be launching the stand-by satellite this year. All other six satellites are operational and are providing the navigation data," A.S. Kiran Kumar, Chairman, Indian Space Research Organisation (ISRO), told IANS.He said the atomic clocks were imported and ISRO would take up the issue with the foreign supplier.Each satellite has three clocks and a total of 27 clocks for the navigation satellite system were supplied by the same vendor. The clocks are important to provide precise data.
Atomic clocks failures onboard Galileo satellitesSSTL_PHMAcross the 18 satellites now in orbit, nine clocks out of 72 have stopped operating. Three are traditional rubidium devices; six are the more precise hydrogen maser instruments that were designed to give Galileo superior performance to the American GPS network.Mitigating actionsIt appears the rubidium failures all seem to have a consistent signature, linked to probable short circuits, and possibly a particular test procedure performed on the ground.The maser clock failures are said to be better understood, with two likely causes, the second of which has caused most grief. The ESA statement said this second scenario was related to the fact that when some healthy [hydrogen maser] clocks are turned off for long periods, they do not restart due to a change in clock characteristics.
Galileo clock anomalies under investigationAs first reported last November, anomalies have been noted in the atomic clocks serving Europe’s Galileo satellites.Anomalies have occurred on five out of 18 Galileo satellites in orbit, although all satellites continue to operate well and the provision of Galileo Initial Services has not been affected.