GNSS Satellite (GIOVE-A)


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Monday, 4 January 2010

Galileo IOV Schedule

First of all a very happy and prosperous 2010 to all of you!

In 2009 saw very little concrete progress within the Galileo project. Behind the scenes a lot has happened, e.g., the cooperation between the EU and ESA has been improved and a lot of progress was made in the negotiations for the full orbit constellation (FOC) contracts. However, from a (scientific) user point of view this is not very concrete progress at all.

A significant issue with the Galileo project is the lack of an open communication principle. In 2009 I was really positively surprised about how open the GPS system has been regarding the issues with SVN-49. This is quite different from the way how the Galileo project is treating things. This is very surprising and even more so if one considers that GPS is still very much a military system whereas Galileo is a civil system. Thus one would expect much more open communications from Galileo!!

Secondly, also the data policy from the Galileo project is not really transparent. Since 2005 GIOVE-A has been in orbit and ESA has been gathering data from this satellite, and its brother GIOVE-B, using a network of 13 Galileo Experimental Sensor Stations (GESS). In principle this data is available to all ESA "trusted users", a status one can apply for on the ESA GIOVE web site. However, I know several institutes that have applied but never received this status. This is really disappointing, especially since a open data policy would most likely lead to much more interest, and consequently investigations and progress, from the scientific community. The currently employed "closed data policy" is very likely more harmful then helpful for the project. Several world leading scientist who would be interested in studying the Galileo, or rather GIOVE, data do not have access to the data. In this sense the Galileo project is very similiar to the Chinese COMPASS project.

So this brings us to the status of the Galileo IOV phase. In this phase 4 satellites will be launched in two launches. Both launches will be from Kourou using the the Russian Soyuz launcher. The four IOV satellites should, in principle be very similar to the final Galileo satellites. In Summer 2009 the IOV schedule foresaw that launch 1 would take place around September 2010 and launch 2 around February 2011. However, ever since the schedule has been slipping. Of course slipping schedules are quite normal in the space business but the lack of communications around it in the case of the Galileo project are untypical and make people wonder about the reasons for the delays. The latest rumours I have heard, and so far these rumours have always been true, is that launch 1 for the Galielo IOV is now scheduled for May 2011. The reason(s) for this (huge!) delay are completely unclear. But, we can speculate a bit about them....

Interesting is that in the FOC negotiations it seems that for building the satellites the consortium around OHB now seems to be winning against the "favourite" EADS consortium. The OHB consortium includes Surrey Satelite Technology Ltd which was responsible for the very successful GIOVE-A satellite. GIOVE-A was build on-time and within budget. And that was a truley great performance as time was the most critical factor in that case. The performance of EADS in building GIOVE-B was quite in constrast to the this with very significant delays and huge cost overruns. So if we put 1 and 1 together and start speculating a bit, it could very well be that the EU and ESA are a bit disappointed with the EADS performance both from GIOVE-B as well as now for the IOV satellites and are thus now favouring the OHB consortium for the FOC phase. It can also be just "politics" but the GIOVE-B and IOV satellites projects are certainly not one of the "best" we have seen. So there is some room for speculation here.....

Of course, in case the OHB consortium wins this will lead to a very inhomogeneous Galileo satellite constellation as the OHB satellites will most likely be quite different from the EADS IOV satellites. Also most likely the FOC constellation will be build in different phase with different generations of satellites. So when Galileo reaches FOC at least 3 different types of satellite will be in orbit.

In any case these are interesting times but before we see any real Galileo satellites in orbit my bet is that we will have to wait until 2011. So for 2010 the highlights we may expect will come from GPS and GLONASS. The GPS system is going to launch its, long overdue, first Block IIF satellite (currently scheduled for May) whereas the GLONASS system is going to launch its first GLONASS-K satellite (scheduled for the end of 2010).

Meanwhile I hope the Galileo project will become a bit more open both in its communication policy and, even more importantly, in its data policy.

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Thursday, 24 December 2009

GNSS Year in Review 2009

So what happened in the GNSS world in 2009!?

Well....not as much as we hoped for but some progress was made. Most progress was made "behind the scenes".


The most exiting and most "visible" was the launch of the GPS satellite SVN-49. This satellite brought new signals to the GPS system as it carries an experimental payload that allows the transmission of the new (future) GPS signals on the L5 band. The L5 experiment was bitterly needed because of the significant delays in getting the GPS IIF (F for Future) satellites ready. Thus the GPS system was at risk of loosing the L5 frequency allocation if they would not get a satellite up and "beeping" on the L5 frequency. The European Galileo system faced, and still faces, a similar challenge for which the launched the Giove-A and Giove-B experimental satellites. Unfortunately, the experimental character of the SVN-49 satellite actually caused some unexpected ill effects on the satellite on which we reported in our BLOG. This is the reason the satellite is still unhealthy although it is planned to turn the satellite healthy soon. However, the satellite will never perform as good as the other GPS satellites due to its anomaly. Besides SVN-49 also SVN-50 was launched marking the last GPS Block IIR-M satellite launch. The next GPS satellite to be launched will be the of the Block IIF type, currently scheduled for May 2010. An other "sad" event in 2009 was that SVN-35 was taken out of service. This satellite was special as it was one of only two GPS satellites that carries a Satellite Laser Ranging reflector array. The loss of this satellite is a grave loss for the scientific world especially because currently no SLR reflector arrays are foreseen on the GPS Block IIF nor on the first batch of the GPS Block III satellites. Hopefully the second batch of GPS Block III satellites will correct this "oversight" of the GPS system.


The most solid progress was made by the GLONASS system. Firstly, one of the three satellites launched in December 2008, GLO-729, is carrying a brand new SLR reflector array design which is 1.5 times better then the previous arrays. This is very exiting because it allows daylight tracking of this satellite which is an absolute "first" in the GNSS world. So far GNSS satellites could only be tracked by the SLR stations during the night. Furhtermore, an other successful triplet launch took place on December 14, 2009. However, also the GLONASS system did have its problems this year. One of the new satellites launched in 2008, GLO-726, developed a problem with its signal generator. As the satellites planned for launch in September 2009 used signal generators from the same batch as this faulty satellite the September launched was cancelled in order to check the satellites and replace the signal generators. The satellites are now scheduled for launch in February 2010. Nevertheless, the progress of GLONASS remains remarkable and they have managed to stick to the schedule that was laid out in 2005! In the space business that is an really astonishing accomplishment!


On the Galileo front things have been very quiet. Giove-A and Giove-B remain to operate which especially for Giove-A is a great accomplishment as it is well past its design life time. However, the schedule of the In Orbit Validation (IOV) seems to remain a "running target". In June the first launch was planned for September 2010. Meanwhile, rumours say the launch has been postponed until May 2011. The reasons for these delays are completely unclear and a more open communication policy would do the project a lot of good. The same holds for the data policy. Since 2005 Giove data has been gathered but the data is only available to ESA "trusted users". Unfortunately, it is practically impossible to obtain a trusted user status with ESA. So the Giove data is only accessible to a very limited number of institutes and thus limits the scientific analysis of the data. Under the surface a lot of things are happening in the Galileo project. The cooperation between ESA and the EU has been improved although it is certainly still not optimal. And a lot of progress has been made for awarding the contracts. The contracts should have been awarded early in 2009 but the process has, not unexpectedly, taken longer then planned. So also for 2010 visibly nothing much will be happening with Galileo. We will have to wait until 2011, at least.


Some progress was made for the COMPASS/Beidou system but since no data is publicly available I can not say too much about it. To my understanding there is still only 1 MEO satellite (MEO is the typical GNSS orbit) and a couple of GEO satellites. One additional GEO satellite was launched but also one was lost and was drifting through the GEO orbit causing quite some concerns for other GEO satellite operators (GEO is the orbits used for most telecommunication satellites). A "wild" satellite in this orbit is very dangerous and can cause a lot of damage.

The Japanese regional QZSS system is making good progress. The signal generator is currently undergoing in space testing as it is being flown on a GEO satellite. The first satellite will be launched in 2010. In principle three satellites are planned but currently funding for only 1 satellite exists.

The only thing remaing to be said is....
Merry Christmas

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Saturday, 22 November 2008

Galileo Status

Short update on the Galileo, or rather Giove, status. Both Giove-A and Giove-B are in good health and cycling the Earth. The 13 Galileo Experimental Sensor Stations (GESS) are tracking the satellite signals. The GESS track Giove-A using 2 channels and Giove-B using 5 channels. This is due to the limit of 7 Galileo (Giove) tracking channels in the GESS hardware, these are truly experimental receivers.

Giove-A, launched in December 2005, is meanwhile passed its design lifetime but still going strong. Giove-B is performing very well. Especially its on-board passive hydrogen maser (PHM) is performing extremly well. Even much better then its specifications. This is a very important result for two reasons. First of all this is the first time such a clock is flown in space. Secondly, this type of clocks holds a promise of significantly improving the navigation quality of the GNSS systems. The main limiting factor today in GNSS navigation solutions is the quality of the predicted clocks. This PHM will allow clock predictions that may be one order of magnitude better than todays atomic clocks. A real break trought for GNSS!

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Wednesday, 15 October 2008

Galileo versus GPS

Several people have asked me "what does Galileo offer that I can not get from GPS?"

Well if you just think of your average car navigation device, be it a Garmin, a Tom Tom, Magellan, or Medion, as user you will probably not notice much difference if it is based on GPS, Galileo, or both. Only in so called "urban canyons", areas where your horizon is obscured by tall buildings (e.g. downtown Manhattan), you would see some improvement. The same holds for any GNSS receiver in a mobile phone.

However, mobile phones you typically use in the center of town where you are likely to suffer more from obstructions of the sky. Thus using a receiver which tracks both GPS and Galileo will certainly give a significant improvement. Especially the time required to get a position estimate will be shorter, which, for mobile applications is very important. So although Galileo will offer a higher accuracy compared to GPS the average usage and users will not really see much impact of that. The main impact will be the combined usage of both systems since it will double the number of available satellites and thus help in cases where the observation geometry is poor, e.g. in the afore mentioned urban canyons.

Of course the fact that Europe has been planning to build Galileo already impacted the GPS system. There are many people who believe, and I am one of them, that selective availability was turned off because Europe is building Galileo. Selective availability (SA) was a significant artifical degradation of the GPS system which gave rise to position estimates at the level of 25 meters rather than the 1 meter level achieved today. With SA turned on GPS would not be "competitive" compared to Galileo.

Furthermore, the Galileo GPS "competition" has given rise to the fact that both systems will offer civilian signals on two frequencies. The access to signals on two frequencies will allow the removal of the signal delay effects caused by the upper layers of the Earth's atmosphere, the so called ionosphere. With two frequencies this effect, which easily reaches the 10 meter level, can be removed at the millimetre level. Thus the advent of civilian signals on two frequencies constitutes a very major improvement compared to the current GNSS systems. Without the advent of Galileo it is questionable if GPS alone would have moved in that direction.

So, in conclusion, the major impact of Galileo is that it has driven the developments of GPS forwards in such a way that GPS has tried to keep up to "spec" with the Galileo plans. In this way the end users are the real "winners". Since it is also the end users, that is us, who pay the systems through their tax money this is quite fair.

One thing I am very glad about is that GPS and Galileo will be fully interoperable. This means that the receivers will not change very much compared to today and that one single receiver will be able to track both systems. Of course the increased number of satellites calls for a larger number of tracking channels but I am sure that technology can easily cope with that. To what extend dual frequency impacts the receiver complexity and thus price is unclear at the moment. This will greatly depend on what the "standard" receiver will be, single or dual frequency. I personally am convinced that dual frequency receivers will be the standard. Full GNSS constellation(s) providing dual frequency civil signals will not be avaiable before 2015. By then I am pretty sure that the receiver manufacturers will be able to make a dual frequency receiver with the same characteristics as todays single frequency receivers. Most importantly: power consumption, size, mass, and price.

So all in all the future looks bright. Especially if one considers that also GLONASS, the Russian GNSS system, is planning to follow the GPS and Galileo developments and want to be interoperable with both. That would be a truly great development.

Stay on track!

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Thursday, 18 September 2008

GNSS Launch Schedule

Since my earlier post this year several things have changed so it is time for a short GNSS launch update.


Galileo has kept its "promise" and successfully launched the Giove-B satellite on April 27, 2008. The real special of this satellite is its extremely stable on board clock, a hydrogen maser clock. This is the first time a clock like that is flown on a GNSS satellite and it seems to be performing really well. The next step in the Galileo project will be the IOV phase (In Orbit Validation). For the IOV 4 satellites will be launched in a constellation that will allow the simultaneous visibility of all 4 satellites for a limited amount of time each day. This is similar to what was done with GPS in its early days. The IOV phase is currently scheduled for 2010, but with this project one never knows. Galileo FOC (Full Orbit Constellation) is scheduled for 2014 although it would be saver to say 201x (if not 20xx).


There were four GPS launches planned for 2008; in March, June, August, and September. The launch in March took place, GPS-48 (PRN07), a Block IIRM (2R-19)satellite, was launched successfully. The launch from June (2R-20) has been postponed and is now scheduled for November 7. The launch of the first Block IIF, (Future) satellite which was planned for August, has been moved to 2009. The third launch (2R-21) is currently TBD (to be determined) sometime in 2009. Although this slippage of the launch schedule looks bad it is not. There are currently 30 active satellites so there is no dire need for fresh new satellites. Unfortunately, GPS-35 (PRN05) is at its end because all its clocks have gone bad. It is one of only two GPS satellites that were equipped with special Satellite Laser Ranging (SLR) refelectors. Currently, none of the future GPS satellites are scheduled to carry such an equipment which is really a big loss for the scientific community. Fortunately, all GLONASS and Galileo satellites will carry SLR reflectors!


The GLONASS schedule promises two triplet launches this year. The first one no September 27, the second on December 25. Currently there are 16 GLONASS satellites although only 14 have been usable in the last weeks. If we assume that all the GLONASS satellites launched before 2005 are decomissioned the GLONASS constellation will still grow to 17 active satellites. Since we can savely assume that some of the 2003 and 2004 satellites will remain active we should see a GLONASS constellation of more then 18 satellites. That would be a very good achievement for the GLONASS system and will make it really usable! The next big step for GLONASS will be the new platform, the GLONASS-K satellites. That will increase the lifetime of the satellites and, more importantly, should move GLONASS from the FDMA technique to the CDMA technique used by GPS and Galileo. That would make all three systems interoperable and will keep the end-user equipment simple and therefore cheap!

Stay on track!

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Monday, 12 May 2008

GIOVE-B is transmitting

After its successful launch on 27 April, GIOVE-B has began transmitting navigation signals on May 7. This is a truly historic step for satellite navigation since GIOVE-B is now, for the first time, transmitting the GPS-Galileo common signal using a specific optimised waveform, MBOC (multiplexed binary offset carrier), in accordance with the agreement drawn up in July 2007 by the EU and the US for their respective systems, Galileo and the future GPS III. These GIOVE-B signals, locked on-board to its highly stable Passive Hydrogen Maser clock, will provide higher accuracy in challenging environments where multipath and interference are present, and deeper penetration for indoor navigation. It demonstrates that Galileo and GPS are truly compatible and interoperable and that positioning services will benefit all users worldwide.

With GIOVE-B broadcasting its highly accurate signal in space using is extremely stable clock we have a true representation of what Galileo will offer to provide the most advanced satellite positioning services, while ensuring compatibility and interoperability with GPS. I am looking forward to the first microwave obeservations (in the RINEX format) from the 13 world wide distributed Galileo Experimental Sensor Stations (GESS) to study the quality of the signals in comparison with GPS and GIOVE-A. In addition this should give us information regarding the stability and behaviour of the on-board clock.

As soon as I have some results I will inform you here (after ESA approval of course).

For more information look here:

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Sunday, 27 April 2008

Giove-B a major step forwards for Galileo

Today, 27-April-2008, Giove-B was launched succesfully!

You can watch the launch at:

The Giove-B satellite, which weight is only 500 kg, was lofted into a medium altitude orbit around the earth by a Soyuz/Fregat rocket departing from the Baikonur cosmodrome in Kazakhstan by launch operator Starsem. Lift-off occurred at 04:16 local time on 27 April (00:16 Central European Summer Time). The Fregat upper stage performed a series of manoeuvres to reach a circular orbit at an altitude of about 23,200 km, inclined at 56 degrees to the Equator, before safely delivering the satellite into orbit some 3 hours and 45 minutes later. The two solar panels that generate electricity to power the spacecraft deployed correctly and were fully operational by 05:28 CEST.

Giove-B will continue the demonstration of critical technologies for the navigation payload of the future operational Galileo satellites. Like Giove-A, Giove-B carries two redundant small-size rubidium atomic clocks, each with a stability of 10 nanoseconds per day. But it also features an even more accurate payload: the Passive Hydrogen Maser (PHM), with stability better than 1 nanosecond per day. The first of its kind ever to be launched into space, this is now the most stable clock operating in earth orbit.

GIOVE-B also incorporates a radiation-monitoring payload to characterise the space environment at the altitude of the Galileo constellation, as well as a laser retroreflector for high-accuracy laser ranging. Signal generation units will provide representative Galileo signals on three separate frequencies broadcast via an L-band phase array antenna designed to entirely cover the visible earth below the satellite. The satellite is now under the control of Telespazio's spacecraft operations centre in Fucino, Italy, and in-orbit checking-out of the satellite has begun.

The next step in the Galileo programme will be the launch of the first four operational satellites, to validate the basic Galileo space and related ground segment, by 2010. Once that In-Orbit Validation (IOV) phase is completed, the remaining satellites will be launched and deployed to reach the Full Operational Capability (FOC), a constellation of 30 identical satellites.

Galileo will be Europe's very own global navigation satellite system, providing a highly accurate, guaranteed global positioning service under civil control. It will be interoperable with the US Global Positioning System (GPS) and Russia's GLONASS, the two other global satellite navigation systems. Galileo will deliver real-time positioning accuracy down to the metre range with unrivalled integrity. Numerous applications are planned for Galileo, including positioning and derived value-added services for transport by road, rail, air and sea, fisheries and agriculture, oil-prospecting, civil protection, building, public works and telecommunications.

I am looking forward to the first real observations from Giove-B and to compute its first accurate orbit and especially accurate clock corrections. The passive hydrogen maser is the real "special" that Giove-B offers. Accurate clocks in space may offer a substantial benefit in all areas of GNSS. For the work I do, high precission GNSS at the mm level, I hope that the accurate Galileo clocks will offer an accuracy improvement of a factor of at least two, maybe more....

As soon as I have some first results I will post a new Blog here.

For more general info on Giove-B and Galileo have a look at:

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Saturday, 29 March 2008


So it has been a while since my last post... Just too busy at work to get any new BLOG entry. However, on the GNSS front several things have happened.

First of all yet another GPS satellite has been launched successfully on March 15. Meanwhile this satelite, GPS-48 with PRN number 07, is already transmitting its signals. It is still set unhealty so most navigation devices will not yet use it but the International GNSS Service ( is producing accurate orbits and clocks for this satellite. The launch of first GPS IIF is no longer planned for 2008 but shifted to 2009. However, the next GPS satellite due for launch, in June 2008, will be able to transmit on three frequencies. This as proof of concept for the GPS IIF satellites. This will be really exiting since it will bring us a complete new set of signals.

GLONASS now has 16 active satellites. Unfortunately the global tracking network still has many gabs and several of the receivers still have problems tracking the satellites with zero and/or negative frequency numbers. Nevertheless, GLONASS is in a much better state then ever in the last decade. With 6 more satellites scheduled for launch this year the future really looks bright. Hopefully the tracking equipment will improve. This will be a important task for Trimble, TPS, JPS, and Co. Also the global tracking network should improve. This is an important task for the IGS.

Last but not least GALILEO. GIOVE-B is getting ready for launch. ESA has set up a special web site for this major event GIOVE-B launch . The launch is scheduled for April 27, less then 1 month from now! As I wrote in my previous BLOG the exiting thing of GIOVE-B is the extremly stable clock, the Hydrogen Maser. This should improve the clock quality for the navigation and other real-time users. For the high accuracy domain it should enable a very significant reduction of the number of estimated clock parameters. This should give an accuracy improvemente comparable, if not more, to integer ambiguity resolution. Furthermore, with GIOVE-A and GIOVE-B in orbit at the same time it will give to opportunity to study how well integer ambiguity resolution may be performed when using the Galileo signals! I am really looking forward of working with the GIOVE-A and B data and especially looking forward at exploiting all the opportunities offered by the new signals and the H-Maser.

Please feel free to comment on this text and join me next time on this BLOG!

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