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".

GPS

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.

GLONASS

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!

Galileo

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.

Others

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....

Labels: Compass, Galileo, GLONASS, GPS, QZSS, SLR, SVN-49 anomaly

On August 17 the last GPS Block IIR satellite will be launched. It will be named SVN50/PRN21. This launch is the end of the aera of the Block IIR, "replenishment", satelites. The next satellite generation to be launched will be the Block IIF, "future", satellites. Of course the lifetime of 10 years will mean that we will use GPS Block IIR satellites for the next decade.

SVN50 will be placed into orbital plane/slot E3, replacing SVN40, a Block IIA satellite launched in July 1996 that is past its design life but still working well. SVN40 will be moved a little further along the orbital path. Successful launch and activation of the new satellite will bring the constellation to 31 operational satellites, not counting SVN49 which is still set unhealthy due to its signal anomaly.

Here it is important to note that SVN50 will not have any payload connected to the J2 auxiliary payload port that proved problematical with the L5 demonstration payload on SVN49, and possibly on other Block IIR/IIRMs.

Labels: GPS, launch schedule, signal anomaly, Status

After publishing the SVN-49 story on InsideGNSS a lot of things have happened. Most of the discoveries and developments you can read about on InsideGNSS and GPS World.

However, one very interesting new issue was brought to our attention. We were informed that other GPS block IIR and IIR-M satellites may show similar problems as SVN-49 because they use a similar configuration as SVN-49 but of course for a different signal then the L5 signal. So we took a close look at the residuals of all the GPS and GLONASS satellites and discovered that several other GPS block IIR and IIR-M satellites suffer from a similar, albeit much smaller, signal anomaly as observed for SVN-49. Most pronounced anomalies are observed for SVN-55 and SVN-43.

Read more about this in our addition the our InsideGNSS article on InsideGNSS

Labels: GPS, GPS World, Inside GNSS, signal anomaly, SVN49

After writing my two earlier blog's on this issue I decided to write a full article about this SVN 49 issue and submit it to Inside GNSS. The article will be printed in the July/August 2009 issue but because of its high news value it is available online now.

Enjoy the reading!

Labels: GPS, SVN-49 anomaly

As promised in my post "Problem with new GPS Satellite SVN-49/PRN-01"here some details regarding what we observe when we analyse the data of this satellite.

Below are two plots. The first one showing the pseudo range residuals of a "normal" GPS satellites. We randomly picked satellite SVN-38/PRN08 for this. The residuals are based on all the observations taken by the stations observing this satellite. The data used was from day 100 in 2009, or in normal date April 10, 2009. The residuals are plotted as a function of the elevation of the satellite above the local horizon of the observing station. That means that at 90 degrees elevation the satellite stands right above the station whereas at 10 degrees elevation the satellite is very low on the horizon. In this figure one can clearly see the increase of the noise of the observations at low elevations which is a well known phenomenon mainly caused by so called "multipath" effects.


The second figure shows the same picture but for our the new GPS satellite SVN-49/PRN01. The behavior of the residuals shows a clear signature which is obviously elevation dependent. Interestingly enought the carrier phase observation residuals do not show such a signature. This indicates that the problem is in the pseudo range observations, e.g., in the so called group delay.


However, the residuals show that the problem is only at the few meter level. But somehow the GPS operators see much larger problems. How and where the see those is still unclear to me. However, to my understanding it is possible to measure the differences between the observations on board of the satellite. Possilbe the >100 meter effects are observed in such measurments. However, for normal users as us there is only a few meter problem which we could live with, more or less. The really big problem comes from the fact that the GPS system operators are trying to solve this problem by changing the broadcast ephemerides. This becomes clear if we compare an orbit estimated by ourselves with the orbit information broadcasted by the GPS satellites. Note that our estimated orbits have a precission of a few centimeters whereas the broadcast ephemeris is normally at the few meter level. The figure below shows such a orbit comparison of the GPS satellites with PRN 1, 2, 3, 4, and 5. The differences for the "normal" GPS satellites is at the few meter level. For PRN 1 the differences amount up to 60 kilometers!!! This of course makes the satellite completely useless for any processing.


All in all the problems with this satellite do not seem to be very severe except for the broadcast ephemerides which are truely horrid!

So whatever you do with GPS do not use the data of the new SVN-49/PRN01 unless you know what you are doing!

(ps. I appologize for the poor quality of the plots. Have to find a better tool to do these plots...)

Labels: GPS, L5, SVN-49 anomaly

It looks as if the newest GPS satellite has a significant problem. This is the GPS satellite which also broadcast signals on the new L5 frequency to ensure that frequencies for the GPS system. The L5 signals were planned to be available from the new GPS Block II-F satellites but due to delays in building these satellites it became necessary as kind of an "emergency rescue" of the L5 frequency band to launch launch some other satellite to use the frequency. The "perfect" solution was found to add the L5 capability to one of the Block II-R satellites. So this was done for the SVN-49/PRN-01 satellite that was launched on March 29, 2009.

However, it seems that something has gone wrong with the signals of this satellite. In my work where we try to get the highest precission out of the GPS system, meaning orbits at the ~20mm level and receiver positions at the ~1mm level, we can see a clear pattern in the pseudo range residuals of this satellite. Now since we typically use the carrier phase observations and not the code this is not really a problem for our type of work. However, the few meter (!!!!) pseudo range residuals are disturbing and they show a clear dependency on elevation.

However, what is more disturbing is that on the GPS system side they seem to be getting even larger effects then the few meters we see in our work. So far this is something I have not yet been able to understand. It seems the GPS system operators see problems with this satellite at the 100 to 200 meter level!!! A true catastrophy! As work around for this problem they GPS system is applying a huge antenna offset when broadcasting the ephemerides and clock corrections of this satellite. These problems also explain why this satellite is still not declared healthy. In fact there is some speculation that because of the observed problems it may never be set healthy.

So in summary the facts are:

1. There is a significant problem difference the code and the phase observations
2. The phase observations seem to be fine as we can do integer ambiguity resolution without too much problems (but of course one can not use the code observations for aiding the ambiguity resolution)
3. The observed differences point in the direction of a significant "group delay". This is a delay which effects the code observations but not the phase observations
4. The GPS system is observing even larger problems (>100m)!? We do not see those problems however!?

In any case it may be that this GPS satellite will never be set healthy making the L5 experiment a rather costly one...

As soon as I find out more details I will let you know!

Cheers,
Springinhetveld

Labels: GPS, L5, SVN-49 anomaly

A company we work with GPS Solutions has developed a really cool application which I would like to introduce to you here.

GPS solutions specialises in high accuracy GPS solutions and applications. Besides accurate positioning there are many other things one can do with GPS. One of these things is using GPS based tropospheric delay estimates to improve numerical weather predictions. So GPS solutions is generating weather predictions based on the more or less standard models and data but in addition includes GPS estimates to improve the weather predictions. The really fun part of this is that they have coupled the weather predictions with Google Earth. Thus you can "click" on any location on the world and get the weather forecast for that location for the next couple of days. I find that a really cool application!

Just think about you want to go out sometime in the next days. You just go to any point on the Earth using Google Earth, click on the location and up comes the weather forcast for the selected location.

Want to try it out, just click this link. This links shows you the location of the main Servolux office and the weather forecast for the next couple of days!

I find this really cool and also very usefull. However, GPS solutions has, so far, been unable to sell this application. If you are interested in this application please let us know or in the least give us some feedback!

Wishing you nice weather and a good forecast!

Labels: GNSS, Google Earth, GPS, weather forecast

On March 24, 2009, a next GPS Block IIR-M satellite was succesfully launched. This satellite carries an interesting innovative payload that is capable of sending signals on the new L5 civil frequency. It was launched successfully with a Delta II rocket from Cape Canaveral Air Force Station in Florida.

Follow-on generations of GPS spacecraft will include an operational L5 signal to improve the accuracy and performance capabilities of the system, in particular for civil users. This new satellite, designated GPS IIR-20(M), will demonstrate this new civil signal located on the L5 frequency (1176.45MHz). The signal will comply with international radio frequency spectrum requirements.

GPS world quotes
Don DeGryse, Lockheed Martin's vice president of Navigation Systems “Working closely with our Air Force partner, and building upon the design capabilities of the IIR-M space vehicle, the team has developed an innovative, low-risk, low-cost demonstration payload that will pave the way for the new operational third civil signal. We look forward to a successful demonstration of this critical capability and setting another modernized GPS spacecraft into operations as quickly as possible.”

The original plan was to demonstrate the new L5 signals on the first Block IIF GPS satellite generation. However, the L5 frequency band was assigned to the GPS system under the condition that it would use the frequency before the end of 2009. Due to significant delays in building the new IIF generation of satellites it became impossible to launch those satellites before 2010. Therefore a special experiment was designed and implemented on this block IIR satellite.

So on this satellite the L5 signals are only an experiment and, to my understanding, the L5 experimental transmitter will only be on "occasonaly" and not permanently. Furthermore, it is unclear whether there are any receivers capable of tracking these new signals when they are transmitted. So although a very interesting innovation it is not something that will widely be used. However, if any L5 data from these satellites becomes available it will be very interesting to have a detailed look at it just as at the Giove-A and Giove-B signals.

Let us wait and see when we get the first L5 "beebs".

Labels: GNSS, GPS, L5, launch schedule

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!

Labels: Galileo, GPS, Navigation

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

Galileo

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).

GPS

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!

GLONASS

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!

Labels: Galileo, GLONASS, GNSS, GPS, launch schedule

The hazards that originate from tsunamis have been recognised for some time. Newspaper reports about undersea earthquakes and movies about meteor-inflicted tsunamis have contributed to public awareness of the threat. Early warning systems were constructed and deployed for instance in the Pacific Rim but many areas in the world are not covered by such traditional warning systems. At the latest in December 2004, when a tsunami devastated wide areas bordering to the Indian Ocean, the extensive media coverage has elevated the sheer possibility, the effects and the dangers of a tsunami into global public consciousness. In the memory and perception of tourists and holidaymakers seashore sites may forever bear tsunami-related dangers, resulting in the desire for effective, reliable and easy-to-use tsunami alarm systems. A tsunami early warning system is a system that should be able to detect tsunamis and issue warnings to prevent loss of life and property. It consists of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of coastal areas. The main beneficiaries of the tsunami alarm system are of course the people who live and travel near the seaside.



There are two distinct types: international tsunami warning systems, and regional warning systems. Both depend on the fact that, while tsunamis travel at between 500 and 1000 km/h (around 0.14 and 0.28 km/s) in open water, earthquakes can be detected almost at once as seismic waves travel with a typical speed of 4 km/s (approximately 15000 km/h). This gives time for a possible tsunami forecast to be made and warnings to be issued to threatened areas. The main problem to overcome is finding a model that is able to predict with a high reliability and certainty which earthquakes will produce significant tsunamis. Otherwise this Earthquake based approach will produce many more false alarms than verified warnings. In the currect operational scenarios, the seismic alerts are used to send out the watches and warnings. Then, data from observed sea level height (either shore based via tide gauges or deep ocean DART buoys) are used to verify the existence of a tsunami. The first rudimentary system to alert communities of an impending tsunami was attempted in Hawaii in the 1920s and more advanced systems were developed in the wake of the April 1, 1946 and May 23, 1960 tsunamis which caused massive devastation in Hilo, Hawaii.

Recently new modern systems have been proposed to augment the existing warning systems. In these new systems GPS, or more generally GNSS, plays a central role. To detect the tsunami wave front and wave height offshore instruments are essential. Offshore instruments are determining the sea level height and the deviation from normality (anomalies) with high accuracy. For the new modern systems high-tech buoys were developed to make several different observations like air pressure, water temperature, its own movement based on movement sensors, and tracking the GPS signals. Furthermore, these high-tech buoys are used as a relay station for ocean bottom pressure sensors, which are anchored on the ocean floor. Thus these high-tech buoys are equipped with meteorological sensors, movement sensors, a computer for data processing, a power supply unit as well as with GPS and a satellite antenna for the communication between the buoys and a warning centre. The integration of these different sensors ensures the security of the system.

The role of GPS and GNSS.
The key role in these systems is played by GPS.The GPS observations allow to determine the change of the sea level height at the few centimeter level provided accurate GPS orbits and clock are available in (near-) real time. Thanks to the developments made in GNSS data processing, especially in the framework of the International GNSS Service (http://igs.org), the computation of accurate GPS orbits and clocks is a reality today. Thus a relatively cheap infrastructure of high-tech high-sea buoys can provide a very accurate and efficient tsunami early warning system.

Here it is worthwhile to point you to the web site of the so-called "GITEWS" (http://www.gitews.org) project which plans the deployment of 10 buoys along the Indonesian coast line to demonstrate the usability of GPS for tsunami alarm systems.

Stay on track!

Labels: GPS, IGS, tsunami

Last week the new iPhone was (finally) introduced in Europe. It was introduced in many countries at the same time and there was a real "run" on the iPhones. This run was further enhanced by the rumour that Apple is fearing to have problems meeting the demand (or was that just some smart marking move to further push up the iPhone sales...)

Anyway, what I would like to dicuss here is that the Apple iPhone comes with an integrated GPS receiver and maps. This means that this phone is capable of replacing your car navigation system. So, considering that car navigation systems are at the €100 level and the iPhone is at a similar level, of course depending on how much the mobile phone companies subsidise it, buying a car navigation system does seem to be a "poor deal". The Apple iPhone is of course not the first and not the only phone with a GPS receiver. But since Apple currently is really "in" the phone may speed up a trend which has been developing over the last years.

The trend that is developing is that GPS positioning is becoming a common good. GPS chips have become so small and cheap that they can be put into any electronic device. The only issue with the GPS chips is the power consumption. But over the last couple of years there have been a lot of developments to counter the power consumption of the GPS chips. With a GPS chip in a device one can compute the position of this device at the few meter level. So now back to trend.
There are currently two "main stream" applications for GPS positions.

1. Car navigation! I never had problems finding my way but having a GPS navigation device in my car has made finding my way even much more simpler.
2. Geotagging of digital pictures, especially in relation with Google maps.

For these two applications one needs a GPS receiver, a computer, and a digital camera. Typically car navigation systems are a GPS receiver and a computer combined into one. Today most digital camera's do not (yet) have a GPS receiver incorporated and even if they would have one would still need a computer to upload the pictures to Google maps. So a device which combines a computer, digital camera, a GPS receiver, and some means of data communication would be ideal, right!? So clearly the trend is towards a (powerfull) mobile phone with a digitial camera (with 3 megabit pixel or more), and a GPS receiver. This device one could use for car navigation and for Geotagging!

Although the Apple iPhone is not the only device offering these capabilities, it will most likely be the top seller in this area. Apple is currently a very "hot", "hip", and "in" brand. So the iPhone has caused quite a bit of a hype. The fact that it comes with only a 2 megabit pixel camera will not keep many people from buying it!

The big losers in this game are the car navigation manufacturers. E.g. TomTom has been hit rather hard, just look at the developments of this company on the stock market. The interesting thing is that they started of focussing on the mobile internet market and were discussing joint ventures (in quite some detail) with both Ericsson and Nokia. Garmin has also been hit although they recognized these develpments a long time ago and launched their own mobile phones (but not very succesfully).

So in short currently Apple is the big winner in this market and the iPhone will certainly capture a significant part of the car navigation market. However, it will not be able to capture a significant share in the digital camera market. So any manufacturer who wants to "beat" the iPhone should focus on doing (much) better on the digital camera side of the device. Here I would expect Sony and/or Sony Ericsson to be able to play a role. Sony could make a really powerfull device out of a combination of its PSP and their Cybershot camera range. The Sony Ericsson joint venture also has all the building blocks (GPS, camera, mobile phone) to come up with a great device. However, from this trio Apple and Sony currently have a (much?) better brand name. Of course there are other potential players here, certainly Nokia and I would also expect something from LG.

In any case I will remain a happy user of GPS car navigation. At the moment with my "Medion" device but in the future most likely with a mobile phone. Furthermore, I am very curious how and where the geotagging applications will leads us in the near future. Geotagging offers a lot of fun applications but can also be used for really serious tracking of goods!

Stay on track!

Labels: Apple iPhone, GPS, Navigation

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 (http://igs.org) 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!

Labels: Galileo, Giove, GLONASS, GNSS, GPS