GNSS Satellite (GIOVE-A)


Subscribe here

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!

Labels: , ,

Sunday, 13 July 2008

GPS on Apple iPhone

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: , ,