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Achieving GPS–Galileo interoperability: the challenges ahead
Space Policy 19 (2003) 95–99
Achieving GPS–Galileo interoperability: the challenges ahead$ Walter F. Blanchard*,1 The Trundle, Tower Hill, Dorking, Surrey RH4 2AN, UK
Abstract The enormous benefits of a worldwide accurate location system can only be achieved if GPS and Galileo can be made truly interoperable. The technical issues involved are relatively easy to deal with but the political and legal problems require far greater attention, with military issues and enactment of legislation the chief difficulties. These are discussed using examples, notably from road traffic law. Given that the US DoD is unlikely to cede control of GPS to the civil sector and design a new, separate system, the best solution might be to set aside part of GPS for purely civil purposes. r 2003 Published by Elsevier Science Ltd.
The term ‘interoperability’ has become something of a mantra whenever Galileo is mentioned. It has even been enshrined at the august level of the EU Transport Ministers: The Council agrees: 8. That Galileo should be interoperable with existing satellite navigation systems; it should in particular be interoperable with GPS and its successor systems through an EU–US agreement that should be negotiated as soon as possible. (Council of European Transport Ministers Statement, 26th March 2002) Some potential users have gone further and said that unless it is ‘interoperable’ they will not use it. No doubt it was this sort of sentiment that caused the Ministerial pronouncement. Unfortunately, it seems somewhat on a level with bishops saying they are against evil—a nice statement of intent without any indication of how it might be achieved. So, at the risk of being thought just another nit-picker, I suggest that they have used the wrong word and should have said ‘interusable’, which at least has some chance of being achievable, for it is not the case that ‘interoperable’ and ‘interusable are the same. ‘Interoperable’ means that the two systems can be used transparently, that is, they can not only be used $ This article is a revised version of a keynote paper that was presented at the Nav02 conference organized by and held at the Royal Institute of Navigation in London in November 2002. *Corresponding author. Tel.: +44-1306-884359. E-mail address: [email protected] (W.F. Blanchard). 1 President of the Royal Institute of Navigation, 1993–1996; FRIN.
0265-9646/03/$ - see front matter r 2003 Published by Elsevier Science Ltd. doi:10.1016/S0265-9646(03)00012-2
with the same set of equipment but also without a change of operating rules or differences in the legalities surrounding them. Many users will have to use a GNSS under legal constraints and it would be quite ridiculous for there to be two sets of operating restrictions, which changed depending on which half of the GNSS was in use. ‘Interusable’ has a more practical implication in that it means the same black box can be used to access either (or both) and will give the same or enhanced end-results in terms of accuracy, reliability and availability, however used. It leaves the tricky questions of legal control and operating authority open and, I submit, is a much more appropriate term. But the approved word is ‘interoperable’ and we must first see what that entails.
1. Why should GPS and Galileo be ‘Interoperable’? It seems so obvious it is stupid to ask. No-one wants to have to install two different receivers; to have two different operating manuals; or to have to organise two sets of training. Much of the interoperability debate arises from a feeling amongst airlines and other heavily regulated bodies that two parallel systems should not have to be installed simply to satisfy different sets of legislators. With all the effort and expense that has to go into the installation on an aircraft of even a relatively simple electronic system this is perfectly understandable. It takes years to ensure total reliability and once having got to that state, it should not be fiddled with, modified or ‘improved’ before extensive further testing is done.
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The installation of a second similar system required for no other purpose than that the legislators in some country or other required it would be ridiculous. This points up the real problem—it is not engineering compatibility that is the major problem, it is ensuring that the two systems can be operated side-by-side under a common set of operating rules and legal liability. If the two systems cannot be used like this, then all the technical advantages of having many more satellites will be nullified. Unfortunately, this is the very problem that, as things are, I believe is incapable of solution without revolutionary changes in political outlook. In fact, fears of having to install multiple black boxes purely for technical reasons are groundless. For aircraft, GPS is already a ‘transparent’ system as regards installation, being merely a card buried in the INS box somewhere, the only necessary addition being an antenna. Galileo will not change that. For general users I suspect the decision will be made, all else being equal, on the grounds of who produces the cheapest receiver and the question of which satellite system it uses will be a minor consideration.
2. Control and operation Although engineering transparency between GPS and Galileo is achievable, legal transparency is another matter. The regulatory authorities have to consider how to reconcile GNSS with existing regulatory structures built up over many years that are impossible to discard and extremely difficult to change. It is necessary here to point up the distinction between non-mandatory systems and those required to be fitted to comply with regulations of one type or another. A prime example of a radio navaid never under direct legislative control was the Decca Navigator system. At its peak one of the most widely used marine radio navaids in the world, it never came under government regulation and was operated solely on the basis of common commercial prudence. It was never adopted as a mandatory navaid in either aircraft or ships and therefore whether one was carried or not was at the discretion of the Master. It is interesting to note that when Decca were making their effort to have it adopted by the International Civil Aviation Authority (ICAO) as a standard aircraft navaid, one of the objections made by the USA was that it would never agree to a nationwide navaid being under the control of a single foreign commercial company. To be adopted in the US Decca would have had to sign over all operational control and relinquish many of its proprietary rights. There was an historical precedent for this. In 1921 the United States discovered that its major transatlantic cable telegraph service was being run by the Marconi Company, a British firm, and decided, for the exact
reasons just outlined, that it could not permit this national asset to continue under foreign control. It therefore compelled Marconi to sell out to a newly formed American consortium set up to do the job, from which the Radio Corporation of America (RCA) eventually emerged. In both cases it was claimed that this was necessary for the USA to maintain its sovereignty, so it is a little strange that the EU is now being criticised in the USA for taking the same stand with Galileo. At present GPS is being used as a non-mandatory navaid and no legislation applies, but consider for what purposes a global navigation satellite system (GNSS) (let us assume a combination of GPS and Galileo) might be used. It is obvious that there is an intention to use it for many applications around which there is already a great deal of legislation with much more to come. In particular, a good part of the considerable expenditure incurred in developing Galileo is being justified on the basis that it will allow automatic location of vehicles of all types so that their movements can be controlled in the same way as air traffic is controlled. Aviation is predicted to comprise only about 1% of total users in a developed system and the vast majority of users will be outside what might be considered the ‘traditional’ navigation sphere. Let us therefore take as example a set of new users familiar to most—road vehicle drivers. GPS used as a vehicle navaid is well established and no self-respecting car manufacturer now offers his top range without one. In-car navigation is voluntary and free from legislation (so far!) so the fact that GPS is not guaranteed is irrelevant—it is a direct parallel to the Decca situation mentioned earlier, although without even the Decca recourse of commercial liability. We are moving into an age when control over which roads may be used at certain times is becoming daily closer. Access control is a major new departure in road regulation and it is now being said at governmental level that unless this sort of control is established our roads will grind to a halt. Road-pricing schemes are the latest hot topic. The fundamental requirement for any scheme of this sort is knowing where vehicles are, or at least where they have been. There are many ways of doing this but satellites, meaning GPS or a GPS-like system, is one of the cheapest and is almost always put forward as a solution. The technical aspects appear to be totally ignored on the basis that ‘the engineers will sort it out’ and much could be written on that alone but here we will consider only the regulatory aspects.
3. Road traffic law Nearly everyone drives these days but it is not thought safe to let anyone just jump into any car they fancy and
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drive off. There are driving tests to be passed; road regulations to observe; and cars themselves must be built to certain standards. Amongst many other restrictions it is considered that ‘‘speed kills’’ so we are not allowed to drive at whatever speed we like but must observe speed limits. All these things are surrounded with law—the totality of ‘law’ affecting anyone taking a car on the road in the UK now runs to seven large volumes. The regulations regarding a superficially simple matter like painting signs on a road alone occupy most of one volume. It is quite certain that any new system to be used for road regulation will be subject to similar volumes of legislation and I will take as illustration just one example. The proliferation of speed cameras in the UK recently has been very noticeable, as has the increased use of other radar and non-radar speed detection devices. The accuracy of these devices is very important since on it can depend a driver’s livelihood if s/he loses his or her licence. In the UK the Road Traffic Offenders Act (1988) required type approval for radar speed meters and the Road Traffic Act of 1991 expanded that to cover all other devices used for the enforcement of road traffic law. A reason given for these requirements was that ‘‘reliance on manufacturers’ instructions alone is not sufficient and operational standards need to be laid down by the police in consultation with the Police Scientific Development Branch’’. I suspect this was partly a result of scepticism regarding manufacturer’s claims and partly a realisation that not all users have degrees in electronics! This results in Home Office instructions being sent out from time to time regarding installation, use and procedures. Among other things, speed meters are required to be regularly calibrated and certificates issued to that effect by competent authorities. This is a simple matter since it is only a matter of checking the design and construction of an instrument. We can assume that the basic laws of Nature affecting the reflection of electromagnetic waves will not change and that therefore the underlying system is completely guaranteed. Access control and charges for road use will require law, just like speed limits, so we can expect regulations typified by ‘‘no person may use Road ‘‘A’’ between the hours of 07:00 and 10:00 unless s/he pays the relevant charge’’. Assume whether he actually uses Road ‘‘A’’ during these hours is to be determined by a readout of his GNSS receiver. It would of course have to be typecertified, just like speed meters, but unlike the speed meter there is an intervening system providing its basic information, which must be above challenge and guaranteed to be there at all times. Post facto evidence from monitor stations (the existing DGPS network would do admirably) about whether GPS satellites were operating correctly at the time could be given, but that is not the point. Would it be possible to put in place a
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major piece of new legislation based entirely on the supposition that a foreign system over which the UK Government had no control would always be available? Not only available but providing a specified accuracy? It would be relevant to ask in court what guarantee the lawmakers had that the controlling system, GPS, would give the right accuracy at that particular time when they made the law. And, if the lawmakers had no guarantee, why did they expect the driver to act as though they had? Clearly, legislation could not be enacted until such a guarantee had been obtained. But no UK body has any control over GPS so this would involve an approach to the US Department of Defense (DoD), the system controllers, for a legally valid guarantee that they would keep the right number of satellites in the right orbits for a considerable time into the future over what is to them a foreign country which does not pay a penny for the service. Of course, no military organisation in its right mind would give such an assurance (neither would a civil one, for that matter, unless it was paid for it). It has been claimed that since the DoD has a commitment to keep GPS going for internal US civil, as well as military, purposes, it would never withdraw it and it would be quite safe to proceed on this basis, but is this also true for foreign users? The DoD can enter into commitments with internal US civil agencies if it wishes (and has done) but not with foreign agencies. Could a situation occur in which the standard positioning service (SPS) was kept going for the American continent but not outside it? ‘Switching off’ satellites, in various forms, is easily possible and is done routinely for maintenance purposes but such a crude method cannot be used for differentiating GPS service between the USA and other countries. GPS satellites cover nearly half the Earth with their signals and since they do not carry narrow-beam steerable antennas their signals cannot be directed only to specific areas. Consequently a ‘switch-off’ of coverage over Europe would also have a severe effect over the Eastern half of the USA. Unfortunately, this leads to a preferred method of ‘denial’, which involves jamming GPS signals locally with a signal that wipes out C/A but has little effect on P. This jamming would very likely be done from aircraft and the question would be whether such jamming could be closely limited to a specified area or could spill over and accidentally jam other areas? Would the UK military themselves jam civil GPS over the UK if thought necessary? We are unlikely to be told. Now consider a little recent history. In 2001 and again in 2002, there were, during the spring months, significant periods on some days when GPS satellite availability was quite marginal over the UK—there were only four satellites at elevations above 15 . This might seem a high cut-off elevation but it is one many people are using and is reasonable for cars travelling in
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built-up areas, where even higher cut-offs might be necessary. These four satellites only provided a horizontal dilution of position (HDOP) of 20 or so (40 was seen on occasion) and the result was very poor accuracy—200 m or more. On these occasions there was nothing wrong with the GPS system; there were no satellites off-air; no maintenance was being done; and there was nothing in the Notice Advisory to Navstar Users (NANU) about it. These periods of poor HDOP were within the published performance limits for the GPS SPS and therefore there was no cause for complaint. The problem was a fortuitous combination of satellite positions caused by some satellites not being quite on station and others being drifted around their orbits to new positions. Only Northern Europe was affected and then only for times less than the outage periods permitted by the statistical availability parameters. It is entirely possible that this could recur in future—and there is absolutely nothing anyone in the UK or Europe could do about it!
bound to its. The UK, on its own, might consider it was so tightly bound to the USA and US policies that one more dependency did not matter but that would not go down well with the remainder of the countries in the European Union. Subordination of sovereignty, which is what this amounts to, has no historical precedent in any major country. After all, the UK Civil Aviation Act of 1921 (and similar Acts in other countries) was passed with the express object of ensuring complete sovereignty over its airspace as well as land, a principle maintained rigorously ever since. Many recent incidents have emphasised the importance attached to this by every country and we need only look at the problems still being encountered with the attempts to establish a common air traffic control system for Europe to see the complications even a slight derogation of this principle can cause.
5. Can Galileo alone fill the bill? 4. Could a legally enforceable guarantee regarding GPS ever be given? The US DoD, like any other national military organisation, is charged with the defence of its national citizens, not the provision of civil services even to its own citizens. That is what other government departments are for. So, although there might be an understanding between civil and military within the USA itself, possible because they at least both operate under the same fundamental legal system, there is no chance that said understanding could be extended to other countries which, considering it at the most venal level, contribute nothing in financial terms. In this respect, it has been suggested that if these ‘foreigners’ got together and offered to pay a reasonable amount towards the operation of GPS then they could be guaranteed GPS service on a commercial basis in return. This falls down on several counts: the DoD has no mechanism for accepting such money and is anyway not a commercial organisation committed to providing value for money; ‘foreign’ part-control of one of its systems would be anathema to it. Nor could a US civil organisation contract for service and then sub-contract a supply of GPS services out to ‘foreigners’ because that would be in essence the same thing by the back door. To enable any of these things to come about would require a major revolution in political thinking, not only in the US but also abroad. Total dependence on a foreign power for a major feature of national economic infrastructure is unthinkable for many reasons. It means that one could never afford to upset that power to the point that it might threaten to withdraw that service and therefore to some degree your own politics would be
One of the major drivers, if not the main driver, behind Galileo was to remedy this lack of a GPS performance guarantee by initiating a civil-based system operated with civil users as its main concern and totally responsible to them. Because Galileo is centred on Europe, the lack of satellites problem mentioned above would be highly unlikely to occur and because it is designed for civil control legal guarantees would be much easier to enter into. The public–private partnership (PPP) concept of operational control is designed in large part to provide some degree of government control over a privately funded enterprise and is being actively discussed for Galileo. The major difficulty Galileo will have is in the formation and working of the overseeing authority. Since aviation will be only a minority partner it cannot be the sole determinant of policy and an organisation such as Eurocontrol will be inappropriate. There appears to be plenty of precedent for a new organisation to be formed along the lines of the European meteorological and telecommunications satellite consortia Eumetsat and Eutelsat; Eunavsat perhaps? The ‘EU’ need not prevent non-EU countries joining in, as already demonstrated by non-EU participation in those two organisations. Although no doubt the usual tedious and lengthy consultations would be involved, there appears to be no really fundamental problem preventing such an organisation being formed. The political and sovereignty issues would still remain, of course, but in a less severe form considering the existence of the European Union. So there appears to be no insuperable political or legal obstacle to the adoption of Galileo, but unfortunately we are then faced with the technical problem that, as
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currently planned, Galileo will not have enough satellites to solve the urban canyon problem. It needs GPS for that.
6. 2010, Galileo, GPS III, and all that In 2010, therefore, if I am right, there will be a civilresponsible Galileo system around which legislation could theoretically be framed but with which GPS is unusable, for political reasons, in any mandatory situation. As already said, this would leave us with exactly the same technical problem as we already have with GPS—a restricted number of satellites causing nonperformance in city areas—and no performance guarantee would be possible. That would immediately prevent any legislation. And what of the millions of drivers who would have GPS-only receivers by then—are they to be told to get rid of them and fit new, certified, Galileo-only models when they would not see any significant difference in performance? At, say, h2000 a time? Captive markets always mean high prices. Aircraft do not experience the same restrictions on satellite visibility and since the legal situation could be resolved, the use of Galileo for approach and landing could be properly authorised. So it might—for European and some other commercial air traffic—but what about long-haul traffic? The USA would no doubt authorise the use of GPS in its own airspace, as it is already doing, and would not want to authorise Galileo for the reverse reason Europeans could not authorise GPS. The result would be that international traffic would have to carry dual capability GPS/Galileo equipment. The important point is that they would be carried not to reinforce one another but so that the appropriate system could be switched in when over different countries. If an aircraft had an incident in the USA while using a dual GPS/Galileo equipment that integrated the two instead of treating them separately
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the US authorities might wash their hands of the problem on the grounds that a non-US-approved system was in use, and the reverse might happen in Europe. This can only be resolved by a total re-think in the USA about the purpose and operation of GPS. To be fair, even if the US eventually did organise a completely civil-responsible GPS service there would remain the problem of legally traceable international control, but at least it would be easier to reach a solution when military considerations were not paramount.
7. Conclusion The enormous benefits of a worldwide accurate location system can be achieved only if GPS and Galileo can be made truly interoperable but this requires a political solution and has nothing to do with engineering. The only way out of the conundrum is for the US to agree to set aside a part of GPS for purely civil purposes that would come under completely civil, and probably commercial, control. The controlling authority would then be free to enter into agreements with foreign users. The catch would be that operations requiring movement of satellites purely for military purposes would have to be foregone and whether this would be acceptable to the DoD would be a matter for them to decide. Even better would be a decision to let GPS fall completely under civil control and for the DoD to go off and design itself a new separate satnav system. However, on that day we might also see the unusual spectacle of pigs flying! Since the answer lies in the political sphere, perhaps it is worth remembering the words of J. K. Galbraith: Politics is not the art of the possible. It consists in choosing between the disastrous and the unpalatable. Not to make GPS and Galileo interoperable would be disastrous.
Achieving GPS–Galileo interoperability: the challenges ahead$ Walter F. Blanchard*,1 The Trundle, Tower Hill, Dorking, Surrey RH4 2AN, UK
Abstract The enormous benefits of a worldwide accurate location system can only be achieved if GPS and Galileo can be made truly interoperable. The technical issues involved are relatively easy to deal with but the political and legal problems require far greater attention, with military issues and enactment of legislation the chief difficulties. These are discussed using examples, notably from road traffic law. Given that the US DoD is unlikely to cede control of GPS to the civil sector and design a new, separate system, the best solution might be to set aside part of GPS for purely civil purposes. r 2003 Published by Elsevier Science Ltd.
The term ‘interoperability’ has become something of a mantra whenever Galileo is mentioned. It has even been enshrined at the august level of the EU Transport Ministers: The Council agrees: 8. That Galileo should be interoperable with existing satellite navigation systems; it should in particular be interoperable with GPS and its successor systems through an EU–US agreement that should be negotiated as soon as possible. (Council of European Transport Ministers Statement, 26th March 2002) Some potential users have gone further and said that unless it is ‘interoperable’ they will not use it. No doubt it was this sort of sentiment that caused the Ministerial pronouncement. Unfortunately, it seems somewhat on a level with bishops saying they are against evil—a nice statement of intent without any indication of how it might be achieved. So, at the risk of being thought just another nit-picker, I suggest that they have used the wrong word and should have said ‘interusable’, which at least has some chance of being achievable, for it is not the case that ‘interoperable’ and ‘interusable are the same. ‘Interoperable’ means that the two systems can be used transparently, that is, they can not only be used $ This article is a revised version of a keynote paper that was presented at the Nav02 conference organized by and held at the Royal Institute of Navigation in London in November 2002. *Corresponding author. Tel.: +44-1306-884359. E-mail address: [email protected] (W.F. Blanchard). 1 President of the Royal Institute of Navigation, 1993–1996; FRIN.
0265-9646/03/$ - see front matter r 2003 Published by Elsevier Science Ltd. doi:10.1016/S0265-9646(03)00012-2
with the same set of equipment but also without a change of operating rules or differences in the legalities surrounding them. Many users will have to use a GNSS under legal constraints and it would be quite ridiculous for there to be two sets of operating restrictions, which changed depending on which half of the GNSS was in use. ‘Interusable’ has a more practical implication in that it means the same black box can be used to access either (or both) and will give the same or enhanced end-results in terms of accuracy, reliability and availability, however used. It leaves the tricky questions of legal control and operating authority open and, I submit, is a much more appropriate term. But the approved word is ‘interoperable’ and we must first see what that entails.
1. Why should GPS and Galileo be ‘Interoperable’? It seems so obvious it is stupid to ask. No-one wants to have to install two different receivers; to have two different operating manuals; or to have to organise two sets of training. Much of the interoperability debate arises from a feeling amongst airlines and other heavily regulated bodies that two parallel systems should not have to be installed simply to satisfy different sets of legislators. With all the effort and expense that has to go into the installation on an aircraft of even a relatively simple electronic system this is perfectly understandable. It takes years to ensure total reliability and once having got to that state, it should not be fiddled with, modified or ‘improved’ before extensive further testing is done.
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The installation of a second similar system required for no other purpose than that the legislators in some country or other required it would be ridiculous. This points up the real problem—it is not engineering compatibility that is the major problem, it is ensuring that the two systems can be operated side-by-side under a common set of operating rules and legal liability. If the two systems cannot be used like this, then all the technical advantages of having many more satellites will be nullified. Unfortunately, this is the very problem that, as things are, I believe is incapable of solution without revolutionary changes in political outlook. In fact, fears of having to install multiple black boxes purely for technical reasons are groundless. For aircraft, GPS is already a ‘transparent’ system as regards installation, being merely a card buried in the INS box somewhere, the only necessary addition being an antenna. Galileo will not change that. For general users I suspect the decision will be made, all else being equal, on the grounds of who produces the cheapest receiver and the question of which satellite system it uses will be a minor consideration.
2. Control and operation Although engineering transparency between GPS and Galileo is achievable, legal transparency is another matter. The regulatory authorities have to consider how to reconcile GNSS with existing regulatory structures built up over many years that are impossible to discard and extremely difficult to change. It is necessary here to point up the distinction between non-mandatory systems and those required to be fitted to comply with regulations of one type or another. A prime example of a radio navaid never under direct legislative control was the Decca Navigator system. At its peak one of the most widely used marine radio navaids in the world, it never came under government regulation and was operated solely on the basis of common commercial prudence. It was never adopted as a mandatory navaid in either aircraft or ships and therefore whether one was carried or not was at the discretion of the Master. It is interesting to note that when Decca were making their effort to have it adopted by the International Civil Aviation Authority (ICAO) as a standard aircraft navaid, one of the objections made by the USA was that it would never agree to a nationwide navaid being under the control of a single foreign commercial company. To be adopted in the US Decca would have had to sign over all operational control and relinquish many of its proprietary rights. There was an historical precedent for this. In 1921 the United States discovered that its major transatlantic cable telegraph service was being run by the Marconi Company, a British firm, and decided, for the exact
reasons just outlined, that it could not permit this national asset to continue under foreign control. It therefore compelled Marconi to sell out to a newly formed American consortium set up to do the job, from which the Radio Corporation of America (RCA) eventually emerged. In both cases it was claimed that this was necessary for the USA to maintain its sovereignty, so it is a little strange that the EU is now being criticised in the USA for taking the same stand with Galileo. At present GPS is being used as a non-mandatory navaid and no legislation applies, but consider for what purposes a global navigation satellite system (GNSS) (let us assume a combination of GPS and Galileo) might be used. It is obvious that there is an intention to use it for many applications around which there is already a great deal of legislation with much more to come. In particular, a good part of the considerable expenditure incurred in developing Galileo is being justified on the basis that it will allow automatic location of vehicles of all types so that their movements can be controlled in the same way as air traffic is controlled. Aviation is predicted to comprise only about 1% of total users in a developed system and the vast majority of users will be outside what might be considered the ‘traditional’ navigation sphere. Let us therefore take as example a set of new users familiar to most—road vehicle drivers. GPS used as a vehicle navaid is well established and no self-respecting car manufacturer now offers his top range without one. In-car navigation is voluntary and free from legislation (so far!) so the fact that GPS is not guaranteed is irrelevant—it is a direct parallel to the Decca situation mentioned earlier, although without even the Decca recourse of commercial liability. We are moving into an age when control over which roads may be used at certain times is becoming daily closer. Access control is a major new departure in road regulation and it is now being said at governmental level that unless this sort of control is established our roads will grind to a halt. Road-pricing schemes are the latest hot topic. The fundamental requirement for any scheme of this sort is knowing where vehicles are, or at least where they have been. There are many ways of doing this but satellites, meaning GPS or a GPS-like system, is one of the cheapest and is almost always put forward as a solution. The technical aspects appear to be totally ignored on the basis that ‘the engineers will sort it out’ and much could be written on that alone but here we will consider only the regulatory aspects.
3. Road traffic law Nearly everyone drives these days but it is not thought safe to let anyone just jump into any car they fancy and
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drive off. There are driving tests to be passed; road regulations to observe; and cars themselves must be built to certain standards. Amongst many other restrictions it is considered that ‘‘speed kills’’ so we are not allowed to drive at whatever speed we like but must observe speed limits. All these things are surrounded with law—the totality of ‘law’ affecting anyone taking a car on the road in the UK now runs to seven large volumes. The regulations regarding a superficially simple matter like painting signs on a road alone occupy most of one volume. It is quite certain that any new system to be used for road regulation will be subject to similar volumes of legislation and I will take as illustration just one example. The proliferation of speed cameras in the UK recently has been very noticeable, as has the increased use of other radar and non-radar speed detection devices. The accuracy of these devices is very important since on it can depend a driver’s livelihood if s/he loses his or her licence. In the UK the Road Traffic Offenders Act (1988) required type approval for radar speed meters and the Road Traffic Act of 1991 expanded that to cover all other devices used for the enforcement of road traffic law. A reason given for these requirements was that ‘‘reliance on manufacturers’ instructions alone is not sufficient and operational standards need to be laid down by the police in consultation with the Police Scientific Development Branch’’. I suspect this was partly a result of scepticism regarding manufacturer’s claims and partly a realisation that not all users have degrees in electronics! This results in Home Office instructions being sent out from time to time regarding installation, use and procedures. Among other things, speed meters are required to be regularly calibrated and certificates issued to that effect by competent authorities. This is a simple matter since it is only a matter of checking the design and construction of an instrument. We can assume that the basic laws of Nature affecting the reflection of electromagnetic waves will not change and that therefore the underlying system is completely guaranteed. Access control and charges for road use will require law, just like speed limits, so we can expect regulations typified by ‘‘no person may use Road ‘‘A’’ between the hours of 07:00 and 10:00 unless s/he pays the relevant charge’’. Assume whether he actually uses Road ‘‘A’’ during these hours is to be determined by a readout of his GNSS receiver. It would of course have to be typecertified, just like speed meters, but unlike the speed meter there is an intervening system providing its basic information, which must be above challenge and guaranteed to be there at all times. Post facto evidence from monitor stations (the existing DGPS network would do admirably) about whether GPS satellites were operating correctly at the time could be given, but that is not the point. Would it be possible to put in place a
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major piece of new legislation based entirely on the supposition that a foreign system over which the UK Government had no control would always be available? Not only available but providing a specified accuracy? It would be relevant to ask in court what guarantee the lawmakers had that the controlling system, GPS, would give the right accuracy at that particular time when they made the law. And, if the lawmakers had no guarantee, why did they expect the driver to act as though they had? Clearly, legislation could not be enacted until such a guarantee had been obtained. But no UK body has any control over GPS so this would involve an approach to the US Department of Defense (DoD), the system controllers, for a legally valid guarantee that they would keep the right number of satellites in the right orbits for a considerable time into the future over what is to them a foreign country which does not pay a penny for the service. Of course, no military organisation in its right mind would give such an assurance (neither would a civil one, for that matter, unless it was paid for it). It has been claimed that since the DoD has a commitment to keep GPS going for internal US civil, as well as military, purposes, it would never withdraw it and it would be quite safe to proceed on this basis, but is this also true for foreign users? The DoD can enter into commitments with internal US civil agencies if it wishes (and has done) but not with foreign agencies. Could a situation occur in which the standard positioning service (SPS) was kept going for the American continent but not outside it? ‘Switching off’ satellites, in various forms, is easily possible and is done routinely for maintenance purposes but such a crude method cannot be used for differentiating GPS service between the USA and other countries. GPS satellites cover nearly half the Earth with their signals and since they do not carry narrow-beam steerable antennas their signals cannot be directed only to specific areas. Consequently a ‘switch-off’ of coverage over Europe would also have a severe effect over the Eastern half of the USA. Unfortunately, this leads to a preferred method of ‘denial’, which involves jamming GPS signals locally with a signal that wipes out C/A but has little effect on P. This jamming would very likely be done from aircraft and the question would be whether such jamming could be closely limited to a specified area or could spill over and accidentally jam other areas? Would the UK military themselves jam civil GPS over the UK if thought necessary? We are unlikely to be told. Now consider a little recent history. In 2001 and again in 2002, there were, during the spring months, significant periods on some days when GPS satellite availability was quite marginal over the UK—there were only four satellites at elevations above 15 . This might seem a high cut-off elevation but it is one many people are using and is reasonable for cars travelling in
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built-up areas, where even higher cut-offs might be necessary. These four satellites only provided a horizontal dilution of position (HDOP) of 20 or so (40 was seen on occasion) and the result was very poor accuracy—200 m or more. On these occasions there was nothing wrong with the GPS system; there were no satellites off-air; no maintenance was being done; and there was nothing in the Notice Advisory to Navstar Users (NANU) about it. These periods of poor HDOP were within the published performance limits for the GPS SPS and therefore there was no cause for complaint. The problem was a fortuitous combination of satellite positions caused by some satellites not being quite on station and others being drifted around their orbits to new positions. Only Northern Europe was affected and then only for times less than the outage periods permitted by the statistical availability parameters. It is entirely possible that this could recur in future—and there is absolutely nothing anyone in the UK or Europe could do about it!
bound to its. The UK, on its own, might consider it was so tightly bound to the USA and US policies that one more dependency did not matter but that would not go down well with the remainder of the countries in the European Union. Subordination of sovereignty, which is what this amounts to, has no historical precedent in any major country. After all, the UK Civil Aviation Act of 1921 (and similar Acts in other countries) was passed with the express object of ensuring complete sovereignty over its airspace as well as land, a principle maintained rigorously ever since. Many recent incidents have emphasised the importance attached to this by every country and we need only look at the problems still being encountered with the attempts to establish a common air traffic control system for Europe to see the complications even a slight derogation of this principle can cause.
5. Can Galileo alone fill the bill? 4. Could a legally enforceable guarantee regarding GPS ever be given? The US DoD, like any other national military organisation, is charged with the defence of its national citizens, not the provision of civil services even to its own citizens. That is what other government departments are for. So, although there might be an understanding between civil and military within the USA itself, possible because they at least both operate under the same fundamental legal system, there is no chance that said understanding could be extended to other countries which, considering it at the most venal level, contribute nothing in financial terms. In this respect, it has been suggested that if these ‘foreigners’ got together and offered to pay a reasonable amount towards the operation of GPS then they could be guaranteed GPS service on a commercial basis in return. This falls down on several counts: the DoD has no mechanism for accepting such money and is anyway not a commercial organisation committed to providing value for money; ‘foreign’ part-control of one of its systems would be anathema to it. Nor could a US civil organisation contract for service and then sub-contract a supply of GPS services out to ‘foreigners’ because that would be in essence the same thing by the back door. To enable any of these things to come about would require a major revolution in political thinking, not only in the US but also abroad. Total dependence on a foreign power for a major feature of national economic infrastructure is unthinkable for many reasons. It means that one could never afford to upset that power to the point that it might threaten to withdraw that service and therefore to some degree your own politics would be
One of the major drivers, if not the main driver, behind Galileo was to remedy this lack of a GPS performance guarantee by initiating a civil-based system operated with civil users as its main concern and totally responsible to them. Because Galileo is centred on Europe, the lack of satellites problem mentioned above would be highly unlikely to occur and because it is designed for civil control legal guarantees would be much easier to enter into. The public–private partnership (PPP) concept of operational control is designed in large part to provide some degree of government control over a privately funded enterprise and is being actively discussed for Galileo. The major difficulty Galileo will have is in the formation and working of the overseeing authority. Since aviation will be only a minority partner it cannot be the sole determinant of policy and an organisation such as Eurocontrol will be inappropriate. There appears to be plenty of precedent for a new organisation to be formed along the lines of the European meteorological and telecommunications satellite consortia Eumetsat and Eutelsat; Eunavsat perhaps? The ‘EU’ need not prevent non-EU countries joining in, as already demonstrated by non-EU participation in those two organisations. Although no doubt the usual tedious and lengthy consultations would be involved, there appears to be no really fundamental problem preventing such an organisation being formed. The political and sovereignty issues would still remain, of course, but in a less severe form considering the existence of the European Union. So there appears to be no insuperable political or legal obstacle to the adoption of Galileo, but unfortunately we are then faced with the technical problem that, as
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currently planned, Galileo will not have enough satellites to solve the urban canyon problem. It needs GPS for that.
6. 2010, Galileo, GPS III, and all that In 2010, therefore, if I am right, there will be a civilresponsible Galileo system around which legislation could theoretically be framed but with which GPS is unusable, for political reasons, in any mandatory situation. As already said, this would leave us with exactly the same technical problem as we already have with GPS—a restricted number of satellites causing nonperformance in city areas—and no performance guarantee would be possible. That would immediately prevent any legislation. And what of the millions of drivers who would have GPS-only receivers by then—are they to be told to get rid of them and fit new, certified, Galileo-only models when they would not see any significant difference in performance? At, say, h2000 a time? Captive markets always mean high prices. Aircraft do not experience the same restrictions on satellite visibility and since the legal situation could be resolved, the use of Galileo for approach and landing could be properly authorised. So it might—for European and some other commercial air traffic—but what about long-haul traffic? The USA would no doubt authorise the use of GPS in its own airspace, as it is already doing, and would not want to authorise Galileo for the reverse reason Europeans could not authorise GPS. The result would be that international traffic would have to carry dual capability GPS/Galileo equipment. The important point is that they would be carried not to reinforce one another but so that the appropriate system could be switched in when over different countries. If an aircraft had an incident in the USA while using a dual GPS/Galileo equipment that integrated the two instead of treating them separately
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the US authorities might wash their hands of the problem on the grounds that a non-US-approved system was in use, and the reverse might happen in Europe. This can only be resolved by a total re-think in the USA about the purpose and operation of GPS. To be fair, even if the US eventually did organise a completely civil-responsible GPS service there would remain the problem of legally traceable international control, but at least it would be easier to reach a solution when military considerations were not paramount.
7. Conclusion The enormous benefits of a worldwide accurate location system can be achieved only if GPS and Galileo can be made truly interoperable but this requires a political solution and has nothing to do with engineering. The only way out of the conundrum is for the US to agree to set aside a part of GPS for purely civil purposes that would come under completely civil, and probably commercial, control. The controlling authority would then be free to enter into agreements with foreign users. The catch would be that operations requiring movement of satellites purely for military purposes would have to be foregone and whether this would be acceptable to the DoD would be a matter for them to decide. Even better would be a decision to let GPS fall completely under civil control and for the DoD to go off and design itself a new separate satnav system. However, on that day we might also see the unusual spectacle of pigs flying! Since the answer lies in the political sphere, perhaps it is worth remembering the words of J. K. Galbraith: Politics is not the art of the possible. It consists in choosing between the disastrous and the unpalatable. Not to make GPS and Galileo interoperable would be disastrous.