Perspectives - August 2007
August 20, 2007 By: Alan CameronOnce you have a given level of capability, how well is that maintained — and is it improved over time? Until we have something in GPS III that provides accuracies in the half-meter range, it would be foolish to turn off NDGPS. We’re degrading a system without any real alternative.
PLUS: The GPS III ground control (OCX) acquisition to come is a real defining point, not only for GPS, but also for Air Force Space and Missile Systems Center. They look at GPS as a model for how to carry out future acquisitions — separating the ground segment from space.
NDGPS and OCX
Something old, something new, something borrowed — no, wait a minute, that’s Galileo, GLONASS, and Compass. Let’s stick with the old and the new: Respectively, the National Differential GPS (NDGPS), and OCX, the next-next generation ground control system that will follow the about-to-be installed Architecture Evolution Plan (AEP).
In this month’s column, I’ll take on two topics. You can go directly to each topic by clicking on the respective link below, or read the whole column by simply starting with the first one. I talked this past week with Charlie Trimble, chairman of the U.S. GPS Industry Council, on the pending decision whether to continue funding the NDGPS, and with Bob Canty, director of Raytheon’s Defense Systems unit, about GPS III Operational Control Segment (OCX).
Trimble on NDGPS: Cost-Saving Move or Premature Decision?
GPS World spoke with Charlie Trimble, chairman of the U.S. GPS Industry Council, and Mike Swiek, the council’s Executive Director, about the pending decision whether to continue the Nationwide Differential GPS (NDGPS).
Charlie Trimble: Basically, four levels of augmentation increase GPS accuracy. The first, WAAS (Wide Area Augmentation System), was designed for providing Air Category I landing capability for fundamentally rural airports.
The second, NDGPS, was originally developed by the U.S. Coast Guard to allow GPS to meet the harbor/harbor entrance navigation accuracy requirements they had, and actually was expanded by a guy deep inside the railroad system. It managed to use the GWEN towers that were being phased out to provide NDGPS across the country.
In terms of accuracy levels, we’re starting out at 15–20 meters, basically, with GPS service. You get roughly 2 meters with WAAS. With NDGPS you have capability of between 15–20 centimeters. Actually, this has become the infrastructure used by local and state governments to support GIS systems. It’s also the basis of the system that has been adopted by 50 countries around the world, largely for the Coast Guard’s harbor/harbor entrance navigation requirement.
Those are the two basically public infrastructure augmentations to GPS to get additional accuracy.
To get to the centimeter level you can have private base stations and real-time kinematic if you want. In fact, all of these systems can provide real-time services. And that’s the half-centimeter/centimeter level of accuracy, depending on how you’re playing it, how far away your base stations are.
Finally, the geodesy people — earth crustal motion people, earthquake monitoring people — put in networks of GPS receivers that can allow them millimeter real-time motion capability.
These are the four levels of increased accuracy you can get with augmentation. The third and fourth are private; the Japanese are providing the fourth one as a quasi-government service. They’ve actually combined the earthquake monitoring function with fundamentally survey base stations. A surveyor only needs one unit rather than two to provide surveying.
As we look forward in the modernization of GPS, and we look at the spectrum of other systems are coming online, we’ve focus a lot on Galileo of late, although I think there’s a fair chance that Compass may be fielded ahead of Galileo. GPS today has fundamentally the pre-eminent position in terms of positioning and navigation. And if we don’t shoot ourselves in the foot in the transition from the GPS we have today to GPS III which is 10 years out, GPS will probably remain the fundamental standard because the only way non-military uses of these additional systems will get early use is by receiver manufacturers putting in dual-reception capability and using the new satellites as they go up, fundamentally as additional ranging signal augmentations. It’s the only way you get early use out of getting a few satellites in the sky.
A lot of whether GPS will retain its standard position has to do with worldwide confidence in the system. We’ve done a pretty good job of maintaining a level playing field for everyone in the world with regards to GPS. There hasn’t been the problems that were experienced with Loran systems which were occasionally turned off and created consternation in Europe. And actually dropping an important accuracy augmentation element of GPS before there are alternatives available would certainly undermine worldwide confidence in the U.S. commitment to continuing to provide service that is equal to or better than what is already there.
The key issue here is that you can have all the paper designs in the world you want, but fundamentally the question is: Once you have a given level of capability, how well is that maintained — and is it improved over time?
With all the machinations that have gone on, the U.S. has done a pretty good job. It basically delivers a set of signals that are better than promised. The system, especially with its augmentations, is clearly better today than it was 10 years ago.
Now, from a policy standpoint, clearly the U.S. does need to transition from where we are to GPS III. We just simply need to do it in a wise manner. The problem that I see with zeroing out the budget for NDGPS is that we save very little money — I believe it’s about $10 million a year to maintain the system
Mike Swiek: The requests have been about $6 to $10 million, and they’ve actually awarded less, and they’ve somehow been able to sort of operate the system on that. So it’s not a lot of money.
Charlie Trimble: For any accountancy firm, it would fall below the line of relevance in the budget.
Until we have something in GPS III that provides accuracies in the half-meter sort of range, which is what’s required for civil GIS work, it would be foolish to turn it off. We’re degrading a system without any real alternative. So this goes well beyond the problem of signals changing and having to do things slightly differently, because obviously receivers on the ground can adapt to the signals. You just need the time, you need the signals first of all, and then you need the time to do that adaptation.
Furthermore, you’re probably going to cost state, local, and federal governments far more than $10 million by turning the system off.
I believe the main commercial use of NDGPS, outside of the GIS realm, is precision agriculture. The arguments to put it in originally were to avoid the “digital divide” and provide the people on the interior of our continent the same sort of services that the coastal regions are provided. Senator (Tom) Daschle at the time was a major proponent at the time of driving this for the American heartland. Now obviously he’s gone, but it’s still, the issue we have is, we don’t have a strong vocal constituency, and frankly state and local governments can’t provide much of a hue and cry for degradation of service.
And losing confidence, undermining international confidence in the U.S. will to maintain a stable system is not a party to the table, either.
GPS World: From the international perspective, the argument is that it’s a perception issue. But international users do not actually use NDGPS itself.
Charlie Trimble: They basically have spent the money to use the systems. They have invested the money to put in comparable base stations in their countries. For the U.S. to discontinue NDGPS undermines and brings into question whether their investment was a good investment.
Mike Swiek: If the U.S. is backing off of NDGPS, it calls into question whether that technology is a viable and cost-effective one, and their own budget people in their own countries will start looking and thinking, gee, is this a path we should be following, or should we be looking at something else?
Charlie Trimble: It’s a confidence issue. There is no economic damage to foreign users.
Mike Swiek: But it’s a perception of undermining GPS credibility across the globe if we pull back support from a system that just a few years ago we deemed to be important and almost essential.
GPS World: What do you say to the question that precision ag and many other potential NDGPS users have switched over to WAAS and that seems to be good enough for them?
Charlie Trimble: There’s no question that WAAS is a good system, but you’re not going to get below a couple of meters, and you’re certainly not going to be able to farm above buried water tape. There’s clearly a market and I believe it’s part of the mix. It turns out it’s really tough to get at the 20-centimeter accuracy level over large distances, and WAAS will not give you that.
[In the case of private services] you need a specialized receiver to receive the correction data. There are enormous tradeoffs in terms of interference in the RF spectrum in the reception of that. Different systems have different pluses and minuses in terms of reception.
GPS World: What do you suggest people in the industry and the community do?
Charlie Trimble: At some point in our transition — I don’t know whether it’s five years from now or 10 years from now — the world is going to be a different place in terms of satellite services and the level of satellite services. It may very well be at some point in the future, this space of 20–50 centimeter accuracy can be very well delivered by a private service, or let’s just say, can be delivered by satellite. At that time, when there are truly other alternatives, I’m not going to be beating my shoe on the desk to maintain a legacy system. The issue in this whole positioning and navigation field is as people are starting to get economic value out of information, starting to introduce hiccoughs into the user stream of productivity enhancement is not a good thing. We say that until there is a viable alternative for the 20–50 centimeter space, we ought to continue sending out the signals. Once there is a viable alternative, then you can certainly transition, look at the cost of transition, and you will probably transition.
But it turns out this is a relatively cheap way of providing information in this space and frankly, we’re a long ways away from using GPS in automated systems that are directly related to safety of life. To get that, you have to play the game that the FAA plays, and worry about seven nines of reliability [[99.99 percent]]. GPS in its augmentation is probably at the one to two nine level. But as the usage increases, by having multiple augmentation systems and using them there is no reason that reliability can’t be increased.
The same arguments that are being used for a modernized Loran as a backup government navigation system work with regards to NDGPS. It’s a vastly different frequency, it’s bio-diverse, so a failure in one area isn’t going to affect another area. Frankly, there actually may be a place, as people want to roll Loran out in a nationwide way, the GWEN towers for DGPS, that Loran could be added to those towers. That would be a really cost-effective way of rolling modernized Loran out. I’m not pushing for that, but it’s a thought.
I think it’s premature. Fundamentally, the word to government is it’s premature to shut off the lights. It may be the right decision at some point in the future, but I think it would cause a lot more problems than the $10 million it would save it it’s done now.
Canty on GPS III Ground Control:
Better Monitoring for Improved Constellation
The next-generation ground control (OCX) acquisition is a real defining point, not only for GPS, but also for Air Force Space and Missile Systems Center. GPS World asked Bob Canty, director of DoD/Space Systems for Raytheon, for his take on what’s happening with GPS III, the Architecture Evolution Plan (AEP), and the GPS III Operational Control Segment (OCX) transition.
GPS World: Everybody’s curious about GPS III, and AEP, and OCX.
Bob Canty: As far as Raytheon goes, there are four segments going forward on the new GPS III acquisition. The first piece is the GPS systems integration piece, which SAIC was selected for last year; Raytheon is a teammate of SAIC on that contract.
The user equipment segment has three competitors who were downselected in 2006. One of them is Raytheon, the group out of Space and Airborne Systems that builds the equipment.
On the space segment side, Boeing and Lockheed are competing. The RFP went out last month. They’re planning on doing a downselect by the end of December to one contractor. Raythoen has some suppporting roles on the Boeing team.
Then for the OCX, which is the next-generation GPS control segment, Raytheon is priming that activity and we are bringing in our sister divisions, which is the folks that do WAAS (Wide Area Augmentation System), that helps us from an integrity standpoint. Raytheon is one of the only companies that has a GPS FAA-certified and accredited system, under WAAS. The OCX proposals were submitted in April, and they plan a three-to-two downselect on October 5.
This whole acquisition is a real defining point, not only for GPS, but also for Air Force Space and Missile Systems Center. They look at GPS as this is the way they want to do acquisitions in the future, which is separating out the ground from space. They are looking at this as the path forward for other space and missile systems; they’re looking at this as being the model.
There are particular reasons why they are doing this.
One of the key reasons is essentially going back into the ’80s and ’90s, when the satellite manufacturer built both the space and the ground. What happened is that as the space slipped, so did the ground. What they want to do is a huge paradigm shift. What they’re basically saying is that the ground can be delivered independent of space and be able to provide technology and new capabilities much more rapidly on the ground than can be done in space.
As an example, our first build replaces the ground system that’s going to be delivered, AEP, but when it gets delivered, it brings on M-code capability, and the third civil signal.
GPS World: OCX does, not AEP.
Bob Canty: That’s correct. Delivery is a critical aspect of the ground procurement. Raytheon has a tremendous track record of being able to deliver grounds on time, independent of space. We’re the only contractor that builds grounds for all the major space contractors.
Once you get the ground on its own schedule, you can start inserting new technology much more rapidly. Space takes anywhere from 10 to 12 years to replace a constellation with new capabilities. Getting the ground separated out does not tie the ground to the satellite vendor.
The paradigm shift is, really, if you will, being able to insert different types of technologies. The types of stuff they’re looking at doing, obviously ground is a major component of accuracy, of the overall system. We can pursue accuracy-type issues much more rapidly on the ground than you can in space.
In the future, doing more things like situational awareness and the actual constellation, being able to look at how the constellation is actually performing much better by having more ground sites that are capable of measuring the system, and being able to do a lot better forward-predictions of how the system is going to operate from a warfighter perspective — that’s critical for advance planning.
Once you get those capabilities onboard, you can start moving towards effects-based operations. How do you use navigation in a much more robust planning, but also if somebody is affecting your system, how do you counteract that? On a much more real-time basis.
The other major aspect of this acquisition is the open architecture that can evolve rapidly. Not only new capabilities being added, but being able to change concepts of operation rapidly.
GPS World: Talking about evolution, the transition to AEP is a changeover from mainframe to networked computers. Hardware changing, and software changing, too. How would you describe the transition from AEP to OCX?
Bob Canty: It’s both hardware and software. It’s updating the computer system to modern technology. From a software standpoint it’s going toward what they call a service-oriented architecture. AEP is more of a client-server type of arrangement and we’re going more towards something that would enable net-centric type operations — and able to much more easily communicate with other systems and with Internet, that sort of thing. It’s really getting more net-enabled.
GPS World: What can you say about security against hacking, or an Internet attack?
Bob Canty: Currently there are no plans to connect to the external public Internet. If data is provided on the Internet, it would be via a whole separate mechanism, a separate system. But within the government itself, it will be going over government-owned communication lines. The government has its own dedicated networks.
GPS World: With AEP, the capability of what the ground control system can run will increase from 32 to 60 satellites. Is there any further expansion under OCX?
Bob Canty: I think the requirement is we can fly up to 66 satellites. But I’m not sure they’re planning on going much more than what the current constellation is. The system is agnostic as far as satellites go — that’s one of the key aspects, as far as which satellite vendor, or which satellite we have. The ground has to be independent of that, and work with all of them. And Raytheon has a track record of working with all the GPS satellite vendors.
GPS World: Such as Lockheed and Boeing.
Bob Canty: Lockheed and Boeing, and possibly a third vendor in the future. But you’re also talking about mixed vehicles, a IIR, a IIR-M, a IIF, a GPS III — generations of technology that change. So your overall approach has to be independent of vendor and independent of technology.
GPS World: Does that hypothetically extend further to management of other GNSSs, to be shared perhaps among ground controls? Taking Galileo interoperability even one step further, so that U.S. ground control can have some control over Galileo satellites and vice versa?
Bob Canty: There is no OCX requirement to do that, but our system does not preclude that.
GPS World: Do you think that’s the wave of the future?
Canty: It’s hard to predict the politics. I can tell you technically, is it feasible? Yes. But it’s more political in nature than a technical problem.
GPS World: Going back to the separation of ground from space acquisition, is GPS being the model for this, paving the way?
Bob Canty: That’s not only for the Air Force. You’re starting to see that for NOAA programs, the GOESS-AR weather satellite coming up. That’s because of the paradigm shift. You can insert technology, make it more useable through the ground than you can in space. Space takes a lot longer to go do it, and what’s becoming more important is usability of information and knowledge, more than advancing the technology itself.
GPS World: Is this a corollary of the rise of software over hardware, in crude terms?
Bob Canty: It’s a combination of the two. Computing hardware continually increases in capacity, at the same time that software implementation is moving more rapidly. A good example of that is your cellphone. If your cellphone’s turned on at night, they can update the software in your cellphone, in some cases without changing the hardware. Cisco does that all the time with their routers. They put excess capacity in the routers, and just update the software to get new features. You can envision that space hardware will have enough sophistication that you can make a lot of ground changes, or software changes, and extend the life of satellites and systems.
GPS World: In your proposals, do you need the satellite builders to build excess capacity aboard the satellites?
Bob Canty: No. There are a lot of things about GPS we can do on the ground. A large component of accuracy can be done on the ground, to advance the systems without space. The more modernizations you have, if you have direct uplink capabilities to the satellites themselves, you can make much quicker updates to the satellites and your system gets more accurate.
GPS World: So, adding more monitoring stations on the ground, and updating the satellites more frequently – is anything else part of your OCX proposal?
Bob Canty: I would say we’d have to wait until after the competition to discuss more details.
GPS World: Would it be safe to say there are more things you can do?
Bob Canty: Those would be the primary ones.
GPS World: But you’ve got more?
Bob Canty: Potentially, yes.
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