Today, Hemisphere GPS announced the new S320 network rover and XF2 handheld data collector. With support for network RTK corrections, the S320 network rover is an integrated solution that simplifies land surveying applications by eliminating the need for a base station and radio modem, the company said.
A variety of public and private organizations post RTK network corrections on the Internet. The S320 GSM cellular communication connects users to Internet-based corrections and processes the data to achieve centimeter-level positioning performance. As a result, users do not need to purchase and operate their own RTK base station and radio modem connection. Users also have the option of using satellite-based L-band corrections for high-precision mapping jobs.
Hemisphere GPS’ XF2 next-generation data collector combined with Carlson SurvCE software provides a familiar and proven interface to the S320. The two products communicate through a Bluetooth wireless connection and attach to a standard survey pole making the system portable and simple to operate, Hemisphere GPS said.
“Hemisphere GPS’ S320 network rover and new XF2 provide a very powerful and cost-effective surveying and mapping solution,” says Phil Gabriel, vice president and general manager of Precision Products for Hemisphere GPS. “The rugged design and versatile performance of our S320 makes it a great fit for a variety of applications.”
Launched one year ago, S320 combines the advanced GNSS receiver performance of Hemisphere GPS’ Eclipse technology, precise geodetic antenna, wireless communication and batteries in a portable, rugged unit. Compatible with a variety of existing surveying equipment, S320 is a multi-GNSS positioning system designed for applications in GIS, mining, construction, mapping, land, and marine surveying.
The S320 network rover and XF2 will be featured by Hemisphere GPS in hall 9, stand B62 at the INTERGEO Conference and Trade Fair in Hanover, Germany from October 9-11. The products are available through the Hemisphere GPS Precision Products global dealer network.
Lift-off is set for 8:10 a.m. EDT (1210 GMT) Thursday for a GPS IIF satellite, reports Spaceflight Now. GPS IIF-3 will replace an aging 19-year-old craft in plane A, slot 1, part of the program to incrementally upgrade the GPS constellation with greater accuracy, better jam-resistance, and a new civilian aviation signal, all of which are features of the Boeing-build Block IIF series.
The United Launch Alliance Delta 4 rocket and GPS satellite payload will undergo a final technical assessment today and a readiness review Tuesday before entering into countdown operations Wednesday night.
The 19-minute launch window is timed to deliver the GPS IIF-3 satellite directly into plane A of the navigation network 11,000 miles above Earth.
The satellite is expected to be checked out and ready for handover to Air Force controllers by mid-November, according to Jan Heide, Boeing’s GPS program director.
A pair of Galileo satellites are now fully fueled and mated together atop the upper stage that will haul them most of the way up to their final orbit. The launch is planned for the evening of October 12, reports the European Space Agency.
Technicians donned protective suits to fill the two satellites’ tanks with hydrazine fuel, used to maintain the satellites’ attitude and orbital position during their planned 12-year lifetime.
Rather than carry a significant amount of extra fuel to insert themselves into their planned orbits – like typical telecommunications satellites or Galileo’s US GPS equivalents – the Galileo satellites are transported to medium orbit by the Fregat fourth stage of their Soyuz ST-B launcher.
Doing without this extra fuel and orbital thrusters means that Galileo satellites are small enough to be launched in pairs aboard the Soyuz – or in fours by the new Ariane 5 variant currently being prepared.
The Galileo satellites are attached to a special dispenser that holds them securely in position during launch, before pyrotechnic mechanisms release them sideways in opposite directions once their set 23 222 km altitude is reached.
The aluminum plates on each side of the satellites are temporary additions to protect their delicate solar panels; these will be removed later.
Galileo’s fit-check with dispenser (credit: ESA).
The combined satellites, dispenser and Fregat upper stage will now be carefully checked ahead of the next major milestone, the fitting of the protective launch fairing on Thursday.
The mission’s satellite launch readiness review will begin at the start of the following week. If that goes well, the combined ‘Upper Composite’ will be moved from the Fregat Integration Building to the launch pad, where it will be attached to the Soyuz launcher.
Completing Galileo’s validation phase
The launch will see these two new Galileo In-Orbit Validation satellites joining the first two that have been orbiting since October 2011.
This is a significant milestone for Europe’s Galileo programme because four is the minimum number required for navigational fixes, enabling full system testing whenever they are all visible in the sky.
This validation phase will be followed by the deployment of more satellites and ground segment components to achieve ‘Full Operational Capability’. After that, users on the ground can exploit the services.
The first four Galileo satellites were built by a consortium led by EADS Astrium, Germany, with Astrium producing the platforms and Astrium UK responsible for the payloads. They were assembled and tested in Rome by Thales Alenia Space.
Galileo IOV in orbit (artist’s rendering, courtesy of ESA.)
The two BeiDou-2/Compass satellites launched on 18 September are now in their circular medium Earth orbits and have started transmitting navigation signals. Several stations participating in the International GNSS Service’s Multi-GNSS Experiment as well as some in the Cooperative Network for GNSS Observation started tracking the satellites on 26 September.
From NORAD/JSpOC, we have the following orbits for the new satellites:
Satellite M5 is using PRN code 13 and M6 is using PRN code 14.
A plot showing the argument of latitude vs. longitude of ascending node for the BeiDou-2/Compass MEO satellites, including the M1/C30 test satellite, can be downloaded.
The plane spacing for the operational satellites is about 120 degrees. The slot spacings seem to be about 45 degrees.
By Ruizhi Chen, Yiwu Wang, Ling Pei, Yuwei Chen, and Kirsi Virrantaus.
A simple and flexible smartphone-based 3D navigation solution uses geocoded images that require neither 3D modeling nor real-time rendering of 3D scenes, making it energy-efficient and cost-effective. Real-world images can be also replaced with screen snapshots of the 3D scenes rendered from existing 3D models. Field tests demonstrate energy efficiency, consuming roughly half the power of a model-based solution with real-time rendering of 3D scenes.
The article “Drone Hack” in the August issue of GPS World and Todd Humphreys’ testimony before a House Subcommittee overseeing the Department of Homeland Security cited results of a spoofing experiment Humphreys conducted with University of Texas colleagues, demonstrating that a drone helicopter, navigating principally on the civil GPS signal, could have its vertical channel spoofed, causing it to descend. Reaction, quite strong from some directions, prompted one observer to investigate whether a “sky-is-falling” perception is fully warranted. Partly for that reason, emails started circulating among various individuals, including some directly involved in the design. When first brought into the group I was not expecting to be the one to summarize, but, as events unfolded, I’m called on to act as techno-sleuth.
Let me first state the conclusion: the sky is not falling. That’s not intended to discourage corrective measures — and it is immediately acknowledged that definitive answers remain unresolved (detailed configuration of the Kalman filter, state estimates, weighting of the baro altimeter). But this much is clear: conditions weren’t 100 percent normal. From here I’ll cover the supporting facts, followed by possible corrective measures. Discussion will be technical, without any hint of administrative authority or approval.
Key revelations came to light in discussion with the chief scientist of Adaptive Flight, who designed the drone’s nav system software and operator interface.
“The reason Todd and his team were able to modify the vertical position of the aircraft even though altitude aiding is actually coming from the pressure sensor,” he stated, “is that the GPS vertical velocity was being used. The spoofed GPS position (altitude error) was actually being ignored.”
We might call that a hybrid mode, using one part of GPS and ignoring another. Selectivity isn’t intrinsically unwise — we need options to reject some data without automatically rejecting other information — but, with GPS-derived altitude ignored for any reason, why not reject all vertical-channel influence from GPS? In fact that’s consistent with normal operation; disabling (again a quote) “GPS vertical velocity as an aid … can be done with a command from the control station (and saved as default for the aircraft).”
Well, then, the demo doesn’t reflect 100 percent normal procedure. Relief: our drones aren’t as vulnerable as we thought, and the fear expressed in various publications can be reduced.
For further support of that conclusion, additional major information from that same designer includes a quote that “The baro altimeter is used to provide a vertical position discrete update to the Kalman filter. This is true for both normal and GPS-denied modes. There are no (automatic) divergence tests in this system. There is some outlier detection/rejection on the GPS (which probably was not triggered in the spoofing tests, but I haven’t seen the data). There is nothing on the baro altimeter.” Finally, he says “it is a trivial change from the control station to make the vertical channel ignore GPS in normal mode by turning off the down GPS velocity measurement update; it would still fly fine.”
The combined weight of all that can justifiably reduce the level of concern — but not all the way down to zero. Now that all this happened, the subject of prevention needs to be addressed.
As Todd Humphreys correctly noted, without spoofing but with existing errors, GPS position updating cannot adequately mitigate low-cost IMU drift.
High-end IMUs bring budget issues (and their motion-sensitive errors limit performance anyway). Spectrum and signal quality is seen by many as an important consideration; residual monitoring is another. For the latter to be effective, the existing (loose) coupling needs upgrading (loose coupling wastes information content; the loss is greatest when GPS coverage is marginal). Extent of refinement (tight/ultratight/deep) and usage of carrier phase (while sidestepping its usual traps) open up a subject with much wider scope: cross-checking. I offer just a few fundamentals here.
Known data-edit capabilities available with existing provisions (for example, baro altimeter cross-checking), rather than something that “can be done” can always automatically disallow any partial influence from GPS instantly upon spoof detection, regardless of its genesis (Kalman filter bias state traceable to past history or any other source).
The step just noted generalizes to include all sensor data extant onboard, including carrier phase. The specter of huge expense for this particular step is nonessential; some receivers output raw measurements that can be put into public domain algorithms.
With access to all the raw data, every solution combination — federated and integrated — can be generated for cross-checking. In all cases, thresholds for residual testing are set with conservative assessments of sensor error statistics; this overbounding enables integrity testing to err on the side of caution (sacrificing some valid data to better ensure rejection of bad). Integrity test algorithms are likewise public domain.
I close by paraphrasing an observation offered by Mitch Narins in a LinkedIn discussion: Deter threats before they happen. With a robust non-GNSS PNT alternative, spoofing will have no affect on safety or security.
— James L. Farrell President, VIGIL, Inc. Severna Park, Maryland
GPS III SATELLITE, artist’s rendering, courtesy Lockheed Martin.
Raytheon Company and Lockheed Martin successfully completed the first launch readiness exercise for the U.S. Air Force’s next-generation GPS III satellites. The exercise is a key milestone demonstrating the team remains on schedule to achieve launch availability in 2014, the companies said.
The Lockheed Martin-built GPS III satellites and the Raytheon-developed next generation GPS operational control system, known as OCX, are critical elements of the U.S. Air Force’s effort to affordably replace aging GPS satellites while improving capability to meet the evolving demands of military, commercial and civilian users worldwide. This is the first space and ground enterprise successfully building the ground control and space vehicles by two independent prime contractors.
The launch readiness exercise, completed over a three-day period by mission operations personnel, validated the basic satellite command and control functions, tested the software and hardware interfaces and demonstrated basic on-console procedures required for space vehicle contacts during the launch and early orbit mission. The event sets the stage for the first GPS III satellite’s mission readiness timeline, which includes five short-duration exercises and six, five-day mission rehearsals leading up tolaunch.
To achieve first launch availability in the 2014 timeframe, the U.S. Air Force awarded Lockheed Martin and Raytheon contracts in January of this year to provide a Launch and Checkout Capability (LCC) for launch and early on-orbit testing of all GPS III satellites. At the heart of the LCC is Raytheon’s Launch and Checkout System that will provide satellite command and control capability, an integral part of OCX’s support of the first GPS III launch.
Rockets on the Pad
As this magazine goes to press on September 17, several GNSS satellite launches are pending, and may have already occurred by the time you read this. Launch dates this fall for GNSS satellites in the coming season are as follows, according to various, not always official, sources. Compilation courtesy of CANSPACE.
Compass M2 and M5. September 18, 18:12 UTC (speculative).
GSAT-10. Carrying a satellite-based augmentation system (SBAS) transponder for the GPS-aided geo-augmented navigation system (GAGAN), a planned implementation of a regional SBAS by the Indian government: September 21.
Compass G6. No earlier than October 1.
GPS IIF-3. October 4. Launch window: 12:10-12:29 UTC.
Galileo IOV FM3 and FM4. October 10, 18:31 UTC.
Luch-5B. For the Russian SBAS. Originally scheduled for October 15, launch has slipped to no earlier than November 1 due to an issue with the Briz-M upper stage, which caused the loss of the Telkom-3 and Ekspress-MD2 communication satellites during their launch on August 6.
GLONASS-K1 (block K2s). November 14.
The fourth Galileo flight model satellite is unloaded at Cayenne Airport in French Guiana August 17. (ESA/EADS Astrium, Raoul Kieffer)
Javad Ashjaee, founder and CEO of JAVAD GNSS, filed a September 7 letter with the U.S. Federal Communications Commission (FCC) concerning his company’s development of technical possibilities in GNSS filter designs and components. He stated “I hope this will be helpful in establishing realistic guidelines for the characteristics of high-precision GNSS receivers that will be used in critical applications.”
The letter reads, in part:
“We have improved our previous L1 filter and have extended the design to include all commercial GNSS bands.”
“Our filter . . . protects GPS L1, Galileo L1 and GLONASS L1 bands. It brings in all the useful signals intact and rejects out of band signals with the slope of about 12 dB/Mhz. Similarly . . . our filter . . . . protects GPS L2, GPS L5, GLONASS L2 and Galileo L5 and has slope of about 9 dB/Mhz.
“These filters not only protect GNSS signals against all LightSquared signals (10L, 10H and 10R handsets) but also from all similar signals that may appear near all commercial GNSS bands in the future. We are proud that our filters help allow better usage of these precious bands, in particular for broadband wireless communication that our country desperately needs.
“These filters apply to wideband high precision GNSS receivers and the cost is even less than earlier conventional filters. The case of narrow-band low precision receivers (e.g. Garmin) is much simpler, as has been demonstrated by GPS receivers in more than 300 million cell phones and mobile devices which are not affected by LightSquared signals. The low precision receivers (L1 C/A code only) require filter slopes 10 times less steep than those presented here and do not necessitate additional costs.”
Galileo Headquarters Moves to Prague
On September 6, the European GNSS Agency (GSA) inaugurated its new premises in Prague, Czech Republic. Previously headquartered in Brussels, the headquarters of the Galileo program moved its seat to Prague this summer, as agreed by the EU heads of state and government in December 2010.
Galileo is expected to be partly operational by the end of 2014. Two in-orbit validation (IOV) satellites will be launched in October, bringing the total in space to four, sufficient for initial check-outs. Beginning in 2013, four more Galileo satellites will be launched every six months until the network of 30 is completed in 2020.
GSA ensures security of satellites and prepares ground for new GNSS products. The agency is responsible for a number of implementation tasks for the European Satellite Navigation programmes Galileo and the European Geostationary Navigation Overlay Service (EGNOS), which are managed by the European Commission. Its two main tasks are:
Security accreditation of satellites, launchers, and sites, and the operation of the Galileo Security Monitoring Centre, and
Market development for the European satellite navigation systems, such as new products and services possible using Internet access to satellite navigation data, among others.
Future Role. A European Commission (EC) proposal for revising the GNSS Regulation foresees that operational responsibility for the GNSS programmes will be gradually transferred from the EC to the GSA over the next multi-annual financial framework (2014-2020). This represents a reversal of an earlier move, or a restoration of a previous state; after delays and budget disputes with manufacturers during the tentative public-private partnership (PPP) phase, the European Commission took direct control of the Galileo program, effectively sidelining the GSA.
The transfer of responsibility will start with EGNOS in 2014, and already a number of preparatory tasks have been allocated to the GSA, including the procurement for the future operations of EGNOS.
To carry out these new functions, the GSA’s staff is expected to increase from about 60 today to more than 180 by the end of next financial framework in 2020.
Budget. The GSA has an annual budget of about €12.75 million ($16.75 million) in 2012, plus €34.4 million ($45 million) for exploitation activities.
According to European Commission calculations, a total budget of € 7 billion ($9.2 billion) is necessary to complete the deployment phase of the Galileo programmes and finance the exploitation phase of the GNSS programmes over the 2014-2020 period.
Compass Energizes China’s Economy
China’s Beidou/Compass system will spur the country’s economic development in the satellite-navigation industry, geoinformation, and location-based services, according to an article in China Daily. China’s civil navigation providers are likely to experience rapid growth during the 12th Five-Year Plan (2011-15) period.
The deputy director-general of the National Administration of Surveying, Mapping and Geoinformation said the government is likely to introduce policies to help the geoinformation industry grow.
“In addition, the nation’s self-developed satellite navigation network, the Beidou Navigation System, will come into commercial use by the end of this year, a move that may stimulate the development of the geoinformation industry in China.”
Aviation NextGen May Show Slow ROI
An inspector from the U.S. Department of Transportation testified in Congress that benefits from the GPS-based air traffic control system Next Gen may take longer to realize than had been expected. Although the Federal Aviation Administration (FAA) has improved its management of the modernization program, years of delays and cost over-runs have left airlines dragging their feet in turn over multibillion-dollar equipment upgrades needed for the new system to work.
The inspector stated the investment will be worth the taxpayer cost in the long run, and will produce significant safety and scheduling benefits. U.S. air travel is expected to nearly double over the next two decades, bringing an unbearable burden onto the current air traffic control system, if not significantly upgraded.
By 2020, the new system is expected to reduce delays by 38 percent compared with the current system; airlines, passengers, and taxpayers are estimated tosave $24 billion.
The FAA plans to spend $2.4 billion over the next five years on a collection of six programs evolving from an outdated, radar-based system to one that uses GPS and telecommunications advances for precision tracking, making routes more direct, eliminating many weather delays, and enabling planes to fly safely at closer distances. Once fully in place, the modernization program will save 1.4 billion gallons of fuel and reduce carbon dioxide emissions by 14 million metric tons, the FAA says.
However, planes must be equipped with new equipment at a cost of hundreds of thousands of dollars per aircraft. NextGen doesn’t start yielding full benefits until a critical mass of planes have the new technology.
Position, navigation, and time (PNT) are essential enablers for warfighter capabilities. They are used in virtually every weapons system of the Department of Defense. The GPS system has become the ubiquitous provider of this military service. In addition, GPS is the backbone of scores of civil applications that have provided startling improvements in safety, productivity, and convenience.
Credit for this achievement should go to the thousands of developers, researchers, and operators. In particular, Air Force Space Command under the leadership of Gen. Willie Shelton has consistently recognized its global stewardship for GPS, the stealth utility.
That said, the job is far from over. New threats, needs, and challenges must be met. The essential overarching goal is PNT Assurance. While GPS is an outstanding system, there are still areas for improvement. In providing PNT assurance, what should be the highest priorities for those improvements? Of course an answer to this question could involve many aspects or dimensions. The GPS Independent Review Team (IRT) focused on a number of attributes it designated as The Big Five.
Instead of the Big Five, for the purpose of this discussion, I would like to examine three key attributes. These could be applied to GPS or any other, alternative, PNT system.
I call these three essential attributes the Three As. They are:
Availability
Affordability
Accuracy
I will discuss each briefly and then add some improvement goals for each attribute. I call these improvements my personal Druthers.
Availability of Position, Navigation and Time
Without assured PNT availability, the warfighter cannot depend on the effectiveness of his weapon systems. Neither can civilian users count on their attendant benefits. To achieve GPS availability, the first requirement is adequate satellite geometry. Fewer than four satellites in view implies that the user will not have a PNT solution. A military user in the middle of a desert does not stress this geometry problem. More difficult is warrior support in mountainous or urban terrain. The steep mountains of Afghanistan can cause availability outages exceeding 10 hours per day for the currently specified 24-satellite constellation. The Department of Homeland Security has similar challenges in urban areas. Many effects-based studies have shown that 30 active satellites plus three spares are the knee in the availability curve.
A 30-satellite constellation plus three spares (optimally distributed) greatly increases availability for the sky-challenged user. Special Operation Forces in mountainous areas or Army forces in villages have precision location and can promptly designate fleeting targets of opportunity. A 30-satellite constellation assures civilian emergency service providers that they can meet their obligations in domestic urban canyons.
There are two new GNSS programs being developed that emulate GPS, named Galileo and Compass. They have made similar availability calculations and both are nominally sized at 30 satellites or more.
To maintain GPS as the gold standard, I therefore propose my first druther:
Druther One. The Department of Defense (DoD) should define the GPS constellation to be 30 satellites plus 3 spares distributed in an optimal manner.
The second aspect of availability is that the user must be able to receive the signal. Independent advisory groups have repeatedly called for increased interference-resistant solutions for the last 14 years. The technical solutions to produce virtually jam-impervious receivers are well-known. More than 33 years ago, the GPS Joint Program Office, allied with a creative program at Wright Patterson Air Force Base, demonstrated over 100 DB of J/S or anti-jam (AJ) resistance. This is enough resistance to defeat any jammer less than 1 kW in effective power. The techniques included deep integration with inertial units, controlled reception pattern antennas (CRPA), and averaging using low-phase noise clocks. To counter the problem of blinking jammers, the CRPA should be beam steering rather than null steering. This leads us to:
Druther Two. The installed GPS user equipment in both commercial and military aircraft should be able to fly directly over a 1 kW jamming source with no effect.
This is readily achievable with technology we understand. We need not employ high anti-jam techniques in all receivers; however, both the DoD and the Federal Aviation Administration (FAA) need to focus on GPS jamming resistance as a requirement. That said, the developers and manufacturers still must focus on affordability for these AJ solutions (see below).
To ensure availability, and to discourage the use of enemy jammers, the U.S. government should deploy augmentation, that is, backup systems. Recently, psuedolites (ground-based transmitters of GPS ranging signals) have become a focus for augmentation. I remain deeply skeptical concerning psuedolites in a fluid battlefield situation. Psuedolites do not perform well for attributes two and three: affordability (including operational complexity and support structure) and accuracy.
Alternatively, low-cost or navigation-grade inertial units are potentially viable augmentations, and the FAA is investigating enhanced versions of distance-measuring equipment (DME) and tactical area navigation systems (TACANs). In addition, a recent study highlighted the value of an enhanced long-range navigation (eLoran) system with its high-power, low-frequency signal. These augmentation alternatives deserve further study.
Spectrum Threats. Federal Communications Commission- (FCC-) licensed jammers are an emerging threat to GPS. Somehow, a myth has grown up that the GPS band is underutilized, and that additional services should be licensed in adjacent frequency bands. With well over a billion users, the GPS spectrum is definitely not underutilized.
An example of the licensing threat is the FCC tentative approval for high-powered, terrestrial, communication transmitters in the band immediately adjacent to GPS. This band had previously been reserved for quiet communication signals from satellites (including GPS corrections). Extensive independent testing has shown that high-powered terrestrial transmitters would have an immediate and devastating effect on military receivers, aviation and commercial receivers, including those used for precision applications such as farming. Fortunately this threat has been, at least temporarily, postponed. Many inquire why GPS is so fragile that it cannot tolerate high-powered transmitters in adjacent bands. Unfortunately, because the proposed 15 kW transmitters/jammers are not those of an enemy, we cannot bomb them. An enemy jammer of such magnitude would not get off so lightly. This leads to:
Druther Three. Ensure the Federal government, particularly the FCC, maintains the frequency bands adjacent to GPS as a quiet neighborhood as they are now.
Affordability of the PNT System
All Federal discretionary programs are under enormous budget pressure. With the threat of sequestration, the DoD is particularly susceptible. The doomsday budget may be rapidly approaching.
For GPS, the most visible segment is spacecraft. Many advocate dual-launch capability, for GPS launches. Launch costs are roughly half the cost of a satellite on orbit. Thus, dual launch could eliminate 25 percent of the cost for this capability. Of course, the real issue is the total cost of a satellite operationally deployed on orbit. A triple-launch capability, or satellite size reductions compatible with more affordable space launch vehicles, will help reduce this total on-orbit cost. This leads us to:
Druther Four. Total on-orbit GPS satellite cost should be less than $175 million.
The GPS program office recently initiated an affordable satellite design study to reduce satellite cost. The affordable satellite should broadcast all GPS signals, with no extra payloads except a laser reflector (a small passive device, added for accuracy).
Additionally, the radio frequency (RF) chain should be improved to create greater efficiency with either gallium nitride power amplifiers or traveling wave tube amplifiers (TWTAs). With the 30+3 orbital configuration, military power should be specified at a 15° Earth mask angle (rather than the standard 5°), which would significantly reduce the amount of RF power required. With an affordable 30+3 SV constellation, users should easily lock on to four, full-power satellites above a 15 degree elevation mask. No flex-power capability need be included since the advantages of the few DB that flex power offers are more easily obtained with user equipment modifications. The net result of these modifications could produce a reduction of approximately 75 percent in the power needs of an operational GPS satellite. Such reductions generate significant savings in satellite weight and cost, as well as making dual or triple launch much more easily achievable.
The military GPS user equipment (UE) program has come under considerable and warranted criticism because military UE does not afford the user the flexibility nor ease-of-use found in less-expensive commercial and/or civil GPS receivers. The current UE program office initiative to demonstrate the advanced design of front-end chips seems a good initial step. In addition to demonstrating representative military applications, the JPO should develop a simple, intuitive, GUI interface similar to existing commercial handheld devices such as Apple, Magellan, Trimble, Garmin, or TomTom. Further, to attain affordable jam resistance, the CRPA costs must be reduced using digital electronics and commercial practices.
This background leads to:
Druther Five. The military GPS user equipment (UE) program should include front-end interfaces conversant with the best commercial devices including small handheld receivers.
Druther Six. The AJ program should leverage modern advances in commercial digital electronics, producing more affordable CRPAs and using the state-of-the-art micro-electromechanical systems (MEMS).
Additionally, the GPS Control Segment should re-examine current and future requirements, particularly those related to training the relatively inexperienced military cadre. A shift to a more permanent, technically-sophisticated, civilian cadre is probably warranted, retaining a military operational commander to direct the essential warfighter capabilities.
Accuracy
In this discussion, accuracy includes bounded inaccuracy: limiting the probability of errant weapons and inaccurate positioning.
For the military, weapons delivery accuracy is usually parsed into three contributors:
target location error (TLE),
weapon location error (WLE), and
weapon guidance error (WGE).
All three components can be affected by GPS accuracy. Focusing on the Special Operations, Army, and Marine operators, the TLE today is limited by the ability of the target designator to determine azimuth. To ensure weapon delivery accuracy is 5 meters or better, we need:
Druther Seven. The DoD should develop and deploy an affordable azimuth-determination device for forward observers with an accuracy that is better than one milliradian.
For GPS, accuracy and bounded inaccuracy is a combination of geometry and user ranging error for all users. Druther One assures the geometry for virtually all users, but it bears repeating here:
Druther Eight. The GPS operational on-orbit constellation size requirement should be set at 30 satellites plus 3 spares. This repeat of Druther One greatly improves both accuracy and availability for many users.
Further improvements can be made in the inherent GPS ranging error through more accurate and sustainable atomic reference systems (clocks) and more accurate measurement of GPS satellite positions (ephemeris) by the user segment. This leads to:
Druther Nine. The GPS program office should pursue a vigorous effort to improve spacecraft atomic reference systems (clocks) and provide retroreflectors onboard all operational GPS satellites.
This will prove particularly beneficial to all users because long-range ephemeris accuracy and clock predictions will improve significantly.
As a longtime participant and observer of the GPS program, I would like to submit this wish list (see sidebar) of druthers to government decision-makers. In particular, if the Department of Defense were to act on these requests, I would regard it as a wonderful Christmas present for all users. Hopefully it will be for an immediate Christmas rather than a Christmas in the indefinite future, which I may not be around to see.
Thank you for your attention.
Brad Parkinson’s Wish List
Availability of PNT
1. The DOD should define the GPS constellation to be 30 satellites plus 3 spares distributed in an optimal manner.
2. The installed GPS user equipment in both commercial and military aircraft should be able to fly directly over a 1 kW jamming source with no effect.
3. Ensure that the federal government, particularly the FCC, maintains the frequency bands adjacent to GPS as a quiet neighborhood.
Affordability of PNT
4. Total on-orbit cost of a GPS satellite should be less than $175 million.
5. The user equipment program must include front end interfaces conversant with the best commercial devices including small handheld receivers
6. The AJ program should leverage modern advances in commercial digital electronics, producing more affordable CRPA’s and using the state-of-the-art MEMS.
Accuracy, Bounded Inaccuracy
7. DoD should develop and deploy an affordable azimuth determination device for forward observers with an accuracy that is better than one milliradian.
8. The GPS operational constellation requirement should be set at 30 satellites plus 3 spares.
9. The GPS program office should pursue a vigorous effort to improve spacecraft atomic reference systems (clocks) and provide retroreflectors on all operational GPS satellites.
Bradford w. Parkinson was the original chief architect, advocate and Program Director for GPS. His numerous awards include the Draper Prize, sometimes considered the Nobel for engineering.
He adds, “All thoughts are mine, and should not be assumed to be the views of the GPS Independent Review Team, the Department of Defense, or any GPS manufacturer.”
The Indian Space Research Organisation’s GSAT-10 geostationary communications satellite was launched from the European spaceport in Kourou, French Guiana, on 28 September at 21:18 UTC. The dual-satellite launch also carried the Astra 2F direct-to-home broadcast satellite into orbit for Luxembourg-based operator SES.
GSAT-10 contains a payload to support the Indian GPS and GEO Augmented Navigation (GAGAN) satellite-based augmentation system. The satellite will likely use PRN code 128 from its orbital slot at 83 degrees east longitude.
NORAD/JSpOC is tracking four objects from the launch, all in geostationary transfer orbits:
The two satellites are accompanied by the Sylda 5 dual-payload adapter and the ESC-A upper stage of the Ariane 5 launch vehicle. It’s not yet known which objects are which.
Once GSAT-10’s GAGAN L-band payload is activated, the satellite will be tracked by stations of the International GNSS Service’s Multi-GNSS Experiment in addition to those of the official GAGAN monitoring and control network.
The following is from a press release issued by ISRO:
“ISRO’s Master Control Facility (MCF) took over the command and control of the GSAT-10 immediately after the injection. Preliminary health checks on the various subsystems of the satellite, namely, Power, Thermal, Command, Sensors, Controls, etc., were performed and all the parameters were found satisfactory. Following this, the satellite was oriented towards the Earth and the Sun using the onboard propulsion system. The satellite is in good health.
“In the coming five days, orbit raising maneuvers will be performed to place the satellite in the Geostationary Orbit with required inclination with reference to the equator. The satellite will be moved to the Geostationary Orbit (36,000 km above the equator) by using the satellite propulsion system in a three step approach.
“After the completion of orbit raising operations, the two solar panels and both the dual gridded antenna reflectors of GSAT-10 will be deployed for further tests and operations. It is planned to experimentally turn on the communication payloads in the second week of October 2012.
“After the successful completion of all in-orbit tests, GSAT-10 will be ready for operational use by November 2012. GSAT-10 will be positioned at 83deg East orbital location along with INSAT-4A and GSAT-12. The operational life of GSAT-10 is expected to be 15 years nominal.
“GSAT-10 Satellite has 30 Communication Transponders [12 in Ku-band, 12 in C-band and 6 in Extended C-Band]. Besides, it has a Navigation payload “GAGAN” that would provide GPS signals of improved accuracy (of better than 7 meters) to be used by the Airports Authority of India for Civil Aviation requirements. GSAT-10 is the second satellite in INSAT/GSAT constellation with GAGAN payload after GSAT-8, launched in May 2011.”
After the September 12 launch of the Apple iPhone 5, which comes equipped with Apple’s own Maps application, users soon found their efforts to navigate thwarted by mislabeled cities, misplaced landmarks, lack of’ transit directions, and strange satellite imagery.
Today, Apple Inc. Chief Executive Tim Cook apologized to customers for the flaws in the Maps app in a letter posted on Apple’s website. The Maps app replaced Google Maps as the standard iPhone mapping application, but Cook is now suggesting customers use the online Google Maps or download other mapping applications while Apple works to fix its application. Google Maps was standard on previous versions of the iPhone. Apple’s newest mobile operating system, iOS 6 doesn’t support Google Maps, so users would have to use that application through the Internet.
Here is the text of Cook’s letter:
To our customers,
At Apple, we strive to make world-class products that deliver the best experience possible to our customers. With the launch of our new Maps last week, we fell short on this commitment. We are extremely sorry for the frustration this has caused our customers and we are doing everything we can to make Maps better.
We launched Maps initially with the first version of iOS. As time progressed, we wanted to provide our customers with even better Maps including features such as turn-by-turn directions, voice integration, Flyover and vector-based maps. In order to do this, we had to create a new version of Maps from the ground up.
There are already more than 100 million iOS devices using the new Apple Maps, with more and more joining us every day. In just over a week, iOS users with the new Maps have already searched for nearly half a billion locations. The more our customers use our Maps the better it will get and we greatly appreciate all of the feedback we have received from you.
While we’re improving Maps, you can try alternatives by downloading map apps from the App Store like Bing, MapQuest and Waze, or use Google or Nokia maps by going to their websites and creating an icon on your home screen to their web app.
Everything we do at Apple is aimed at making our products the best in the world. We know that you expect that from us, and we will keep working non-stop until Maps lives up to the same incredibly high standard.
