Quotes Of The Quarter
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"As as 'honest broker' for technology, the ION can remain engaged in the public policy arena and have an immediate and lasting impact safeguarding the nation's critical infrastructure." Conclusion from maritime conference sponsored by ION/NOAA/U.S. Coast Guard Academy
"Clearly, a GPS/Loran alternative to WAAS may have
significant cost and operational advantagesand failure to maintain the investment
in Loran infrastructure at this time would be irresponsible." Report
on Senate FAA appropriations bill for FY99
From The President
Frank van Graas
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It is a great opportunity for me to serve as President of the ION during a year in which the Institute is in excellent health. The day-to-day operation of the Institute is in the capable hands of the National Office staff, who also have great working relationships with the many ION volunteers.
During the past several years, Council and Executive Committee meetings have focused on the mission of the Institute. There certainly has not been a shortage of good ideas to increase membership services, grow the ION membership, record and disseminate technical information, and to promote navigation and related art and sciences.
To implement these new ideas, the ION Council took two important steps at the June meeting. First, a Strategic Plan was approved to serve as an outline for the management of the infrastructure of the Institute. Second, an ad-hoc New Initiatives Committee was established to track the implementation of new initiatives.
The approved Strategic Plan finds its roots in the ION Strategic Five-Year Plan prepared by David C. Scull in 1993. In 1995, this plan was revised by George Lowenstein and Stan Lewantowicz and circulated to Council as the ION Strategic Plan. Last year, the Strategic Planning Committee updated this plan with approved objectives from Council motions and actions. Because of this rich history, the current ION Strategic Plan contains many worthy objectives that support the mission of the Institute.
Some of the initiatives that I will be personally involved
with during this year are to provide an increased support for the ION Sections
and Student Chapters, as well as to raise the visibility of the Institute
by reaching out to policy makers with technical information support. I look
forward to contributing to the Institute's vision of "a society where
navigation is effortless" (quoted from the ION Strategic Plan).
ION Membership At New High; Council Discusses
Expanded Member Benefits
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ION membership grew about 10 percent during the last year, reaching a record high in January, and reflecting several years of steady growth, according to data supplied the ION Council at the organization's Annual Meeting held in Denver June 1-3.
The previous year, on a June-to-June basis, membership had risen by slightly more than 13 percent. If comparable growth occurs during the same period of the current year, membership will exceed 4000 in 1999.
During the report by the Membership Committee, discussion arose over the dues structure and whether the ION should continue to provide services that benefit not just members, but the navigation community as a whole. Views were expressed that the current dues structure was adequate, that the finances of the organization, including reserve funds, seemed to be basically sound. As for ION activities, it was felt that services that benefit non-members should not be a problem, but some suggestions were made for expanded benefits to members only.
These suggestions on expanded member benefits were referred to a newly created New Initiatives Committee for further study. They included proposals that members receive copies of papers free of copyright fees, priority meeting notification, creation of a job bank, and assistance in providing information to interested parties on members' products or companies. In the latter case, Carl Andren, ION Technical Director, is making arrangements to hyper link corporate members listed on the ION web page to their company's home page.
Sections Report
The Council approved a motion to provide each Section Chair a map of his/her section, with the location of each member plotted on the map, to improve methods in the future for selecting meeting sites, and for other local Section purposes. The national office will review other membership information tools that may be helpful to Section Chairs. Currently, the ION has 10 sections; the formation of a new section, in Dallas, is being considered.
In other business, the Council was told that work was moving forward on the preparation of the "red book" series on WAAS and LAAS. Dr. El-Arini Bakry, Mitre, and Todd Walter, Stanford, have been selected as editors of the WAAS publication, to be Vol. VI in the series, and editors for the LAAS volume, to be Vol. VII in the red book series, will be determined shortly.
A project to provide a searchable, computerized database
of all ION Journal articles has been completed and provided to the ION for
inclusion on its web page. The Council approved a grant for a Penn State
student to upgrade the ION Journal archiving system, and investigate a similar
database for symposium proceedings. The Council directed that recommendations
on how the ION can capture oral and historical navigation records be prepared,
and presented for action at the next Council meeting in January.
The GPS Modernization Dilemma And Some Topics
For Resolution
By Keith D. McDonald
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For the past several years, there has been considerable interest and effort by both the military and the civil communities in attempting to establish and agree upon the most effective way to assure that the new generation of GPS spacecraft meet current and future needs. This has not been easy. This process has required the military departments, the civil agencies and the concerned industries to take a new look at the requirements that can be satisfied by GPS as well as the capabilities, performance and deficiencies of GPS.
Substantial efforts during the past several years have been sponsored by the National Academy of Sciences and their National Research Council, the National Academy of Public Administration, the Defense Science Board, the Air Force Scientific Advisory Board and the RAND Critical Technologies Institute. Also heavily involved are the GPS Joint Program Office, the Department of Transportation, the NOAA National Geodetic Survey, the RTCA and the Congress. Much of this work influenced the White House
development and release of a Presidential Decision Document on GPS in March of 1996. However, the basic issues facing the military and civil communities' joint use of GPS have not been resolved. This modernization of GPS was to be completed by now. The scheduled date for resolution was August 25 of 1998 which was delayed until September 2nd which apparently has been slipped to the end of September or possibly later.
Purpose and Outline
The overall modernization situation was discussed in the Winter 1997-98 ION Newsletter which covered most of the GPS Modernization activities through early March of 1998. Developments since then include several new issue areas and a number of
peripheral concerns. The purpose of this paper is to outline these evolving concerns and the signal structure developments which have influenced the signal selection process that is in the final stages of resolution.
Figures 1, 2 and 3 illustrate the current status of the signals being provided to users by the current constellation of GPS spacecraft, as well as most of the alternatives. This includes the alternatives that have been considered during the past several years, current alternatives and others which appear to have merit. The alternatives shown in the figures are not intended to be comprehensive but to show a number of feasible approaches for achieving very substantial performance improvements to both civil and military users. The advantages, shortcomings, constraints and opportunities provided by these signal structures for the future will be discussed. The signal alternatives described in the figures are arranged in a logical sequence illustrating the various stages of their development.
Signal Representation and Current Status
The current status of the GPS signal structure is shown in Figure 1(a) which illustrates the C/A-code signal at the center of the L1 band (at 1575.42 MHz) and the P/Y-codes centered in the L band and in the L2 band (at 1227.6 MHz). At L1, the C/A-code signal is in phase quadrature with the P/Y-code as indicated. This basic signal structure for GPS was
developed in the early 1970's and has served users since the launch of the first Block I developmental spacecraft on February 22, 1978. Although GPS has transitioned through the Block I's into the operational Block II and IIA and now to the Block IIR replenishment spacecraft, the signal structure has been stable in the sense that it has not changed.
This stable signal structure has provided some excellent results: microprocessor chips, including ASICS and DSPs, with appropriate software, have been developed and produced to the point where civil GPS receivers are comparable in cost with popular wristwatches and small appliances. Similarly, military receivers have improved substantially in performance and cost, and have been found to operate successfully in a large number of military applications. The GPS signal characteristics have played a significant role in the evolution and success of GPS.
GPS Signal Deficiencies
However, there are some deficiencies associated with the GPS signals. Civil users have been concerned with the following for many years:
For the military users, the first two listed considerations don't apply, and the third is valid but apparently not of great concern. However, the fourth, relating to increased spacecraft signal power, is of substantial interest to the DOD for operations in jamming and interference conditions.
Also of great interest to the DOD is the maintenance of its full GPS capabilities in a region of operations, denying GPS access to an adversary and leaving unaffected the civil use of GPS outside the region. The DOD has also been concerned with avoiding or minimizing the influence of the military signal on the civil signal. For some time, the DOD has desired separate frequency bands of operation for the two services, although frequency spectrum congestion makes this nearly impossible. Also, the current signal structure implementation requires DOD users to access the C/A-code first (in nearly all cases) in order to obtain GPS timing information (from the HOW word) in order to acquire the P/Y-code. For this reason, direct Y-code acquisition is a requirement high on their priority list.
The Coded Second Civil Frequency
In Figure 1(b), the possible placement of a second coded civil frequency at the center of the L2 band is shown. There is concern that the GPS L2 band doesn't have sufficient protection for use in a safety service (e.g., by the FAA) since the band is co-primary under ITU rules with the radiolocation band which includes many ground-based radars. The FAA has requested placement of the civil L2 (L2c) in the part of the aeronautical radionavigation services (ARNS) band just below the GPS L2 band (i.e., between 1150-1210 MHz). DOD has not accepted this because its Joint Tactical Information Distribution System (JTIDS) operates throughout this region.
Several years ago I suggested that the GLONASS L2 band (1240-1260 MHz) be seriously considered as a location for a second coded civil frequency. This band has the proper ITU designation (RNSS) and a civil GPS signal could very likely operate on a non-interference basis with GLONASS, especially since the GLONASS L2 band constriction (with their L1) leaves about the top half of the band unused. However, it has been pointed out that the GLONASS L2 band has the same protection problem (and possibly worse) as the GPS L2 band, as well as international coordination concerns that could be lengthy and unsuccessful.
Vice President Gore announced in March of 1998 that a civil coded second frequency would be placed in the GPS L2 band and that a search would continue for a location for a civil L3.
The Frequency Re-Use Proposal
Figure 1(c) illustrates the frequency re-use signal arrangement proposed by the USAF GPS Joint Program Office (JPO). This arrangement was an attempt at a compromise since it did not appear feasible, after about a three year spectrum search, for separate frequency bands to be available for military and civil users. The military signals at L1 and L2 would be modulated, by Manchester coding or by other means (tri-code hexaphase) such that most of a new Lm (military link) signal would be in the outer 8 MHz regions. Nearly all of the civil signal would be in the center 8 MHz region.
Figure 1(d) was a variant of Figure 1(c) in which the L2 band would be exclusively for military use if L2c could be placed in theARNS band. Concerns relating to interactions between the civil and military signals resulted in these signal structures not gaining the needed level of support.
The Split Spectrum Signal
In Figure 2(a), a signal structure is shown which proposes placement of civil C/A-codes (or other codes) at the P/Y-code nulls, or nearby. This has the advantage of providing DOD with a wide-band signal with maximum robustness and of placing the civil signals in the regions where the Lm signal level is very low. I proposed this signal structure in August of 1997 for two principal reasons. First, to minimize the interaction between the civil and military signals and second, to take advantage of the approximately 20 MHz separation between the civil signals to provide for the determination of a very wide (or "hyper") lane of ~15 m. This provides rapid, high confidence, real time resolution of carrier phase measurements to the centimeter level. Carrier phase measurements are the most accurate
measurements available from GPS, so a method for instantaneous resolution of the integer ambiguity in the ranging (and difference) measurements appeared to have significant promise for the future accuracy demands placed on GPS.
This dual, or split spectrum, signal was advocated for both L1 and L2. It also appeared, as shown in Figure 2(a), that a C/A-code centered at L1 would be needed for backward compatibility, or "legacy," purposes. Since this signal is needed by both civil and military users, it is designated L1cm. Unfortunately, this arrangement requires five C/A-code signals in lieu of the two civil signals initially considered.
Lm Shift to Provide Legacy Signal
Figure 2(b) illustrates a technique for reducing the number of C/A-coded signals in the L1 band from 3 to 2. By shifting Lm up infrequency by 10.23 MHz, and with the C/A-codes placed at the ends of the Lm band, then only two C/A-codes are required. A drawback is that the upper C/A-code (L1c') is above the currently assigned GPS band and GPS transmissions fall into the 10 MHz region below the GLONASS L1 band. The Europeans have indicated a plan to use this region of the spectrum but the status of this frequency band is currently unclear.
Figure 2(c) retains the up-shifted split spectrum signals in the L1 band region and down-shifts the split spectrum signals in the L2 band to the ARNS band. These split spectrum signals can be separated by any convenient frequency (possibly limited to 1.023 MHz increments) from about 20 MHz to 60 MHz (hyper lanes of 15 to 5m.). The 20 MHz is a smaller separation than needed but fits conveniently in the GPS assigned bands.
Code Features of Split Spectrum Signals
Dr. James Spilker has demonstrated that the split spectrum technique also has substantial advantages in its code performance. These advantages are significant in that two separated narrow band signals (e.g., C/A-codes) can provide several times better code ranging performance than obtainable from the P/Y-code signals currently used by the DOD.
DOD Use of Split Spectrum Signals
Recognizing the accuracy improvement potential of the split spectrum signals, the DOD has announced that they plan to use this signal structure for their Lm signal at both L1 and L2, as shown in Figure 3(a). The assumption by many in the civil community is that single civil signals will be placed at the centers of L1 and L2 as shown. The shaded regions around the split spectrum Lm signals indicate planned DOD flexibility in signal bandwidth and power.
It is somewhat surprising to some of us to see the DOD exploit the split spectrum signal. The civil community has generally beenthe accuracy driver for GPS while the DOD has been concerned more with obtaining low vulnerability to jamming and assuring robustness of the signal. The split spectrum has advantages but it is doubtful that improved jamming immunity is one of them. Also, by jamming one of the split spectrum signals, the system performance may become considerably worse than the current P/Y-code system. Also, with DOD use of the split spectrum signals at both L1 and L2, much of the available power on the IIF spacecraft will be committed to the DOD signals. The new split spectrum economics (4 DOD signals in lieu of 2) may allow only a very basic set of signals for the civil community. I hope this estimate of the situation is pessimistic.
Other Civil Possibilities
Figures 3(b) and 3(c) show other possibilities. The signal structure of Figure 3(b) shows the second coded civil signal vacating L2 in favor of an ARNS band location, leaving L2 for exclusive use by the military. To provide the civil community with the advantages of split spectrum operation, an L1c' signal is placed above the GPS L1 band, just below the GLONASS band, as shown. This signal cannot be placed in the lower part of GPS L1(or nearby) without possibly interfering with or being affected by L1m.
The final configuration shown in Figure 3(c) provides split-spectrum signals to both the military and civil users in about the only way it can be arranged in both RNSS L-band regions. This signal structure combination provides excellent capabilities to the military and civil users in the future. It provides the most desirable locations in L1 and L2 to the DOD signals yet provides split spectrum signals to civil users. Also, it provides this capability in a protected band (L1) and provides a single coded civil signal for ionospheric correction and for other purposes in the ARNS band.
There are other signal combinations, some of which may
have some merit. However, the signal structure combinations discussed represent
most of the principal candidates as well as a few new ones that may warrant
consideration.
ION Elected Officers For This Year: 199899 President: *Dr. Frank van Graas, Ohio University Executive Vice President: *Dr. Per Enge, Stanford University Treasurer: *Larry Hothem, US Geological Survey Eastern RegionVice President: *Karen van Dyke, DoT/Volpe Center Central Region Vice President: *Dr. Michael Braasch, Ohio University Western Region Vice President: *John Lavrakas, Overlook Systems Technologies Immediate Past President: *Capt. Benjamin Peterson, USCG Academy Eastern Council Member-at-Large: Joseph Spalding, US Coast Guard R&D Ctr. Central Council Member-at-Large: Stephen Peters, Battelle Western Council Member-at-Large: Stephen Peck, Hughes Aircraft Co. Space Representatives: Capt. Christopher Shank, Natl. Reconnaissance Office; Glenn Lightsey, NASA Goddard Air Representatives: Dr. James Farrell, NaVIGIL; Boyd Holsapple, ARL/SNR Land Representatives: Sally Frodge, DoT Hqtrs; Jonathan Ladd, Ashtech Marine Representatives: Cdr. Douglas Taggart, Overlook Systems Tech.; David Minkel, NOAA/Natl Geodetic Survey
* Member, ION Executive Committee |
Strategic Planning Reviews Co-Sponsored
Meetings The ION Strategic Planning Committee, meeting at the June Annual Meeting in Denver, discussed several initiatives for the coming year, including opportunities for ION to co-sponsor one or both of its two non-GPS meetings each year with other organizations. Following up on suggestions arising from the earlier Council meeting, the Committee assigned actions to be carried out on establishing a members-only page on ION's web site, creating a jobs database, and providing demographic data (maps with membership distribution) for ION Sections. In other actions, the committee decided to look further into the concept of hiring a public relations firm for the organization. It agreed on organizational moves to invite the Satellite Division to name a delegate to serve on the Strategic Planning Committee, and to name the following persons to serve on the newly created New Initiatives Committee: the immediate past president, the treasurer, Strategic Planning Committee chair/executive vp and the Satellite Division chair. Keith McDonald, a former ION president, submitted a concluding report on GPS Modernization, summarizing the work of the Modernization Group that held four meetings attended by more than 100 professionals from various parts of the country. The Group provided input on the signal structure for a GPS second coded civil signal, and its location in the spectrum, as well as options for a third coded signal and evaluations of various civil alternatives. |
Annual ION awards were presented to a talented group of recipients for their singular contributions to the science of navigation at ceremonies held in the Adam's Mark Hotel during the ION Annual Meeting in Denver on June 2. The ION Awards Committee, chaired by Dr. Per Enge, performed the tough job of selected the final award winners from a distinguished group of candidates. The Institute is pleased to extend its congratulations to the recipients, its profound thanks to all those who submitted nominations, as well as to those members who served with anonymity so effectively on the Awards Committee.
Early Achievement Awards - This is a new award which recognizes outstanding achievement early in a navigation career.
Dr. Christopher Hegarty, Mitre Corp., was a Student Paper competition winner at the 1992 ION-GPS conference. He joined Mitre in 1992, where he performed interference studies relating to the WAAS program, and served as chairman of the pseudolite subgroup of RTCA's Working Group 4A. Dr. Hegarty has performed recent work on the proposed split C/A waveform and the second and third Civil GPS signals. He was Best Paper winner at the ION-GPS 96 and selected Editor of ION's journal, Navigation, in 1997.
Bruce DeClenne, FAA, is responsible for certification of GPS airborne equipment, and lead technical representative for FAA operational services for GPS. He formulated the navigation performance requirements for the WAAS and LAAS programs at FAA, devised the final airborne protection level algorithms for WAAS and LAAS integrity contained in the RTCA MASPS. DeCleene serves as a permanent member of the U.S. delegation to the ICAO GNSS panel, and he is a member of the FAA's satellite operational implementation team (SOIT).
Superior Achievement Award
Maj. Bernard E. Mater, 517th Airlift Squadron, Air Force, was a recipient in recognition of his work as an active navigator on the 11th Air Force staff, and a leader in airlift activities within Alaska. In 1997, he flew more than 70 Alaska resupply sorties, including 10 to one-way runway sites that sit on mountains with slops up to 10 percent. While Chief of Airlift Plans and Exercises, Maj. Mater pioneered the development and use of GPS instrument approach procedures for remote USAR airfields, devising methods for safe use of GPS even at extreme northern latitudes.
Maj. Kari L. Smith, 412th Flight Test Squadron, Air Force, distinguished herself as Mission Commander and navigator for a flight carrying a Congressional delegation to historic peace talks in North Korea in 1997. The U.S. delegation was led by Sen. Ted Stevens, R-Alaska. The approach to Sunan airport at Pyongyang involved no air traffic control, primitive radio navigation aids, charts that gave height above ground level rather than international standard height above sea level, altimeter settings were in millimeters versus inches. Making conversion "on the fly", the party landed safely. Maj. Smith also carried $60,000 cash to pay for aircraft serving of a U.S. military plane, an accounting nightmare requiring several trips to exchange currency.
P.V.H. Weems Award
Professor Brian O'Keeffe, University of Canberra, Australia, was selected for his many contributions and long service to civil aviation. In 1984, he became the Australian member, and later vice chairman, of the ICAO Special Committee on Future Air Navigation Systems (FANS), which developed the first comprehensive, satellite-based international system for CNS and air traffic management. He was elected chairman of FANS Phase II in 1990. ICAO accepted the FANS system in 1991, and O'Keeffe helped develop the institutional arrangements and global coordinated plan for FANS that was completed in 1993. He is also Adjunct Professor in Communications Engineering at the University of Canberra.
Norman P. Hays Award
Robert Loh, currently chief scientist for the FAA's satellite program office, received the award. Loh is credited as the architect of WAAS, as well as system design and concepts for LAAS. But his selection provoked a warmth beyond the mere conventional acknowledgments for the record of his professional accomplishments. "There are many personal qualities that make Mr. Loh deserving of the Hays Award," declared ION President Ben Peterson. "He is driven by an infectious desire to revolutionize navigation and help make aviation safer for all. He actively supports the professional development of new members of our field... He lets others share the glory of his accomplishments and rarely seeks the spotlight."
Thomas L. Thurlow Award
Dr. A.J. Van Dierendonck, A.J. Systems, received the Thurlow plaque for the breadth and depth of his influential contributions to the science of navigation over more than 20 years. The recipient was cited as the co-inventor of the concept of using narrow-correlator GPS receiver technology to mitigate multi-path errors; co-chairman of the RTCA special committee formulating minimum operational performance standards (MOPS) for WAAS; primary author of interference requirements used by RTCA as standards for LAAS; developer of format and data content for RTCM Special Committee 104 differential GPS messages, an RTCM standard.
Samuel M. Burka Award
Siebren van der Werf, University of Groningen, The Netherlands, received the award for his paper in the 1997 Spring issue of Navigation, entitled, "The Lunar Distance Method in the 19th Century: A Simulation of Joshua Slocum's Observation on June 16, 1896." The recipient, not
present, sent a wry written thanks which said, in part: "At this very moment, 19:00 local Denver time, or a bit later, the moon just passed your meridian. When you look outside you will see it, because the Internet says Denver never has a cloudy day. ...Tomorrow it will be there again, and if you look at the moon and the sun around mid-afternoon, you will see very much the same situation that (Capt.) Slocum saw on June 16, 1896. I propose that you raise your glasses in his honor. Thank you."
Distinguished Service Award
As the Editor of the ION journal, Navigation, Ron Braff,
The Mitre Corporation, was acknowledged for his significant contributions
over the past 12 years in maintaining the prestige, and expanding the scope,
of the ION publication. Braff also has served as the ION's Publications
Chair, and helped direct the publication of several volumes of the ION's
renowned Red Book series on GPS.
Your New Committee Chairs
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Two new ad hoc committees were established at the ION Annual Meeting held in Denver June 1-3. As customary, the newly elected president of ION, Frank van Grass for the current year, appointed committee chairs. The new chairpersons for the current year, approved by the ION Council, are:
Standing Committees
Ad Hoc Committees, Related Offices
ION Division Officers
Europe took another step in satellite navigation planning when three agencies signed an agreement in June formalizing their commitment to establishing an independent, all-civil global navigation satellite system (GNSS).
Meeting in Luxembourg, the European Space Agency (ESA), the European Community (EC) and the European Organization for the Safety of Air Navigation (EUROCONTROL) agreed to cooperate in a two-stage process aimed at eventually developing a full-blown civil system, GNSS-2.
The first step, known as GNSS-1, utilizes GPS and GLONASS signals, augmented by EGNOS, the latter a European overlay system consisting of leased navigation payloads on two Inmarsat satellites coupled with a ground station network. The second generation envisions a full-scale global system, known as GNSS-2, under civil operation and control, targeted for service in 2010. A decision on how to proceed with GNSS-2 is to be made in Europe by mid-1999.
A press statement said GNSS will benefit aviation, land
and marine users. "As well as improving safety," the statement
added, "a European contribution to a global navigation satellite system
will greatly contribute to improve economic prosperity, industrial returns,
employment and quality of lifein Europe."
Long Live LORAN
________________
Hundreds of thousands of long-time land, sea and air users of Loran-C were elated over news that the U.S. DoT apparently has decided to extend the life of the ground-based radionavigation system beyond 2000. While no new termination date has been officially announced, Loran backers say the government is planning to operate the system through 2008 or longer.
U.S. policy as enunciated in the biannual Federal Radionavigation Plan (FRP) has been to shut down Loran Dec. 21, 2000, relying on the more accurate GPS. But bowing to political and user pressures, and buttressed by findings from an independent Booz-Allen & Hamilton study, DoT appeared in early August on the verge of a formal announcement from Secretary Slater to change the policy and extend Loran's life.
"More than 80,000 general aviation aircraft are equipped with Loran receivers," Phil Boyer, president, Aircraft Owners and Pilots Assn., said in an AOPA statement. "For VFR point-to-point navigation, Loran is a simple, inexpensive system that meets the needs of our members."
Outside of aviation, by far the largest user group is the marine industry - an estimated one-half million - as well as vehicle fleet operators, backpackers and recreational users, and others.
Congress Weighs In
The report on a House bill authorizing FAA spending for FY99 mandated some extension of Loran life: "The Secretary (of DoT) shall maintain and upgrade Loran-C navigation facilities throughout the transition period to satellite-based navigation." This, in turn, reflects findings of the Presidential Commission for Critical Infrastructure, which recommended in 1997 that it would be unwise to rely on any one system for essential navigation-timing services.
Beyond this, a draft circulated of the B-A&H study, commissioned by DoT, reportedly found it would cost $764 million to discontinue Loran, most of that cost, a total of $693 million, to be absorbed by the Coast Guard and FAA to buy new GPS equipment; the balance of $71 million would be for decommissioning costs for old Loran transmitters. To keep it until 2015 would cost $473 million, including capital costs of $109 million to upgrade the system, and $27 million annually over 15 years for maintenance; users with Loran receivers, of course, would entail no costs.
The Coast Guard and FAA must work out arrangements to share costs of extending Loran and for how long. The Coast Guard, which operates Loran, is prepared to continue operation of Loran until 2008, two years of transition beyond the 2006 date for withdrawing Selective Availability from GPS, or even longer. The FAA is less supportive, and wants it made clear Loran is not an air carriage requirement or a full backup for GPS (see related GPS AS A STAND-ALONE this issue), but more of a lesser-of-two-equals.
Integrated GPS/Loran
In a paper at the ION Annual Meeting in Denver in June, results of tests with integrated receivers found "significant improvement in both accuracy and availability."
The paper, authored by USCoast Guard Academy personnel, among them, immediate ION past president Capt. Ben Peterson, presented results from two different approaches, one using a tightly coupled Kalman filter to synchronize GPS and Loran timing, the other using Kalman filter with GPS pseudoranges and the Loran TOA inputs and a time constant. Other authors were CDR Richard Harnett, LCDR Dean Brucker and Ensign Rebecca Heatherington.
The paper said that, "the optimum design for an integrated receiver combines the absolute accuracy of GPS averaged for an hour or two, with the repeatable accuracy of Loran over that same period. Besides these improvements in accuracy, other studies have found that integrated GPS/Loran can provide much better fix availability in urban canyons and much better system availability/integrity for non-precision approaches in aviation."
The paper also outlined several methods to improve stand-alone
Loran accuracy, from the much advertised .25 nautical mile (2drms), to 7-to-20
meters in many cases.
Mapping Cliff-Dwelling Species
___________________________
Through a cooperative program with the Department of Defense (DoD), the U.S. Interior Department currently has more than 1200 Precise Positioning Service (PPS) handheld receivers in use to map natural resources and help manage a significant portion of the vast public lands under federal control.
A paper presented at the ION Annual Meeting in Denver in June outlined how a high-security military device designed for weapons targeting is being used by civilians to map bird nesting sites on cliff faces, and perform fire perimeter mapping from the air. Karl E. Brown, with Interior's Center for Biological Information in Denver, manages the authorization from DoD, ordering and crypto keying of all PPS units in use by such Interior agencies. These include the Bureau of Land Management, National Park Service, U.S. Geological Survey, Fish and Wildlife Service, Bureau of Indian Affairs, Bureau of Reclamation, Minerals Management Service and Office of Surface Mining.
DoD first authorized Interior use of PPS under specific conditions and requirements in August 1994. By 1996, Interior had about 250 Y-code receivers, expanding to more than 1200 by June of this year, Brown related. Interior now uses both SPS and PPS systems enhanced with differential signals. PPS-based Y-code receivers cost an average of about $2500, Brown said, up to $4000. Interior is using the PLGR and the open market Trimble Centurion for handheld Y-code receivers.
Encryption loading is required about every 54 weeks. "Performance in 1997," Brown described, "averaged about eight meter solutions, non-WAGE. Wide Area GPS Differential (WAGE) has delivered about four meters since 1996-97, depending on tree canopy factors and geometry." Until 1997, PPS cost per point was lower than radio-linked DGPS options for civil SPS receivers. "Costs have leveled in 1998," the speaker said, "with DGPS equipped C/A code handhelds priced under $2000." But PPS coverage is far better than DGPS-SPS, and is expected to remain so for next 2-to-3 years.
"In summary," Brown concluded, "PPS provides
a very cost effective tool for collecting biological, physical and cultural
data." For the future, Interior expects to optimize the proposed National
DGPS options in concert with PPS capabilities to achieve Department-wide
1-to-4 meter accuracies.
More Monitoring Stations For GPS
_________________________________
The ground network for monitoring the global GPS constellation is being expanded to provide full-time coverage of the system.
The original five GPS monitoring stations did not provide full coverage at all times, leaving gaps when some of the satellites were not in view of ground facilities that relay data received from the satellites back to the master control station in Colorado. But GPS monitoring equipment is now being added to existing NIMA stations operated by the National Imagery and Mapping Agency.
As of early July, the seventh NIMA station, located at Eielson AFB in Alaska, came on line, giving Air Force managers of GPS a total of 12 stations supplying a stream of data on GPS satellites, according to Pentagon officials. Additional NIMA stations with GPS capability will be added. The ground network, including the five original stations and the NIMA augments, rings the earth, with stations in the United States, South America, Africa, Europe, Asia, as well as Ascension Island in the Atlantic, Kwajalein in the Pacific and Diego Garcia in the Indian Ocean.
The expanding ground network will provide full-time coverage
of all satellites in the constellation. Resulting additional orbital, timing
and health data from the satellites will bring improvements in navigation
messages supplied by the master control center and broadcast by the system,
thus improving positioning accuracy for military users. Because of selective
availability (SA), civil users will not now enjoy similar benefits, but
in the long-term, when SA is turned off, similar improvements should accrue
to the civil community.
Amelia Earhart And Fred Noonan:Navigating
The Pacific Circa 1937
By Major William L. Polhemus
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In the summer of 1967, 30 years after Earhart and Noonan vanished on a round-the-world flight, the author flew as navigator on a commemorative flight in a restored Lockheed L-10 over the remote New Guinea area where the famed aviatrix and her navigator were lost. The author retraces highlights of that Earhart-Noonan flight, based on known logs of radio contacts and other data, to produce a fascinating navigational history of a mysterious disappearance. Polhemus served as an aircrewman on Curtis Helldivers and Grumman Avengers in WWII, as a navigator-bombardier on B-26s in the Korean War and with SAC on B-47s. He is a past president (196970) of ION.
SUMMER 1937
In the early summer of 1937, Amelia Earhart and Fred Noonan had successfully completed more than two-thirds of their flight around the earth at or near the Equator, the first flight of its kind. Their geographic position was the relatively undeveloped 3000 ft. airstrip at Lae, New Guinea (see figure 1). Their Lockheed Electra 10-E was loaded to more than 150% of its design maximum gross weight, with extra fuel necessary to travel 2,228 nautical miles eastward to Howland Island.1
Fifteen hundred miles of their flight would be across an expanse of water where ships were few and far between, and alternate airports were non-existent. The fuel reserve portion of total fuel available would be insufficient for finding islands or atolls suitable for emergency landing and survival.
There would be no radionavigation aids available on the flight to Howland Island. Fred Noonan had navigation tools such as a handheld bubble sextant, an unstabilized driftmeter, a pelorus mounted at the side window in the aft cabin, three chronometers, a magnetic compass, an altimeter, and an airspeed meter. Pilotage navigation would be feasible only as far as the Nukumannu Islands, located east of Bouganville in the Solomons (approximately seven hours into the flight). In case of emergency they might have diverted to Nauru Atoll which lay within sixty miles of their intended track (approximately the halfway point between Lae and Howland Island) where they would be shortly after sundown.
Noonan would have been severely limited in his field of view and the number of stars observable, and in his ability to work around breaks in cloud overhead2. Since only celestial navigation would be available to Noonan during the final two-thirds of the flight, it would be essential that cloud cover above the aircraft be minimal.
During daylight hours and in the absence of cloud cover between their aircraft and the ocean surface, Noonan could determine aircraft drift angle and ground speed to one degree and 1-2 Kn. These factors integrated with sextant and pelorus observations would have given Noonan a good knowledge of their position so he could maintain an accurate track.
In order to see Howland Island clearly from a distance, the plan would have been to arrive during daylight hours. Flight time from Lae to Howland Island was estimated at eighteen hours, so taking off in the early morning would not put the travelers at Howland Island during daylight hours. But taking off during mid-day would have meant a heating of the Lae airport surface and airspace, which would have reduced take-off performance and thus increased required take-off distance. These factors would account for the selection of 10:00 a.m. Local Mean Time (LMT) for take-off.
Communications equipment aboard the Lockheed Electra 10-E consisted of a Western Electric supplied HF transmitter and receiver containing three preset frequencies (6210 kHz for daylight communications, 3105 kHz for nighttime communications, and 500 kHz for emergency communications), as well as a tunable crystal. A developmental series, manually operated, direction finding (DF) loop antenna was mounted above the cockpit on the external surface of the aircraft and was controlled by the pilot while she simultaneously flew the aircraft. Apparently, this DF receiver system was only capable of receiving within the band 200-1430 kHz (the radio logs indicate that Earheart requested transmission of reference signals of 7500 kHz as well as 3105 kHz and 6210 kHz, but reported that she could not receive an identifiable signal).
Amelia Earhart and Fred Noonan were to be assisted in homing in on Howland Island (see figure 2) upon arrival in the area. They were to have the assistance of two communication teams, a United States Navy and a United States Coast Guard (USCG) team placed on the beach for that very purpose. The USCG Cutter Itasca stood offshore and served as local Command Post. Other preparations for assistance in landing consisted of two temporary runways that had been bulldozed into the sand by personnel from the Department of the Interior (it is not known if runway lighting was available in the event of a nighttime arrival from Lae).
Information such as weather forecasts, winds aloft, and estimated cloud cover were supplied by the United States Navy facilities in Honolulu, and were augmented by observations made by personnel at Lae, Nauru Island, and the Coast Guard Cutter, Itasca. This information said little concerning cloud cover east of Nauru Island, the critical portion of the flight.
There were no alternate airports identified in Earhart's flight plan and fuel on board would only be sufficient for the 2200+ nautical mile flight (plus an estimated four-hour reserve at reduced power setting).
And thus were the preparations for Earhart and Noonan's landing on Howland Island. But Noonan's Flight Plan estimate of time en route (ETE) of eighteen hours (ETA 2000 GMT or 0600 LMT) was in error by approximately one hour, twelve minutes (1h12m). At 1912 GMT (0712 Local Mean Time Howland)3, Earhart reported to the USCG Itasca, "Must be on you now but cannot see you. Thirty minutes of gas remaining. Been unable to 'read' you by radio. We are flying at 1,000 feet."
One hour later, at 2013 GMT (0813 LMT H.I.) Earhart is reported to have stated, "Line of position 157º/337º." Two minutes later she reported, "KHAQQ calling Itasca. Position [sic] 157º/337º. Will repeat this message on 6210 kHz. Wait. Listening on 6210 kHz. We are running North and South." The Itasca reported that the amplitude of the Lockheed Electra's five transmissions at 1815 GMT and thereafter were "good" to "very loud," confirming that the Lockheed was close aboard Howland Island and not headed off toward some clandestine activity.
The 1930 GMT transmission by Earhart provides the best clue to readers concerning the probable source of failure of the DF procedure that was to have been executed between Earhart and the Howland Island based communication team. Earhart stated, "We received your signals [Itasca had sent a series of the letter A in Morse (CW)] on 7500 kHz but unable to get a minimum. Please take bearing on us and answer 3105 with voice." (Here, long dashes were sent on 3105 kHz for five seconds or so.)4
Itasca did not receive any further calls, but Nauru Radio later reported that they logged transmissions broadcast on 6210 kHz (the correct daytime frequency) at 2033 and 2054 GMT.
Radio logs of navigation activities indicate that, at least initially, the Earhart team was utilizing a sunline landfall procedure. At 1816 GMT, the time of Earhart's 100-mile call, the sun's height above the horizon at Howland Island would have been 07º10' true azimuth 067º, ETA at Howland Island would then be approximately 1854 GMT. Aircraft true heading would have been 074º ± drift correction angle. The sun would have been rising slightly to the left of the nose of the aircraft and would not have been observable from the navigator's station, given that he had to use the flat window in the side of the aircraft. (see footnote 2)
In order for the navigator to be confident as to which side of the destination he is closing in on, the sunline landfall procedure utilizes an arbitrary turn off-coursesome number of minutes before expiration of the ETA. This, however, is under ideal visibility conditions, and uncertainty can be quite great if cloud cover during the final hours of the flight prevents the accomplishment of a good fix by the navigator.
Ordinarily, the navigator would turn towards the approaching "limb" of the sun's line of position (the normal to the sun azimuth). In this case, Noonan would have turned to the north, as the sun would have been in a northerly declination at this time of the year. A maneuver to the left of track would have placed the sun on the right side of the aircraft so that it would not be observable from the navigator's station.
According to Earhart's messages recorded in the communications log, no off-course maneuver was employed, only that they were circling at 1928 GMT. At 1955 GMT, Earhart states that they were finally employing the sunline landfall procedure, steering along the 157º/337º LOP. By this time, however, the sun's orientation with respect to Howland Island required the use of a line-oriented, 153º/333º. This error could have introduced several miles lateral error at the time aircraft passed (if it did) abeam the island on one of its N/S legs.
The Earhart transmissions from 1816 GMT through 2025 GMT were reported as strong and emanating from the northwest quadrant relative to Howland Island. At that time, Earhart and Noonan would have already utilized 2h25m of their estimated four-hour fuel reserve5. It is difficult to imagine that with knowledge of their position in doubt, and a ship and shore party actively trying to help them, they would have departed for another group of atolls 300 miles away! Itasca logged its last reception from Earhart at 2031 GMT (but the message was uninterpretable). Nauru Radio reported that their last reception occurred at 2054 GMT.
SUMMER 1967
Thirty years had passed from the time of Amelia Earhart's and Fred Noonan's "grand sortie." On July 1, 1967, at 0600 local time, in Lae, New Guinea, a new crew advanced the throttles of a restored Lockheed L-10 (see figure 4). The crew consisted of Ann Pellegreno as pilot, William Polhemus as navigator, Bill Payne as co-pilot, and Lee Koepke who was the owner and restorer of the aircraft (see figure 5).
This flight would take Pellegreno to Howland Island via Nauru Island, sixty miles north of the direct Great Circle track between Lae and Howland Island. The landing strip on Howland Island prepared in 1937 by the United States Department of the Interior had long since
disappeared and there were no facilities for servicing Pellegreno's aircraft. So Pellegreno's flight plan called for a refueling stop at Nauru, then a "flare-pot" take-off to over-fly Howland Island at the time of Earhart's planned arrival. There would be a brief period of maneuvering over and around Howland Island before continuing on to Canton Island some 300 miles to the southeast.
Pellegreno's flight was timed to place her aircraft over Howland Island at approximately the same time of day on July 2nd, the expected arrival date of Amelia Earhart and Fred Noonan. Pellegreno's navigator log shows time of arrival as 1936 GMT (Earhart, transmitted at 1928 GMT, "circling, trying to pick up island.").
During one of the low passes across the island, Ann Pellegreno turned over control of the aircraft to co-pilot Bill Payne. She went to the rear of the aircraft where Lee Koepke (owner of the Lockheed 10 aircraft) forced the cabin door open against the slipstream enough to allow the release of a wreath commemorating the history-making effort of Amelia Earhart and her navigator, Fred Noonan.
FOOTNOTES
1 Howland Island is a barren spit of sand resembling a pumpkin seed approximately 8,000 feet long, 3,000 feet or less in width and at highest elevation eight feet above sea level.
2 Roy Blay, an engineer with the Lockheed Corporation, states that Earhart's aircraft was not equipped with an overhead window or astrodome. After final modifications, the Electra was equipped with only one side window (in the aft cabin) with the "optically-flat" glass suitable for observing stars with a sextant.
3 This, according to a synthesis of the radio logs prepared by the Coast Guard and Navy personnel following the disappearance of the Earhart team.
4 The Lockheed Paper (see Footnote 2) states that the installed DF receiver equipment was limited to the range of frequencies 200-1430 kHz. If this were true, Earhart could not have achieved a null (bearing to transmitter) on 7500 kHz. Furthermore, 3105 kHz was the preferred night time frequency for communication.
5 W.L. Polhemus estimate.
Aviation Wants Study Of GPS As A Stand-Alone
System
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Concerned about reliance on GPS as a stand-alone system, three major aviation groups have selected Applied Physics Laboratory (APL) of Johns Hopkins University to conduct an independent risk assessment study of GPS-based sole-means navigation operations.
The Aircraft Owners and Pilots Assn. (AOPA), representing 340,000 general aviation members, the Air Transport Assn. (ATA), the nation's largest airline trade group with 23 U.S. and 5 international carriers, and the Federal Aviation Administration asked APL in July to conduct a six-month study to determine the ability of GPS, and the FAA's GPS-based WAAS and LAAS systems, to serve as the only navigation system required for aircraft operating in the National Airspace System (NAS).
Earlier AOPA and ATA had joined for the first time in supporting both WAAS and LAAS, and urging rapid implementation of satellite navigation services. At the time, in April, the two organizations had called for a risk assessment, and early development of a second civil frequency on GPS.
"GPS is already delivering cost-benefit advantages to general aviation," AOPA President Phil Boyer said in a July statement. "The Hopkins study will address whether back-up is required to assure the full benefit of GPS, including new instrument approaches at thousands more general aviation airports."
Pursuing airline reports of total loss of GPS earlier this year, the Hopkins study also will determine if there are any valid threats to reliance on GPS for civil aviation, and assess the potential risk of either intentional or unintentional interference with the GPS signal. The final report is due in January 1999.
"We are confident that Johns Hopkins will thoroughly and competently examine all the complex issues associated with sole-means GPS navigation," declared Carol B. Hallett, ATA president and ceo. "The GPS navigation system offers the opportunity for expanding capacity to accommodate air traffic growth."
The FAA's $3 billion WAAS system, scheduled to start service beginning in 2001, eventually is designed to replace ground-based VORs for enroute navigation and non-precision instrument approaches. It also is to provide Category I precision approaches, opening more than 5,000 general aviation airports to such instrumented approaches. LAAS is to provide Category II and III precision approach, replacing ILS, at many major fields used by commercial airliners.
In joining last April, AOPA and ATA said at that time that
FAA should maintain existing ground- based radionavigation services. And
they asked that the FAA seek consensus with the user community on a transition
schedule before changing over to space-based radionavigation.
Challenges Of The IIF
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Speakers at the ION Annual Meeting outlined possible cost savings being studied by the Air Force that would result from changing GPS constellation replenishments from the present system of launching spacecraft on a fixed schedule, to one of a launch-on-demand basis.
In a paper authored by Dr. Aron Pinker and Joseph W. Sapp, both of ANSER, and LtCol Stephen R. DeCou, Air Force, the authors noted that currently the Air Force requires 60 days after a need is identified to launch and establish useable navigation signals from an in-orbit replenishment satellite.
The Air Force is now working with Florida's SpacePort Authority to line up a three-pad facility to provide 72-hour launch-on-demand service.
Because of launch constraints and a fixed launch schedule, presently 26 or 27 satellites must be on orbit - up to three spares - to sustain a 24-satellite constellation. If replenishment were cut to seven days under a faster launch-on-demand schedule, only 25 on-orbit satellites would be necessary. At a cost of about $50 million per Delta launcher, substantial cost savings could be realized. In addition, the authors suggested that one Delta might be able in the future to handle a package of two GPS satellites, further sharply slicing launch costs.
Because of the shift in the utility of GPS, where the military now constitutes only about 5 percent of the users but carries 100 percent of the cost burden, the authors suggested that acquisition be moved to the civil side. Any changes in GPS, civil or military, now must go through a proscribed DoD procurement hierarchy: mission need statements, operational requirement documentation, interservice validation and coordination, DoD bid procedures, etc. "We might consider an acquisition process that is driven and mainly financed by the civil user community with the DoD serving as the executor of the civil requirements," the paper said. It could be a win-win situation - "It would be to the DoD advantage," the paper declared, "to maintain its control over the GPS, reduce the financial burden, and have a modern GPS."
Concerning the capability of the IIFs to accommodate civil
(or military) add-ons, the paper noted that the Block IIFs have a reserve
capacity for up to 250 pounds, 25 feet in length and 260 watts of power
for other payloads, compared with just 25 pounds and 25 watts of reserve
on the current Block IIRs.
Congress Scrutinizes Funding For NDGPS
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Department of Transportation (D0T) officials remained optimistic that funding will be provided by a divided Congress to resume progress on the $30 million program for a national differential GPS (NDGPS) network of reference stations serving the interior of the country.
A bill passed by the Senate in late July provides $6.92 million in appropriations for fiscal year 1999 (FY99) for NDGPS; House appropriators, however, zeroed out all funding for NDGPS. Lawmakers prepared to meet in a conference committee to work out a compromise between the differing House and Senate transportation appropriations bills.
While the fate of the funding for next year was unknown at the time of this writing, DoT officials said three surplus Air Force GWEN sites should be fully converted to GPS reference sites by early October. They are located at Whitney, Neb., Savannah Beach, GA, and Chico, CA. A DoT official said the Air Force has accelerated decommissioning and now plans to shut down all its GWEN sites next year, leaving them available for civil conversion in an earlier time frame.
The Coast Guard converted the three sites under a $2.4 million appropriation it received earlier for the program in the current FY98 budget. The Coast Guard also would be the recipient of FY99 funds under the pending Senate bill.
The overall program calls for 66 stations to be installed to broadcast redundant differential signals covering the entire CONUS land mass, and serving Alaska. The program will entail an estimated $30.5 million in capital costs, and about $5.2 million per year in operating costs. Coast Guard findings indicate that a similar low-frequency beacon system now ringing U.S. coastal areas routinely achieves 3-to-5 meter accuracies for marine positioning/navigation.
From The Editor
Hale Montgomery
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A revealing chapter in U.S. space spying history was opened publicly for the first time during the 75th anniversary of the Naval Research Laboratory (NRL) in June. It strongly conveyed the sense of intrigue and armed threat that prevailed at the height of the almost 40-year-long U.S.-Soviet Cold War.
At the week-long diamond jubilee celebration at the NRL facilities in Washington, DC, officials announced the declassification of the first intelligence satellite that signaled back information on Soviet radar sites, called GRAB (Galactic Radiation and Background Experiment). Actually, even the name GRAB was mostly a cover. That was its publicly announced name, a satellite to measure solar radiation. It carried another more important electronic package for its real mission, a secret until this June, known in intelligence circles by the name of ELINT, or a mission to collect electronic intelligence.
During the jubilee, many other highlights of NRL's 75 years of proud scientific history also were celebrated, including the accomplishments of Roger Easton, an ION Thurlow award winner and member of the ION Hall of Fame. More about Mr. Easton later.
The first GRAB, developed and built by NRL, was launched in June of 1960, four days after Gary Powers was shot down in his U-2 over Soviet territory. It piggybacked on a two-stage Thor-Able rocket that carried a larger payload, the third Navy TRANSIT navigation satellite.
In two years of operation, the GRAB missions were able to collect information on air defense radars hidden deep in Soviet territory. The data from the basketball-sized satellites were relayed to ground facilities, taped, and the magnetic tapes taken by couriers to the National Security Agency and Air Force SAC for analysis. At a time of deep public fears of a U.S.-Soviet nuclear conflict, the intelligence permitted U.S. forces to make sound judgments on Soviet radar defenses.
Perhaps Albert Wheelon, a leader in the technical intelligence revolution, summed up best the unheralded work of so many Cold War warriors, like those at NRL: "When the American government eventually reveals the (full range of) reconnaissance systems developed by this nation, the public will learn of space achievements every bit as impressive as the Apollo moon landings. One program proceeded in utmost secrecy, the other on national television. One steadied the resolve of the American public; the other steadied the resolve of American Presidents."
Special recognition during the jubilee was given to Easton, an engineer at NRL for 37 years and the holder of basic patents relating to GPS. Easton worked on the design of 25 satellites while at NRL, according to an NRL information kit. In 1964, Easton put together the concept of using atomic clocks in satellites to fix the position of receivers listening passively to satellite transmissions, a one-way ranging technique that included a simplified method for interpreting the information received from the clocks. His 1964 concept was recognized in 1974 with U.S. patent 3789409 entitled "Navigation Systems Using Satellites and Passive Ranging Techniques." Many persons deserve credit for making essential contributions to the development of GPS, but Easton's filing is the enabling patent.
Section News
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ION Sections provided annual reports on their activities to the ION Annual Meeting in June. Karen van Dyke, ION Sections Committee chair, said no new sections had been added to the 10 existing ones in the past year. The 10 include Alberta, Rocky Mountain, New England, Greater Philadelphia, Washington, DC, Dayton, Houston, Southern New Mexico, San Diego and Southern California. The latter two were inactive. Organizers are considering starting a new Section in Dallas.
Student sections currently are active at the California Maritime Academy, University of Colorado, Ohio University, Stanford University, University of Calgary and University of Florida.
Alberta Section. Three speakers were featured at the yearend meeting of the Section, held in the University Club at the University of Calgary on May 28. Tom Goddard, a soil conservationist with the Alberta Agriculture, Food and Rural Development, spoke on the evolution of precision agriculture in Alberta. Tom Ford, NovAtel, talked about his company's new product, the Beeline. Barbara Cameron, Industry Canada Trade Centre in Calgary, outlined new Federal/Provincial initiatives in trade. After the summer recess, Section meetings are planned every two months, starting with a Sept. 10 meeting.
Southern New Mexico Section. In a report to the ION Annual Meeting in June, Section Chair Michael Hadfield said the Section had been quite active. Meetings are held in conjunction with the local AIAA and IEEE chapters, and attendance typically has been 40-to-70 persons.
Dayton Section. New officers elected for the current year: Danny W. Keen, Aeronautical Systems Center, Wright-Patterson AFB; Michael Berarducci, Air Force Laboratory; Maj. Juan Vasquez, AF Research Laboratory, Secretary; Debbie Thompson, Honeywell, Administrative Secretary; Ken Weis, Honeywell, Treasurer.
Houston Section. This new Section got off to a strong start, according to Dr. Lee Ott, the past year's Chair, in a report submitted to the ION Annual Meeting. The April 28 meeting was held at the local NASA facility, with a turnout of 44 persons. The good turnouts are attributed to a phone reminder system two to three days prior to a meeting, following earlier newsletter and e-mail announcements. The Section meets quarterly.
Greater Philadelphia Section. The Section dedicated its navigation library located at ARL/PSU Warminster on May 26, according to a report from Marvin May. The Section typically meets every six months.
New England Section. A timely talk on Loran and GPS was delivered by Ed McGann, Megapulse, and Martin Pope, Cambridge Engineering, at the June 17 meeting of the Section. In a report to the Annual Meeting, Karen van Dyke said the Section is quite active, and some of the success of its bi-monthly meetings can be attributed to maintaining a core working group of persons to organize the sessions.
Rocky Mountain. New officers for current year: Mike Cimafonte, chair; Dan Knezha, vice chair; Mike Phillips, secretary; Bob Cass, Treasurer, and Hank Skalski, program chair.
From The ION Historian One of a series of columns by ION Historian Marvin
May. The last three articles in this series recounted the distinguished histories of three venerable radionavigation systems that either have died or linger on their deathbed. This article is about "dead reckoning" which it is feared, from the name, may further reinforce the notion that your ION historian is really the ION mortician. The dead reckoning method of position determination is heuristically understood to be the determination of present position by vectorially adding velocity measurements multiplied by the applicable time interval to a previously determined position fix. Dutton's Navigation and Piloting states that, "it is the process of determining an approximate position by applying to its last well-determined position a vector or a series of consecutive vectors representing the run that has since been made, using only the true courses with considering current." Examples of dead reckoning systems are inertial navigators, which integrate accelerometer outputs to obtain the velocity vector, speed logs in coordination with gyrocompasses, and Doppler logs in coordination with attitude heading reference systems. Although there is little current debate about the mathematics of implementing dead reckoning systems, there is considerable uncertainty as to the origin of the term. Palmer Hanson, one of the principle engineers involved in the 1950's development of the electrostatic gyro inertial navigation system - perhaps still the most accurate dead reckoning system - has researched some of the sources which contend to know the term's derivation. He reports that the Eleventh Edition of Dutton's Navigation and Piloting states: "One of the four main divisions of navigation is termed dead reckoning. Historically speaking, the title originally stemmed from the process whereby trigonometric computations were used to compute or deduce the position of the ship with relation to a point of departure or to an established fix. Custom has since converted deduced reckoning into its present form of dead reckoning" Hanson reports that another revered naval text on navigation, the American Practical Navigator, commonly known as "Bowditch" (H.O. Publication No. 9 U. S. Government Printing Office, 1966) states: "Dead reckoning is the determination of position by advancing a known position for courses and distances" "The expression "dead reckoning" probably originated from use of the Dutchman's log, a buoyant object thrown overboard, to determine the speed of the vessel relative to the object, which was assumed to be dead in the water. Apparently, the expression deduced reckoning was used when allowance was made for current and wind. It (deduced) was often shorted to ded reckoning and the similarity of this expression to dead reckoning was undoubted the source of confusion that is still associated with these expressions" Yet another interpretation is offered by J. M.Slater's Inertial Guidance and in Allan Bayless's response in The Navigator's Newsletter of Spring 1997. These sources consider it more likely that dead reckoning has the same origin as "dead aim", "dead right", dead on", etc., expressing the navigator's certainty in his predictions. It is noted that several new texts, perhaps to avoid morbidity or to avoid the controversy of its derivation, downplay the term dead reckoning and refer to the technique directly as DR. In view of the decommissioning of most radionavigation systems except GPS, and the potential vulnerabilities of GPS, one may argue that "dead reckoning" systems are gaining a new life. While on the subjects of death and dead reckoning, I am saddened to note the death of Mary Tornich Janislawski. She was the oldest member of the ION in both age and membership. According to Len Sugarman, himself a noted navigator and historian, Mary's navigation accomplishments merit considerable attention. After graduating Berkeley's astronomy department in 1930, she went on to study navigation techniques for ships and aircraft with the widely recognized expert, Captain P.Z.H. Weems. Mrs. Janislawski, at the time, was the only woman in her field. She became Capt. Weems' associate and taught hundreds of pilots and sea captains Weems' innovative celestial navigation techniques at Annapolis. In a book authored by Ms. Tornich in 1940 entitled "Radius of Action of Aircraft", she covered the entire field of dead reckoning navigation. |
Corporate Profile OHIO UNIVERSITY is a public university offering baccalaureate and advanced degrees in engineering, arts and sciences, fine arts, education, business, and osteopathic medicine. The Russ College of Engineering and Technology, through its departments, supports a variety of research centers, of which the Avionics Engineering Center, in the School of Electrical Engineering and Computer Science, is the largest and oldest. Undergraduate and graduate students can obtain Electrical Engineering degrees with a concentration in avionics or electronic navigation systems. The School also offers a one-year, non-thesis MS degree with concentration in electronic navigation systems. The Avionics Engineering Center, formed in 1963, has been continuously supported by the Federal Aviation Administration. The Center performs research and engineering tasks under contract or grant for FAA, NASA, and a variety of DoD, state, and industry sponsors. Facilities shared with the School of Electrical Engineering and Computer Science include the Stocker Engineering and Technology Center, the $11.7 million research and educational complex in which the Center is located. Research facilities also include a hangar with flight program support and laboratory space at the Ohio University Airport. On airport facilities include a CAT I commissioned ILS as well as an experimental MLS and GPS LAAS. Flight test aircraft include several single-engine aircraft as well as a Douglas DC-3 research aircraft, which is equipped with advanced navigation instruments, including GPS attitude and heading determination, a ring-laser gyro inertial navigation system, a radar altimeter, and digital air data systems. NAVIGATION SPECIALTIES/INTERESTS Areas of specialization at the Avionics Engineering Center include instrument and microwave landing systems, VOR, Loran-C, inertial navigation, and all aspects of the GPS, including attitude determination, the local area augmentation system, and pseudolites. Unlike most university-affiliated programs, the Center, in addition to pursuing theoretical research, also undertakes mathematical modeling and the actual design, development, implementation, testing, and improvement of various electronic systems for aviation. |
New Corporate Members The ION extends a warm welcome to the following new Corporate Members:
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Calendar October 1998 Sept. 30-2 Oct: RTCA 98 Symposium; Operations, Certification and Standards, and Cornerstones for the Future; Sheraton Premiere Hotel, Tysons Corner, VA; Contact: Dee Clarke, Tel: 202-833-9339 11-15: International Loran Association (ILA) Annual Technical Convention and Symposium 1998; Ferncroft Conference Resort, Danvers, MA; Contact: Bill Roland, Tel: 617-275-2010, E-mail: broland@megapulse.com 20-23: GNSS 98; EUGIN/Institut Francais de Navigation; Contact: Tel: 33 1 44 381 043; Fax: 33 1 40 619 319, E-mail: infranav@micronet.fr November 1998 16-19: 24th Joint Services Data Exchange (JSDE); Sheraton Anaheim Hotel, Anaheim, CA; Contact: John Carvil, Tel: 757-464-7750, E-mail: carvil@nosc.mil 22-24: ISIS 98 International Symposium Information on Ships; Kiel, Germany; Contact: The German Institute of Navigation (DGON), Tel: 49 (0) 228-201 970, Fax: 49 (0) 228-201 9719, E-mail: dgon.bonn@t-online.de 30-4 Dec: International Symposium on Marine Positioning (INSMAP 98); Florida Institute of Technology, Melbourne, FL; Contact: Professor George A. Maul, Florida Institute of Technology, Tel: 407-674-7453, Fax: 407-674-7212, E-mail: gmaul@marine.fit.edu December 1998 9-11: NAV 98; Royal Institute of Navigation; Contact: Tel: 44 (0) 171 589 5021, Fax: 44 (0) 171 823 8671, E-mail: rindir@atlas.co.uk January 1999 25-27: ION National Technical Meeting, ION CIGTF; Catamaran Hotel, San Diego, CA; Contact: ION, Tel: 703-683-7101, Fax: 703-683-7105, Web Site: http://www.ion.org May 1999 24-26: Sixth St. Petersburg International Conference on Integrated Navigation Systems; St. Petersburg, Russia; Contact: Dr. George Schmidt, Draper Laboratory, Tel: 617-258-3841, Fax: 617-258-3355, Web Site: http://www.draper.com June 1999 28-30: ION 55th Annual Meeting; Royal Sonesta Hotel, Cambridge, MA; Contact: ION, Tel: 703-683-7101, Fax: 703-683-7105, Web Site: http://www.ion.org |
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