From: skunk-works-digest-owner@harbor.ecn.purdue.edu To: skunk-works-digest@harbor.ecn.purdue.edu Subject: Skunk Works Digest V2 #78 Reply-To: skunk-works-digest@harbor.ecn.purdue.edu Errors-To: skunk-works-digest-owner@harbor.ecn.purdue.edu Precedence: bulk Skunk Works Digest Friday, 12 February 1993 Volume 02 : Number 078 In this issue: Medals GPS and AI index FAA and DGPS FAA and DGPS GPS pseudolites Re: FAA and DGPS other interesting GPS usage GPS... See the end of the digest for information on subscribing to the skunk-works or skunk-works-digest mailing lists and on how to retrieve back issues. ---------------------------------------------------------------------- From: Stefan Skoglund Date: Thu, 11 Feb 93 08:29:09 -0100 Subject: Medals Yesterday I saw a film on TV. In that film somebody had a medal of some sort. Description : Round, George W. in profile on blue bottom. What is this ? Purpur-heart or that ? As you hear I don't know that much about American medals. - ----------------------------------------------------------------------- Stefan Skoglund I Home : 0500 450878 sp2stes1@obelix.his.se, I ----------------- University of Skoevde, Sweden I +46 500 450878 Int ------------------------------ From: "S.K. Whiteman" <@VM.CC.PURDUE.EDU:WHITEMAN@IPFWVM> Date: Thu, 11 Feb 93 09:55:12 EST Subject: GPS and AI index My reference for the GPS comment is: FAA Satellite Navigation Program Plan FY 92-97, Feb 12,1992 Available through: Federal Aviation Administration Satellite Program Office ADR-70 800 Independence Avenue SW Washington, DC 20591 Phone 202-267-7219 The entire comment was to point out the foolishness of two go'mnt organizations working against one another. The report isn't technical over and above that the pseudolites use l-band, there is no mention of USCG (Uncle Sam's Confused Group); but the report does go into the use of GLONASS with GPS. GPS is the replacement for the failed MLS and gives the time line for implementation. :-) About time the FAA got into the 20th century. Now that you've used the four letter 'W' (work). I am employed by a university, we don't work, and we don't get paid for it either; but we have fun doing it. :-() Air International January 1993: - Front cover: A line of 32 CISAF Su-27 at Chojina Poland, home of the 582nd IAP - NASP - waveriders in a hypersonic sky part 1. An examination of the development of the National Aero-Space Plane. - Farewell Poland: As the CISAF withdraws form Poland, this article examines the history of the units that have been stationed there. - Lightning lives: the last airworthy English Electric Lightnings are being used as RADAR targets for Tornado squadrons. - Eurofighter's EFA - wonderplane or costly luxury: a technical description of the RAF's version of the new fighter. - Icelandair: A history and future direction of this small airline. - Fury - the Navy's Sabre: The warbird feature is the FJ-3 (F-86) Fury. The history and operation are recounted - Fighters A to Z: SIAI S.67 to the Siemens-Schuckert DD.5 - Flying colours: He 219. Air International February 1993: Front cover: One on the Saab JAS 39 Gripen prototypes. - SAAB 2000 - an exercise in growth and commonality: A rather slick looking twin turboprop 50 passenger airliner. - Sweden's JAS 39 Gripen: 'The worlds only new-generation lightweight multi-role fighter' - Swallow to Airbus: A history of United Airlines - Medium with the mostest - the B-25 Mitchell: A history of the A/C. - VVA-14 - a russian enigma: This is a WIG, wing in ground effect machine, and some of the history of its designer. - NASP - waveriders in a hypersonic sky part 2. An examination of the development of the National Aero-Space Plane. - FAPA - a force alone: A report on the Angolian air force now that the Cubians are gone. - Fighters A to Z: Siemens-Schuckert series. Sam ------------------------------ From: THOMSONAL@CPVA.SAIC.COM Date: Thu, 11 Feb 1993 8:58:28 -0800 (PST) Subject: FAA and DGPS Robert Herndon writes: > I'm not aware of any major (or even minor) FAA effort to build > pseudo-lites (a contraction of "pseudo satellites"). What HAS been > done is to build several differential GPS beacons, and the work is > being done by the U.S. Coast Guard, not the FAA. It is true that the USCG is ahead of the pack in installing DGPS stations around the country, but the FAA and private companies are in there as well. Recent issues of AvWeek are full of stories on the amazingly rapid introduction of DGPS: - ---------------------------------------------------------------------- FAA Steps Up Program to Introduce GPS as Instrument Approach Aid Aviation Week & Space Technology August 17, 1992; Pg 35 BYLINE:PHILIP J. KLASS [EXCERPTS--this was a long article and is worth reading in its entirety] Federal Aviation Administration is accelerating its program to introduce GPS (Global Positioning System) as an adverse-weather landing aid. This includes determining whether GPS can meet rigorous Category-2 and Cat.-3 requirements. Recent tests conducted at the FAA Tech Center in Atlantic City using Differential-GPS (D-GPS), in which accuracy is enhanced by corrections determined through airport-based equipment and transmitted to aircraft via data link, reportedly demonstrated near-Category-1 instrument landing system (ILS) capabilities. The tests used a Gulfstream-4 outfitted by Honeywell. FAA recently opted to advance by five years, to 1995, its timetable for determining whether GPS can provide accuracies needed to meet Cat.-2 and Cat.-3 requirements. This target date coincides with the time the FAA must decide whether to contract for initial MLS production. Inmarsat has taken a first step toward becoming a commercial supplier of [satellite navigation] GNSS service by deciding to outfit its third- generation satellites to transmit a GPS-type signal from their geosynchronous orbits. The new Inmarsat-3s also will transmit differential corrections and integrity information to identify any GPS satellites whose signals are out of tolerance. First Inmarsat-3 launch is slated for late 1994/early 1995. At a recent Inmarsat sponsored avsatcom conference in Montreal, FAA's John A. Burt, executive director for system development, said, "We would welcome other nations to launch GPS type satellites as well as commercial ventures." Burt noted that GPS will eventually save the FAA the $83.5 million it now spends every year to modernize and maintain its ground-based nav-aids. Routine use of GPS as a stand-alone Cat.-1 precision approach aid is not expected before 1995-96, when all of the new Inmarsat-3 satellites will be operational to transmit differential correction signals. Current FAA plans call for installation of 15-20 ground monitoring stations throughout the U. S. to measure required differential GPS corrections. Current Inmarsat-3 orbital deployment plans would leave a midwest coverage gap which has prompted the FAA to suggest slightly different orbital slots. Later, FAA plans to install several hundred "local-area" GPS monitoring stations in the vicinity of major airports to provide more accurate corrections for aircraft using GPS as a precision approach aid. Whether these corrections would be transmitted via ARINC's existing ACARS very high frequency (VHF) data link or Mode-S data link has not yet been determined. - ------------------------------------------------------------------------------ Klass' article inspired me to write the following letter, which was published in AvWeek of 7 September 1992: "Twenty years in Washington have exposed me to many strange things, but the situation with regard to the Global Positioning System sets a new record for the bizarre. "On one hand, the Defense Dept.--the system's proprietor--has undertaken several measures to deny hostile users the ability to get better than 100-meter positioning accuracy. On the other hand, the FAA and the Coast Guard are developing and deploying differential GPS (DGPS) stations, which will provide 10-meter or better accuracies over much of the U.S. "This may be ill-considered, despite its undoubted value to civil aviation and maritime users, as DGPS defeats all GPS security features. Do we want to provide other countries with precision weapons delivery over the U.S?" ------------------------------ From: rick@ssg.com (Rick Emerson) Date: Thu, 11 Feb 93 20:35:04 GMT Subject: FAA and DGPS writes: > Robert Herndon writes: > > > I'm not aware of any major (or even minor) FAA effort to build > > pseudo-lites (a contraction of "pseudo satellites"). What HAS been > > done is to build several differential GPS beacons, and the work is > > being done by the U.S. Coast Guard, not the FAA. > > It is true that the USCG is ahead of the pack in installing DGPS > stations around the country, but the FAA and private companies are in > there as well. Recent issues of AvWeek are full of stories on the > amazingly rapid introduction of DGPS: > > [AvWeek article deleted] > > Klass' article inspired me to write the following letter, which was > published in AvWeek of 7 September 1992: > > "Twenty years in Washington have exposed me to many strange > things, but the situation with regard to the Global Positioning System > sets a new record for the bizarre. > "On one hand, the Defense Dept.--the system's proprietor--has > undertaken several measures to deny hostile users the ability to get > better than 100-meter positioning accuracy. On the other hand, the FAA > and the Coast Guard are developing and deploying differential GPS (DGPS) > stations, which will provide 10-meter or better accuracies over much of > the U.S. > "This may be ill-considered, despite its undoubted value to civil > aviation and maritime users, as DGPS defeats all GPS security features. > Do we want to provide other countries with precision weapons delivery > over the U.S?" > Sigh... you've spent too much time inside the Beltway. Even if DoD slapped on all the jittering, anti-spoofing, and related nonsense it could find, there's at least one system with comparable accuracy available. The Russian GLONASS system is completely S/A free and it's there for any Tariq, Abdul, or Hakim to receive and use. And, at last check, it seems highly unlikely DoD is going to exert much control over the system. And, of course, there's also ARGOS which could be adapted for all sorts of interesting applications -- and I rather doubt DoD is going to get the French to shut it down, either. Frankly, you're locking the gate long after the horse got up and left on its own. Rick | Richard B. Emerson | Replies may be sent to: | | System Support Group | rick@ssg.com | | 940 Delaware Avenue |-------------------------------------------------+ | Lansdale, PA 19446 USA | "When you ski, you dance with the mountain -- | | Voice: 215.855.1607 | and the mountain always leads." | ------------------------------ From: rick@ssg.com (Rick Emerson) Date: Thu, 11 Feb 93 20:17:42 GMT Subject: GPS pseudolites Sam Whiteman writes: > > > Does this mean that the stuff is starting to float? Wanta buy a > > tape recorder Mr. Nixon? It seems that these folks will never learn; > > secrets can't kept in a free society. This reminds me of the DOD/FAA > > argument pertaining to GPS. It seems that DOD wanted to limit accuracy > > to 100 meters and the FAA needed 10 meters. So, the FAA is building, > > new buzz word, pseudolites around major airports. As I understand it > > a pseudolite is a GSP satellite on the ground. Burn them $$$$... > > This isn't terribly accurate, so I'll do my best to correct it. > Someone with a more rigorous background in GPS technologies can > probably correct or better explain anything I goof up, but: > > I'm not aware of any major (or even minor) FAA effort to build > pseudo-lites (a contraction of "pseudo satellites"). What HAS been > done is to build several differential GPS beacons, and the work is > being done by the U.S. Coast Guard, not the FAA. Some were built for testing before satellites were put up but that's no surprise. > What these GPS beacons do is, on a frequency NOT used by GPS > satellites, transmit the error that a receiver at a known location sees > from each satellite (the receiver must be at an exactly known position). > This error signal can be used by GPS receivers to correct their position > to yield a much more accurate position. It works within about 250 km of > the differential GPS beacon, and near the beacon can yield accuracies on > the order of 10 meters or so. (This accuracy is *better* than straight, > military grade GPS can provide.) The DGPS stations you describe can, with some effort, generate centimeter accuracies but the DGPS sets now begining to appear in the marine and aviation market place are, as you say, on the order of 10 meters. > It works by compensating for several effects: > > 1) ionospheric propagation delays; > 2) selective availability (the DoD's effort to limit GPS accuracy > to "unauthorized" users); and > 3) inaccuracies in the satellites' broadcast positions or times > (other than those caused by selective availabilty). And there's also anti-spoofing. > It should also be possible to use the DGPS beacon as a check on the > basic sanity of the GPS constellation's signals (tho' I do not know if > this is in fact being done at the present time). > > At the present time there are DGPS beacons at: > > Location Position Current status > Portsmouth HR, NH N43 04.20 W70 42.50 On-line operational testing > Montauk Point, NY N41 04.03 W71 51.64 On-line operational testing > Cape Henlopen, DE N38 47.15 W75 05.90 On-line operational testing > Cape Henry, VA N36 55.58 W76 00.45 On-line operational testing > Galveston, TX N29 19.73 W94 44.10 On-line operational testing > Aransas Pass, TX N27 50.30 W97 03.54 On-line operational testing > Whitefish Point, MI N46 46.27 W84 57.45 On-line operational testing > > All of these were pre-existing HF navigation beacons. Each now > broadcasts a low-bit-rate signal (50 or 100 bits/second) on its > beacon; this signal can be used by GPS units with differential > GPS capability to yield a more accurate position near the beacon. All of the USCG DGPS RDF beacons have been upgraded to 100 bps. Whitefish Pt was installed sending 100 bps while the rest were initially 50 bps but by now all stations should be at 100 bps. The signal from these beacons has a slight warble due to the digital data but the USCG says this shouldn't affect the beacons' accuracy. > Robert Herndon Rick | Richard B. Emerson | Replies may be sent to: | | System Support Group | rick@ssg.com | | 940 Delaware Avenue |-------------------------------------------------+ | Lansdale, PA 19446 USA | "When you ski, you dance with the mountain -- | | Voice: 215.855.1607 | and the mountain always leads." | ------------------------------ From: gwh@lurnix.COM Date: Thu, 11 Feb 93 11:31:37 -0800 Subject: Re: FAA and DGPS >Klass' article inspired me to write the following letter, which was >published in AvWeek of 7 September 1992: > "Twenty years in Washington have exposed me to many strange >things, but the situation with regard to the Global Positioning System >sets a new record for the bizarre. > "On one hand, the Defense Dept.--the system's proprietor--has >undertaken several measures to deny hostile users the ability to get >better than 100-meter positioning accuracy. On the other hand, the FAA >and the Coast Guard are developing and deploying differential GPS (DGPS) >stations, which will provide 10-meter or better accuracies over much of >the U.S. > "This may be ill-considered, despite its undoubted value to civil >aviation and maritime users, as DGPS defeats all GPS security features. >Do we want to provide other countries with precision weapons delivery >over the U.S?" Wether it's well publicized or not, there's a solution to that problem that IS being included in the system. The DOD has an off button for the D-GPS systems going in at airports, etc. Basically, in the case of national emergency (attack) the Pentagon (probably NORAD) can shut down all the D-GPS systems immediately. They had initially refused to approve D-GPS (and were mumbling about defeating it technically) but were satisfied by an apparently reasonable national security "Fuse" that was installed, so they can prevent anyone from precision-targeting within the US if an attack is underway. This information is coming through some Sattelite Applications academics who were working with early D-GPS concept field tests, so I would rate its accuracy as moderately high. They reported that they'd gotten accuracies of closer to 1 meter average out of the early test rigs in aircraft, so the FAA may have "detuned" the production system at the DOD's request, in addition to the shutdown feature. - -george william herbert gwh@lurnix.com ------------------------------ From: "S.K. Whiteman" <@VM.CC.PURDUE.EDU:WHITEMAN@IPFWVM> Date: Thu, 11 Feb 93 16:16:43 EST Subject: other interesting GPS usage I hope this isn't too far afield, but GPS seems to be of some interest: The Aug 1992 issue of NASA Tech Briefs; Vol 16, No 8, has an article on page 34 pertaining to the use of two GPS receivers mounted on an aircraft to detect location, speed, and attitude. NASA's use is to correct SAR, Synthetic-Aperture Radar, data. This device, according to the author, can locate the aircraft position within 15 meters; 0.015 m/s in velocity; 0.012 degrees in azimuth; and 0.038 degrees in pitch. Auto pilot anyone? My interest in these matters is due to the geophysical exploration possibilities. Sam ------------------------------ From: I am the NRA Date: Thu, 11 Feb 93 13:41:48 PST Subject: GPS... From: US1RMC::"rick@ssg.com" "Rick Emerson" 11-FEB-1993 16:29:31.76 > writes: > > "Twenty years in Washington have exposed me to many strange > > things, but the situation with regard to the Global Positioning System > > sets a new record for the bizarre. > > "On one hand, the Defense Dept.--the system's proprietor--has > > undertaken several measures to deny hostile users the ability to get > > better than 100-meter positioning accuracy. On the other hand, the FAA > > and the Coast Guard are developing and deploying differential GPS (DGPS) > > stations, which will provide 10-meter or better accuracies over much of > > the U.S. ...and the Ag department subsidizes Tobacco, while HEW fights cancer. Nothing new in contradictions. > > "This may be ill-considered, despite its undoubted value to civil > > aviation and maritime users, as DGPS defeats all GPS security features. > > Do we want to provide other countries with precision weapons delivery > > over the U.S?" ca 1943, the UK "wizards" spotted a set of German emissions, which turned out to be a nav system, moderately similar to LORAN or DECCA. The wizards offered to jam it, but the request received was: "build us some receivers". The system provided good nav coverage over the Bay of Biscay (off Spain) where the UK had no nav system....) The UK used the German nav system as long as it stayed on the air... On a speculative note, I wonder of the pseudolites have provision for remote turn off, and where the control box is.... >Sigh... you've spent too much time inside the Beltway. Even if DoD >slapped on all the jittering, anti-spoofing, and related nonsense it >could find, there's at least one system with comparable accuracy >available. The Russian GLONASS system is completely S/A free and it's >there for any Tariq, Abdul, or Hakim to receive and use. And, at last >check, it seems highly unlikely DoD is going to exert much control >over the system. And, of course, there's also ARGOS which could be >adapted for all sorts of interesting applications -- and I rather >doubt DoD is going to get the French to shut it down, either. indeed. regards dwp ------------------------------ End of Skunk Works Digest V2 #78 ******************************** To subscribe to skunk-works-digest, send the command: subscribe skunk-works-digest in the body of a message to "listserv@harbor.ecn.purdue.edu". 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