Last IIR-M GPS Satellite Produced

Lockheed Martin Completes Work On Modernized GPS Satellites
(WebWire) 3/21/2007 10:29:40 PM
Related Topics
• Aerospace/Defense
Last of Eight Block IIR-M Spacecraft Ready to Support Future Launch
KING OF PRUSSIA, Pa., March 21, 2007 -- Lockheed Martin [NYSE: LMT] announced today the delivery of the eighth and final satellite in the modernized Global Positioning System Block IIR (GPS IIR-M) production program to the Air Force.
The GPS constellation provides critical situational awareness and precision weapon guidance for the military. The worldwide system also supports a wide range of civil, scientific and commercial functions – from air traffic control to the Internet – with precision location and timing information.
There are currently three IIR-M spacecraft on-orbit, along with 12 original Block IIR satellites within the overall 30-spacecraft GPS constellation. Each satellite in the Block IIR-M series includes a modernized antenna panel that provides increased signal power to receivers on the ground; two new military signals for improved accuracy, enhanced encryption and anti-jamming capabilities for the military; and a second civil signal that will provide users with an open access signal on a different frequency.
Based on the navigation user range error, which measures GPS accuracy, the Block IIR satellites enable properly equipped users to determine precise time and velocity and worldwide latitude, longitude and altitude to within one meter.
Over 250 employees from Lockheed Martin, navigation payload provider ITT of Clifton, N.J., and representatives from the U.S. Air Force and other government agencies, gathered at Lockheed Martin’s facilities in Valley Forge, Pa., to celebrate the achievement and the overall success of the GPS IIR program.
"This historic milestone is the result of our team’s commitment to superior program execution and dedication to achieving mission success for our customer," said Don DeGryse, Lockheed Martin’s vice president of Navigation Systems. "We take great pride in the outstanding on-orbit performance of these advanced spacecraft and look forward to further enhancing the worldwide constellation with the launch of the remaining IIR-M spacecraft."
Lockheed Martin Space Systems, Denver, Colo., is the prime contractor for the GPS IIR program. The company designed and built 21 IIR spacecraft for the Global Positioning Systems Wing, Space and Missile Systems Center, Los Angeles Air Force Base, Calif.
The final eight spacecraft, designated Block IIR-M, were modernized to enhance operations and navigation signal performance for military and civilian GPS users around the globe. The company is also responsible for launch and flight operations support of the GPS IIR and IIR-M satellites.
The third GPS IIR-M spacecraft was launched successfully on Nov. 17, 2006 and was declared operational on Dec. 12 by Air Force Space Command’s 2nd Space Operations Squadron (2 SOPS) at Schriever Air Force Base, Colo., which manages and operates the GPS constellation for both civil and military users.
The fourth GPS Block IIR-M satellite has been delivered to Cape Canaveral to support a late 2007 launch. Remaining satellites delivered to storage are available for launch when requested by the Air Force for constellation sustainment.
The company is leveraging its proven record of building advanced global positioning system satellites for the next-generation system, known as GPS III. The Lockheed-led GPS III Space Segment team, which includes ITT and General Dynamics, is currently working under a Phase A Concept Development contract, with the Air Force expected to award a multi-billion dollar development contract to a single contractor in late 2007.

Loran and GPS Vunerability

Loran Gets a Witness
Mar 1, 2007
GPS World
The Radio Technical Commission for Maritime Services (RTCM) has joined more than 900 other organizations and individuals in responding to the request for comments on Loran. RTCM comments verbatim:
RTCM's Board of Directors has adopted a position in support of maintaining the Loran-C system, and its modernization to e-Loran standards. Loran provides an important backup to the Navstar Global Positioning System (GPS) and other Global Navigation Satellite Systems (GNSS), not only for position and navigation purposes, but for timing applications as well. In deciding on this position, RTCM has taken the following into consideration:
GPS/GNSS augmentation: The accuracy of GPS/GNSS systems is improved by the availability of additional satellites. In a combined GPS/Loran receiver, Loran signals can function like an additional satellites, thereby improving positional accuracy. Combined GPS and Loran receivers are currently available, and the accuracy provided by the envisioned e-Loran system will enhance their usefulness.
Vulnerability of signals: The signals from GNSS satellites are very weak at the earth's surface. Although it is difficult, jamming of civil GNSS signals is possible. Loran's stronger signal makes jamming more difficult. The following is from the 2005 Federal Radionavigation Plan:
1.6.2.1 Vulnerability of GPS in the National Transportation Infrastructure
The Final Report of the President's Commission on Critical Infrastructure Protection concluded that GPS services and applications are susceptible to various types of radio frequency interference, and that the effects of these vulnerabilities on civilian transportation applications should be studied in detail.
Shielding is another potential issue. Loran's stronger signal would enable land navigation and tracking systems to continue to operate with a combined GNSS/Loran receiver in some places such as tunnels and areas of dense vegetation, where GNSS reception is shielded.
Vulnerability of satellites: As has been recently demonstrated, satellites may be vulnerable to destruction by a future adversary. Loran stations are land-based, and easier to defend. Should the GNSS system be compromised as the result of a conflict, Loran receiver input to shipboard systems such as the Automatic Identification System (AIS) and Long Range Identification and Tracking (LRIT) System, would enable those systems to continue to function. Both systems are considered essential to maritime security, a concern that would certainly take on added importance in a time of conflict. Recent experiments have shown e-Loran capable of meeting Harbor and Harbor Entrance positioning requirements.
Loran is needed as a reliable backup to GPS for timing purposes. Modern communications systems (e.g. cellular telephone) depend on timing derived from GPS and/or Loran, and would not be able to function without them.
Legacy users: Many recreational boaters and smaller commercial vessels have Loran-C receivers, which provide them with sufficient navigational accuracy for their purposes. Termination of Loran-C service would render their equipment useless and their investment in it would be lost. Many commercial boat operators use both GPS and Loran-C, and consider Loran-C a vital supplement to GPS. They are quite familiar with periods of GPS unavailability, and charter boat operators have to use Loran-C under those conditions to find wrecks, rocks, or reefs for fishing or SCUBA diving.
International compatibility: Loran providers in Europe, Asia, and the Middle East have committed to continuing Loran service. The United States needs to commit to Loran in the interest of a seamless international position, navigation, and timing service.
For the Radio Technical Commission for Maritime Services,
— R. L. Markle, President
Sprint Nextel Chimes In

Critical Patch for Daylight Savings Time for Windows Mobile Devices (GeoExplorers, Recon, PDAs)

Find this critical Patch at

http://www.microsoft.com/windowsmobile/daylightsaving/default.mspx#followsteps

New OPUS-RS works for Survey GPS files as short as 15 minutes

from GPS World on-line
Perspectives — February 2007
With OPUS, one person can operate one L1/L2 receiver to bring NSRS-compatible control into a project with a time investment measured in terms of a few man-hours or less.
Feb 26, 2007
By: Eric Gakstatter
OPUS-RS: Rapid Static Processing
This newsletter has a significant international distribution, and I know I just wrote about the US National Geodetic Survey (NGS) a few months ago, but the new OPUS-RS NGS program has international implications. It paints an interesting picture of where things are headed in the geodetic/survey community with respect to Continually Operating Reference Stations (CORS) — not just in the United States, but around the world.
OPUS-RS is a derivative of OPUS (Online Positioning User Service). After 15 months of testing, OPUS-RS was declared operational on January 31, 2007.
A little background: the original OPUS is a free, geodetic-quality, post-processing service for L1/L2 GPS data. It was introduced five years ago by the NGS and is operated/maintain by the NGS. In simple terms, here’s how it works:
• Collect at least 2 hours of L1/L2 GPS data.• Use the NGS OPUS web-based submission form to send your data to them in Receiver Independent Exchange Format (RINEX) format; some manufacturer formats are supported too.• Specify the antenna type.• Specify the antenna height.
Within minutes, the data is processed with respect to three CORS sites (based primarily on distance, site stability and number of observations) and the centimeter-level results are emailed to your inbox in a standard or extended report format. Results are provided in ITRF and NAD83/CORS96 epoch 2002.0 and also in geodetic, State Plan and UTM coordinates, all tied to the National Spatial Reference System (NSRS).
The value of the OPUS/OPUS-RS concept:
Simple to operate. Easy/quick access to the National Spatial Reference System (NSRS).
Low overhead. One person can operate one L1/L2 receiver to bring NSRS-compatible control into a project with a time investment measured in terms of a few man-hours or less.
Robust solution. Multiple baselines used.
The OPUS concept would be much more difficult to implement without the CORS system in place. Briefly, CORS is a network of just more than 1,000 GPS reference stations spread throughout North and Central America. NGS owns very few of these. They are owned/operated by government agencies and private companies who choose to participate in the NGS CORS program and follow the NGS specifications for operating/maintaining a CORS site.
For detailed information on the CORS program, you can visit:
http://www.ngs.noaa.gov/CORS/
For more information on the OPUS program, you can visit:
http://www.ngs.noaa.gov/OPUS/
That brings us to the newest flavor of OPUS called OPUS-RS (Rapid Static). Whereas OPUS is much like the hours-long static GPS work you may have done in the past, OPUS-RS resembles rapid-fast/static approach you may have used in the past, except it uses publicly available GPS reference stations.
If you recall from above, OPUS requires at least two hours of observation time. OPUS-RS can process data sets with as little as 15 minutes of observation time. Where it differs from the rapid/fast static processing you may have done in the past is that OPUS-RS uses reference stations as far as 200 kilometers away. Given the density of CORS sites in North America, this means you can use the service in most locations in Canada, the United States (including Alaska/Hawaii), Mexico, Central America, Virgin Islands, and several smaller regions.
Although the OPUS-RS user interface appears strikingly similar to OPUS, OPUS-RS uses an entirely new software engine developed by the NGS and contractor Ohio State University. OPUS-RS is the first product using the new software engine, and that is the cornerstone of future NGS products.
If you’ve ever been involved in a static GPS survey campaign and had to manage more than one GPS receiver, you’ll appreciate OPUS-RS as well as its predecessor, OPUS. Without OPUS/OPUS-RS, you would have to setup and operate your own reference station(s) and perform the post-processing yourself.
OPUS-RS uses up to six GPS reference stations up to 200 kilometers away to produce a centimeter-level solution. OPUS-RS is picky about site stability, distance, and number of observations, so it won’t always select the closest reference stations to you. If you choose to select the reference station manually, you can select up to six.
To give OPUS-RS (or OPUS) a run and get comfortable with its performance, you don’t have to own a GPS receiver or even leave your office for that matter. You can download data from the CORS site nearest you and then submit it to OPUS-RS as if you collected it yourself. You can push the OPUS-RS envelop by submitting very short datasets or datasets during various times of the day.
Here are the steps and links if you want to do this yourself.
To download data that you’ll submit to OPUS-RS:
Go to http://www.ngs.noaa.gov/CORS
Click on the CORS coverage map and find a station you want to use. Remember, you will use data from this station to simulate your own that you’ve collected. For this exercise, I downloaded data from the CORV site.
Once you’ve clicked on the name of the station you want to use, look on the left side of the screen and click on Custom Files (UFCORS).
Then select a day/time of the data you want. For Number of Hours of data you wish to receive, select “1”.
In next screen, choose 30 seconds between points and select YES for NGS data sheet.
Then click Submit.
Note that data downloaded from CORS is sent to you in minimum 1-hour blocks. If you want to challenge OPUS-RS with shorter datasets like 15 minutes, you’ll have to use a text editor like Windows Notepad to shorten the data file. The data file is in RINEX format, which is an ASCII format. If you’re in a patient mood, a very useful but non-user-friendly program exists called TEQC that does a good job of manipulating RINEX files a number of different ways. You can download TEQC free of charge at:
http://facility.unavco.org/software/teqc/ teqc.html
I used TEQC to chop up the RINEX data into 15-minute sections that I was interested in processing.
Once you have the data ready to submit to OPUS-RS, you need one more piece of information: the type of antenna. In my case, the antenna used by CORV is an Ashtech 700936E_C. You can find this in the header section at the beginning of the RINEX file.
Now, go to the OPUS-RS web site at:
http://www.ngs.noaa.gov/OPUS/OPUS-RS.html
You are prompted for your email address, the name of the file you want to send to OPUS-RS, the antenna type, and the antenna height. I left the antenna height at 0.0 because I used the CORV data. If you collected your own data in the field, you’d need to enter the correct antenna height.
Once the form is completed, click on the Submit button and check your email in a few minutes. The email you receive from OPUS-RS will contains geodetic results in the NAD83(CORS96) datum as well as in ITRF00. Also, you’ll receive State Plane Coordinates and UTM Coordinates referenced to the ITRF00 datum. You are also provided the ellipsoid height and ortho height based on GEOID03 and the NAVD88 vertical datum.
I processed two 15-minute datasets per day over a 10-day period from February 1 to February 10, 2007. Based on mission planning software, I choose a 15-minute period in the morning (~9am local time) when the PDOP was low and one in the afternoon when it was higher (~4pm local time).
Here are results from some of the days I processed. The values are in State Plane, Oregon North, meters. These are 15-minute datasets.
CORV = N105971.566, E2277335.373, 107.514 HAE
DATE/START
N
E
Z
dn
de
dz
Feb. 1 9:10amFeb. 1 4:00pm
105971.548105971.546
2277335.3872277335.389
107.455107.498
.018.020
-.014-.016
.059.016
Feb. 2 9:05amFeb. 2 3:50pm
105971.547105971.545
2277335.3882277335.389
107.503107.491
.019.021
-.015-.016
.011.023
Feb. 3 9:00amFeb. 3 3:50pm
105971.546105971.544
2277335.3892277335.390
107.526107.495
.02.022
-.016-.017
-.012.019
Feb. 4 8:55amFeb. 4 3:45pm
105971.545105971.544
2277335.3892277335.389
107.506107.488
.021.022
-.016-.016
.008.026
Feb. 5 8:50amFeb. 5 3:40pm
105971.546105971.545
2277335.3882277335.390
107.529107.500
.02.021
-.015-.017
-.015.014
Feb. 6 8:50amFeb. 6 3:40pm
105971.547105971.542
2277335.3902277335.390
107.515107.493
.019.024
-.017-.017
-.001.021
Feb. 7 8:45amFeb. 7 3:35pm
105971.545105971.543
2277335.3692277335.382
107.545107.511
.021.023
.004-.009
-.031.003
Feb. 8 8:40amFeb. 8 3:30pm
No solution105971.567
—2277336.923
—108.759
—-.001
—-1.55
—-1.245
Feb. 9 8:35amFeb. 9 3:30pm
105971.548105971.537
2277335.3842277335.389
107.437107.5
.018.029
-.011-.016
.077.014
Feb. 10 8:30amFeb. 10 3:25pm
105971.550105971.540
2277335.3872277335.392
107.519107.498
.016.026
-.014-.019
-.005.016
In looking at the data, what’s interesting is the precision of the collected data is pretty tight (with the exception of the Feb. 8 data which is discussed below). At first, I thought I had made an error somewhere in calculating the CORV State Plane coordinates, antenna selection, and so on, because the offset from CORV of each of the solutions was pretty consistent. However, I had the NGS folks check my work and I had done things right. They attributed the offset to error in the published CORV coordinates, seasonal variation of coordinates, and movement not accounted for in the NGS velocity models as CORV (Corvallis, OR) is in a region of considerable tectonic stress.
You’ll notice the difficulty on the Feb. 8 datasets. No solution was possible for the morning dataset even when I extended the dataset to 60 minutes — too many cycle slips. Also, the Feb. 8 afternoon solution had significant errors. It’s important to note that the quality indicators in the OPUS-RS report raised a red flag on these two datasets and also on the Feb. 9 morning dataset where the N and E components were very reasonable but the Up component was a little sloppy.
One item I was paying attention to were instances where the quality indicators were positive, but a poor solution was provided. I didn’t see this so it speaks well, given a limited dataset, of the integrity of the solution. OPUS-RS provides two sets of quality indicators for you to evaluate the position solution.
OPUS-RS also reports the reference stations that were used to determine the solution. There were six with the closest being 42km and the furthest being 187km away. Who would have thought you could obtain cm-level positioning using 15 minutes of data with those sorts of baseline distances?
I could spend a lot more time writing about this because there’s much more, but the great part about it is that you can try OPUS-RS without even leaving your desk. I even went back and processed some datasets I had from a current project. Give it a shot.
About the Author
Eric Gakstatter
About Eric Gakstatter
email: egakstatter@questex.com
See more articles by Eric Gakstatter

Update for Daylight Savings Time for Windows Mobile Devices

Fix for these devices running Windows mobile or Windows mobile 2003 is found at

http://www.microsoft.com/windowsmobile/daylightsaving/default.mspx#followsteps