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Author Topic:   GPS Modernization
jimh posted 03-16-2012 08:12 AM ET (US)   Profile for jimh   Send Email to jimh  
The U.S. Air Force NAVSTAR global satellite navigation system is in a long process of modernization to improve coverage and accuracy. A small step in the process occurred recently when the prototype of the next-generation NAVSTAR space vehicle, the Block III satellite, was delivered by the contractor, Lockheed Martin, to a test facility in Colorado. Lockheed Martin was awarded a contract by the Air Force in March 2008 to build two Block III GPS satellites. Launch of the first Block III spacecraft is scheduled for 2014.

The Block III satellites will carry the first implementation of the new civilian signal, the L1C. The L1C signal is designed to enable interoperability between GPS and other international navigation systems, such as GALILEO, Japan's QZSS, India's IRNSS, and China's COMPASS system. The designator L1C refers to the radio frequency, 1575-MHz, and the intention of use by civilians. The current signal used by most civilian GPS receivers is known as the L1 C/A, for L1 frequency and "coarse acquisition."

The L1C signal is just one of many improved signals to be added to the GPS system. The L2C signal, for second civilian signal at 1227.60-MHz, has already begun to be deployed in the GPS Block IIR spacecraft, beginning in 2005. This signal is being transmitted at higher power than the L1 C/A to provide better reception in difficult environments. When two signals are available to civilian receivers, position finding accuracy will improve due to the ability to make corrections for ionospheric variations. In order to take advantage of the L2C signals, civilian GPS users will have to wait until there are 24 satellites in orbit with them. Users will have to wait until about 2016 for that milestone to be reached.

A third civilian signal, the L5 signal, is being deployed for use by civilian aircraft. The L5 signal is transmitted at 1176.45-MHz. Reception of the L5 signal in coordination with the L1 C/A and L2C signal will provide position fix with sub-meter accuracy. L5 began deployment in May 2010 on the GPS IIF satellites.

You can find more details on the very informative website .

PeteB88 posted 03-20-2012 11:20 AM ET (US)     Profile for PeteB88  Send Email to PeteB88     
Thanks - interesting.
Mambo Minnow posted 03-22-2012 07:20 AM ET (US)     Profile for Mambo Minnow  Send Email to Mambo Minnow     
[From an article carried on Reuters on the cost of the Block III satellite development]: " 18-percent cost overrun on development and production of the first two Global Positioning System (GPS) III satellites being built by Lockheed Martin Corp...will drive their cost up to $1.6 billion."

[I deleted about 90-precent of the article that was posted because it was not about GPS modernization--jimh]

jimh posted 03-22-2012 08:25 AM ET (US)     Profile for jimh  Send Email to jimh     
Thanks for the information on the cost of the Block III spacecraft. The price is now $800-million each. And we are going to need 24 of them--about $20-billion. Maybe the price will come down a bit with mass production.

If past practice is any guide, the Air Force seldom builds more than a dozen satellites of any one type. They usually have some improvements to add before any one type is built out to provide a full constellation.

jimh posted 03-22-2012 08:34 AM ET (US)     Profile for jimh  Send Email to jimh     
To put the cost of the GPS system into perspective, let us consider the cost per taxpayer. I don't know the exact figures, but let us assume that in our population in the USA there are about 100-million people who actually pay taxes. I know that perhaps a lot more people file income tax returns, but a lot of them don't actually pay any taxes. So let's use 100-million as the number of citizens who actually pay taxes. If we are going to spend $20-billion building GPS satellites, I think that works out to $200 per person, spread over the next ten years. That is an annual cost of $20-per-person-per-year.

As a GPS user, I think $20 per year is a fair cost basis for the service.

Hoosier posted 03-22-2012 12:13 PM ET (US)     Profile for Hoosier  Send Email to Hoosier     
That's just the cost of the satellites, It doesn't say it includes launch and Operation and Maintenance (O&M) costs over the live of the program that can easily be double the acquisition cost.
andygere posted 03-22-2012 02:15 PM ET (US)     Profile for andygere  Send Email to andygere     
jimh, nice article, and interesting financial analysis. I suggest that the actual cost to the average taxpayer will be more, since this project is likely financed. There's probably no way for us to know how much it will actually cost once debt service is factored in.
jimh posted 03-23-2012 08:15 AM ET (US)     Profile for jimh  Send Email to jimh     
By adding the second civilian signal, a civilian GPS receiver will be able to simultaneously receive the L1 C/A (or the L1C) at 1575-MHz and the L2C signal at 1227.60-MHz. The two signals will come from the same satellite. Because the two signals will be on different frequencies, a sophisticated receiver will be able to make an inference about the propagation delay experienced by the two signals as they pass through the ionosphere. The delay effect varies with frequency, and by compensating for ionospheric propagation delay variables, a more accurate position fix can be calculated. This enhancement should be useable in c.2016, once there are more satellites in the space segment that are transmitting the L2C signal and civilian receivers become available that can make use of that signal.
Mambo Minnow posted 04-17-2012 09:39 AM ET (US)     Profile for Mambo Minnow  Send Email to Mambo Minnow     
Per Bloomberg News, the new GPS III satellites are designed to deliver more accuracy, an anti-jamming capability and a civilian signal that can operate with Europe’s Galileo system.

Lockheed Martin beat Boeing in May 2008 for the opportunity to build the first of as many as 12 GPS III satellites. The Air Force may eventually buy as many as 32 satellites.

jimh posted 04-17-2012 12:43 PM ET (US)     Profile for jimh  Send Email to jimh     
Per Bloomberg News, the new GPS III satellites are designed to deliver more accuracy, an anti-jamming capability and a civilian signal that can operate with Europe’s Galileo system.

It sounds like Bloomberg News is saying the same things I said in the article I posted a month ago. I don't know how they're reading "anti-jamming" into the equation. The new satellites have higher power transmitters, so the signals arriving on Earth may be a bit stronger, but there is really no way to actively prevent jamming. That is a misnomer, from what I can see. Actually, I think Bloomberg News mentioned this due to the large contract penalty recently assessed to the satellite contractor, Lockheed-Martin.

Here are a few links to views of Lockheed-Martin building and testing GPS spacecraft.

A Lockheed Martin engineer works on a GPS IIR-M satellite set-72157625171465765/

The core structure of the GPS III Non-Flight Satellite Testbed (GNST) stands vertical in Lockheed Martin’s GPS III Processing Facility. Learn more at set-72157625171465765/

Lockheed Martin officially opened its new GPS III Processing Facility (GPF) on February 21, 2012. The GPF, built in the company’s former rocket assembly building, has nearly 50,000 square feet of spacecraft assembly and test area, and is specifically designed to reduce the cost of building each GPS III satellite. set-72157625171465765/

Mambo Minnow posted 04-17-2012 06:34 PM ET (US)     Profile for Mambo Minnow  Send Email to Mambo Minnow     
Lockheed basically has lost its award fee of $16M due to cost over runs but will recover all its costs.

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