GPS II R-M (SVN 49) PRN 01 was modified before launch to include the new L-5 signal. Unfortunately the antenna connections were cross-wired and while it could broadcast L5 it could not broadcast a reliable L1/L2 signal. The jury rigging was done because the US had a deadline to broadcast L5 from space otherwise some other country could claim the frequency. In 2010 with the launch of the first GPS II F satellite (SVN 62) PRN 25, L1/L2/L5 were reliably broadcast and they have had a year to fiddle with PRN 01. It appears that no correction could be made and SVN 49 was deactivated yeasterday never having broadcast a useable signal. The second GPS II F is scheduled for a July 2011 launch and will most likely be assigned PRN 01 after launch.
In other GPS news, 3 GLONASS M satellites are scheduled for July 2011 and 2 Galileos are scheduled for August 2011 launches.
Another item of interest, it is planned to add laser retro-reflectors to the next series of GPS, block III sattelites, to allow precise tracking without clock errors. Reflectors are standard on GLONASS and will be also added to Galileo satellites.
Paul in PA
How many millions of dollars does a GPS satellite cost?
$100-$150 Million Each, Including Launch
Based on the latest contract for Lockheed to build 2 or 12.
We also had 1 GPS destroyed on a launch failure, but the fact that they last twice what was expected, makes them a true value.
Paul in PA
$100-$150 Million Each, Including Launch
Except the one that failed was built by Boeing right?
I sure hope the Russians get stations outside their country going soon though, otherwise GLONASS isn't that great for here, perhaps an correction program called ?om?ade OPUS would be nice too.
Lockheed-Martin Built The Failed ? Satellite
Lockheed-Martin built the GPS II R and GPS II R-M (L2C added after construction) satellites.
Boeing is building the GPS II F (L1/L2/L5) satellites with L1/L2/L5 antenna arrays. Boeing was having delays because it was not as easy to boost the signal power as the military thought. Because of that delay, Lockheed got the next contract and the following happened.
Because of the deadline to get the L5 signal broadcast the Air Force opted to add an experimental L5 package (changed the frequency on an existing L2 transmitter) to an already modified II R-M. They elected to send the experimental L5 signal through the L1/L2 antennas. They chose not to test that on the ground, where it would have been easier to find the cause of the signal feedback which could have been fixed with a simple filter. In essence the L1/L2 signal goes from the L1/L2 antenna down the L5 feed wire and is reflected back with a delay to the antenna. The reflected signal is sufficiently strong that a typical receiver cannot filter it out giving an incorrect distance. Thus making the satellite usesless in L1/L2 mode even after they turned the L5 signal off because the feed wires are still there. It is highly possible that engineers knew about the problem prior to launch but had no choice but to get that bird in the air to broadcast the L5 signal which is all it did prior to the II F launch. Don't expect anyone to step forward and volunteer that they blew $100 million. The satellite did not fail, it did exactly what physics said it would do.
I expect that Air Force will keep the satellite alive for some possible future testing with multiple other L5 capable satellites.
Paul in PA
I wonder about that... If it was just about locking up the spectrum, one would think they could have just floated a simple, inexpensive, solar powered transmitter beacon without the cesium clock and the rest of the stuff a GPS satellite has out of the shuttle bay and into orbit.
