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First modernized GPS satellite Launched
A reader writes "The first GPS 2R-M satellite has launched from Cape Canaveral, Florida on top of a Boeing Delta 2 rocket. The government is now competing with Europe's Galileo system, and has added two additional military channels and one civilian channel, which will increase the accuracy and performance of GPS - as well as increase its resistance to jamming."
You know, I was about to ask the rocket scientists hanging around here (hi guys!) about how small new generation comsats were going to be. After all, there has been a tremendous increase in miniturization and technology since the original GPS sats were launched. (e.g. better microprocessors, denser batteries, more efficient solar panels, better propulsion, etc.) If we could get these sats small enough, it might be possible to deploy a GPS system for Mars in one or two launches.
Then I saw the borg cube that assimilated the Willy Wonka Chocolate Factory (Mirror) Excuse me while I pick my jaw up off the floor.
On another note, the picture makes it look like the design hasn't changed much from the original NAVSTAR configuration. I assume that these satellites are merely sharing the same chassis, and have very different internals?
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Jammed? Raspberry. There's only one man who would dare give me the raspberry. Lone Starr!
Sierra Tango Foxtrot Uniform
The new civilian channel is in addition to the existing channel, so your existing equipment should work. As more of these sats go online, you can expect to see gear that provides access to the second civilian channel. (Source)
What I have to wonder, though, is what will they do with the two new military channels? It seems that all the field soldiers tend to use civilian gear because the military gear is too heavy, unfriendly, ugly, and is in short supply. I suppose it would make the missiles hit their targets better, but it would be nice to know that our entire military can use the equipment.
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" The government is now competing with Europe's Galileo system "
Lets see :
Galileo has not launched yet.
Galileo will not be free.
The 2R-M was planning before Galileo was anounced.
Galileo operational capibility is not planned until 2008.
I'm failing to see the link to the vaporware...
You have to remember that they're overengineering these things by terrestrial standards, because the satellites have to withstand some fairly harsh conditions while in orbit (such as radiation, EM storms from solar flares, etc). I imagine they're also hardened to some degree against human-generated interference, given all the worrying the Air Force has been doing lately about space warfare. Given all that, I'm not surprised that they seem excessivly bulky by the standards of present technology.
Problem with active GPS jamming is that it's a "damned if you do, damned if you don't" situation. Any sort of active jamming on the battle field is a huge beacon on the battlefield screaming BLOW ME UP! It then becomes a question of whether or not to turn on the jammer at all, as at most it'll be good for slightly de-accurizing (if that's not a word, it ought to be) one bombing run before being obliterated. If they were cheap enough, maybe, but even still...
If a job's not worth doing, it's not worth doing right.
I remember watching a press conference with a military general at the opening of the last gulf war. The press was all lathered up about reports that Iraq was jamming GPS signals - it was assumed the Russians had given them the equipment - and the general commented that whoever was running that equipment had the worst job with the shortest life expectancy in the world at that time. Like you alluded to, any military equipment that relies on an outgoing radio signal instantly becomes a big bright target.
The other thing to keep in mind is that there are many things that contribute to the total spacecraft mass in addition to the electronics. Not all of them have undergone the same kind of Moore's law reductions in mass (or improvements in capability) that electronics have.
The new civilian code is probably a longer signal that repeats less often. This gives better accuracy but takes longer to determine position when first switched on. Using the lower accuracy signal would allow for a rapid first estimate of postion while the GPS would become more accurate once the position using the new signal was calculated. The military GPS systems use the civilian signal to estimate their position more quickly.
I use a laptop-integrated GPS in my car, and I drive by the Pentagon regularly for work. The GPS goes nuts on certain roads that pass near the building... the "position" of the vehicle jumps all over the place. Same thing happens near the capitol building. No suprise of course...
-R
Actually, it will appear as PRN (pseudo-random noise) #17 on receiving equipment. That PRN is currently unused. The current vehicle in slot C4 is PRN07, and it will keep that PRN assignment until it is decommissioned by the USAF.
Unless you're in a very flat area, in the air, or on an ocean, you won't see five or six sats 100% of the time. 70-80% is more like it. If one of the sats is down (which happens; PRN #5, plane B, slot 4, wss down for 8 days recently), the outages are longer.
GPS uses six rings of four satellites each, with all rings in polar orbit. The four satellites in each ring are 90 degrees apart. So, when a satellite in a ring is near the zenith, it's usually the only one visible in that ring. The original design called for more satellites per ring; with six per ring, you'd always have at least two satellites visible per ring, as long as you could see to within 30 degrees of the horizon. But there was a budget cut in the early days of GPS.
GLONASS is a GPS (global positioning system), so Aviation Week is right. One of the first examples of Russian GPS-guided bombs is the KAB-500S-E with a 1500 lb device also available.