New GPS Satellite

December 22, 2003

There's a new GPS satellite in orbit. See the story here:

http://story.news.yahoo.com/news?tmpl=stor...atellite_launch

4k · December 22, 2003

cool

December 22, 2003

Thanks for pointing the way to this site, but a question does arise.

At one stage I know that there were at least 21 sats in orbit and to get a fairly accurate fix you needed at least 4 of them lined up properly.

How will one new sat improve accuracy? Or am I missing something somewhere?

Anyone out there care to comment?

Thanks

Metro Nomad

December 22, 2003

you go air force with your satellites

December 22, 2003

(SNIP)
How will one new sat improve accuracy? Or am I missing something somewhere?

Anyone out there care to comment?

Thanks

Metro Nomad

There are, and have been all along, 24 active GPS satellites. There are also usually three spares in orbit.

All of the birds in orbit use a bit of fuel to adjust their orbit from time to time, and eventually run out. Between fuel usage and normal wear and tear, the service life of a GPS satellite is 4 to 5 years.

From time to time one of the 24 "in service" birds will either fail or approach the end of normal life and need to be replaced by one of the orbiting spares. When this happens, or is expected to, a new spare is launched.

This has no effect on system accuracy.

Dave_W6DPS

December 22, 2003

(SNIP)
How will one new sat improve accuracy? Or am I missing something somewhere?

Anyone out there care to comment?

Thanks

Metro Nomad

There are, and have been all along, 24 active GPS satellites. There are also usually three spares in orbit.

All of the birds in orbit use a bit of fuel to adjust their orbit from time to time, and eventually run out. Between fuel usage and normal wear and tear, the service life of a GPS satellite is 4 to 5 years.

From time to time one of the 24 "in service" birds will either fail or approach the end of normal life and need to be replaced by one of the orbiting spares. When this happens, or is expected to, a new spare is launched.

This has no effect on system accuracy.

Dave_W6DPS

Why can't it use solar power to move / adjust itself or recharge batteries? Can't the space shuttle "re-fuel" it considering that it's such an expensive piece of US taxpayers money in the first place?

December 22, 2003

Dave

I agree with you, hence the question raised above. The first line of the above-mentioned article reads:

CAPE CANAVERAL, Fla. - A rocket lifted off early Sunday, carrying into orbit a satellite designed to increase the accuracy of Global Positioning System signals for both military and civilian users.

If this satellite isn't in my GPS' line of sight, I fail to see how it can improve my accuracy at that particular point in time.

Metro Nomad

7.2k · December 22, 2003

Here is a little more:

http://biz.yahoo.com/prnews/031218/sfth056_1.html

The satellite, designated GPS IIR-10, features significant performance upgrades, including an advanced antenna panel, which will increase power for GPS receivers.

There are eight new-generation GPS IIR spacecraft currently on orbit out of a total GPS constellation of 28 satellites. GPS IIR satellites are designed to improve global coverage and increase the overall performance of the GPS constellation.

I would imagine that they actually mean that it has increased power output so GPSR's can get the signal better. Maybe this will help under the trees!

EDIT: Here is another one from today too (Lockheed Martin press releases):

http://biz.yahoo.com/prnews/031221/sfsu003_1.html

Edited December 22, 2003 by mtn-man

December 22, 2003

Thanks mtn-man, I read the article quickly and you could be right. The transmission power of the sats were a bit weak and perhaps they're upgrading it.

Metro Nomad

7.2k · December 22, 2003

I don't think it was you. I think it was the way it was written. Those of us that use GPSR's know better I guess.

1.1k · December 22, 2003

Compared to the existing Block II's & IIA's, the oldest of which is now around 13 odd years, the IIR's are better "technology", better clocks, better everything and improved timing (new Rb standard) does translate into improved accuracy.

Even though the system spec is a constellation of 24 + 3 spares a GPS satellite's life span is not increased by being "off-line" so all are available but if the odd one fails then the redunancy reduces towards what the specifications are actually framed around.

With every new launch of a IIR the system is improved in many ways, design life of a IIR is 10 years, the current II/IIA's is 7.5 years, yet many are way past this mile stone so many of these are in affect past there use by date.

With this one makes 9 IIR's (IIR-1 was destroyed during launch in Jan 1997) and with every new IIR the system becomes that little bit more up to date. IIR-14 will be the start of something completely different, starting maybe sometime next year (at this rate).

Cheers, Kerry.

December 22, 2003

The figure for number of sats in orbit is 26 according to info I have read. This means 24 active and 2 spare.

I can remember using my first GPS long ago and being rather disappointed with the 100m accuracy, still it was fun and I didn't quite mothball it. Then one morning I was having fun tracking to a local park when all of a sudden, to my suprise and delight, I noticed that the unit was following me far more closely and reporting the accuracy we are accustomed to today. I didn't realise at the time that the S.A. had just been turned off. It was a very short time after this that Geocaching was born and I did my first cache.

I guess we may not even notice the reported accuracy improvement this time, but it's a nice thought to know that the system is going to get even better.

I can't confirm this but a long time observation of mine, is that whenever SAT GPS11 was in orbit above my position I did seem to lose a bit of sharpness on the positioning. I wonder if it is 11 that got replaced.

The 2 dogs.

2.3k · December 22, 2003

Why can't it use solar power to move / adjust itself or recharge batteries? Can't the space shuttle "re-fuel" it considering that it's such an expensive piece of US taxpayers money in the first place?

The satellites are in a higher orbit than the space shuttle can obtain.

Well, they probably could attain a higher orbit, but getting back would be the problem...

4k · December 22, 2003

Why can't it use solar power to move / adjust itself or recharge batteries? Can't the space shuttle "re-fuel" it considering that it's such an expensive piece of US taxpayers money in the first place?

The satellites are in a higher orbit than the space shuttle can obtain.

Well, they probably could attain a higher orbit, but getting back would be the problem...

Most Satellites use either liquid/solid fuel boosters for attitude adjustment (no, not the kind you're thinking of) and some use compressed gas. There is nothing that can be done with solar power. That may recharge batteries, but to change orbit and direction, you need propulsion, and battery powered propulsion would have to be in the form of a propeller of some type, and propellers won't work in a vacuum....nothing to push against.

Yours truly,

Cliff Clavin

9.4k · December 22, 2003

Most Satellites use either liquid/solid fuel boosters for attitude adjustment (no, not the kind you're thinking of) and some use compressed gas. There is nothing that can be done with solar power. That may recharge batteries, but to change orbit and direction, you need propulsion, and battery powered propulsion would have to be in the form of a propeller of some type, and propellers won't work in a vacuum....nothing to push against.

Yours truly,

Cliff Clavin

I'm going to nickname the new satellite 'Sparky Clavin'

4k · December 22, 2003

Most Satellites use either liquid/solid fuel boosters for attitude adjustment (no, not the kind you're thinking of) and some use compressed gas. There is nothing that can be done with solar power. That may recharge batteries, but to change orbit and direction, you need propulsion, and battery powered propulsion would have to be in the form of a propeller of some type, and propellers won't work in a vacuum....nothing to push against.

Yours truly,

Cliff Clavin

I'm going to nickname the new satellite 'Sparky Clavin'

Cool! I'll be FAMOUS! Wait a minute........

9.4k · December 22, 2003

I'm going to nickname the new satellite 'Sparky Clavin'

Cool! I'll be FAMOUS! Wait a minute........

That;s better than FLAMEous

2.3k · December 22, 2003

I'm going to nickname the new satellite 'Sparky Clavin'

Cool! I'll be FAMOUS! Wait a minute........

You'll also be responsible for feeding and maintaining your new satellite.

Keep those thruster ports clean now!!

4k · December 22, 2003

I'm going to nickname the new satellite 'Sparky Clavin'

Cool! I'll be FAMOUS! Wait a minute........

You'll also be responsible for feeding and maintaining your new satellite.

Keep those thruster ports clean now!!

So, will I be responsible for the information it sends to certain smurfy cachers, too?

7.2k · December 22, 2003

That may recharge batteries, but to change orbit and direction, you need propulsion, and battery powered propulsion would have to be in the form of a propeller of some type, and propellers won't work in a vacuum....nothing to push against.

Yours truly,

Cliff Clavin

Oh man, thanks Sparky Clavin! That was a good one. I needed a good chuckle. While doing a google search, I found this image below. I guess they abandoned the propeller idea.

2.3k · December 22, 2003

Oh man, thanks Sparky Clavin! That was a good one. I needed a good chuckle. While doing a google search, I found this image below. I guess they abandoned the propeller idea.

Well at least they got the engines in the right place...

Sometimes you gotta wonder....

1.2k · December 22, 2003

How many of these new sats will need to fly before we see any real improvement down here?

4k · December 22, 2003

How many of these new sats will need to fly before we see any real improvement down here?

From what I understand, a whole bunch!

1.1k · December 22, 2003

About a half dozen more and my Cobra GPSr will finally be able use all those CHANNELS.

December 22, 2003

I have a Garmin E-Trex Legend and my reception of sats. is great, within a few feet of my find. Dense tree cover in the summer throws mine off but I been geoing just as fall started and can walk right up to a hide, so my point is sat. reception around North East South Carolina on my Garmin is good and can only get better with a new and improved one going up. Just my opinion. Jeff24

1.1k · December 22, 2003

Looking at the age of what's currently up there, 2 Block II's, 16 Block IIA's all more than 7.5 years old (oldest June 1989), 2 Block IIA's just under 7.5 years old and 8 Block IIR's (oldest one of which is 6+ years) plus the 1 yet to be brought on line, that makes 28+1

"a half dozen more" with room for only 32 (actually 30), won't help ya much at all.

PRN11 these days is a Block IIR (IIR-3) launched Oct 99

Cheers, Kerry.

1.1k · December 22, 2003

"a half dozen more" with room for only 32 (actually 30), won't help ya much at all.

Kerry,

Sorry if my comment was unclear. It can be challenging to properly convey sarcasm in text. Cobras GPS is an 18 channel. With 24 active sats, evenly distributed around the globe, using all 18 channels seems like a stretch.

Thanks for the info though. I have to assume you work in a technical field of some sort.

Edited December 22, 2003 by Johnnie Stalkers

1.1k · December 23, 2003

Kerry,

Sorry if my comment was unclear. It can be challenging to properly convey sarcasm in text. Cobras GPS is an 18 channel. With 24 active sats, evenly distributed around the globe, using all 18 channels seems like a stretch.

Thanks for the info though. I have to assume you work in a technical field of some sort.

yeah am aware of the 18 channel receivers and for sure it would be a stretch, gee even 12 can be a stretch even for some of the time. Actually for a fleeting glimse there might be times with 13 (even 14) in view but that would certainly no be from the standard 24 satellite constellation and one certainly wouldn't want to blink. On some days at the north pole one "might" pull 15 satellites in view (at a pinch).

Now if some of those channels actually could use Glonass then that would make 18 channels sound reasonable (there are 24 channel receivers available that specifically do this), but somehow I can't imagine the Cobra would/could do that.

Cheers, Kerry.

Edited December 23, 2003 by Kerry.

3.8k · December 23, 2003

Cobras GPS is an 18 channel. With 24 active sats, evenly distributed around the globe, using all 18 channels seems like a stretch.

If it's a WAAS enabled receiver at least you wouldn't lose two of the regular channels to the WAAS Geos

4k · December 23, 2003

Looking at the age of what's currently up there, 2 Block II's, 16 Block IIA's all more than 7.5 years old (oldest June 1989), 2 Block IIA's just under 7.5 years old and 8 Block IIR's (oldest one of which is 6+ years) plus the 1 yet to be brought on line, that makes 28+1

"a half dozen more" with room for only 32 (actually 30), won't help ya much at all.

PRN11 these days is a Block IIR (IIR-3) launched Oct 99

Cheers, Kerry.

I'd have to agree with you on this one, Kerry....except that I have absolutely no clue what that all means!

But, I'll take your word for it!

New GPS Satellite

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