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Gps Satellite #50 To Be Launched


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In the past Rockwell designers of the Global Positioning System created a revolution in navigation, equal to or greater than even the compass or the sextant. Certainly GPS advancements in navigation accuracy, agility and availability are light years beyond any dream of the ancients.

 

The 50th of these marvels is poised for delivery into space Saturday, March 20, on a Boeing Delta II rocket – another industry workhorse built by Boeing employees. It joins the 24-satellite system circling the globe every 12 hours. (While many of the satellites deployed over the years lasted significantly longer than their design life, they do occasionally have to be replaced.)

 

For the record, the three-stage Delta II rocket will blast off from Space Launch Complex 17B at Cape Canaveral Air Force Station, Fla., at 12:39 p.m. Eastern time.

 

“Saturday’s launch is an important milestone for the Boeing Delta team,” said Dan Collins, vice president and program manager, Boeing Delta Program. “Our team’s commitment to mission assurance has played a critical role in the success of the GPS program and the services it provides to the U.S. military as well as civilian users around the world.”

 

The signals are so accurate, time can be figured to within a millionth of a second, velocity within a fraction of a mile per hour and locations to within a few feet.

 

GPS gives users 24-hour navigation services such as:

 

Extremely accurate, three-dimensional location information (latitude, longitude and altitude), precise time and velocity. GPS atomic clocks are accurate to one second in one million years.

24/7, all-weather operations

Continuous real-time information

Support to an unlimited number of users and areas

Support to civilian users at a slightly less accurate level

The successful deployment of GPS satellites aboard Delta II rockets has enabled the U.S. military to use GPS to assist aircraft, ships, land vehicles and ground personnel using handheld devices.

 

GPS also provides directional guidance for the freefall flight of the Boeing-built Joint Direct Attack Munition smart weapon system, now being used in the war on terrorism.

 

Another one for the record: Boeing Delta II rockets have launched all of the Block II GPS satellites that make up the current operating constellation.

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If you were to place a micro attached to the satellite, I wonder

what the coords would be.

 

I suppose someone could create a locationless for anyone who

can get a picture & coords of a GPS satellite launch. Maybe a picture

of yourself holding up your GPS receiver with the launch in the background.

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In a way it's a milestone but the "50th of these marvels is poised for delivery into space Saturday" claim is not really correct. GPS IIR-11 might be the 50th launch but only 48 have ever made it into space as GPS I-7, a block I test satellite and GPS IIR-1 (the first of the IIR's) were both lost in launch failures.

 

So it's the 50th launch and the 48th in space (if and when it makes it).

 

Cheers, Kerry.

Edited by Kerry.
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But it's the 50th built... which fits the wording.

 

The linked report has what I consider a logic flaw...

It calls it a "Lighthouse in the sky"

 

A lighthouse can't tell you where you are, or where to go, only

where to stay away from.

 

I'm used to being told where to go.

Edited by Mark 42
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Anyone know how often the sats are replaced and when? I live close to VAFB, CA where the west coast launch facilities are and often over the past 20 years seen launches of rockets and missiles. Probably saw most of the GPS unit launches that were made from here.

 

I finally quite running outside to watch them but this would give me a reason to watch another and I could catch a picture and post it here. All I need to know is when the next replacement launch from the west coast was going to be.

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But it's the 50th built... which fits the wording. No not really correct either as there were 21 GPSIIR's actually built and 12 of these have been modified as GPS IIR-M's and still sitting in storage as has the other IIR's been sitting waiting to be launched as required, just that sats are remaining healthy and working way past their expected life. Also satellites built are not launched in order and there is also a IIR in storage at Cape Canaveral at all times in case of emergency launch requirements.

 

Block I sats were SVN's 1 to 12

Block II sats SVN's 13 through 21

Block IIA sats SVN's 22 through 40

Block IIR sats SVN's 41 through 62

 

PRN's (max for 32) are reallocated but SVN's are not.

 

All GPS Sats I believe have been launched from Cape Canaveral as this is where a backup GPS monitor station is located, which is primarily used for final vehicle checkout prior to launch.

 

Cheers, Kerry.

Edited by Kerry.
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But it's the 50th built... which fits the wording.

 

The linked report has what I consider a logic flaw...

It calls it a "Lighthouse in the sky"

 

A lighthouse can't tell you where you are, or where to go, only

where to stay away from.

 

I'm used to being told where to go.

:blink: Actually lighthouses do tell you where you are and where to go. Sea travelers knew to go to the left or right of a lighthouse to head up a river, and the lights where how they knew where they where.

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This may be going a little off topic - but we emailed this info on the new satellite to a non-geocaching friend who is interested in the subject of satellites in general. He asked questions about our GPSR's that we don't know the answers to. Where else would we go for the answers except to the forums??? Below is some of his email:

 

". . . found a couple of little models that had barometric altimeters. I had hoped that the satellite would be feeding that information, rather than relying on the unit's own small barometer.

 

From my old flight training, I learned that the planes' altimeters (actually barometers) had to be set to the prevailing pressure conditions to be accurate.

 

So let's say your GPS receiver is sitting on your table, and you're in the middle of a low pressure system. You leave the receiver on the table, but a high pressure system moves in. Will the receiver show different elevations, even though it hasn't been moved? Do you have an adjustment available to you?

 

What is the smallest increment of elevation change it will measure?"

 

UMMM - we know nothing about the elevation changes that might happen! So hoping for answers here! Thanks!

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Anybody know where "Plane C, Slot 3 position in the GPS network" is located?

Well yes, but as of March 18 PRN 31 was sitting in C3.

 

Cheers, Kerry.

"GPS 2R-11, also known as Space Vehicle No. 59, is expected to complete post-launch testing and enter service by mid-April. It is destined to fill the Plane C, Slot 3 position in the GPS network.

 

The spacecraft being replaced -- GPS 2A-19 or Space Vehicle No. 31 -- was launched 11 years ago this month."

 

Let's see 31 goes into 59... (carry the 2)... 1.9032258 times... that's gonna leave a mark!

 

What were we talking about?

Edited by greengecko
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"GPS 2R-11, also known as Space Vehicle No. 59, is expected to complete post-launch testing and enter service by mid-April. It is destined to fill the Plane C, Slot 3 position in the GPS network.

 

The spacecraft being replaced -- GPS 2A-19 or Space Vehicle No. 31 -- was launched 11 years ago this month."

 

Let's see 31 goes into 59... (carry the 2)... 1.9032258 times... that's gonna leave a mark!

Yes, (now checked a little further) GPS 2A-19 is still sitting in C3 and is SVN 31 and it's also PRN 31, so GPS 2R-11 is SVN 59 but I don't recall seeing anything anywhere yet about its PRN number? Could become PRN31 but normally this isn't made available until just before being brought on line?

 

Actually 2A-19 is still showing in the almanac? I'm using (only a week or so old) but I thought with all the problems from 19 several months ago it had been shutdown as it really went wild in early Jan, 2004.

 

So obviously they have to kick 19 out (if in fact it hasn't already been done) in the next few weeks.

 

Cheers, Kerry.

Edited by Kerry.
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So let's say your GPS receiver is sitting on your table, and you're in the middle of a low pressure system. You leave the receiver on the table, but a high pressure system moves in. Will the receiver show different elevations, even though it hasn't been moved? Do you have an adjustment available to you?

 

What is the smallest increment of elevation change it will measure?"

GPS doesn't use barometric pressure to determine altitude.

 

I think you can get a GPS with a built in barometric type altimeter,

but that's not GPS altitude.

 

GPS uses the distances from several satellites to calculate

the location of the receiver. I think it's a sort of doppler like

effect (difference in time it takes a signal to get to the GPSR

from various sat's) combined with traingulation.

 

Anyway, atmospheric pressure will not effect altitude readings

of a GPSR.

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So let's say your GPS receiver is sitting on your table, and you're in the middle of a low pressure system.  You leave the receiver on the table, but a high pressure system moves in.  Will the receiver show different elevations, even though it hasn't been moved?  Do you have an adjustment available to you?

 

What is the smallest increment of elevation change it will measure?"

GPS doesn't use barometric pressure to determine altitude.

 

I think you can get a GPS with a built in barometric type altimeter,

but that's not GPS altitude.

 

GPS uses the distances from several satellites to calculate

the location of the receiver. I think it's a sort of doppler like

effect (difference in time it takes a signal to get to the GPSR

from various sat's) combined with traingulation.

 

Anyway, atmospheric pressure will not effect altitude readings

of a GPSR.

Well, that's sort of right but not entirely accurate. GPSr's with a built-in barometric altimeter will give you a GPS altitude if you have a 3d lock, but it'll be wrong if you have only a 2d lock or if your GPS accuracy isn't all that good. That's where the barometer comes in. It will sense smaller differences in air pressure to give you a more accurate altitude.

 

But your question about the ambient air pressure changing is a good one. In this case, you have some options. The GPSr's I've used with barometric altimeters (Garmin eTrex Vista and Garmin GPSMap 76S) give you some options. You can elect to have the barometric altimeter "auto-calibrate" - that is, it calibrates itself based on the GPS altitude when it has a good 3d GPS lock with a good (high) level of accuracy, and so the GPS altitude is quite accurate. If you then lose your 3d lock or accuracy, the barometric altimeter is more accurate as it can sense the small pressure changes and convert that into a rise or drop in altitude. If you know the precise elevation of your current position, or if you have a good wall barometer (that you trust) or have some other source of accurate ambient pressure, you can use either of these to manually calibrate your altimeter before you head out.

 

I usually use the auto-calibrate mode, and after you get a good solid 3d lock (or better yet a 3d WAAS or differential lock) it gives amazingly accurate results.

 

If you imagine that you're going for a hike up a mountain, but in the forest, you can have the GPSr auto-calibrate itself while it has good satellite lock on your drive to the trailhead, and it'll use the newly calibrated barometric altimeter to give you a good elevation during your hike. By comparison, if you did the same hike with a "regular" GPSr (no barmoetric altimeter), your GPS altitude would remain the same if you were hiking up a mountain but only had a 2d lock due to tree cover etc. This makes a big difference when you like to see your elevation profile on your track log after the fact!

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My question is will my Magellan Meridian know to read this new satellite (and if so, what number will it show up as on my GPS screen), or will I need a new software upgrade?

Once a new satellite is finalized and checked out (normally takes 4 weeks or more) it will be set to healthy and GPS receivers will automatically pick this fact up the next time it receives almanac data, which it is basically doing all the time anyway. Just do nothing and when it comes on line it will automatically show up.

 

It will show as (PRN) 19.

 

Cheers, Kerry.

Edited by Kerry.
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