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Author Topic:   GPS Satellites 2F-5, 2F-6
jimh posted 05-01-2014 10:38 AM ET (US)   Profile for jimh   Send Email to jimh  
GPS 2F-5

The launch of the most recent GPS satellite, GPS 2F-5 (or IIF-5 if you like Roman Numerals) was delayed several months from the originally announced date as a result of various concerns about the Delta 4 rocket booster that would propel it into orbit. The delay and then the ultimately successful launch were a topic of discussion in

http://continuouswave.com/ubb/Forum6/HTML/003286.html

The satellite has now been in orbit since February 20, 2014, but its operational status as part of the GPS constellation is still set to "Do Not Use." In previous launches, a delay of about a month between launch and operational status has been considered typical.

An article at GPSWORLD.COM by Professor Richard Langley of the University of New Brunswick explains the cause of the delay. The 2F-5 satellite is being used in an extended navigation test in which the ephemeris data is being allowed to age. For more details see

http://gpsworld.com/ delay-in-setting-recently-launched-block-iif-satellite-healthy/

For more on how to check the status of satellites and their real-time position relative to ground, see

http://continuouswave.com/ubb/Forum6/HTML/003559.html

GPS 2F-6

The next satellite in the 2F series is set for launch in about two weeks. According to

http://www.ulalaunch.com/site/pages/Launch.shtml#/50/

GPS 2F-6 will be launched on May 15, 2014 about 8 p.m. The Delta 4 rocket will again be used. Although an evening launch, due to time of year it will probably not be a spectacular night launch in darkness. However, the Delta 4 looks like a rather significant rocket, and it would be a treat to see one come off the launch pad.

jimh posted 05-18-2014 09:41 AM ET (US)     Profile for jimh  Send Email to jimh     
The most recent launch of a GPS satellite was accomplished successfully on Friday, May 16, 2014, when GPS-2F-6 (GPS IIF-6) was put into orbit by a Delta 4 rocket from Cape Canaveral, Florida. The launch was about 24-hours delayed due to weather. The on-line version of GPS WORLD magazine has a nice summary and links to many images and recordings of the launch at

http://gpsworld.com/ gps-iif-6-launched-into-orbit-following-weather-delay/

Also see a very detailed article about the launch and the satellite at

http://www.spaceflight101.com/delta-iv-gps-iif-6-launch.html

jimh posted 05-18-2014 02:02 PM ET (US)     Profile for jimh  Send Email to jimh     
GPSIIF-5 (as PRN30) remains with its status set to DoNotUse. See below:

Graphic: Plot of GPS satellite ground track and status

jimh posted 05-21-2014 11:41 AM ET (US)     Profile for jimh  Send Email to jimh     
In a bit of irony, the position of the rocket launching the GPS IIF-6 satellite was tracked, not by the usual RADAR methods, but by having a GPS receiver on the rocket vehicle. This new development is explained in more detail in an article at

http://www.spaceflightnow.com/delta/d366/140518tracking/#.U3zG_yjA5PJ

Also regarding tracking, the cameras that follow the rocket are just amazing. In watching one of the launch videos (see the linked articles above), the rocket is clearly seen on camera as the narrator says something like "the vehicle is now 30-miles high and 70-miles downrange." Even more impressive, you can still hear the sound of the rocket engine at that range. I don't know if there are special microphones in use to pick up the sound at that great range.

wally910 posted 05-27-2014 01:20 PM ET (US)     Profile for wally910  Send Email to wally910     
Funny enough, I was at a rehearsal dinner Friday before last on the St Johns River in Jax, FL, about 90-100 miles N of the launch pad. I looked out and saw the launch. Didn't realize they were sending one up until I got on my phone to confirm what I thought I saw.
David Pendleton posted 05-27-2014 05:04 PM ET (US)     Profile for David Pendleton  Send Email to David Pendleton     
In the graphic above, what does "not monitored" mean in that context?
jimh posted 05-28-2014 10:28 AM ET (US)     Profile for jimh  Send Email to jimh     
David has a good question. The graphic is from the FAA, and the status is related to the GPS and WAAS system accuracy for use in making a precision approach via aircraft to a runway. The status "Not Monitored" is applied when the satellite's position in orbit is beyond the range of use for the area covered by the FAA WAAS. A satellite's status will change on that graphic as it moves out of the FAA operating range to Not Monitored from Position Approach. I suppose it is an artifact of the ability of the FAA monitoring process that they cannot monitor the satellite when it is no longer in range of their monitoring stations.

The graphic is dynamic and is found at

http://www.nstb.tc.faa.gov/RT_WaasSatelliteStatus.htm

It is a good resource for discovering what satellites in the GPS constellation are in view for North America and what their status is.

I just checked the status page and it is showing PRN06 as red and Do Not Use (DNU). That has me curious. I looked for more information at

http://www.navcen.uscg.gov/?Do=constellationStatus

and found a notation there:

quote:
CONDITION: GPS SATELLITE SVN36 (PRN06) WAS UNUSABLE AS OF JDAY 052 (21 FEB 2014)
AND REMOVED FROM THE GPS CONSTELLATION ON JDAY 052 (21 FEB 2014).

The GPS IIF-6 satellite is also known as SVN 67 (Space Vehicle Number). From what I can tell, GPS IIF-6 is going to use PRN06. I assume that the satellite now being monitored by the FAA as PRN06 is the new GPS IIF-6 (SVN67) in orbital plane D4. That is based on this resource:

http://earth-info.nga.mil/GandG/sathtml/satinfo.html

What I have found in the past is that a satellite in the GPS that is set to "Do Not Use" status will not show up on my consumer grade GPS receivers in their satellites-in-view data.

jimh posted 05-28-2014 10:32 AM ET (US)     Profile for jimh  Send Email to jimh     
Here is a bit more information about these two most recent satellites in the GPS constellation. It sounds like their PRNs, 30 and 06, are confusing some receivers. The USCG explains:

http://www.navcen.uscg.gov/pdf/gps/GPSOC_PRN%2030_Notice.pdf

jimh posted 06-23-2014 11:57 PM ET (US)     Profile for jimh  Send Email to jimh     
While doing a bit of living aboard and cruising last week, I noticed that PRN30 was showing up on my GPS receiver status page. The new satellite was set to USEABLE on May 30, 2104. Also, PRN06 was set to USEABLE on June 10, 2104.

This means both of our newest GPS satellites in orbit are now in normal operation.

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