General Notes:

    1.    "SV Number" refers to space vehicle number. "PRN Number" refers to the satellite's unique pseudorandom noise code.
    2.    Clock: Rb = rubidium; Cs = cesium. No clock changes were made since this Almanac was last published in December 2010.
    3.    "Launched" and "Usable" dates are based on Universal Time.
    4.    The current GPS constellation consists of 10 usable Block IIA satellites, 12 Block IIRs, 7 Block IIR-Ms, and 1 Block IIF for a total of 30 satellites and is under FOC (Full Operational Capability). The constellation is in the 24+3 (or "Expandable 24") configuration with satellites occupying the fore and aft bifuracted slots in the B, D, and F planes. There are currently four reserve satellites, SVNs 32, 35, 37, and 49 near slots F1, B4, C1, and B1-F, respectively.
    5.    SVN35 and 36 carry onboard corner-cube reflectors for satellite laser ranging (SLR). SLR tracking of the satellites permits analysts to differentiate between onboard clock errors and satellite ephemeris errors in GPS tracking. SVN35/PRN05 was initially decommissioned from active service on March 26, 2009.
    6.    Selective availability (SA) was set to zero on all satellites by presidential order on May 2, 2000 at approximately 4:00 UT. Previous Almanacs provide a history of SA status.
    7.    Antispoofing (AS) was activated on January 31, 1994, on all Block IIs. AS is occasionally off for testing and other purposes. Previous Almanacs provide a history of AS status.
    8.    The design life and mean-mission duration goals of the Block IIA, IIR, and IIF satellites are 7.5 and 6 years, 10 and 7.5 years, and 12 and 9.9 years, respectively.
    9.    GPS World believes this information to be correct as of press time. However, because of the satellite constellation's evolving nature, readers should contact GPS information services listed on these pages for more current data.
    10.    Dr. Richard Langley of the University of New Brunswick provided the GPS satellite status information and compiled the notes.

Performance Notes:

    A.    The orbital positions of six satellites were rephased between January 2010 and June 2011 to yield the "Expandable 24" configuration. See also General Note 4.
    B.    SVN30/PRN30 was set unusable on May 13, 2011. It was decommissioned from active service on July 20, 2011.
    C.    SVN49 continued to be set unusable since launch due to an L1/L2 satellite multipath issue. It was removed from "active" service and stopped transmitting L-band signals on May 6, 2011.
    D.    The M-code signal on SVN62/PRN25 was turned off for an indeterminate period on or about April 5, 2011.
    E.    SVN63/PRN01 was launched on July 16, 2011, at 06:41 UTC.

Source:http://www.gpsworld.com/gnss-system/almanac/the-almanac-4265#gpschart