Re: GPS 2R-M1 FINALLY LAUNCHED

mellow wrote:
Thanks Sam. Do you have any info on how exactly these new satellites will benefit civilian GPS receivers?



Ref: http://www.ion.org/vol101/vol10.htm
Status of Additional Civil Signals

In March 1996, a presidential decision directive made GPS a dualuse,
dualservice system. The White House announced (during 1998 and
1999) that two civil signals will be provided: a C/A code will be added
to L2 (signal at 1227 MHz), and a new L5 signal will be provided at
1176 MHz. The C/A code on L2 is intended for surface applications
able to tolerate occasional interference from the many radars
operating in the 1215-1385 MHz band. The L5 signal is be located in
the Aeronautical Radio Navigation Service band (i.e., 960-1215 MHz),
where all emitters are managed by civil aviation authorities for
safetyoflife applications. To minimize the impact on existing systems,
the new L5 civil signal will have 6 dB more power than the L1 and L2
C/A signal and a higher chipping rate (i.e., 10 vs. 1 MHz), and the
receiver will be required to incorporate a ?pulse blanker,? and
improved selectivity. In addition, current systems in the band (i.e.,
DME, TACAN, and JTIDS/MIDS) may be ?rechanneled? to assure
proper L5 reception.

An incremental implementation plan is being developed for these civil
signals under the oversight of the Interagency GPS Executive Board.
The implementation plan being considered by the GPS Joint Program
Office is to add the C/A code on L2 starting with some Block IIR
satellites, add both the L2 and L5 signals to the Block IIF satellites,
and include both signals in the GPS III modernization. A
constellation of at least 24 space vehicles having the L5 signal is not
expected before about 2014.

L5, when operational, will provide two primary benefits to safetyoflife
applications. First, the L5 signal removes the singlefrequency
vulnerability by duplicating the WAAS and LAAS service on L5. (Will
it be duplicated at L2 also? - Editor) In addition, L1/L5 avionics
could use both frequencies to measure ionospheric delays thereby
improving the availability of precision approach service.
.

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