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XXXI. GPS Space Segment - NAVSTAR SATELLITE CONSTELLATION

The baseline Navstar satellite constellation nominally consists of 24, properly

geometrically spaced operational satellites (Block II, IIA, IIR, and IIR-M), It is precisely this

system that can be used to locate the wireless apparatus black box,.

Each satellite broadcasts three pseudo random noise (PRN) ranging codes: the

precision (P) code, which is the principal NAV ranging code; the Y-code, used in place of the

P-code whenever the anti-spoofing mode of operation is activated; and the

coarse/acquisition (C/A) code which is used for acquisition of the P (or Y) code (denoted as

P(Y)) and as a civil ranging signal. A navigation (NAV) message based upon data

periodically uploaded from the Control Segment is provided by adding the NAV message

data to both the 1.023 MHz C/A-code sequence and the 10.23 MHz P(Y)-code sequence.

The satellite modulates the two resulting code-plus-data sequences onto a 1575.42 MHz

L-band carrier (L1), and modulates just the 10.23 MHz code-plus-data sequence onto a

1227.6 MHz L-band carrier (L2); and then both modulated carriers are broadcast to the user

community.

The two broadcast carrier signals are referred to in this application as the PPS SIS. A

subset of the PPS SIS, referred to in this document as the SPS SIS, comprises only the

1.023 MHz code-plus-data sequence on the 1575.42 MHz L-band carrier (L1). Collectively,

the PPS SIS and the SPS SIS are known as the satellite's navigation signals (or navigation

SIS).

These signals can be part of the black box's data collection and may also be used to

locate both wireless devices via a direct link to the satellite since there exist a remote

connection between the satellite and the actual physical black box. Thus the precise location

of the physical black boxes may now be immediately discovered upon demand.

Docket No. : Ticket 2180/215 26