This Civil Monitoring Performance Specification (CMPS) is published and maintained at

the direction of the Program Manager for Civil Applications, Global Positioning Systems

Wing (GPSW). The purpose of this document is to provide a comprehensive compilation

of requirements for monitoring the GPS civil service and signals based on top level

requirements to monitor all signals all the time. Upon approval this CMPS will be used

by the GPS community to determine the adequacy of civil monitoring and provide focus

for any needed monitoring improvements.

This CMPS defines a set of metrics for assessing GPS performance against standards and

commitments defined in official U.S. Government documents such as the Standard

Positioning Service Performance Standard, the Navstar GPS Space Segment/Navigation

User Interfaces (IS-GPS-200), Navstar GPS Space Segment/User Segment L5 Interfaces

(IS-GPS-705), and Navstar GPS Space Segment/User Segment L1C Interfaces (IS-GPS-

800). This CMPS will be revised to track changes in these key reference documents.

The implementation of a system that satisfies these requirements will allow operations as

well as users to verify that civil GPS performance standards and commitments are

achieved. To the extent practicable, each metric defined is traceable to one or more

specifications or commitments of performance. In cases where the metric is an indirect

measurement of performance, the connection between the metric and the standard is

explained and the threshold and/or goal necessary to achieve acceptable performance

provided.

This document also defines the scope and range of monitoring needs not directly

traceable to the key reference documents but expected by civil users. These needs

include the ability of the service to detect defects in signal and data, the rapid report of

anomalous service behavior to satellite operations for resolution, and notification to users

of the causes and effects of such anomalies for their various service types (e.g.,

positioning, timing, and navigation). This CMPS also addresses the need for archives of

key data and events to support future improvements in GPS service and to respond to

external queries about actual GPS service levels.

This CMPS addresses the current L1 C/A signal and the GPS Standard Positioning

Service (SPS) provided via that signal. It also includes the planned L1C, L2C, and L5

signals along with semi-codeless use of the GPS signals.

This performance specification is not intended to state how civil monitoring will be

implemented nor does it address the monitoring system architecture. The purpose of this

CMPS is to provide the current requirements for monitoring of the civil service and

signals for use by the U.S. Government in planning GPS development efforts. As a

result, many of the requirements contained in this CMPS may be incorporated into the

next generation operational control system (OCX), while other requirements may be

allocated to other government entities for implementation.