2.6 Test Performance Requirements

The following sections list key requirements for minimum UTT system performance that will be required during the test.

2.6.1 Accuracy

Definition

Requirements for the accuracy of position reporting of the UTT system are listed in this section. Position accuracy is a function of GPS receiver performance, configuration parameters, satellite visibility of the antenna, satellite constellation, and U.S. Government-controlled Selective Availability (SA).

Performance constraints and requirements

2.6.1.1 The location accuracy of the UTT system and UTT system-provider default configuration parameters shall be a position accuracy of 100 meters approximately 95% of the time. (Position accuracy better than 100 meters will often be seen, but cannot be relied upon. These numbers take into consideration the uncontrollable variables that may affect performance. Many variables contribute to errors in position accuracy. For example, position accuracy is a function of GPS receiver performance, configuration parameters, satellite visibility of the antenna, satellite constellation, and selective availability. An industry standard for GPS accuracy has not been defined. Every manufacturer uses its own means of defining, measuring, and calculating position accuracy.)

2.6.2 Repeatability

2.6.2.1 The UTT system shall provide repeatable performance throughout the test period for all functions specified in this document.

2.6.3 Reliability during the Test

Availability of the network operations center, operated by the UTT system provider, has been at least 99.9% from 1999 to 2003 including both planned and unplanned downtime. The UTT system is expected to perform with similar reliability, but its performance is highly dependent on local conditions during the test. UTT system performance may vary by region and is dependent on variables such as cellular coverage and terrain around the mobile terminal.

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