• 12-channel GPS receiver complying with TSO C129 (B1)
• Supports RAIM, Predictive RAIM, FDE
• ARINC 743A compliant
• Supports primary means GPS navigation in oceanic/remote areas
• Supports field loading of application software
• Growth to WAAS to support GSP primary means navigation and nonprecision approaches with vertical guidance
• Fully integrated with Rockwell Collins Pro Line 4 and Pro Line 21 FMS systems to provide terminal navigation, en route navigation and nonprecision approaches

The Rockwell Collins GPS-4000A Global Positioning System sensor provides aircraft equipped with flight management systems (FMS) the capability for GPS-based en route and terminal navigation as well as GPS-based approach capability. Growth options include upgrade via service bulletin to the GPS-4000S Space Based Augmentation System (SBAS) sensor for primary means navigation and precision final approach ILS look-alike capability.

The GPS-4000A processes the transmissions of up to 12 GPS satellites simultaneously, calculating navigation solutions based on information from all satellites in view.

A minimum of four satellites with acceptable geometry or three satellites plus calibrated barometric altitude are required in order to calculate a navigation solution. With additional satellites, the system can improve the fault tolerance and accuracy of the navigation solution and provide Receiver Automomous Integrity Monitoring (RAIM) to detect and isolate defective satellites. The unit also provides predictive RAIM, which is used to determine whether the satellite geometry at the destination airport will be sufficient to support at the planned time of arrival. The computed position, velocity and teim are input to the FMS, which integrates this data inot the flight plan-based navigation solution.

The Rockwell Collins GPS-4000A is a 2MCU unit that houses the GPS processor, GPS receivers, processing circuitry and necessary inputs and outputs. The unit is fully digital, uses 28  V  DC power and requires a minimum of interconnect. The unit uses standard ARINC 429 interfaces and complies with ARINC 743A communication requirements. When connected with a compliant antenna, the GPS-4000A provides a GPS position solution for use by the FMS and other equipment. The GPS-4000A integrates with all Rockwell Collins Pro Line 4 and Pro Line 21 applications that include an FMS.

The FMS utilizes the GPS-4000A inputs to navigate en route and terminal areas and to fly GPS based approaches. The GPS-4000A can be used for primary means navigation in oceanic/remote areas. As the industry progresses, it is capable of upgrade to support primary means navigation and approaches with vertical guidance.

The GPS processor is an evolution of the precision lightweight GPS receiver, the U.S. military standard receiver produced by Rockwell Collins. The processor accepts 12 GPS channels and outputs Earth-Centered, Earth-Fixed (ECEF) position, velocity and GPS time to the applications processor and provides a time mark discrete coincident with GPS seconds. The engine also provides RAIM, using all satellites in view for both the navigation and solution and RAIM. Altitude aiding enhances the availability of the navigation solution and RAIM, and it accepts external aircraft velocity to aid its tracking loops. Reacquisition after power off is aided by self-contained nonvolatile memory of the satellite almanac, last calculated position, velocity, time and by input of external aircraft position, velocity and time.

The RF front end feeds signal processing Application Specific Integrated Circuits (ASICs) to form a GPS receiver with 12 coarse acquisition code channels. The ASICs share addresses and data with the microprocessor, RAM and ROM to form the digital subsystem.

• Dead reckoning in the event of a loss of satellite signals using velocity and heading data from other aircraft systems; maintaining aircraft position aids in rapid reacquisition of the satellite(s)
• Latitude/longitude conversion from the ECEF coordinate system to the WGS-84 World Geodetic System, the required coordinate system for navigation
• ARINC 429 aircraft systems input/output interfaces
• ARINC 624 built-in test equipment/onboard maintenance system functions
• ARINC 615 software data loading management

Since the data loading function and the maintenance diagnostic computer interface function are classified as nonessential (they have no involvement in the calculations or transmission of the PVT solution), these functions are partitioned from the rest of the software to ensure that no failures in them can prevent a higher-level software function from operating satisfactorily. The maintenance software is common with other Rockwell Collins Pro Line 4 products.

The maintenance function supports such functions as interface with the aircraft maintenance diagnostic computer and storage and retrieval of fault data. A separate maintenance output bus provides diagnostic data on the test bench that is useful for troubleshooting the system.

The 2MCU mechanical package of the GPS-4000A has been designed to provide improved heat dissipation and greater strength. Increased reliability is provided through improved shock and vibration resistance and reduced interconnect. Extensive use of surface-mount components and large-scale integration circuits reduces size and weight and improves performance.

To facilitate software service bulletin updates, software data loading functionality is provided in the GPS-4000A. Programming of the operational software can be accomplished either on the test bench or in the aircraft with a portable ARINC 615-III data loader.

Expansion of the maintenance function is possible with the continued evolution of onboard maintenance systems and the use of shope-mode maintenance. Provisions have been made to allow 100 percent growth in the maintenance software without necessitating hardware changes.