The Microchip/TrueTime GPS-VME is a single-slot 6U VMEbus-compatible timing module that provides precise time synchronization for critical infrastructure, telecommunications, and data acquisition systems. Operating across three distinct modes—Generator, GPS Synchronized Generator, and Code Synchronized Generator—the card derives accurate time and position data from GPS signals or disciplined external IRIG B time code references. Time and status information is accessible directly to the VME computer via the VMEbus, enabling seamless integration into existing systems requiring sub-microsecond synchronization.
Technical Specifications
• Form Factor: Single-slot 6U VME standard height
• VMEbus Compliance: IEEE 1014 C-1 VMEbus Specification
• Time Accuracy (GPS Mode): Better than 2 microseconds to UTC
• Time Accuracy (IRIG-A/B Synchronization): Better than 1 microsecond
• Time Accuracy (RS-422 IRIG-A/B): Approximately 500 nanoseconds
• Time Accuracy to UTC (SA Mode): 1 microsecond
• Time Output Stability: 100’s nanoseconds through thousands of years
• Position Accuracy: 25 meters (without SA)
• GPS Receiver Input: 1575 MHz L1 C/A code
• Satellite Tracking: Up to six satellites
• GPS Acquisition Time: Less than 2 minutes (satellites visible)
• Internal Oscillator Stability: 1 PPM over 0°C to +50°C
• Data Format: Time and position available in five packed 16-bit BCD words
– Key Features
• Disciplined internal oscillator removes frequency offset and minimizes drift
• Automatic leap year calculation using year information
• Supports both amplitude-modulated and DC shift (RS-422) IRIG B code formats
• Generator mode allows time preset, start, and stop control via VMEbus or external 1 PPS pulse
• Phase-lock capability to external IRIG B time code during GPS loss
– Typical Applications
• Infrastructure timing synchronization
• Telecommunications network synchronization
• Data acquisition systems requiring UTC alignment
• Systems demanding sub-microsecond timing precision
– Compatibility & Integration
The GPS-VME integrates directly into VMEbus systems conforming to IEEE 1014 C-1 specifications. Time and position data transfer to the host VME computer through standard VMEbus protocols, supporting seamless deployment in existing architectures.
