The Microchip/TrueTime XL-AK is a GPS-synchronized time and frequency receiver delivering timing accuracy to 40 nanoseconds RMS against UTC/USNO and frequency stability better than 1×10⁻¹². The unit acquires satellite locks in under 2 minutes (warm start) to 20 minutes (cold start) and tracks up to six satellites on the L1 GPS signal at 1575.42 MHz.
Technical Specifications
Timing and Frequency Performance
• Time accuracy: <40 ns RMS to UTC/USNO
• Frequency accuracy: <1×10⁻¹²
• Position accuracy: ±10 m RMS (latitude, longitude, altitude) after 24-hour averaging, referenced to WGS84
• Maintains specified accuracy under Selective Availability implementation
GPS Receiver Core
• Operating frequency: 1575.42 MHz (L1 C/A code)
• Satellite tracking: Up to 6 satellites
• Acquisition time: <2 minutes warm start; <20 minutes cold start; <2 minutes with visible satellites and position known within 100 km
• High-gain antenna: 40 dB gain
Output Signals
• Five user-configurable rear-panel BNC connectors (analog or digital drivers)
• 1 PPS output: TTL into 50 Ω, 20 µs pulse width, rising edge on time, 50% duty cycle
• IRIG B time code: 1 kHz AM carrier, 3 Vpp into 600 Ω
• Programmable pulse rates: 500 Hz to user-defined periods with integer millisecond half-periods
• Fixed rates available: 1 PPS, 1 kPPS, 10 kPPS, 100 kPPS, 1 MPPS, 10 MPPS
• Serial I/O: RS-232 up to 19200 baud; 9600 bps default (8 data bits, no parity, 1 stop bit)
– Key Features
• 2-line, 32-character LCD display with front-panel keypad for parameter viewing and alarm/status messages
• 16-bit DAC control interface for external oscillator disciplining
• RS-232 configuration and telemetry port; outputs time of day and day-of-year data in ASCII
• Rack-mount form factor
– Typical Applications
Power utility synchronization, range timing systems, data acquisition requiring phase-coherent timestamps, frequency standards for test and measurement.
– Compatibility & Integration
RS-232 serial interface supports user-selectable protocols. External oscillator control via 16-bit DAC enables integration with precision frequency standards. Compatible with standard GPS L1 antenna systems.
