National Instruments 780063-01 PXI Synchronization Module 

National Instruments part number 780063-01 is an identifying part number for the PXIe-6672, a PXI Synchronization Module with TCXO Clock Type, 1.6 ppm Onboard clock accuracy and SMB male, 50 Ω Front panel connectors. The NI 780063-01 can generate two types of clock signals. The first clock is created using the onboard DDS chip, and the second is produced with a precise 10 MHz oscillator. The frequency tuning word specifies the desired frequency. 

On each master clock cycle of the 780063-01, the frequency tuning word is added to the accumulator, which resets when it reaches its maximum value. The accumulator value determines a point in the sine-lookup table, which the DAC converts to an analog voltage. For example, if the sine table is 128 points long and the frequency tuning word is one, the accumulator takes 128 clock cycles to output one sine wave. If the frequency tuning word is changed to 3, the accumulator cycles through the sine table three times faster, producing a sine wave in 128/3, or 42.6, clock cycles. 

This module can drive PXI star trigger lines, import and export PXI backplane clocks and triggers, and produce a high-stability DDS clock. Users may improve the accuracy of devices, synchronize a PXI Express system with external instruments and hardware, and synchronize several PXI Express systems using the NI 780063-01 Synchronization Module. The TCXO in this Module has a nominal frequency of 10 MHz. Its accuracy is within ±3.5 ppm within the first year after calibration adjustment and when operating in the temperature range of 0 ºC to 55 ºC. The long-term stability is ±1 ppm per year. The stability over the operating temperature range of 0 to 55 ºC is less than 1.6 ppm peak-to-peak. The recommended calibration interval for the TCXO is one year.