這國家文書 PXIe-6672(零件號:780063-01)是一個同步模塊。該模塊能夠驅動PXI星觸發(fā)線，導入和導出PXI背板時鐘和觸發(fā)器，直接產(chǎn)生高穩(wěn)定性分辨率 數(shù)字合成(DDS)時鐘，并創(chuàng)建一個高穩(wěn)定度溫度補償晶體振蕩器(TCXO) 10 MHz參考時鐘安排。這鎳PXIe-6672同步模塊使用戶能夠同步不同的PXI快速框架，同步PXI快速框架與外部儀器和設備，并增加PXI快速框架內部設備的精度。

這美國國家儀器公司PXIe-6672同步模塊可以產(chǎn)生兩種時鐘信號。主時鐘由本地DDS芯片產(chǎn)生，而第二個時鐘由一個精確的10 MHz振蕩器產(chǎn)生。頻率調諧字是一個表示所需頻率的數(shù)字。在每個主時鐘周期，頻率調諧字被添加到累加器中，當達到最大值時，累加器移動。累加器esteem用于獲取正弦查找表中的一個點，該點由DAC轉換為模擬電壓。例如，如果正弦表的長度為128個焦點，頻率調諧字為1，則累加器需要128個時鐘周期來輸出一個正弦波。如果用戶決定將頻率調諧字改為3，累加器將以三倍的速度步進正弦表，并在128/3或42.6個時鐘周期內輸出一個正弦波。

The National Instruments PXIe-6672 (Part Number: 780063-01) is a Synchronization Module. This module has the capability to drive the PXI star trigger lines, import and export PXI backplane clocks and triggers, produce a high-stability resolution direct digital synthesis (DDS) clock, and create a high-stability temperature-remunerated crystal oscillator (TCXO) 10 MHz Reference Clock for arrangement. The NI PXIe-6672 Synchronization Module enables the user to synchronize different PXI Express frameworks, synchronize a PXI Express framework with outer instruments and equipment, and increment the precision of devices inside a PXI Express framework.

The National Instruments PXIe-6672 Synchronization Module can create two sorts of clock signals. The main clock is created by utilizing the locally available DDS chip, while the second is produced with an exact 10 MHz oscillator. The frequency tuning word is a number that indicates the desired frequency. On each master clock cycle, the frequency tuning word is added to the accumulator, which moves over when it gets to its most extreme esteem. The accumulator esteem is utilized to get a point in the sine-lookup table, which is changed over to an analog voltage by the DAC. For instance, if the sine table is 128 focuses in length and the frequency tuning word is one, the accumulator takes 128 clock cycles to output one sine wave. If the user decides to alter the frequency tuning word to 3, the accumulator steps through the sine table three times as quick and outputs a sine wave in 128/3, or 42.6, clock cycles