NEL晶体振荡器清理模块

NEL基于晶体振荡器的清理模块

NEL晶振频率控制提供一系列清理模块，从非常紧凑的基于VCXO的SMD石英晶振，到具有良好保持性能的基于TCVCXO的单元，再到基于超低相位噪声(ULPN) OCVCXO的金属罐模块和机架式设备。

Modern electronic equipment, like Radar, Test and Measurement, Instrumentation, Avionics, etc. require precision frequency sources with low phase noises. Frequency accuracy and precision can derive from atomic clocks (such as Rubidium or Cesium) or GNSS. In many cases, however, frequency accuracy and precision does not necessarily accompany low phase noise. Similar problems occur when the clock signals distribute over long distances through noisy environments.

现代电子设备，如雷达、测试和测量、仪器仪表、航空电子设备等。要求具有低相位噪声的精确频率源。频率的精度和精度可以从原子钟（如铷或铯）或GNSS中得到。然而，在许多情况下，频率精度和精度并不一定伴随着低相位噪声。当时钟信号在嘈杂的环境中进行长距离的分布时，也会出现类似的问题。

One example of precision atomic clock based sources with poor phase noise performance is a Chip Scale Atomic Clock (CSAC). Typical examples of phase noise performance on a 10 MHz output are shown in Table 1.

基于精密原子钟的相位噪声性能较差的源的一个例子是芯片级原子钟（CSAC）。在10 MHz输出上的相位噪声性能的典型例子如表1所示。

The Solutions

解决方案：

The goal is to maintain accuracy, precision and long-term stability of the source, while significantly improving the phase noise of the signal. Achieving this goal is accomplished through so called cleanup Modules, based on different types of Quartz Crystal Oscillators.

其目标是保持源的精度、精度和长期稳定性，同时显著提高信号的相位噪声。实现这一目标是通过所谓的基于不同类型的石英晶体振荡器的清理模块来实现的。

Here are two possible scenarios:

以下是两种可能的情况：

1. The source is based on GNSS. In this case, there’s the potential to lose the satellite signal. Therefore, the module must provide good accuracy and stability in the absence of the reference signal, during the so-called holdover. The module would need to be based on either an OCXO or high performance TCXO.

1.该源代码是基于GNSS的。在这种情况下，有可能失去卫星信号。因此，在所谓的保持过程中，模块在没有参考信号的情况下必须提供良好的精度和稳定性。该模块将需要基于一个OCXO或一个高性能的TCXO晶振。

2. The source is based on Atomic clock. In this case, if the source signal is lost, it is most likely lost forever. No holdover is required. A VCXO based module is sufficient in this situation.

2.这个源是基于原子钟的。在这种情况下，如果源信号丢失，它很可能会永远丢失。不需要保留。在这种情况下，一个基于VCXO的模块就足够了。

How It’s Done

如何完成：

The basis for the clean-up is a high performance (Low or Ultra Low Phase noise) Quartz Crystal Oscillator with Voltage Control function, which is locked to the incoming accurate, but noisy signal via PLL. A simplified block diagram of a typical clean-up module is shown on Fig. 1. 

清理的基础是一个高性能（低或超低相位噪声）石英晶体振荡器，它通过PLL锁定到输入的准确，但有噪声的信号。一个典型的清理模块的简化方框图如图1所示。

Instead of using the OCVCXO, depending on the application, one could use a TCVCXO or VCXO.

人们可以使用TCVCXO或VCXO，而不是使用OCVCXO。

NEL Frequency Controls offers a family of clean-up Modules from very compact VCXO-based SMD units, to TCVCXO based units with good holdover performance, to Ultra Low Phase Noise (ULPN) OCVCXO based metal can modules and rack mountable appliances.

NEL频率控制提供了一系列清理模块，从非常紧凑的基于VCXO的SMD单元，到具有良好保持性能的TCVCXO单元，到基于超低相位噪声（ULPN）OCVCXO的金属罐模块和机架安装设备。

The modules provide phase noise performance improvement of up to 50 dB. An example of a phase noise improvement for an OCVCXO based module with a bench top Rubidium Clock input is shown on Fig. 2.

该模块提供了高达50 dB的相位噪声性能改进。图2显示了一个基于带有台式铷时钟输入的OCVCXO模块的相位噪声改进实例。