Inside Frequency Control

RF engineers are always trying to improve the performance of the systems they work on, but a perfect, 100% stable signal that never deviates from the intended frequency will probably never be attainable. The toll that the physical environment and time will take on a crystal remains a fact of life.

But that doesn’t stop us from always working towards getting as close to possible to that ideal. The effects of the physical environment and time can both be mitigated by selecting a high-quality quartz crystal oscillator. Picking the right one for the job depends on the application and other factors, like the amount of power available.

In this article, we will make the case that for those who are trying to minimize the effects of aging and improve stability without using a lot of power, a temperature compensated crystal oscillator (TCXO) might be the right solution.

Temperature compensated crystal oscillators (TCXOs) are widely used in applications where accurate frequency sources are needed. Because they're less expensive and smaller than oven controlled crystal oscillators (OCXOs), they offer an ideal solution for many portable units that require a reasonably accurate source.

In this blog, we'll review several performance qualities of TCXOs, as well as four common types. 

You've probably heard of ultra-stable oscillators, but what are they good for? Just by the name, you can probably tell they're great for maintaining frequency stability in applications. But what specific applications require very high stability to perform optimally? 

In this blog, we'll discuss the top four applications for ultra-stable oven controlled crystal oscillators (OCXOs).

GPS disciplined oscillators (GPSDOs) are becoming a necessary component for CubeSats and other small satellites (SmallSats).

GPSDOs are comprised of a Global Position System (GPS) receiver, an oven controlled crystal oscillator (OCXO), and a phased-locked loop (PLL). In this blog, you'll get a deeper look into how GPSDOs are designed to help achieve mission success for your small satellite applications.

To make the long journey to earth's orbit or beyond, spacecrafts must be designed to have very precise functionality. Even simple vibrations during pre-launch transportation and powered flight can interfere with the spacecraft’s functionality. These simple vibrations come from many different sources and can inhibit the spacecraft from reaching its full potential.

Spacecraft engineers must also be concerned about very small vibrations, known as micro-vibrations, from a spacecraft’s own moving parts as it operates in orbit. Micro-vibrations are typically sinusoidal with the chance of some integer harmonics and random vibration being present.

In this blog, we'll discuss four of the most common sources of vibration and micro-vibration in satellites and spacecrafts, and how you can reduce or prevent them in your application. 

We've seen some confusion over which timing device works best in satellite communication applications. Should you use a standard oscillator (OCXO), a GPS disciplined oscillator (GPSDO), or an atomic clock in your satellite?

The short answer is, "it depends." You'll need to choose your timing device based on on your specific needs, limitations, and operational orbit. Let's take a look at each operational orbit (LEO, MEO, and GEO) and which types of timing devices their satellites require.

Swept quartz crystals are necessary in timing applications that require radiation resistance, but it's important to understand how they work and when you should use them. 

In this blog, we'll review what swept quartz crystals are, how they're manufactured, their common applications, and a common misconception about their benefits.

The process of buying crystal oscillators can be a headache if you don't know what to expect. But learning the basics of how to procure frequency control devices can help you plan accordingly and reduce your frustration. 

There are three main things you should know about crystal oscillators and frequency control devices when ordering them:

1. They have long lead times
2. They typically have a long shelf life
3. They have large purchased lot sizes

Let's dive a little deeper into each of these to give you a better idea of how they'll impact your purchasing strategy. We'll keep this blog short and to the point, but if you want to learn more, we've included links to our more in-depth articles on each topic.

When it comes to NTP stratum levels and minimum performance requirements for digital network synchronization, there's definitely a lot to know. A standard first released in 1987 entitled "Synchronization Interface Standards for Digital Networks" from the American National Standards Institute (ANSI) lays out all the official information and requirements. 

With the advances of RF technology over the last many years, most modern spectrum analyzers can now automatically detect changes in phase noise levels (mostly of sine wave signals) measured in units of dBc or rads.

But it’s always a good idea for RF engineers to understand how modern spectrum analyzers measure integrated phase deviation. Or better yet, for them to understand how to optimize a spectrum analyzer’s measurements even further. Believe it or not, but many spectrum analyzer readings of phase noise can be significantly off.

Measuring phase noise deviations is easier than it sounds. All you really have to do is learn how to determine the Root Mean Square (RMS). This is done by calculating the ratio of power from the single-sideband (SSB) phase noise to the carrier.