Inside Frequency Control

Do you know all about Atomic Clocks in space and how they work? If not, it's about TIME you do. (Haha. Ha. Ha...)

Timing is everything when it comes to GPS satellites and other space applications. Even just a one microsecond error in timing can lead to an error of 300 meters on the ground. Atomic clocks can maintain very precise timing, making them a great timing solution for GPS and other LEO satellites.

I have a feeling you're in need of some new test equipment... a new signal generator to be exact. If so, you've come to the right place. Maybe your current signal generator is outdated. Or maybe you're looking for your first one (in which case we'd be honored). 

No matter the reason, we wanted to share with you the best selection of waveform signal generators on the market today to help you make the best purchase based on your needs.

Before we dive into the differences between the 5 GNSS constellations... It's important that we're all on the same page with the difference between GNSS and GPS.

Many people get GNSS and GPS technology confused. A good way to think about the Global Navigation Satellite Systems (GNSS) is as the backbone (or underlying technology) behind GPS. The Global Positioning System (GPS) GPS is a GNSS constellation, but GNSS is not always GPS. GPS one of the 5 GNSS constellations used around the world.

The 5 GNSS constellations include GPS (US), QZSS (Japan), BEIDOU (China), GALILEO (EU), and GLONASS (Russia). We'll cover each of these constellations in depth in this post.

Quartz crystal oscillators are the high and mighty option for low phase noise and added frequency stability in circuit design. Yes, simple oscillators like those made with resistor-capacitor (RC) or inductor-capacitor (IC) resonators are fine for some circuits. But if you're dealing with higher performance applications in aerospace, military, and space industries... you're going to want a higher performance crystal oscillator that can maintain low phase noise & strong stability. Otherwise, you'll risk deviating from the very specific (and many times critical) center frequency selected for your design.

Want to know what's better than a crystal oscillator? A crystal oscillator combined with Electronic Frequency Control (EFC). Of course, it really comes down to your specific application and what requirements you're looking for to determine if EFC would be a good addition to your crystal oscillator circuit design, and if so, which method is best for you.

There are 4 options to choose from when selecting an Electronic Frequency Control method for your crystal oscillator. These 4 options are

1. Pulse Width Modulation & Low Pass Filter
2. Reference RF Signal & Phase Locked Loop (PLL)
3. Voltage Divide
4. Digital-to-Analog Converter (DAC)

In this post, let's take a closer look at each option and compare the pros and cons between them.

Surface Acoustic Wave (SAW) filters offer a reduced size, weight, & cost compared to other filter technologies. However, there are many tradeoffs that need to be considered when selecting a SAW filter for your system design.

What are SAW filters? What are some common SAW filter applications? How are SAW filters used for mobile communications? We'll answer these questions and more in this post.

There is often some confusion as to which timing device would work best in satellite communication applications. Should you use a standard oscillator, GPS Disciplined Oscillator (GPSDO), or atomic clock (cesium and rubidium) in your satellite application?

GPS Disciplined Oscillators (GPSDO) are one of today's most trusted and accurate sources of timing.  These powerful devices (sometimes called GPS clocks) consist of a high-quality stable oscillator and a GPS receiver. The GPSDO works by disciplining (or steering) the oscillator output to a GPS device or GNSS satellite signal via a tracking loop.

A Modular Open Systems Approach (MOSA) is becoming critical in Department of Defense (DoD) systems. If you're unfamiliar with this critical system design approach (or need a little brush-up) you're in the right place (and should totally keep on reading to discover the 5 core principles).

But first, a few quick basics. MOSA is a business and technical strategy for easily developing new defense systems or modernizing existing ones. This will help the Department of Defense provide joint combat capabilities required for 21st century warfare.

MOSA also provides the ability to support and evolve these 21st century capabilities over their total life-cycle.