Terminology » RF Components » OCXO vs. Rubidium Oscillators: Key Differences Explained

OCXO vs. Rubidium Oscillators: Key Differences Explained

ocxo rubidium oscillator frequency stability atomic clock

This article clarifies the distinctions between OCXO (Oven Controlled Crystal Oscillator) and Rubidium oscillators.

OCXO, TCXO, and MCXO fall under the category of quartz oscillators, while Rubidium, RbXO, and Cesium are classified as atomic oscillators.

Here’s a comparison table summarizing the key specifications:

SpecificationsOCXORubidium
Oscillator TypeQuartz OscillatorAtomic Oscillator
Accuracy (per year)1 x 10-85 x 10-10
Aging/year6 x 10-92 x 10-10
Temperature Stability (�?�C range)1 x 10-9 (-55 to +85)3 x 10-10 (-55 to +68)
Stability, σy(τ)1 x 10-123 x 10-11
Size (cm3)20 to 200800
Warm-up time (minutes)4 (to 1 x 10-8)3 (to 5 x 10-10)
Power (Watt) (@ lowest temp.)0.25 to 420
Price in $2000 (Low)8000 (High)

Delving Deeper: OCXO vs. Rubidium

The table highlights the fundamental differences between these two oscillator types. Let’s break down some key aspects:

  • Oscillator Type: As mentioned, OCXOs are based on the piezoelectric properties of quartz crystals, while Rubidium oscillators are based on atomic transitions within rubidium atoms. This difference in fundamental technology leads to significant performance variations.
  • Accuracy & Stability: Rubidium oscillators offer superior long-term accuracy and stability compared to OCXOs. This makes them suitable for applications demanding very precise timing. Think of it this way: an OCXO might drift a bit over time, while a Rubidium oscillator is designed to stay locked to a very precise frequency determined by the nature of rubidium atoms.
  • Aging: Aging refers to the gradual change in frequency output over time. Rubidium oscillators exhibit significantly less aging compared to OCXOs.
  • Size and Power: OCXOs generally have a smaller footprint and consume less power than Rubidium oscillators.
  • Price: Due to their complexity and use of atomic technology, Rubidium oscillators are considerably more expensive than OCXOs.

When to Use Which?

The choice between OCXO and Rubidium depends heavily on the application:

  • OCXO: Suitable for applications where good stability is needed but ultimate precision isn’t paramount, and where cost, size, and power consumption are important factors. Examples include communications equipment, test and measurement instruments, and some types of navigation systems.
  • Rubidium: Ideal for applications requiring extremely high accuracy and long-term stability, such as:
    • Telecommunications: Synchronizing network infrastructure.
    • Metrology: High-precision frequency standards.
    • Scientific Research: Experiments requiring precise timing.
    • Satellite Navigation: Ensuring accurate satellite positioning.