A frequency reference is a type of calibrator used to measure time and frequency relative to a fixed reference. The different types of frequency references include rubidium, GPS, and cesium clocks. ATEC offers frequency reference rentals from leading manufacturers like Fluke and Keysight.
What Is A Frequency Reference?
Frequency references are precision references for calibrating the device under test (DUT) by providing a standard output, mainly used for synchronizing wired and wireless telecom infrastructure, BTS, and systems. They are commonly used by laboratories and calibration houses.
Frequency references are also utilized in fixing the frequency and timing of other test equipment that has an external reference input, such as network analyzers, spectrum analyzers, digital oscilloscopes, signal generators, and more.
If the reference frequency is 10 MHz and the goal is to measure a 50 MHz signal, the instrument would measure the ratio of two frequencies (5.0) and then multiply it by the reference frequency. The same concept applies to time measurements, which are measured in increments of the period of the reference.
Types of Frequency References
There are different types of frequency references for various applications, including rubidium oscillators, GPS-disciplined frequenct references, and cesium standard clocks.
Rubidium Frequency References
Rubidium frequency references are atomic-disciplined oscillators that are also referred to as quartz or crystal oscillators. Rubidium oscillators java lower power and they operate by disciplining a crystal oscillator to the rubidium hyperfine transition of approximately 6.8347 GHz. When the rubidium vapor in the resonance cell is exposed to microwave power near the transition frequency, the light intensity from a rubidium discharge lamp reaching a photodetector through a resonance cell will drop approximately 0.1%.
GPS Frequency References
A GPS frequency reference is an off-air, GPS-disciplined oscillator. GPS frequency references use satellite signals to continuously calibrate the frequency of the oscillator. The timing signals can achieve accuracy up to nanoseconds and are capable of generating accurate and stable frequency to parts per trillion.
Cesium Standard Clocks
The cesium standard clocks are the most accurate frequency references. They control the output frequency with cesium atoms when the photon absorption by transitions between the two hyperfine ground states. Cesium standard clocks have a natural resonance frequency of the cesium atom: 9,192,631,770 Hz.
Frequency References Features
- Environmental factors
- Temperature: the error from ambient temperature variations
- Aging per day: the maximum drift per day
- Aging per year – the maximum drift per year
Contact ATEC for frequency references rental needs.