Frequency standard
（重定向自Frequency reference）
![These precision 100 kHz oven controlled crystal oscillators at the US Bureau of Standards (now NIST) served as the frequency standard for the United States in 1929.](/Images/godic/202501/14/Early_NBS_crystal_oscillator_frequency_standards1156.jpg")
A frequency standard is a stable oscillator used for frequency calibration or reference. A frequency standard generates a fundamental frequency with a high degree of accuracy and precision. Harmonics of this fundamental frequency are used to provide reference points.