1. The transmitters use a primary frequency standard to derive the frequencies used. 2. Another important thing for a frequency standard is low phase noise. 3. An atomic clock uses an atomic resonance frequency standard as its timekeeping element. 4. A "'frequency standard "'is a stable oscillator used for frequency calibration or reference. 5. The official time signal is given by the Time and Frequency Standards Laboratory. 6. But the really accurate atomic clocks, called Primary Frequency Standard , are far fewer. 7. A simple electronic feedback loop can lock the repetition rate to a frequency standard . 8. A "'frequency comb "'allows a direct link from radio frequency standards to optical frequencies. 9. A frequency standard generates a fundamental frequency with a high degree of accuracy and precision. 10. Atomic hydrogen determines the frequency of hydrogen masers which are used as precise frequency standards .
