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Commercial rubidium clocks are less accurate than caesium atomic clocks, which serve as primary frequency standards, so a rubidium clock is usually used as a secondary frequency standard. Commercial rubidium frequency standards operate by disciplining a crystal oscillator to the rubidium hyperfine transition of 6.8 GHz (6 834 682 610.904 Hz).
Atomic clocks based on rubidium standards are therefore regarded as secondary representations of the second. Rubidium standard clocks are prized for their low cost, small size (commercial standards are as small as 1.7 × 10 5 mm 3) [33] and short-term stability. They are used in many commercial, portable and aerospace applications.
Amongst the building blocks of a GPS Time and Frequency solution the oscillator is a key component [11] and typically they are built around an Oven Controlled Crystal Oscillator or a Rubidium based clock. The dominant factors influencing the quality of the reference oscillator are taken to be aging and temperature stability.
For a 10 MHz clock, this would be equivalent to 13 mHz RMS movement. If the phase stability of an oscillator is needed, then the time deviation variants should be consulted and used. One may convert the Allan variance and other time-domain variances into frequency-domain measures of time (phase) and frequency stability. [7]
Using the Smith chart, the normalised impedance may be obtained with appreciable accuracy by plotting the point representing the reflection coefficient treating the Smith chart as a polar diagram and then reading its value directly using the characteristic Smith chart scaling. This technique is a graphical alternative to substituting the values ...
Crystal oscillators can be manufactured for oscillation over a wide range of frequencies, from a few kilohertz up to several hundred megahertz.Many applications call for a crystal oscillator frequency conveniently related to some other desired frequency, so hundreds of standard crystal frequencies are made in large quantities and stocked by electronics distributors.
A crystal oscillator is an electronic oscillator circuit that uses a piezoelectric crystal as a frequency-selective element. [1] [2] [3] The oscillator frequency is often used to keep track of time, as in quartz wristwatches, to provide a stable clock signal for digital integrated circuits, and to stabilize frequencies for radio transmitters and receivers.
A GPS disciplined oscillator unit with a GPS antenna input, 10 MHz and 1 pulse-per-second (PPS) outputs, and an RS-232 interface.. A GPS clock, or GPS disciplined oscillator (GPSDO), is a combination of a GPS receiver and a high-quality, stable oscillator such as a quartz or rubidium oscillator whose output is controlled to agree with the signals broadcast by GPS or other GNSS satellites.