Subminiature rubidium frequency standard for commercial applications

A new family of low-cost Rb frequency standards for use in commercial applications has been developed. These standards are designed to replace precision quartz oscillators, without any additional cost, but considerable improvement in performance. These devices are about a factor of two smaller than the smallest previously available commercial Rb standards, and dissipate about 25% less power, but with no compromise in performance capability. An important feature of these devices is an adaptable output interface which is easily tailored to different user demands. Any selected output interface is provided within the total package outline of 1.4 × 3 × 3 inches. The simplest (and least expensive) version provides a sine-wave output at 50.255+ MHz (a submultiple of the atomic resonance). This option is ideal for users needing a stable clock reference for direct digital synthesis (DDS) systems in which the absolute frequency of the reference is not important. Another version incorporates a factory-set direct digital synthesizer in the output interface. This makes possible virtually any user-specified output frequency between 1 Hz and 20 MHz, with the full stability of the Rb atomic system. A third version incorporates a digital communication link in addition to the DDS output