Rubidium Atomic Frequency Standards for GPS Block IIR.

Download or read book Rubidium Atomic Frequency Standards for GPS Block IIR. written by and published by . This book was released on 1990 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: EG & G, Inc. has been selected to provide the Rubidium Atomic Frequency Standards (RAFS) for the GPS Block IIR NAVSTAR satellites. These satellites will replenish and upgrade the space segment of the Global Positioning System in the mid 1990s. The EG & G GPS RAFS Rb clocks are the latest generation of the high-performance rubidium frequency standards described at this conference in 1981, 1983, 1985, and 1987. They offer an aging rate in the low pp10(14)/day range and a drift-corrected 1-day stability in the low pp10(14) range. The Block IIR version of these devices will have improved performances, higher reliability, smaller size, and greater radiation hardness. The GPS Block IIR atomic clocks have a "natural frequency" configuration whereby they output a frequency of about 13.4 MHz that is a submultiple of the atomic resonance of Rb (or Cs). The RAFS operates at a low, fixed C-field for increased stability. The unit has been repackaged into a smaller 4.6" x 8.5" x 5.8" outline, but is somewhat heavier (12 lbs.) because of additional radiation shielding. Elimination of the ground tuning logic and the secondary loop synthesizer (with its ovenized crystal oscillator) has reduced the RAFS complexity and improved its reliability to 0.80 for the 7.5-year mission. The RAFS power consumption is only 13 W at +20 deg. C in vacuum. This paper describes the GPS Block IIR RAFS design, including the changes and improvements made, and the test results obtained, since the last report at this conference in 1987.