Ultrastable Quartz Oscillator for Spacecraft
Abstract
A new series of quartz oscillators that have excellent performance has been developed for use in spacecraft. Some oscillators using this design have demonstrated 24-hour aging rates of less than 1 x 10(-11), 100-s Allan variances of 7 x 10(-14), and a phase-noise floor of -158 dBc. Variations in resonator performance exceeding factors of 10 have been found during the evaluation of resonators using the same test oscillator; this finding indicates that oscillator performance is still dominated by the quartz resonator. SC cut resonators manufactured by different companies using a variety of mounting techniques and resonator enclosures have been used in this design. Some performance parameters are directly related to resonator type. The oscillators are designed to survive the rigorous environment of a rocket launch. They are projected to have a minimum useful life of 5 years in a space environment through the use of conservative design margins; high-reliability components, and a rugged mechanical package. A vibration isolation system is incorporated that attenuates the band of frequencies generated by currently available launch vehicles that could potentially damage the oscillator. The oscillators are compact and low weight and have low power consumption. A dual thermal insulating system using a unique Dewar flask design and a space blanket (alternate layers of a porous spacer and radiation-reflective aluminized Mylar) is used to isolate critical oscillator components from the thermal environment and to reduce power consumption. The design of the Dewar flask, which is made from titanium, requires no pinch-off tubes or other protrusions outside of the basic cylindrical envelope of the Dewar. A clearly defined frequency versus ambient pressure change was recognized during development of these oscillators.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 01, 1989
- Accession Number
- ADA518816
Entities
People
- Jerry R. Norton
Organizations
- Johns Hopkins University