ultrastable quartz oscillator
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The Johns Hopkins University APPLIED PHYSICS LABORATORY
Characteristics of the ultrastable quartz oscillator. Allan variance: 1 × 10–13 at 10 s Magnetic susceptibility: <2 × 10–12/g
Phase noise: –137 dBc/Hz at 1 Hz Harmonic signals: –60 dBc
Aging rate: <7 × 10–13/day Spurious signals: –80 dBc
Radiation susceptibility: <1 × 10–11/rad (Si) Power: 0.6 W at 25°C
Temp. susceptibility: <4 × 10–13/°C Mass: 0.4 kg
The unmatched frequency stability of The Jonhs Hopkins University Applied Physics Laboratory (JHU/APL) space-qualified ultrastable quartz oscillators has been proven in nearly 50 years of space applications. JHU/APL oscillators have a demonstrated frequency stability of 1 × 10–13 (10 s) and a temperature coefficient of 4 × 10–13/°C. Since the quartz oscillator is often critical to the spacecraft mission, long-term, reliable operation of the oscillator is as important as its frequency stability. Oscillators used in the Navy Navigation Satellite System accumulated over one million hours of operation in orbit without failure. One oscillator provided continuous service for more than 21 years. Over 400 JHU/APL ultrastable oscillators have been placed in orbit on a wide variety of spacecraft beginning in 1958.
The environment in which the oscillator must operate has a large influence on the ultimate performance of an oscillator. Through careful design, the effects of environmentally induced frequency changes of the oscillator output frequency have been reduced to levels approaching the noise on the output frequency, as shown in the table. One environmental effect,
Ultrastable Quartz OscillatorUnmatched Reliable Performance
ionizing radiation, can be a substantial problem in some orbits. To address this problem, JHU/APL began conducting research on radiation effects on quartz oscillators in the late 1960s. We have developed a design that provides effective shielding from most sources of ionizing radiation found in orbit, except high-energy protons (>100�MeV), thereby mitigating this effect.
The inherent stability of our ultrastable oscillator can be translated to other frequencies that are coherent to the oscillator frequency by using very low noise frequency multipliers and frequency synthesis. High-isolation, low-noise buffer amplifiers provide multiple outputs with minimum cross-coupling between ports.
Performance excellence and high reliability are the pr imary goals for JHU/APL ultra-stable oscillators; however,
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Applied Physics Laboratory11100 Johns Hopkins Road
Laurel MD 20723-6099240-228-5000 / Washington443-778-5000 / Baltimore
07-00963-UQO
Matt ReinhartSection Supervisor
For more information, contact:
http://www.jhuapl.edu/nss
power consumption, mass, and size also receive careful attention. These parameters tend to be application-specific, but oscillators with power consumption of less than 0.6 W and a mass of less than 0.4 kg are available.
1x10 14
1x10 13
1x10 12
1x10 11
1x10 10
0. 1 1 10Tau (s)
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100 1000
APL ultrastable quartz oscillator
Small military rubidium
High-performance cesium
High-performance rubidium
Quartz Oscillator CapabilityPerformance parameter ValuePrimary output frequency 5 MHzAging rate/24 h 7 × 10–13
Phase noise Frequency offset (Hz) 1 –137 dBc 10 –149 dBc 100 –155 dBc 1,000 –158 dBc 10,000 –160 dBcFrequency as a function of Temperature/°C 4 × 10–13
Load <1 × 10–12
Input voltage <1 × 10–12
CustomersInstitute of Space and Astronautical Science (ISAS), JapanJet Propulsion LaboratoryNASANaval Research LaboratoryU.S. Air ForceU.S. Navy
Potential ApplicationsSpace Clocks Frequency references Radio science Navigation Event timers Doppler beacons Local oscillators for communications receivers
Space MissionsCassini Mars Global ObserverCOBE Mars ObserverCONTOUR MSXDodge New HorizonsDPCS NOVAEUVE Planet-B (Japan)Geosat SAS GEOS-C SeasatGPSPAC Topex/PoseidonGRACE Transit
Ground Clocks Frequency references GPS timing systems Calibration references Test and measurement equipment
Allan variance of precision frequency standards.
Duane DealDirector
National Security Space Programs 240-228-1633
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