Frequency electronics, inc. Rb and quartz oscillators for space applications

Июль 25, 2022

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Frequency electronics, inc. Rb and quartz oscillators for space applications

Содержание

2. Frequency Electronics, Inc. FEI was started 51 years ago with a mission to bring precision timing
3. Development of Rb and Quartz Oscillators for Space Applications Quartz Clock Performance in Space Rb Atomic
4. Introduction For the past 50 years, most satellite systems have used precision quartz oscillators as the
5. Technology Trade-offs Quartz oscillators are the most reliable, lowest cost technology for providing precision frequency and
6. Development of Rb and Quartz Oscillators for Space Applications Quartz Clock Performance in Space Rb Atomic
7. State of the Art Quartz Performance in Space Usage of “Premium Q Swept Quartz” or radiation
8. Radiation Effects on Quartz Quartz sensitivity to most radiation has been shown to be approximately: -1E-12
9. State of the Art Quartz Oscillator Lᵠ(f) = -133 dBC/Hz @ 1 Hz offset ADEV =
10. Development of Rb and Quartz Oscillators for Space Applications Quartz Clock Performance in Space Rb Atomic
11. Overview Compared to crystal oscillators, atomic clocks are inherently insensitive to space radiation.1 Compared to other
12. Milstar Rb Clocks The Milstar Rb atomic clocks are manufactured by Frequency Electronics, Inc. (FEI) The
13. On-Orbit Data: Rb Satellite Clocks Functional Fit: y(t) = Ae-γwt + Be-γet + Dt Empirically, we
14. Six clocks have operated on orbit (data for three presented here)4 Longest operating time on-orbit is
15. Development of Rb and Quartz Oscillators for Space Applications Quartz Clock Performance in Space Rb Atomic
16. Design Goals Precision Rubidium Atomic Frequency Standard (RAFS) for Space Applications Best possible frequency stability 20
17. Development of Rb and Quartz Oscillators for Space Applications Quartz Clock Performance in Space Rb Atomic
18. Rb Atomic Frequency Standard (RAFS) 15 x 4.6 x 5.2 inches (381 x 117 x 132
19. Block Diagram Temperature controlled chassis (±1°C) operates from -34°C to +25°C Modular Design Digital Rb control
20. Digital Rb Control Loop Digital processing of analog signal from physics package Space qualified FPGA Direct
21. 6.8 GHz Frequency Synthesizer Phase locked CRO at 2.278 GHz Output signal at 6.8 GHz has
22. Radiation Hardening Component selection FPGA Frequency setting stored on select resistors connected to input pins Fuse
23. Development of Rb and Quartz Oscillators for Space Applications Quartz Clock Performance in Space Rb Atomic
24. Relative Frequency vs Time prototype unit in vacuum
25. Allan Deviation Prototype Unit in vacuum
26. Allan Deviation multiple units, in vacuum
27. Warm-Up and Stabilization SN 01 in vacuum, -4°C
28. Initial Warmup SN 01 in vacuum, -4°C
29. Frequency vs Temperature SN 01, in vacuum 1E-14 per °C
30. Power Consumption SN 01 in Vacuum
31. Frequency vs Magnetic Field SN 01 in vacuum
32. Allan Deviation SN 03 SN 03, vacuum
34. Скачать презентацию

Слайд 2

Frequency Electronics, Inc.
FEI was started 51 years ago with a mission

to bring precision timing technology from the laboratory to the real world
FEI is a Long-Recognized Technology Leader
High Precision Timing, Space Applications
Low Phase Noise Microwave Sources and Synthesizers
Low “G”- Sensitivity Clocks
Timing/Frequency Systems for Severe Environments

Слайд 3

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

in Space
Rb Atomic Clocks in Space – The Results So Far
Next Generation Rb Atomic Clock for Space Applications
Design, Rb Atomic Frequency Standard (RAFS)
Performance Results, RAFS

Слайд 4

Introduction
For the past 50 years, most satellite systems have used precision

quartz oscillators as the time and frequency reference
Reliable
Low Power
Light Weight
Atomic Frequency Standards have demonstrated reliable operation in space during the last 25 years on a limited number of programs
GPS
Glonass
Milstar/AEHF
Galileo

Слайд 5

Technology Trade-offs
Quartz oscillators are the most reliable, lowest cost technology for

providing precision frequency and time in space applications
Quartz is inherently sensitive to nuclear radiation
Atomic frequency standards cost more, are less reliable, but provide improved frequency stability, and are relatively immune to radiation

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Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

in Space
Rb Atomic Clocks in Space – The Results So Far
Next Generation Rb Atomic Clock for Space Applications
Design, Rb Atomic Frequency Standard (RAFS)
Performance Results, RAFS

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State of the Art Quartz Performance in Space
Usage of “Premium Q

Swept Quartz” or radiation hardened quartz material.
SC-cut crystals (SC-cut crystals stabilize faster than AT-cut crystals. The retrace of SC-cut crystals is orders of magnitude better than AT-cut crystals).
5th overtone resonators (aging is significantly affected by the thickness of the resonator, hence, the thickest quartz blank should be used at the highest practical overtone for best aging performance).
Crystals exhibiting monotonically-positive aging slope (radiation offsets the positive aging trend of quartz as further explained below).

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Radiation Effects on Quartz
Quartz sensitivity to most radiation has been shown

to be approximately: -1E-12 per Rad
Typical background radiation for geosynchronous orbit is: 6 Rads/day
Typical frequency aging on earth is ~1E-11/day for high precision quartz oscillators
On-orbit compensation resulting in frequency aging of ~1E-12/day is possible for positive aging quartz resonators
Quartz sensitivity to protons is similar magnitude, but less predictable; and can result in positive or negative frequency changes

Even with compensation for background radiation:
best performance observed in space is ~2E-13/day
effect of solar flare is 1E-10 to 4E-10 over several days

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State of the Art Quartz Oscillator
Lᵠ(f) = -133 dBC/Hz @ 1

Hz offset
ADEV = 7E-14 @ 10 sec

Слайд 10

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

in Space
Rb Atomic Clocks in Space – The Results So Far
Next Generation Rb Atomic Clock for Space Applications
Design, Rb Atomic Frequency Standard (RAFS)
Performance Results, RAFS

Слайд 11

Overview
Compared to crystal oscillators, atomic clocks are inherently insensitive to space

radiation.1
Compared to other types of atomic clock (e.g., Cs),
Rb clocks have the advantage of size, weight, and power,
Rb clocks have the (believed) disadvantage of relatively large frequency aging.
To better understand the utility of Rb clocks for long-term space missions, we have investigated Milstar Rb clocks (on-orbit) over the past two decades.
Contrary to popular mythology,
Rb clocks can have exceptionally long life with stable operation,
Rb clocks can have extremely low frequency-aging rates: 10-14 to 10-15/day

1) J. Camparo, S. Moss, & S. LaLumondiere, Space-system timekeeping in the presence of solar flares, IEEE Aerospace and Electronic SYSTEMS Magazine, 19(5), 3-8 (2004).

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Milstar Rb Clocks
The Milstar Rb atomic clocks are manufactured by Frequency

Electronics, Inc. (FEI)
The clock is a classical Rb vapor-cell design, with optical excitation using an rf-discharge lamp.2
The clock has a 10 year design life.
The clock has a weight of 2.3 kg (i.e., 5 lbs.).
The clock frequency can be tuned with a resolution better than 1× 10-12.

2) T. McClelland, I. Pascaru, M. Meirs, Development of a Rb Frequency Standard for the MILSTAR Satellite System, 41st Annual Symposium on Frequency Control, 1987, p. 66

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On-Orbit Data: Rb Satellite Clocks Functional Fit: y(t) = Ae-γwt + Be-γet

+ Dt

Empirically, we find that as a family the data is well fit by a bi-exponential plus linear term:
Clock “warm-up”
Ae-γwt
This term may be due to movement of the liquid Rb pool in the discharge lamp.
Clock Equilibration4
Be-γet
The mechanism of equilibration is not yet understood.
Nevertheless, helium permeation remains an open possibility.
Linear Frequency Aging
Dt
The mechanism of linear frequency aging is not yet understood.

Слайд 14

Six clocks have operated on orbit (data for three presented here)4
Longest

operating time on-orbit is 14.8 years
Including estimates for ground operation, 3 of these clocks have logged more than 18 years of operation!

Milstar Rb Satellite Clocks Summary

4) J. Camparo, T. McClelland, and J. Hagerman, “Long Term Behavior of Rb Clocks in Space,” European Frequency and Time Forum, 2012.

Слайд 15

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

in Space
Rb Atomic Clocks in Space – The Results So Far
Next Generation Rb Atomic Clock for Space Applications
Design, Rb Atomic Frequency Standard (RAFS)
Performance Results, RAFS

Слайд 16

Design Goals
Precision Rubidium Atomic Frequency Standard (RAFS) for Space Applications
Best possible

frequency stability
20 year operating life
Emphasis on frequency stability rather than size, weight and power (SWAP)
“Classical” Rb vapor frequency standard
Optical pumping using Rb lamp to create ground state hyperfine population difference
Temperature controlled filter cell with Rb85
Temperature controlled resonance cell, with Rb87, in microwave cavity
One prototype, 3 engineering models

Слайд 17

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

in Space
Rb Atomic Clocks in Space – The Results So Far
Next Generation Rb Atomic Clock for Space Applications
Design, Rb Atomic Frequency Standard (RAFS)
Performance Results, RAFS

Слайд 18

Rb Atomic Frequency Standard (RAFS)
15 x 4.6 x 5.2 inches (381 x

117 x 132 mm)
16.5 Lbs (7.5 kg)
28 VDC Input
30 Watts
10 MHz Output

Слайд 19

Block Diagram
Temperature controlled chassis (±1°C) operates from -34°C to +25°C
Modular Design

Digital Rb control loop

Слайд 20

Digital Rb Control Loop
Digital processing of analog signal from physics package
Space

qualified FPGA
Direct Digital Synthesizer (within FPGA) to tune output frequency (1 x 10-14 tuning resolution)

Слайд 21

6.8 GHz Frequency Synthesizer
Phase locked CRO at 2.278 GHz
Output signal at

6.8 GHz has no sidebands within a ±2.278 GHz window

Слайд 22

Radiation Hardening
Component selection
FPGA
Frequency setting stored on select resistors connected to input

pins
Fuse programmed (write once)
Hardware triple redundant logic, with three way voting to minimize single event effects
Software triple redundant logic with 3 way voting of critical values (digital output to DAC (quartz oscillator control voltage))
Radiation shields
Chassis, covers (material and thickness)
Spot shields for critical components

Слайд 23

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

in Space
Rb Atomic Clocks in Space – The Results So Far
Next Generation Rb Atomic Clock for Space Applications
Design, Rb Atomic Frequency Standard (RAFS)
Performance Results, RAFS

Слайд 24

Relative Frequency vs Time prototype unit in vacuum

Слайд 25

Allan Deviation Prototype Unit in vacuum

Слайд 26

Allan Deviation multiple units, in vacuum

Слайд 27

Warm-Up and Stabilization SN 01 in vacuum, -4°C

Слайд 28

Initial Warmup SN 01 in vacuum, -4°C

Слайд 29

Frequency vs Temperature SN 01, in vacuum
1E-14 per °C

Слайд 30

Power Consumption SN 01 in Vacuum

Слайд 31

Frequency vs Magnetic Field SN 01 in vacuum

Слайд 32

Frequency electronics, inc. Rb and quartz oscillators for space applications

Содержание

Frequency Electronics, Inc.FEI was started 51 years ago with a mission

Development of Rb and Quartz Oscillators for Space ApplicationsQuartz Clock Performance

IntroductionFor the past 50 years, most satellite systems have used precision

Technology Trade-offsQuartz oscillators are the most reliable, lowest cost technology for

Development of Rb and Quartz Oscillators for Space ApplicationsQuartz Clock Performance

State of the Art Quartz Performance in SpaceUsage of “Premium Q

Radiation Effects on QuartzQuartz sensitivity to most radiation has been shown

State of the Art Quartz OscillatorLᵠ(f) = -133 dBC/Hz @ 1

Development of Rb and Quartz Oscillators for Space ApplicationsQuartz Clock Performance

OverviewCompared to crystal oscillators, atomic clocks are inherently insensitive to space

Milstar Rb ClocksThe Milstar Rb atomic clocks are manufactured by Frequency

On-Orbit Data: Rb Satellite Clocks Functional Fit: y(t) = Ae-γwt + Be-γet

Six clocks have operated on orbit (data for three presented here)4Longest

Development of Rb and Quartz Oscillators for Space ApplicationsQuartz Clock Performance

Design GoalsPrecision Rubidium Atomic Frequency Standard (RAFS) for Space ApplicationsBest possible

Development of Rb and Quartz Oscillators for Space ApplicationsQuartz Clock Performance

Rb Atomic Frequency Standard (RAFS)15 x 4.6 x 5.2 inches (381 x

Block DiagramTemperature controlled chassis (±1°C) operates from -34°C to +25°CModular Design

Digital Rb Control LoopDigital processing of analog signal from physics packageSpace

6.8 GHz Frequency SynthesizerPhase locked CRO at 2.278 GHzOutput signal at

Radiation HardeningComponent selectionFPGAFrequency setting stored on select resistors connected to input

Development of Rb and Quartz Oscillators for Space ApplicationsQuartz Clock Performance

Relative Frequency vs Time prototype unit in vacuum

Allan Deviation Prototype Unit in vacuum

Allan Deviation multiple units, in vacuum

Warm-Up and Stabilization SN 01 in vacuum, -4°C

Initial Warmup SN 01 in vacuum, -4°C

Frequency vs Temperature SN 01, in vacuum1E-14 per °C

Power Consumption SN 01 in Vacuum

Frequency vs Magnetic Field SN 01 in vacuum

Allan Deviation SN 03 SN 03, vacuum

Похожие презентации

Frequency Electronics, Inc.
FEI was started 51 years ago with a mission

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

Introduction
For the past 50 years, most satellite systems have used precision

Technology Trade-offs
Quartz oscillators are the most reliable, lowest cost technology for

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

State of the Art Quartz Performance in Space
Usage of “Premium Q

Radiation Effects on Quartz
Quartz sensitivity to most radiation has been shown

State of the Art Quartz Oscillator
Lᵠ(f) = -133 dBC/Hz @ 1

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

Overview
Compared to crystal oscillators, atomic clocks are inherently insensitive to space

Milstar Rb Clocks
The Milstar Rb atomic clocks are manufactured by Frequency

Six clocks have operated on orbit (data for three presented here)4
Longest

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

Design Goals
Precision Rubidium Atomic Frequency Standard (RAFS) for Space Applications
Best possible

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

Rb Atomic Frequency Standard (RAFS)
15 x 4.6 x 5.2 inches (381 x

Block Diagram
Temperature controlled chassis (±1°C) operates from -34°C to +25°C
Modular Design

Digital Rb Control Loop
Digital processing of analog signal from physics package
Space

6.8 GHz Frequency Synthesizer
Phase locked CRO at 2.278 GHz
Output signal at

Radiation Hardening
Component selection
FPGA
Frequency setting stored on select resistors connected to input

Development of Rb and Quartz Oscillators for Space Applications
Quartz Clock Performance

Frequency vs Temperature SN 01, in vacuum
1E-14 per °C