“g”-Compensated, Miniature, High Performance Quartz Crystal...

Hugo [email protected] 2006

Frequency Electronics Inc.

““gg””-- Compensated, Miniature, Compensated, Miniature, High Performance Quartz High Performance Quartz

Crystal OscillatorsCrystal Oscillators

2Frequency Electronics Inc.

Discussion OutlineDiscussion Outline

• Introduction• Specific Applications• Osc. PN Performance under Vibration• “g”- Compensation Scheme• Compensation Test Results• The Hardware• Oscillator Spec Goals


IntroductionIntroduction

The Issue

• Sophisticated military electronic systems aboard helicopters, missiles,and UAVs must provide superior performance while subjected tosevere environmental conditions.

• Of these dynamic disturbances, vibration, acceleration, and shock

have the greatest influence on performance.

• The Precision Quartz Oscillator is the common component in all thesesystems and is also the most sensitive to environmental disturbances.

• A chasm therefore exists between how well these systems work in the

quiescent state vs. being dynamic, due to the Qz Osc performance.

• Through electronic “g”-compensation of the Qz Oscillator, near quiescent levels performance is regained, while the platform is in the operational dynamic state.


IntroductionIntroduction

SLCET-TR-88-1 (Rev.8.4.3) AD-A328861 (revised)

For Frequency Control and Timing ApplicationsA Tutorial

John R. VigU.S. Army Communications-Electronics Command

Attn: AMSEL-RD-C2-PTFort Monmouth, NJ 07703, USA

J.Vig@ IEEE.org

January 2001

Approved for public release.Distribution is unlimited.

QUARTZ CRYSTALRESONATORS AND OSCILLATORS

4-76

To “see” 4 km/h targets, low phase noise 70 Hz from thecarrier is required. Shown is the probability of detection of 4 km/h targets vs. the phase noise 70 Hz from the carrier of a 10 MHz reference oscillator. (After multiplication to 10 GHz the phase noise will be at least 60 dB higher.) The phase noise due to platform vibration, e.g., on an aircraft, reduces the probability of detection of slow-moving targets to zero.

100

80

60

40

20

-140 -135 -130 -125 -120 -115 -110

High NoiseLow Noise

Phase Noise (dBc/Hz)at 70 Hz from carrier, for 4 km/h targets

Prob

abili

ty o

f Det

ectio

n (%

)

Coherent Radar Probability of Detection

Original Publication:

1962,

2nd Ed. 1980

3rd Ed. 2001

John VigJohn Vig’’s reference to this book by s reference to this book by Merrill I. SkolnicMerrill I. Skolnic, recently revised, , recently revised, was very helpful in establishing the was very helpful in establishing the requirements from which oscillator requirements from which oscillator Phase Noise specs can be Phase Noise specs can be determineddetermined


Specific ApplicationsSpecific Applications

• Radars and sensors mounted on helicopters Severe low and medium frequency vibration environment; noise translates to lower precision imaging and false target detection.

• Sensors mounted on unmanned air vehicles (UAVs)

Vibration levels during target “loitering”; noise affect sensor precision and communications data rate with the control center.

• Airborne emitter detection and signal analysis systems

Loss of detection range (vehicle must be closer to the threat for ID) and slower signal analysis process (time needed for positive ID of threat).

• Dynamic host Navigation, guidance, and targeting systems

Accuracy degradation of GPS-aided navigation, guidance, and targeting systems operating in severe environments.

• Broadband, High Data Rate Communications Systems Platform dynamics degrade the signal to noise ratio, increasing BER (bit error rate), requiring data rate decrease to maintain desired BER.


Steady State ApplicationSteady State Application

• Using John Vig’s example of a 4 km/h moving object, being engaged by a 10 GHz X-Band Radar

Doppler Shift for Objects Moving Toward Fixed Radar (Hz)

5

0

10

15

20

25

30

40

10 100 1K 10K 100K 1M

R a

d a

r F

r e

q u

e n

c y

( G

H z

)

4 km

/h -

Man

or S

low

Mov

ing

Vehi

cle

100

km/h

- Veh

icle

, Gro

und

or A

ir

700

km/h

- Sub

soni

c Ai

rcra

ft2,

400

km/h

- Mac

h 2

Airc

raft

X-Band RADAR

~70 Hz

Courtesy of Dr. John Vig


P h

a s

e N

o I

s e

( d

B c

/ H

z )

Single Sideband Frequency Offset from Carrier (Hz)10 100 1,000 10,000 100K 1M 10M

-160

-140

-130

-120

-110

-100

-90

-80

-70

-65

~70 Hz

10 GHz Radar Frequency Source ~performance to detect

4 km/hr. Objects

-150

““Good” 10 MHz Quartz Oscillatorphase noise performance (at rest)

“Good”” 10 GHz Quartz/DRO- combination Oscillator phase noise performance

(at rest)

10 MHz Quartz Oscillator Spec to “see”a 4 km/hr object (2 approx. - 130 dBc at ~70 Hz

σ)

Oscillator Phase Noise Performance Oscillator Phase Noise Performance for 4 km/hr. Object Detectionfor 4 km/hr. Object Detection


Radar Radar -- Probability of DetectionProbability of Detection

Phase Noise (dBc/Hz) - 10 MHz Quartz Oscillator

P r

o b

a b

I l i

t y o

f D

e t

e c

t I o

n (

% )

100

80

60

40

20

-140 -135 -130 -125 -120 -115 -110

Higher NoiseLower Noise

at 70 Hz from the Radar Carrier Frequency, for 4 km/hr objects1σ (~68%)

2σ (~95%)

Courtesy of Dr. John Vig, (modified by HF)


V i

b r a

t i o

n g

2 / H

z

300

0.2

0.3

0.4

0.5

10 100 1000

Frequency (Hz)

20 30 40 50 70

Helicopter

0

0.1

200

Loiter Aircraft

0.08g2/Hz0.04g2/Hz

5g2/Hz

Typical Helicopter and Loiter Typical Helicopter and Loiter Aircraft Random VibrationAircraft Random Vibration


Frequency Offset from Carrier (Hz)

P h

a s

e

N o

i s

e (

d B

c /

H z

)

-170

-160

-150

-140

-130

-120

-110

-100

-90

-80

-70

1 10 100 1,000 10,000

Crystal Gamma of 1E-09/gCrystal Gamma of 1E-10/g

Crystal Gamma of 2E-11/gCrystal Gamma of 2E-12/g

Oscillator under Loiter Aircraft Vibration Level

(~0.04 g2/Hz)

4 km/hr Radar Detection Requirement

70 Hz

Phase Noise vs. 10 MHz Oscillator Phase Noise vs. 10 MHz Oscillator ““gg”” Sensitivity (Gamma)Sensitivity (Gamma)(Loiter Aircraft Random Vibration Environment) (Loiter Aircraft Random Vibration Environment)


P h

a s

e N

o i

s e

(d B

c /

H z

)


-150

-140

-130

-120

-110

-100

-90

-80

10 100 1,000 10,000

Gamma of 1E-9/g

Helicopter 4 km/hr

detection spec

70 Hz 200 Hz

Proposed 10 MHz Oscillator Phase Noise Spec for

Helicopter Radar at rest

Gamma of 5E-11/g

Electronic Compensation

Required Shock Mount Required

Phase Noise vs. 10 MHz Oscillator Phase Noise vs. 10 MHz Oscillator ““gg”” Sensitivity (Gamma)Sensitivity (Gamma)(Helicopter Random Vibration Environment) (Helicopter Random Vibration Environment)


Expected PN of 10 MHz Osc. “g” Sensitivity of ~5E-12/g (Helicopter Random Vibration Environment)

P h

a s

e N

o i

s e

(d B

c /

H z

)


-150

-140

-130

-120

-110

-100

10 100 1,000 10,000

Gamma of 5E-11/g

Helicopter 4 km/hr detection spec

70 Hz 200 Hz

Electronic Compensation

Expected performance with compensation to

~5E-12/g Shock Mount Resonance

Shock Mount

Proposed 10 MHz Oscillator Phase Noise Spec for

Helicopter Radar at rest


Quartz Resonator responds

(E)

(B)

Z

X

Y Quartz Crystal Resonator base

Г = (x2 + y2 + z2)½Quartz Disk

The actual product

encloses the disk with a cap

Sensing devices mounted in each axis

Sensing devices respond (D)

Vibration applied to the Oscillator (C)

(A)

Electronics adjusts amplitude and phase as needed to compensate

(F)Oscillator

Output

(G)

Functional Description of the gFunctional Description of the g--Compensation Compensation Technology for Phase NoiseTechnology for Phase Noise


The HardwareThe Hardware

Stand-alone “g”-Compensated Qz Oscillators

Master Clocks – GPS, Rb, and Compensated Qz(Maintains lock with ~ 22 gRMS, 10 to 2,000 Hz environment)

GPS Rbg-Comp Qz

Time/Frequency Sync Hold-over• Good performance

under vibration• Low PN


Uncompensated

Compensated4 km/hr detection spec4 km/hr detection spec70 Hz70 Hz

Vibration Profile: 4g RMS total, Random; 0.08gVibration Profile: 4g RMS total, Random; 0.08g22/Hz, 10 to 200 Hz/Hz, 10 to 200 HzApproximate Sensitivity per g (Approximate Sensitivity per g (ΓΓ))10 Hz10 Hz 50 Hz50 Hz 100 Hz100 Hz

UncompensatedUncompensated 1.1 E1.1 E--99 7.9 E7.9 E--10 8.9 E10 8.9 E--10 10 CompensatedCompensated 6.3 E6.3 E--1212 2.2 E2.2 E--11 4.0 E11 4.0 E--1111


Vibration Profile: 4g RMS total, Random; 0.08g2/Hz, 10 to 200Vibration Profile: 4g RMS total, Random; 0.08g2/Hz, 10 to 200 HzHzApproximate Sensitivity per g (Approximate Sensitivity per g (ΓΓ))10 Hz 50 Hz 100 Hz10 Hz 50 Hz 100 Hz

Uncompensated 2.2 EUncompensated 2.2 E--11 11 2.8 E2.8 E--11 2.2 E11 2.2 E--1111CompensatedCompensated 2.8 E2.8 E--12 2.5 E12 2.5 E--12 5.0 E12 5.0 E--1212

Uncompensated

Compensated4 km/hr detection spec4 km/hr detection spec70 Hz70 Hz


Uncompensated

Compensated

4 km/hr detection spec4 km/hr detection spec70 Hz70 Hz

Vibration Profile: 4g RMS total, Random; 0.08g2/Hz, 10 to 200Vibration Profile: 4g RMS total, Random; 0.08g2/Hz, 10 to 200 HzHzApproximate Sensitivity per g (Approximate Sensitivity per g (ΓΓ))10 Hz10 Hz 50 Hz 100 Hz 50 Hz 100 Hz

UncompensatedUncompensated 7.0 E7.0 E--1111 8.9 E8.9 E--11 7.0 E11 7.0 E--1111CompensatedCompensated 1.8 E1.8 E--11 3.1E11 3.1E--11 3.5 E11 3.5 E--1111


“g”-Sensitivity:Compensation to better than 2E-12/g, 10 Hz to 2 KHz In Production: Compensation to 1E-11

Uncompensated at Qz level, 2E-10 (best in class)

Power Consumption:100 mWIn Production: 1.5 W

Volume: 8 cm3; a reduction from traditional units, usually at least 40 cm3 or more

Short Term Stability:1E-13 @ 1 to 100 seconds In Production: 1E-12

Aging:1E-8 over 10 yearsIn Production: 1E-10 per day

Temperature Coefficient:+/- 2E-11 from -40C to +85CIn Production: +/- 1E-10

Oscillator Spec Oscillator Spec GoalsGoals

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