Impact of Temperature and High Vibration in Ground, Shipboard and - - PowerPoint PPT Presentation

Impact of Temperature and High Vibration in Ground, Shipboard and Aircraft Platforms on GPS-disciplined, Low Phase Noise, Time and Frequency References

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CONTENT

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• 1. INTRODUCTION
• 2. HIGH FREQUENCY VIBRATIONS
• 3. LOW FREQUENCY VIBRATIONS
• 4. RESONANT FREQUENCY RELATED TO THE CHASSIS/SYSTEM
• 5. TEMPERATURE CHANGE AND SYSTEM RESPONSE
• 6. CONCLUSION

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INTRODUCTION

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Customer come to Orolia looking for GPS referenced, time and frequency products that can meet its specifications while being exposed to vibration and temperature changes. Working with our customers, Orolia has developed products to address the harsh environmental problems that can be seen on many platforms. Some examples of the issues we have addressed are:

• High Frequency Vibrations
• Low Frequency Vibrations
• Resonant Frequency related to the Chassis/System
• Temperature Change and System Response

Each of these environments will affect the products in different ways. So it is critical for us to work closely with the customer to review all requirements at the product and system level.

HIGH FREQUENCY VIBRATIONS

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The causes of vibration can come from many sources. The source is not always related to platform.

• Phase noise output of

standard 1U product with a 100MHz output

• Large spike was found

around 4KHz

• UUT was in an static, non-

vibration environment

• Noise was not from Power

Supply or Oscillator.

HIGH FREQUENCY VIBRATIONS

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Source of Phase Noise spike was cooling fan in system

• High frequency noise was

eliminated with new 100MHz oscillator with low g-sensitivity

• Low g-sensitivity

specifications will vary on vibrations

• Mechanical isolation may

also be required in high frequency vibrations

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LOW FREQUENCY VIBRATION

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Environments such as shipboard and seismic applications, vibrations that are generated are much lower in frequency. Usually below 100Hz.

• Plot shows 10MHz phase

noise in standard 1U rack mount product under shipboard vibration

• Standard oscillator with no

mechanical isolation

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LOW FREQUENCY VIBRATION

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Phase noise measurement of 10Mhz output with standard product and low g-sensitivity

• scillator
• Oscillators with low g-

sensitivity can improve phase noise but not enough to meet required spec

• UUT used a standard 1U

chassis with no modifications

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LOW FREQUENCY VIBRATION

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Phase noise measurement of 10Mhz output with multiple updates/modifications

• Oscillator updated with

mechanical and electronic damping

• Mechanical solutions can

cause harmonics on lower frequency that make phase noise worse

• A ruggedized chassis with

minimal harmonics in

• perational vibration zone
• Software updates to

minimize single large adjustments to oscillator

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RESONANT FREQUENCY IN CHASSIS/SYSTEM

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Resonant Frequency sweep of a standard 1U chassis used in static rack mount applications

• Accelerometers mounted in

key locations. Near oscillator, power supply, etc

• Large resonant frequency

around 66Hz. Smaller ones above 100Hz

• In applications where the

chassis is not exposed to vibrations, chassis can provide a stable platform for the oscillator without any degradation to its performance

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RESONANT FREQUENCY IN CHASSIS/SYSTEM

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Resonant Frequency sweep of a standard 1U chassis compared to a typical vibration profile of a Turboprop Aircraft

• Large resonant frequency

around 66Hz would be amplified by the vibrations from aircraft

• Phase noise performance

expected by the UUT might never be reached

• Modifications to

chassis/enclosure will be required

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RESONANT FREQUENCY IN CHASSIS/SYSTEM

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To minimize any mechanical resonances that may be caused by the enclosure, Orolia had designed several custom chassis and enclosures.

• Minimize any mechanical resonances or move resonances beyond operating vibration profiles
• Matched up to each customer’s environmental conditions

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RESONANT FREQUENCY IN CHASSIS/SYSTEM

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• All chassis and enclosures are run through a resonance sweep to identify potential issues.
• Important to test all connectors and cabling to chassis/enclosure

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TEMPERATURE CHANGE AND SYSTEM RESPONSE

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Two of the most common environmental factors that will affect the performance of an oscillator are Temperature and Vibration. When designing a system to address these environments, it may be necessary to

• ptimize for one while compromising on the other due to cost, size or schedule limitations.
• System was optimized for good phase noise under vibration
• Needed solution to compromise made to Temperature performance

Phase error plot of the oscillator.

• T1 is the change in phase to a temperature change.
• T2 is the systems response to the change in phase and its disciplining the oscillator back to the GPS
• reference. Matched up to each customer’s environmental conditions

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TEMPERATURE CHANGE AND SYSTEM RESPONSE

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Phase Noise of 10MHz

• utput showing the effect
• f a large change to the
• scillator’s tuning voltage
• Even small adjustments

can affect the phase noise

• This will show up as noise

at the low frequencies between 1 and 10Hz

• Solution was:
• Custom software to

discipline oscillator to minimize phase noise errors

• Feed real-time phase

error on serial message to customer application

TIME AND FREQUENCY YOU CAN TRUST

At Orolia, we understand the importance of working with our customers to know their requirements.

We have the products and resources to address any problems a customer may have and provide the best solution for their programs.

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www.orolia.com

Timothy Tetreault Lead Engineer Phone: (585) 684-0752 tim.tetreault@oroliads.com