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 1

CONTENT 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 2

INTRODUCTION 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. 3 3

HIGH FREQUENCY VIBRATIONS 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. 4

HIGH FREQUENCY VIBRATIONS 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 5

LOW FREQUENCY VIBRATION 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 6 6

LOW FREQUENCY VIBRATION Phase noise measurement of 10Mhz output with standard product and low g-sensitivity oscillator • 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 7 7

LOW FREQUENCY VIBRATION 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 operational vibration zone • Software updates to minimize single large adjustments to oscillator 8 8

RESONANT FREQUENCY IN CHASSIS/SYSTEM 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 9 9

RESONANT FREQUENCY IN CHASSIS/SYSTEM 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 10 10

RESONANT FREQUENCY IN CHASSIS/SYSTEM 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 11 11

RESONANT FREQUENCY IN CHASSIS/SYSTEM • All chassis and enclosures are run through a resonance sweep to identify potential issues. • Important to test all connectors and cabling to chassis/enclosure 12 12

TEMPERATURE CHANGE AND SYSTEM RESPONSE 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 optimize 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 13 13

TEMPERATURE CHANGE AND SYSTEM RESPONSE Phase Noise of 10MHz output showing the effect of a large change to the oscillator’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 14 14

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. 15

www.orolia.com Timothy Tetreault Lead Engineer Phone: (585) 684-0752 tim.tetreault@oroliads.com 16