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Round Trip Phase Stability Status

Round Trip Phase Stability Status. Steven Durand & Terry Cotter May 19 ,2004. Round Trip Phase. Fiber System Photographic Tour Block Diagram Temperature Effects Movement Effects. OFS BrightWave Cable. Double armor loose tube cable

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Round Trip Phase Stability Status

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  1. Round Trip Phase Stability Status Steven Durand & Terry Cotter May 19 ,2004 LO/IF/FO - May 19-20, 2004

  2. Round Trip Phase Fiber System Photographic Tour Block Diagram Temperature Effects Movement Effects LO/IF/FO - May 19-20, 2004

  3. OFS BrightWave Cable • Double armor loose tube cable • Corrugated, copolymer coated carbon, steel tape applied longitudinally • Polyethylene jacket • 1.4 mm outer, 1.2 mm middle, 1.0 mm inner • Glass/epoxy composite dielectric rod core LO/IF/FO - May 19-20, 2004

  4. Cable Cross Section LO/IF/FO - May 19-20, 2004

  5. OFS Matched Cladding Fiber • Matched cladding single-mode • Nonzero-dispersion optical fiber • Gel-filled buffer tubes • Installed in a reverse oscillation lay • 12 fibers per tube LO/IF/FO - May 19-20, 2004

  6. OFS Matched CladdingSpecifications @ 1310 nm • Attenuation coefficient: 0.31-0.35 dB/km • Chromatic dispersion: -9 ps/nm-km • Dispersion slope: 088 ps/nm2-km • Group index of refraction: 1.471 • Polarization M dispersion: ≤0.5 ps/(km)1/2 • Rayleigh Backscattering: -49.6 dB • Coefficient of Expansion*: 6 PPM/˚C * NRAO Estimate LO/IF/FO - May 19-20, 2004

  7. LO Technical RequirementsBased on the Scientific Goalsafter all Round-Trip Corrections • Short Term: < 0.5 ps RMS per second • Long Term: < 1.4 ps per 30 minutes ~20 degrees at 40 GHz • Delta Slope: < 0.2 ps change per minute Over 30 minutes LO/IF/FO - May 19-20, 2004

  8. Phase Error Allocation • Front End 0.4 ps per 30 Min • LO Converters 0.6 ps per 30 Min • Fiber System (RTP) 0.4 ps per 30 Min • RTP measurement accuracy* 0.01 ps • 512 MHz + 128 Hz jitter* 0.1 ps • Fiber induced errors 0.25 ps *NRAO estimates LO/IF/FO - May 19-20, 2004

  9. LO Optical System LO/IF/FO - May 19-20, 2004

  10. Pad Enclosure LO/IF/FO - May 19-20, 2004

  11. Connectors LO/IF/FO - May 19-20, 2004

  12. Fiber Umbilical LO/IF/FO - May 19-20, 2004

  13. Fiber Umbilical LO/IF/FO - May 19-20, 2004

  14. Fiber UmbilicalAntenna Junction Box LO/IF/FO - May 19-20, 2004

  15. After the Cable Wrap LO/IF/FO - May 19-20, 2004

  16. Elevation Cable Bend LO/IF/FO - May 19-20, 2004

  17. Riser LO/IF/FO - May 19-20, 2004

  18. Old RTP Test Setup Test designed and operated by Doug Gerrard and Don Haenichen LO/IF/FO - May 19-20, 2004

  19. RTP Test Hardware LO/IF/FO - May 19-20, 2004

  20. Analog Mixer as a Phase Detector LO/IF/FO - May 19-20, 2004

  21. Temperature Effects • Seasonal • Phase angle changes slowly with ground temperature • Diurnal • Sunrise and direct Sun issues LO/IF/FO - May 19-20, 2004

  22. Fiber Enclosure Temperature(Not Insulated) LO/IF/FO - May 19-20, 2004

  23. Pad Box Insulation LO/IF/FO - May 19-20, 2004

  24. Insulated Fiber Box Temperatures LO/IF/FO - May 19-20, 2004

  25. Temperature Trends LO/IF/FO - May 19-20, 2004

  26. Old 4-Day Stability Test Test Apparatus drift is +/- 0.5 ° per day ~ 0.22 ps per 30 minutes 1° Phase Shift = 5.4 ps LO/IF/FO - May 19-20, 2004

  27. Old Test Fixture • The effects we tried to measure were smaller than the accuracy of the old test fixture. ~ 0.5 degrees (2.7 ps) at 512 MHz “The Universe is full of Magical things, patiently waiting for our wits to grow sharper” Eden Phillpots ~ 1900 LO/IF/FO - May 19-20, 2004

  28. New RTP Block Diagram LO/IF/FO - May 19-20, 2004

  29. New Round Trip Block Diagram LO/IF/FO - May 19-20, 2004

  30. Diurnal EffectsUsing New Equipment LO/IF/FO - May 19-20, 2004

  31. Rate of Change of RTPNew Equipment LO/IF/FO - May 19-20, 2004

  32. Rate of Change of RTP LO/IF/FO - May 19-20, 2004

  33. Rate of Change of RTP LO/IF/FO - May 19-20, 2004

  34. Rate of Change of RTP • Is noise limited - about 0.04° accuracy (0.22 ps) • Goal: RTP measured and adjusted 10 times/second with an accuracy of 0.01° at 512 MHz LO/IF/FO - May 19-20, 2004

  35. Old Movement Data LO/IF/FO - May 19-20, 2004

  36. New Movement Data LO/IF/FO - May 19-20, 2004

  37. New Movement Data • Test results: < 0.04 ° shift @ 512 MHz • 0.1° =.54 ps LO/IF/FO - May 19-20, 2004

  38. Rate of Change of RTP • The Round Trip Phase variation is less than the noise and/or accuracy of the measurement system. LO/IF/FO - May 19-20, 2004

  39. Conclusion • The Diurnal Magnitude and rate of change of the phase shift is tolerable: Estimated to be Less than 0.22 ps / Second • The Magnitude Effects of the motion is smaller than the accuracy of the present equipment: Less than 0.22 ps We need to determine the un-compensated effects LO/IF/FO - May 19-20, 2004

  40. What is Next? • Obtain a better mixer • Use an A/D to sample the 128 Hz signal • FFT to determine the phase • Take more Measurements LO/IF/FO - May 19-20, 2004

  41. LO Technical Requirementsafter all Round-Trip Corrections • Short Term: < 0.5 ps RMS per second • Long Term: < 1.4 ps per 30 minutes (0.4) ~20 degrees at 40 GHz • Delta Slope: < 0.2 ps change per minute Over 30 minutes LO/IF/FO - May 19-20, 2004

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