Early In Orbit Performance Of Gps Block Iir Rubidium Clocks

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Early In Orbit Performance Of Gps Block Iir Rubidium Clocks

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Author :
language : en
Publisher:
Release Date : 1997

Early In Orbit Performance Of Gps Block Iir Rubidium Clocks written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1997 with categories.

The first Block IIR GPS navigation satellite, placed in orbit on July 22, 1997, carried a new generation of rubidium clocks. Since then, two of these clocks have been activated, and both are performing well. This paper reports on those early results, and compares the in-orbit performance with ground acceptance test data. EG & G has delivered about two-thirds of the 66 Rubidium Atomic Frequency Standards (RAFS) needed for the Block IIR GPS program Composite frequency and time stability plots are presented for all delivered units, and more detailed acceptance test stability data shown for the two RAFS that are operating on-board SVN43. In addition, similar life test data shown for the two units that are undergoing life testing at NRL. In-orbit stability and drift data are presented for RAFS S/N 005 and 006 using all available 15-minute precise ephemeris/clock data from the National Imagery and Mapping Agency (NIMA). RAFS S/N 006 was turned on 8/13/97 and was used as the active clock until 9/26/97. RAFS S/N 005 was turned on 8/22/97 and became the active clock on 9/26/97 at the beginning of a 2-month extended navigation test. Both are showing excellent stability and early drift stabilization.

Gps Iir Rubidium Clocks In Orbit Performance Aspects

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Author :
language : en
Publisher:
Release Date : 2004

Gps Iir Rubidium Clocks In Orbit Performance Aspects written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.

The GPS Block IIR rubidium clocks have proved to be the best performers in the current GPS constellation, starting with the first IIR operational clock (launched on July 23, 1997). This discussion covers a number of topics, including the frequency accuracy, the frequency variation, and the projected lifetimes of these clocks. The performance of these clocks in orbit and their life expectancy are compared with that experienced with previous GPS clocks. The superior performance and lifetimes of the GPS IIR Rb clocks are highlighted. Because these clocks are so well behaved, it has been possible to detect various features and phenomena that were not previously detectable. The full drift of the IIR clocks is not observed by the user because of onboard cancellation by the Time Keeping System. The diagnostic and reprogrammability capability of the GPS IIR Satellites allows these discrepancies to be addressed. The long-lived features of the clocks indicate that they will outlive the GPS satellite mission duration.

Gps Block Iir Rubidium Atomic Frequency Standard Life Test

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Author :
language : en
Publisher:
Release Date : 1998

Gps Block Iir Rubidium Atomic Frequency Standard Life Test written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.

The rubidium clocks in the GPS Block IIR spacecraft have no previous flight experience, and will be the only atomic clocks used on the Block IIR satellites. The U.S. Naval Research Laboratory (NRL),) in cooperation with the Global Positioning System Joint Program Office (GPS-JPO), the GPS control Segment, Lockheed Martin, ITT, and EC & G, is conducting a three year life-test of two flight qualfied EG & G Rubidium Atomic Frequency Standards (RAFS) selected from the operational spacecraft inventory. The two RAFS, serial numbers 28 and 30, were selected as representative of the flight configuration build for Block IIR by ITT and provided by the JPO to NRL for this test. The test is intended to build confidence in these units as operational spacecraft clocks and establish a database of fundamental performance characteristics. The two units are being operated in independent thermal vacuum chambers with high resolution monitoring of the clock's frequency compared to the NRL hydrogen maser references. The units' internal monitors that would normally be sent as telemehy and environmental test conditions are monitored and recorded with high resolution. Output from one of the two units has been used as input to the NRL Time Keeping System Simulator (TKSS). The TKSS was originally built to evaluate the implementation and algorithms used in the Block IIR on-board Time Keeping System (TKS), which determines the satellite's clock signal to the transmitter. Data from the TKSS have been used to evaluate TKS on-orbit performance and serve as an analysis reference. RAFS data from the beginning of the test on 31 March 1997 to August 1998 and representative TKSS data will be presented. Frequency stability results of the RAFS have routinely shown Allan deviation performance in parts in 10( -14) at one day, much better than initially expected.

Long Term Ground Test Results For Two Gps Block Iir Rubidium Clocks

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Author : Ronald L. Beard
language : en
Publisher:
Release Date : 2000

Long Term Ground Test Results For Two Gps Block Iir Rubidium Clocks written by Ronald L. Beard and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2000 with Aids to navigation categories.

The rubidium clock used in the GPS Block IIR space vehicles is a design that had not flown previously in space.

Analysis Of On Orbit Behavior Of Gps Block Ii R Time Keeping System

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Author :
language : en
Publisher:
Release Date : 1998

Analysis Of On Orbit Behavior Of Gps Block Ii R Time Keeping System written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1998 with categories.

This paper presents three phases of the Time Keeping System analysis (TKS) of the first on-orbit GPS IIR Satellite, SVN 43. The first phase is a comparison of the performance of the SVN 43 Rubidium Atomic Frequency Standard (RAFS) to other GPS satellite clocks. The results indicate that the SVN 43 RAFS is performing better than specification and ranks highly when compared to the other clocks in the constellation. The second phase was to analyze all available data to determine the causes of several transients seen in the SVN 43 TKS. This led to a concentration on the RAFS and associated inputs and outputs, as well as the utilization of TKS simulation tools. The third phase was to examine the entire system to determine how to improve our visibility into the TKS operation. This led to an SV software enhancement whose purpose is to buffer TKS related data in SV memory for subsequent dump and analysis. An example will be presented showing the value of this new TKS buffer capability in the investigation of some TKS events that occurred in August 1998.

Rubidium Atomic Frequency Standards For Gps Block Iir

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Author :
language : en
Publisher:
Release Date : 1990

Rubidium Atomic Frequency Standards For Gps Block Iir written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1990 with categories.

EG & G, Inc. has been selected to provide the Rubidium Atomic Frequency Standards (RAFS) for the GPS Block IIR NAVSTAR satellites. These satellites will replenish and upgrade the space segment of the Global Positioning System in the mid 1990s. The EG & G GPS RAFS Rb clocks are the latest generation of the high-performance rubidium frequency standards described at this conference in 1981, 1983, 1985, and 1987. They offer an aging rate in the low pp10(14)/day range and a drift-corrected 1-day stability in the low pp10(14) range. The Block IIR version of these devices will have improved performances, higher reliability, smaller size, and greater radiation hardness. The GPS Block IIR atomic clocks have a "natural frequency" configuration whereby they output a frequency of about 13.4 MHz that is a submultiple of the atomic resonance of Rb (or Cs). The RAFS operates at a low, fixed C-field for increased stability. The unit has been repackaged into a smaller 4.6" x 8.5" x 5.8" outline, but is somewhat heavier (12 lbs.) because of additional radiation shielding. Elimination of the ground tuning logic and the secondary loop synthesizer (with its ovenized crystal oscillator) has reduced the RAFS complexity and improved its reliability to 0.80 for the 7.5-year mission. The RAFS power consumption is only 13 W at +20 deg. C in vacuum. This paper describes the GPS Block IIR RAFS design, including the changes and improvements made, and the test results obtained, since the last report at this conference in 1987.

Cesium And Rubidium Frequency Standards Status And Performance On The Gps Program

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Author : M. J. Van Melle
language : en
Publisher:
Release Date : 1993

Cesium And Rubidium Frequency Standards Status And Performance On The Gps Program written by M. J. Van Melle and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1993 with categories.

This paper is an update of the on-orbit operational performance of the frequency standards on the Block I GPS 8 to 11 Navstar satellites, the Block 11 GPS 13 to 21 Navstar satellites and the Block IIA GPS 22 to 40 Navstar satellites. A brief history of the frequency standards depicting improvements incorporated in the GPS Program with corresponding results will be presented. The frequency standards configurations from the start to the present, including the various Block IIA clock configurations will be discussed. Topics such as clock observations and long term trending analysis which could enhance on-orbit performance analysis will be covered.

China Satellite Navigation Conference Csnc 2016 Proceedings Volume Iii

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Author : Jiadong Sun
language : en
Publisher: Springer
Release Date : 2016-04-26

China Satellite Navigation Conference Csnc 2016 Proceedings Volume Iii written by Jiadong Sun and has been published by Springer this book supported file pdf, txt, epub, kindle and other format this book has been release on 2016-04-26 with Technology & Engineering categories.

These Proceedings present selected research papers from CSNC2016, held during 18th-20th May in Changsha, China. The theme of CSNC2016 is Smart Sensing, Smart Perception. These papers discuss the technologies and applications of the Global Navigation Satellite System (GNSS), and the latest progress made in the China BeiDou System (BDS) especially. They are divided into 12 topics to match the corresponding sessions in CSNC2016, which broadly covered key topics in GNSS. Readers can learn about the BDS and keep abreast of the latest advances in GNSS techniques and applications.

Performance Of New Gnss Satellite Clocks

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Author : Gonzalez Martinez, Francisco Javier
language : en
Publisher: KIT Scientific Publishing
Release Date : 2013-12-24

Performance Of New Gnss Satellite Clocks written by Gonzalez Martinez, Francisco Javier and has been published by KIT Scientific Publishing this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013-12-24 with Science categories.

In Global Navigation Satellite Systems (GNSS), the on-board clocks are a key component from which timing and navigation signals are generated. This thesis reviews the performance of the first Passive Hydrogen Maser (PHM) launched by the Galileo system in 2008; and demonstrates how the new PHM can be consider as the best clock in space, pushing the physical clock error contribution below the noise floor of geodetic time transfer capabilities. Furthermore, overall GNSS clock peformance is reviewed

Frequency Equilibration And The Light Shift Effect For Block Iir Gps Rubidium Clocks

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Author :
language : en
Publisher:
Release Date : 2004

Frequency Equilibration And The Light Shift Effect For Block Iir Gps Rubidium Clocks written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2004 with categories.

Over the past several years, evidence has grown indicating that rubidium (Rb) vapor-cell frequency standards exhibit a long "frequency equilibration" period following activation. Though frequency equilibration can have important implications for diverse timekeeping systems, the mechanism driving the behavior is not well understood and has been the subject of debate. Here, we investigate this phenomenon, as well as frequency aging, for a number of Block IIR GPS Rb clocks. Consistent with previous work, we find that all six Rb clocks in the study showed a frequency equilibration phenomenon with time constants ranging from 98 to 584 days. Further, all clocks displayed a strong correlation between clock frequency and light intensity during equilibration. Significantly, five of the GPS clocks displayed small light-intensity jumps (~ 0.3%) that could be correlated with small jumps in clock fractional frequency (~ 3x10-13); these were used to estimate the various clocks' light-shift coefficients. The broad range of equilibration time constants and the light-shift coefficient determinations cast doubt on the two mechanisms most often cited to explain frequency equilibration: helium permeation through the resonance cell's glass envelope, and the intensity-dependent light-shift effect. Additionally, the light-shift coefficient determinations cast doubt on the intensity-dependent light-shift effect as the driver of frequency aging.