National Technical Reports Library

The National Technical Information Service acquires, indexes, abstracts, and archives the largest collection of U.S. government-sponsored technical reports in existence. The NTRL offers online, free and open access to these authenticated government technical reports. Technical reports and documents in its repository may be available online for free either from the issuing federal agency, the U.S. Government Publishing Office’s Federal Digital System website, or through search engines.

Details

GPS Block IIR Rubidium Atomic Frequency Standard Life Test.

ADA509515

Publication Date	1998
Personal Author	Beard, R.; White, J.; Brad, J.; Stebbins, S.; Smathers, J.
Page Count	16
Abstract	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.
Keywords	Global positioning system Frequency standards Monitoring High resolution Vacuum chambers Atomic clocks Algorithms Life tests Masers Rubidium Stability Artificial satellites
Source Agency	Non Paid ADAS
Corporate Authors	Naval Research Lab., Washington, DC.
Supplemental Notes	See also ADA415578. Presented at the Annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting (30th) held in Reston, VA on 1-3 Dec 1998. Published in the Annual Precise Time and Time Interval Systems and Applications Meeting Proceedings, p145-160, Dec 1998.
Document Type	Technical Report
Title Note	Conference paper.
NTIS Issue Number	201007

GPS Block IIR Rubidium Atomic Frequency Standard Life Test.

GPS Block IIR Rubidium Atomic Frequency Standard Life Test.
ADA509515

Publication Date	1998
Personal Author	Beard, R.; White, J.; Brad, J.; Stebbins, S.; Smathers, J.
Page Count	16
Abstract	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.
Keywords	Global positioning system Frequency standards Monitoring High resolution Vacuum chambers Atomic clocks Algorithms Life tests Masers Rubidium Stability Artificial satellites
Source Agency	Non Paid ADAS
Corporate Authors	Naval Research Lab., Washington, DC.
Supplemental Notes	See also ADA415578. Presented at the Annual Precise Time and Time Interval (PTTI) Systems and Applications Meeting (30th) held in Reston, VA on 1-3 Dec 1998. Published in the Annual Precise Time and Time Interval Systems and Applications Meeting Proceedings, p145-160, Dec 1998.
Document Type	Technical Report
Title Note	Conference paper.
NTIS Issue Number	201007