# Presentation: 769825

## USNO ReportCGSIC Timing SubcommitteeSeptember 11, 2001

**Mihran Miranian**
**Time Service Department**
**202-762-1452; DSN 762-1452**
**mm@usno.navy.mil**

## Overview

- Mission
- Master Clock
- GPS Timing Operations
- Precise Positioning Service (PPS)
- Standard Positioning Service (SPS)
- Network Time Servers
- Internet and Other Time Products
- Precise Time and Time Interval (PTTI)

- CGSIC Timing Subcommittee

- September 11, 2001

## U.S. Naval Observatory

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO Mission(http://www.usno.navy.mil)

- 1.	Determine the positions and motions of celestial bodies, motions of the Earth, and precise time.
- 2.	Provide astronomical and timing data required by the Navy and other components of the Department of Defense for navigation, precise positioning, and command, control, and communications.
- 3.	Make these data available to other government agencies and to the general public.
- 4.	Conduct relevant research, and perform such other functions as may be directed by higher authority.
- Astrometry Department	- Astronomical Applications Department
- Earth Orientation Department	- Flagstaff Station
- Time Service Department
- Alternate Master Clock (Colorado Springs)

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO Master ClockTime Service Department

- Ensemble of
- 60 Cesium standards
- 14 Hydrogen masers
- Measure of atomic time or Coordinated Universal Time (UTC)
- Real-time realization of UTC(USNO)
- Clocks incorporated into International Atomic Time (TAI)

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO GPS Timing Operations

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO Precise Positioning Service (PPS) GPS Timing Operations

- Provide GPS with reliable and stable reference to UTC(USNO)
- GPS Time Synchronization to UTC(USNO)
- GPS Time corrections provided to GPS MCS Personnel daily
- Current Operations
- Single channel receivers, dual-frequency, schedule dependent
- Future Operations
- 12-channel receivers (all-in-view), dual-frequency, temperature stabilized antenna electronics and cables
- Run in parallel with current operational receivers

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO PPS Receiver Performance Evaluation

- GPS Time Measurements
- GPS Time Stability
- GPS Receiver Hardware Stability

- CGSIC Timing Subcommittee

- September 11, 2001

## GPS Time Measurements

- CGSIC Timing Subcommittee

- September 11, 2001

## GPS Time Stability

- CGSIC Timing Subcommittee

- September 11, 2001

## Hardware Stability

- CGSIC Timing Subcommittee

- September 11, 2001

## GPS Time Synchronizationto UTC(USNO)

**5MHz**

**1PPS**

**U.S. Naval Observatory**

**Secure Line**

**GPS MCS**

**Ground Antenna**

**GPS Satellites**

- CGSIC Timing Subcommittee

- September 11, 2001

## Precise Positioning Service (PPS)UTC(USNO) - GPS Time (2-day avg.)

**GPS Time Stability**
**6.4 ns std**

- CGSIC Timing Subcommittee

- September 11, 2001

## Precise Positioning Service (PPS)UTC(USNO) - UTC(USNO) via GPS (1-day avg.)

**1.92 ns std**

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO Standard Positioning Service (SPS) GPS Timing Operations

- Backup to incorporate USNO clocks into TAI computation
- Primary Two-Way Satellite Time Transfer (TWSTT)
- Time steering of remote clocks (LORAN-C)
- Time comparisons made with national and international timing centers (NIST, NPL, PTB)
- Current Operations
- Motorola Oncore receiver (8-channel, single frequency)
- April 1, 2001 (MJD 52000) 0000 UT replace single channel receiver
- Additional Systems
- 3S Navigation GPS/GLONASS, NovAtel GPS/EGNOS/WAAS

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO Network Time ServersTime Service Department

**Internet ****(http://tycho.usno.navy.mil/ntp.html)**
- 17 U.S. Stratum-1 Time Servers
- USNO Master Clock & GPS SPS Time References
- Millisecond Time Synchronization
- 11 Billion Network Requests since January 1, 2001
**Classified DoD Internet (SIPRnet)**
- 2 U.S. Stratum-1 Time Servers
- USNO Master Clock References
- Expansion sites planned for Hawaii and Germany
- Contact:  Richard E. Schmidt, res@usno.navy.mil, 202-762-1578; DSN 762-1578

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO Network Time ServersTime Service Department

- CGSIC Timing Subcommittee

- September 11, 2001

## USNO Internet and Other Time ProductsTime Service Department

**Anonymous ftp server** (ftp://tycho.usno.navy.mil)
- 9 million connections/month
**Time Service Web server** (http://tycho.usno.navy.mil)
- 5 million connections/month
**RealAudio© Master Clock Voice Announcer** (http://tycho.usno.navy.mil/what.html)
- 75 thousand connections/month
- 4 second delay (RealAudio© )
**Telephone Voice Announcer** (202-762-1400; DSN 762-1400)
**Modem** **Time** (202-762-1594; DSN 762-1594; 1200 8N1)

- CGSIC Timing Subcommittee

- September 11, 2001

## Precise Time and Time Interval (PTTI) Systems and Applications Meeting

- Objectives
- Disseminate and coordinate PTTI information at the user level;
- Review present and future PTTI requirements;
- Inform Government and Industry engineers, technicians, and managers of precise time and frequency technology and its problems; and
- Provide an opportunity for an active exchange of new technology associated with PTTI.
- Meeting Information (http://tycho.usno.navy.mil/ptti.html)
- Annual:  rotates between DC and California
- Sponsors:  USNO, NRL, NASA JPL, USCG NAVCEN, DISA, USAF
- Attendees:  U.S. government, military, industry and international
**33rd PTTI:  27-29 November 2001 in Long Beach, CA**

- CGSIC Timing Subcommittee

- September 11, 2001