# Presentation: 769826

## USNO Report

- U.S. Naval Observatory
- Washington, DC and Colorado Springs, CO
- Demetrios Matsakis

- CGSIC Timing Subcommittee  Sept. 13, 2005

## Overview

- USNO 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  Sept. 13, 2005

## USNO Master ClockTime Service Department

- Ensemble of
- 72 Cesium standards
- 21 Hydrogen masers
- Real-time realization of UTC(USNO)
- Clocks incorporated into International Atomic Time (TAI)

- CGSIC Timing Subcommittee  Sept. 13, 2005

## USNO GPS Operations	Time Service Department

- GPS Time Monitoring
- Provide GPS MCS with a reliable and stable reference to UTC(USNO)
- GPS Time Synchronization to UTC(USNO)
- GPS Time corrections provided daily to GPS MCS

- CGSIC Timing Subcommittee  Sept. 13, 2005

## USNO GPS OperationsTime Service Department

-  **GPS Time Monitoring**

- CGSIC Timing Subcommittee  Sept. 13, 2005

## USNO GPS OperationsTime Service Department

- Common-View (CV) Time Transfer
- Used as a backup to Two-Way Satellite Time Transfer (TWSTT) to:
- Incorporate USNO clocks into TAI
- Steer Remote Clocks to UTC(USNO)
- Participate in worldwide relative GPS calibrations conducted by the BIPM

- CGSIC Timing Subcommittee  Sept. 13, 2005

## USNO GPS OperationsTime Service Department

**USNO**

**GPS Satellites**

**Remote Site**

- Subtract

- USNO-Remote Clock

**  ****Common-View Time Transfer**

- CGSIC Timing Subcommittee  Sept. 13, 2005

## Precise Positioning Service (PPS)USNO Receivers

- AOA TTR-12 SM
- 12-channel based on GPS MSRE
- Dual-frequency
- All-in-view Tracking
- Temperature stabilized antenna electronics & cables
- Primary purposes
- GPS Time Monitoring for GPS MCS
- CV Time Transfer between DC & CO
-  SAASM receivers
- Under Development
- Prototype unit being debugged

- CGSIC Timing Subcommittee  Sept. 13, 2005

## Standard Positioning Service (SPS)USNO Receivers

- Current Operations
- Motorola Oncore-based receiver system (TTS-2)
- 8-channel, single frequency
- 3S Navigation GPS/GLONASS
- Additional Systems
- Ashtech
- JPL Real Time Global Differential System
- NovAtel GPS/WAAS/EGNOS
- Monitor UTC(USNO)-WNT

- CGSIC Timing Subcommittee  Sept. 13, 2005

## GPS Time Monitoring

- CGSIC Timing Subcommittee  Sept. 13, 2005

## WAAS Network Time (WNT) MonitoringUTC(USNO) –WNT, offset removed

- CGSIC Timing Subcommittee  Sept. 13, 2005

## USNO Network Time ServersTime Service Department

**Internet ****http://tycho.usno.navy.mil/ntp.html**
- 26 U.S. Stratum-1 Time Servers
- USNO Master Clock & GPS SPS Time References
- Millisecond Time Synchronization
- 100 Billion Network Requests yearly
**SIPRnet**
- 2 U.S. Stratum-1 Time Servers operational
- 2 OCONUS under consideration
- USNO Master Clock References
**Contact:  Richard E. Schmidt, 202-762-1578  DSN 762-1578,  res@usno.navy.mil**

- CGSIC Timing Subcommittee  Sept. 13, 2005

## Internet and Other Time ProductsTime Service Department

**ftp server,** **ftp://tycho.usno.navy.mil**
- 9 million connections/month
**Time Service Web server, ****http://tycho.usno.navy.mil**
- 5 million connections/month
- Audio Service installed
**Telephone Voice Announcer**
- USNO DC, **202-762-1401 (DSN 762)**
- USNO AMC,** 719-567-6742 (DSN 560)**
**Modem** **Time**
- USNO DC, **202-762-1594 (DSN 762); 1200 baud 8N1**
- USNO AMC**, 719-567-6743 (DSN 560); 1200 baud 8N1**

- CGSIC Timing Subcommittee  Sept. 13, 2005

## Improvements in the works

**Two Way Satellite Time Transfer (TWSTT)**
**Radome**
- Provides thermal stability
**Satellite Simulators**
- Delivered, to be tested
- Continuous calibration monitor
**Experimenting with higher chip rates **
- Promises improved SNR
**GPS simulator development**

- CGSIC Timing Subcommittee  Sept. 13, 2005

## Radome Installation

- CGSIC Timing Subcommittee  Sept. 13, 2005

## DISCLAIMER

- Manufacturers and products are identified only for technical clarity
- Use by USNO does not imply an endorsement
- Past record at USNO may not be a reliable predictor of future performance.

- CGSIC Timing Subcommittee  Sept. 13, 2005