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Transmitter Performance Section

Transmitter Performance Section. Participants LSU NAVCEN NAVCEN (West) Peterson Integrated Geo-positioning, Inc BAH. LORIPP Meeting #2 Portland, OR September 23-24, 2002. Tasking from LORIPP Meeting 1. TOTM calibration to USNO-UTC

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Transmitter Performance Section

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  1. Transmitter Performance Section • Participants • LSU • NAVCEN • NAVCEN (West) • Peterson Integrated Geo-positioning, Inc • BAH LORIPP Meeting #2 Portland, OR September 23-24, 2002

  2. Tasking from LORIPP Meeting 1 • TOTM calibration to USNO-UTC • ABS threshold and time to blink from onset to fault, P(OOT w/o blink) • Determine transmitted ECD and blink if OOT. • Monitor requirements at transmitter and what certification requirements on monitors. • Chain Operations (TOE verses SAM)

  3. LRP Status • NSSX sites • LSU • LORSTA George, WA • LORSTA Narrow Cape, AK • LORSTA Dana, IN • SLEP • TFE • MOD 5 • Delivery Feb 03

  4. TOT Measurement System Temporary for calibration Ethernetto LSU Antenna current transformers Digital Averaging O’scope USB Computer Temporary at antenna base RS-232 TrueTime XLDC GPS Timing Rcvr Event Time Input Envelope Trigger Circuitry Permanent

  5. Standard Zero Crossing Strobe from Envelope Trigger Start of Pulse

  6. Zero Crossing @ Oscilloscope Zero Crossing @ Transformer Time read from GPS receiver Start of pulse @ Antenna Delay: Transformer to Oscilloscope (148ns) 30 usec Delay GPS to O’scope (15ns) Oscilloscope Measurement (15.54us) Calibration value = 30 + 15.54 + 0.148 – 0.015 = 45.673 us Example of Calibration (data is for Carolina Beach)

  7. Note: 0.0996 * 133 = 0.0798 * 166 = 13.2468 sec.

  8. Note: 8970M (Dana) off by –0.9 usec per USCG TOTM and approx. 0 per USNO. Note: 8290M (Havre) off by 2.3usec per USCG TOTM and 0.1 usec per USNO.

  9. Pulse Analysis System Pentium PC w/ICS-650 (12 bit) or ICS-652 (14 bit) Antenna Current Transformer • Prototype developed & tested at Baudette 9/05/02 • 800 MHz P3, ICS-650 • Logged TOT, ECD, and Amplitude of each pulse, no raw RF data • Processed 2/3 of the PCI’s (one rate only) • Will continue development on 2 GHz P4 w/ICS-652, log raw RF

  10. Note: Outliers indicate need to log raw RF and visually verify why

  11. Future Plans • Visit to Seneca 8-10 Oct w/DCN (funded by NELS) • Effort to get common, worldwide, definition of what is meant by sync to UTC (presently 2.5 usec offset between USCG and NELS) • Visit to Boise City • Test new pulse analysis system • 2 usec Offset between USCG TOTM and USNO data • Visit to Dana • Long transmission line to resolve sign of delay term • Installation at what other secondaries? • TFE installation starts in Mar 03 in SEUS and will be about 1/month. Do we need the data now? • Gillette, Las Cruces, Searchlight, Middletown, etc. • Canada? • Have about 4 more GPS receivers available, do we procure more?

  12. Conclusions • TOTM system works well and is getting valuable data • I have long felt that large secondary offsets in TOT may be due to offsets between published and actual emission delays • Hence a need for minimum of 12 months of data to establish new values to avoid large position jumps in legacy receivers when going to TOT control. • Getting this data now may enable earlier transition to TOT control • Large offsets may be in master TOT and new emission delays may be unnecessary

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