Status – U. S. Maritime Backup Issues


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Status – U.S. Maritime Backup Issues

  • Session 2 , 28 October 2002
    • Status & Plans of LORAN-C Service Providers
  • 31st Annual
  • Convention & Technical
  • Symposium
  • of the
  • International LORAN Association
  • Crowne Plaza
  • Washington National Airport

Status – U.S. Maritime Backup Issues

FY02 LORAN-C Performance

  • A year of recapitalization and system modernization

FY02 LORAN-C Performance

  • LORAN-C Availability Review for the Period 1 October 2001 to 1 October 2002
  • The LORAN Operations Information System (LOIS 2 NT) was used to generate this report
  • LT Bob Berger and CWO Scott McDonald, NAVCEN LORAN Planning Branch provided the data analysis
  • Tok
  • NC
  • SC
  • PC
  • LOIS DATA GOA 7960 Oct 1, 01 – Oct 1, 02

NOCUS (8290) UUT by Cause

GLKS (8970) UUT by Cause

SOCUS (9610) UUT by Cause

USWC (9940) UUT by Cause

NEUS (9960) UUT by Cause

NORPAC (9990) UUT by Cause

FY02 LORAN-C AVAILABILITY

FY02 AVAILABILITY (less AUTM)

FY02 AVAILABILITY (less AUTM & Solar)

Status – U.S. Maritime Backup Issues

  • FY2002 U.S. LORAN-C Performance
    • LCDR Max Caruso, USCG NAVCEN Western Operations Officer
  • Synchronization to UTC
    • Gene Schlechte NAVCEN Operations Planning Division
  • Maritime Backup Assessment
    • CAPT Curtis Dubay, USCG NAVCEN Commanding Officer

LORAN Synchronization to UTC

  • Time Of Transmission Measurement (TOTM) Project started at LSU in late 1990s
  • 1997 - TOTM equipment installed at Williams Lake
  • Now - TTM installed at every US Master including the two in Alaska.

LORAN Synchronization to UTC

  • US Public Law 100-223, Section 310 requires the control the transmission of LORAN signals to within +/- 100 nanoseconds of UTC at times of coincidence (TOC).
  • The Coast Guard has worked with USNO to steer LORAN transmissions to UTC
  • USNO monitors & measures LORAN time differences (TD) in far field to determine difference between LORAN Chain & UTC

North American Loran-C System

  • DESTIN
  • MIDLAND
  • WHIDBEY ISLAND
  • FAIRBANKS
  • COLD BAY
  • GEORGE
  • NARROW CAPE
  • SHOAL COVE
  • GILLETE
  • NANTUCKET
  • CARIBOU
  • LSU
  • GREAT FALLS
  • GRAND JUNCTION
  • GRANGEVILLE
  • MALONE
  • CAROLINA BEACH
  • MONTAGUE
  • LUMSDEN
  • COMFORT COVE
  • ST. ANTHONY
  • DUNBAR FOREST
  • BAUDETTE
  • HAVRE
  • SPOKANE
  • PORT HARDY
  • SAND SPIT
  • JUNEAU
  • TOK
  • GALENA
  • PORT CLARENCE
  • SPRUCE CAPE
  • ST. PAUL
  • PETROPAVLOVSK, RUSSIA
  • ALEXANDROVSK, RUSSIA
  • WILLIAMS LAKE
  • MEDICAL LAKE
  • PT. PINOS
  • NAVCENDET
  • PETALUMA
  • PT. CABRILLO
  • MIDDLETOWN
  • FALLON
  • SEARCHLIGHT
  • LAS CRUCES
  • BISMARK
  • BOISE CITY
  • LITTLE ROCK
  • DANA
  • NEW ORLEANS
  • JUPITER INLET
  • MAYPORT
  • NAVCEN
  • ALEXANDRIA
  • PLUMBROOK
  • SANDY HOOK
  • CAPE ELIZABETH
  • SENECA
  • CAPE RACE
  • FOX HARBOR
  • RAYMONDVILLE
  • ATTU
  • CONTROL SITE
  • TRANSMITTER STATION
  • PCMS SITE
  • USNO Monitor

Time of Transmission System

  • Provides a means to monitor Loran transmissions directly at the transmitting antenna.
    • Eliminates propagation path uncertainties making +/- 100 nanosecond control possible

Time of Transmission System

  • UTC at USNO
  • GPS Time

TTM Installation at Master Station

SOCUS (9610) TTM Data Plot 15JUL -13OCT 2002

SOCUS (9610) TTM Log Sheet

NEUS (9960) TTM Data Plot 15JUL -13OCT 2002

NEUS (9960) TTM Data Plot 15JUL -13OCT 2002

TTM Calculation

  • TTM
  • = T2 Raw Data Avg + T1 Cal - Pulse Tracking Point - Cable Delays
  • (all in nanoseconds)
  • = ( 5108.6631+ 27088.251 - 30000 - 112 ) = 2085 nanoseconds
  • TTM
  • TTM Formula for USCG installation:
  • Sample TTM Calculation for NEUS (9960) on 13 October 2002:

Summary of UTC Measured Offsets

  • The following offsets have been established utilizing the installed TTM equipment:
    • NOCUS (8290-M): +2.3 usec
    • NORPAC (9990-M): +2.5 usec
    • SOCUS (9610-M): +1.8 usec
    • USWC (9940-M): +1.3 usec
    • GOA (7960-M): +1.2 usec
    • GLKS (8970-M): -0.4 usec
    • SEUS (7980- M): +0.1 usec
    • NEUS (9960-M): +0.02 usec

Plan to Remove LORAN UTC Offsets

  • NAVCEN is planning to time step one chain per week
  • We will send advance user notice before a Chain time step
  • We Plan to insert one time step for each chain on a Tuesday at 0900 Local time
  • The time step amount (in microseconds) will be included in the user notice
  • This process is considered to be the least problematic for the timing/legacy user.

USCG LORAN TTM Contacts

  • Navigation Center (Operations Planning)
    • LT Bob Berger, RBerger@navcen.uscg.mil
  • LORAN Support Unit (Technical)
    • Mike Campbell, MCampbell@lsu.uscg.mil
  • Program Manager’s Staff (Policy)
    • LCDR John Merrill, JMerrill@comdt.uscg.mil

Status – U.S. Maritime Backup Issues

  • FY2002 U.S. LORAN-C Performance
    • LCDR Max Caruso, USCG NAVCEN Western Operations Officer
  • Synchronization to UTC
    • Gene Schlechte NAVCEN Operations Planning Division
  • Maritime Backup Assessment
    • CAPT Curtis Dubay, USCG NAVCEN Commanding Officer

Maritime Assessment

  • Volpe Study shows vulnerability of GPS
      • Maritime modes concur
      • Current infrastructure satisfactory
      • E-navigation poses growing vulnerability

Maritime Assessment

  • Future vision – “System of systems” that incorporates adequate backups
      • Conventional navigation capability,
      • Regulatory procedures,
      • Development of alternate “e-inputs”

Maritime Assessment

  • Two Safety Critical Applications
    • Harbor, harbor approach, and constricted waterways
        • Total reliance on DGPS is a concern
    • Automatic Identification System (AIS)
        • Positioning and timing are concerns

Maritime Assessment

  • Comments on Study Recommendations
    • Continue LORAN-C modernization
      • Assess capabilities of “enhanced LORAN”
    • Certification of GPS receivers
      • By July 2002, a maritime certification program will be in place under SOLAS
      • USCG participation in domestic and international standards setting bodies

Maritime Assessment

  • Backup System Initiatives
    • Leverage FAA’s LNAV LORAN study
    • Partner with industry to analyze enhanced LORAN capabilities
    • Develop & assess integrated maritime receiver technology

Status – U.S. Maritime Backup Issues

  • Session 2 , 28 October 2002
    • Status & Plans of LORAN-C Service Providers
  • 31st Annual
  • Convention & Technical
  • Symposium
  • of the
  • International LORAN Association
  • Crowne Plaza
  • Washington National Airport


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