ILA 36 ILA 36 –– Orlando FloridaOrlando Florida1616‐‐17 October 200717 October 2007

Dr. Gregory Johnson, Ruslan Shalaev, Christian Oates, Alion Science & TechnologyCapt. Richard Hartnett, PhD, US Coast Guard AcademyDr. Peter Swaszek, University of Rhode Island

RequirementsRequirementsAccuracy, availability, integrity, continuity Accuracy, availability, integrity, continuity 

Accuracy RequirementsAccuracy RequirementsAviation: NPA Aviation: NPA –– RNP 0.3 (309 meters)RNP 0.3 (309 meters)

Maritime: HEA (8Maritime: HEA (8‐‐20 meters)20 meters)

LimitationsLimitationsSpatial and temporal variations in TOA observed by the Spatial and temporal variations in TOA observed by the receiver and presented to the position solution algorithmreceiver and presented to the position solution algorithm

10/17/2007 ILA 36 - Orlando, FL 2

ASF corrected TOAsASF corrected TOAsTo remove spatial component:To remove spatial component:Use published grid, interpolate between grid pointsUse published grid, interpolate between grid pointsIssues include grid density, regions of interest, and grid creation

To remove temporal component:To remove temporal component:Local monitor receiver, broadcast offsets over LDCLocal monitor receiver, broadcast offsets over LDCIssues include correlation distance, monitor averaging, multiplemonitor interpolation

10/17/2007 ILA 36 - Orlando, FL 3

Spatial ASF GridsSpatial ASF GridsHarbor Survey MethodologyHarbor Survey Methodology

Converting to a gridConverting to a grid

Required grid densityRequired grid density

Performance examplesPerformance examples

Temporal CorrectionsTemporal CorrectionsLDC architecture for live broadcast of differential LDC architecture for live broadcast of differential correctionscorrections

Prototype eLoran ReceiverPrototype eLoran ReceiverSample navigation performanceSample navigation performance

10/17/2007 ILA 36 - Orlando, FL 4

Identify the HEA area and generate sail plans that Identify the HEA area and generate sail plans that will cover all of the areas of interestwill cover all of the areas of interesttypically a 200m spacingtypically a 200m spacing

Tracks must be planned on inside and outside edges of Tracks must be planned on inside and outside edges of channelschannels

in general the area of interest needs to be overin general the area of interest needs to be over‐‐bounded.bounded.

Conduct field testConduct field testStatic monitor somewhere in the harbor area (harbor Static monitor somewhere in the harbor area (harbor monitor) monitor) 

Perform data collection mapping throughout the harbor; Perform data collection mapping throughout the harbor; measure ASFs and GPS positionmeasure ASFs and GPS position

10/17/2007 ILA 36 - Orlando, FL 5

Convert the measured ASFs to relative ASFs by Convert the measured ASFs to relative ASFs by subtracting the reference site ASF for the corresponding subtracting the reference site ASF for the corresponding times of the vessel ASF measurements.times of the vessel ASF measurements.This eliminates any temporal variations (due to daily, seasonal,This eliminates any temporal variations (due to daily, seasonal,weather, or system timing effects) from the measurements. weather, or system timing effects) from the measurements. 

Create spatial ASF grid from tracks of relative ASFsCreate spatial ASF grid from tracks of relative ASFsProcedure developed and refined over a series of Procedure developed and refined over a series of harbor surveysharbor surveysNew LondonNew LondonNew YorkNew YorkNorfolkNorfolkBostonBoston

10/17/2007 ILA 36 - Orlando, FL 6

Continuous vessel tracks in upper harborContinuous vessel tracks in upper harborStatic locations in upper harborStatic locations in upper harbor

VesselVesselVan on shoreVan on shore

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10/17/2007 ILA 36 - Orlando, FL 8

10/17/2007 ILA 36 - Orlando, FL 9-74.25 -74.2 -74.15 -74.1 -74.05 -74 -73.95 -73.9

40.35

40.4

40.45

40.5

40.55

40.6

40.65

40.7

40.75

9960-Seneca 9960-Caribou

9960-Nantucket

9960-Carolina-BSI RefSta

10/17/2007 ILA 36 - Orlando, FL 10

ASF<=-1-1<ASF<=-0.95-0.95<ASF<=-0.9-0.9<ASF<=-0.85-0.85<ASF<=-0.8-0.8<ASF<=-0.75-0.75<ASF<=-0.7-0.7<ASF<=-0.65-0.65<ASF<=-0.6-0.6<ASF<=-0.55-0.55<ASF<=-0.5-0.5<ASF<=-0.45-0.45<ASF<=-0.4-0.4<ASF<=-0.35-0.35<ASF<=-0.3-0.3<ASF<=-0.25-0.25<ASF<=-0.2-0.2<ASF<=-0.15-0.15<ASF<=-0.1-0.1<ASF<=-0.05-0.05<ASF<=-1.1102e-016-1.1102e-016<ASF<=0.050.05<ASF<=0.10.1<ASF<=0.150.15<ASF<=0.20.2<ASF<=0.250.25<ASF<=0.30.3<ASF<=0.350.35<ASF<=0.40.4<ASF<=0.450.45<ASF<=0.50.5<ASF<=0.550.55<ASF<=0.60.6<ASF<=0.650.7>ASF

-74.075 -74.05 -74.025-74.1 -74

40.6

40.65

40.7

40.75

boat datavan data

10/17/2007 ILA 36 - Orlando, FL 11

Vessel collected data at Vessel collected data at 25 static locations in the 25 static locations in the harborharbor

Held station next to buoy, Held station next to buoy, pier, etc.pier, etc.

Van collected data at 19 Van collected data at 19 static locations around static locations around the harborthe harbor

Different VesselDifferent VesselContinuous Track in lower harborContinuous Track in lower harborRepeat Upper harborRepeat Upper harbor12 static locations12 static locations

10/17/2007 ILA 36 - Orlando, FL 12

10/17/2007 ILA 36 - Orlando, FL 13

10/17/2007 ILA 36 - Orlando, FL 14-74.15 -74.1 -74.05 -74 -73.95 -73.9 -73.85 -73.8 -73.75

40.35

40.4

40.45

40.5

40.55

40.6

40.65

40.7

9960-Seneca9960-Caribou

9960-Nantucket

9960-Carolina-B

SI RefSta

8/22 – magenta8/23 – green8/24 - blue

10/17/2007 ILA 36 - Orlando, FL 15

-74.15 -74.1 -74.05 -74 -73.95 -73.9 -73.85 -73.8 -73.7540.35

40.4

40.45

40.5

40.55

40.6

40.65

40.7

40.759960-Nantucket

ASF<=-1-1<ASF<=-0.95-0.95<ASF<=-0.9-0.9<ASF<=-0.85-0.85<ASF<=-0.8-0.8<ASF<=-0.75-0.75<ASF<=-0.7-0.7<ASF<=-0.65-0.65<ASF<=-0.6-0.6<ASF<=-0.55-0.55<ASF<=-0.5-0.5<ASF<=-0.45-0.45<ASF<=-0.4-0.4<ASF<=-0.35-0.35<ASF<=-0.3-0.3<ASF<=-0.25-0.25<ASF<=-0.2-0.2<ASF<=-0.15-0.15<ASF<=-0.1-0.1<ASF<=-0.05-0.05<ASF<=-1.1102e-016-1.1102e-016<ASF<=0.050.05<ASF<=0.10.1<ASF<=0.150.15<ASF<=0.20.2<ASF<=0.250.25<ASF<=0.30.3<ASF<=0.350.35<ASF<=0.40.4<ASF<=0.450.45<ASF<=0.50.5<ASF<=0.550.55<ASF<=0.60.6<ASF<=0.650.7>ASF

USCG AUX Vessel MystUSCG AUX Vessel MystOct 2006Oct 2006Nov 2006Nov 2006

Test VanTest VanMar 2006Mar 2006

Other vesselsOther vesselsMar, Apr 2006Mar, Apr 2006

10/17/2007 ILA 36 - Orlando, FL 16

ILA 36 -Orlando, FL 17

10/17/200

7

-72.11 -72.1 -72.09 -72.08 -72.07 -72.06 -72.0541.28

41.29

41.3

41.31

41.32

41.33

41.34

41.35

41.36

41.37

41.38

9960-Seneca

9960-Caribou

9960-Nantucket

9960-Carolina-Beach

CGA RefSta

NL Hbr H-field, 10/16NL Hbr H-field, 10/17NL Hbr H-field, 11/8NL Hbr H-field, 11/9

-72.09 -72.088 -72.086 -72.084 -72.082 -72.08

41.335

41.34

41.345

41.35

41.355

NL Hbr H-field, 10/16NL Hbr H-field, 10/17NL Hbr H-field, 11/8NL Hbr H-field, 11/9

10/17/2007 ILA 36 - Orlando, FL 18

-72.11 -72.1 -72.09 -72.08 -72.07 -72.0641.28

41.29

41.3

41.31

41.32

41.33

41.34

41.35

41.36

41.37

41.38

9960-Nantucket

-72.11 -72.1 -72.09 -72.08 -72.07 -72.06 -72.0541.28

41.29

41.3

41.31

41.32

41.33

41.34

41.35

41.36

41.37

41.38

9960-Seneca

-0.95<ASF<=-0.9-0.9<ASF<=-0.85-0.85<ASF<=-0.8-0.8<ASF<=-0.75-0.75<ASF<=-0.7-0.7<ASF<=-0.65-0.65<ASF<=-0.6-0.6<ASF<=-0.55-0.55<ASF<=-0.5-0.5<ASF<=-0.45-0.45<ASF<=-0.4-0.4<ASF<=-0.35-0.35<ASF<=-0.3-0.3<ASF<=-0.25-0.25<ASF<=-0.2-0.2<ASF<=-0.15-0.15<ASF<=-0.1-0.1<ASF<=-0.05-0.05<ASF<=00<ASF<=0.050.05<ASF<=0.10.1<ASF<=0.150.15<ASF<=0.20.2<ASF<=0.250.25<ASF<=0.30.3<ASF<=0.350.35<ASF<=0.40.4<ASF<=0.450.45<ASF<=0.50.5<ASF<=0.550.55<ASF<=0.60.6<ASF<=0.650.65<ASF<=0.70.7<ASF<=0.750.75<ASF<=0.80.8<ASF<=0.850.85<ASF<=0.90.9<ASF<=0.951>ASF

Chesapeake Bay approach channel into Norfolk HarborChesapeake Bay approach channel into Norfolk Harbor

10/17/2007 ILA 36 - Orlando, FL 19

10/17/2007 ILA 36 - Orlando, FL 20

10/17/2007 ILA 36 - Orlando, FL 21

10/17/2007 ILA 36 - Orlando, FL 22

-76.4 -76.35 -76.3 -76.25 -76.2 -76.15 -76.1 -76.05 -76 -75.95 -75.936.85

36.9

36.95

37

37.05

37.1

9960-Seneca

0<ASF<=0.050.05<ASF<=0.10.1<ASF<=0.150.15<ASF<=0.20.2<ASF<=0.250.25<ASF<=0.30.3<ASF<=0.350.35<ASF<=0.40.4<ASF<=0.450.45<ASF<=0.50.5<ASF<=0.550.55<ASF<=0.60.6<ASF<=0.650.65<ASF<=0.70.7<ASF<=0.750.75<ASF<=0.80.8<ASF<=0.850.85<ASF<=0.90.9<ASF<=0.950.95<ASF<=1

Continuous tracks inner harbor, main channels, and Continuous tracks inner harbor, main channels, and entrance approach areaentrance approach area

10/17/2007 ILA 36 - Orlando, FL 23

10/17/2007 ILA 36 - Orlando, FL 24

10/17/2007 ILA 36 - Orlando, FL 25

-71.05 -71 -70.95 -70.9 -70.85 -70.8

42.3

42.32

42.34

42.36

42.38

42.4

42.42

42.44

Seneca

Caribou

NantucketCarolina-B

Dana

Cape-Race

Jupiter

RefSta

710200771120077122007

10/17/2007 ILA 36 - Orlando, FL 26

ASFs/TOAs processed to remove receiver filtering ASFs/TOAs processed to remove receiver filtering and velocity vector toward towers (and time lag)and velocity vector toward towers (and time lag)Precise track computed using L1/L2 GPS data postPrecise track computed using L1/L2 GPS data post‐‐processed with GrafNav s/w using CORS reference processed with GrafNav s/w using CORS reference stationsstationsASFs recalculated using precise track position and ASFs recalculated using precise track position and unfiltered TOAsunfiltered TOAsRelative ASFs calculatedRelative ASFs calculated

(ASF(ASFboatboat –– ASFASFrefref))

10/17/2007 ILA 36 - Orlando, FL 27

‐‐ Method for converting tracks to a gridMethod for converting tracks to a grid‐‐ Required grid densityRequired grid density‐‐ Performance examplesPerformance examples

Overdetermined least squares estimation method Overdetermined least squares estimation method akin to an akin to an ““inverse interpolationinverse interpolation”” (ION GNSS 2006)(ION GNSS 2006)

10/17/2007 ILA 36 - Orlando, FL 29

Recall standard linear interpolation: Recall standard linear interpolation: GivenGiven a function at grid points, we can interpolate a a function at grid points, we can interpolate a general general FF((x, yx, y)) by by 

with with 

Xj,Yk Xj+1,Yk

Xj,Yk+1 Xj+1,Yk+1

X,Y

10/17/2007 ILA 36 - Orlando, FL 30

( )( ) ( )( ) ),(),(1

),(1),(11),(

111

1

+++

+

+−+

−+−−=

kjkj

kjkj

yxabFyxFabyxFbayxFbayxF

kk

k

jj

j

yyyyb

xxxx

a−−

=−

−=

++ 11

and

a

b

Turn the equations around:Turn the equations around:

a, b, and F(x, y) are knowna, b, and F(x, y) are known

so each data point yields a linear equation in 4 unknownsso each data point yields a linear equation in 4 unknowns

solve large set of simultaneous linear equations to get gridssolve large set of simultaneous linear equations to get grids

10/17/2007 ILA 36 - Orlando, FL 31

( )( ) ( )( ) ),(),(),(1

),(1),(11

111

1

yxFyxabFyxFabyxFbayxFba

kjkj

kjkj

=+−+

−+−−

+++

+

-72.11 -72.1 -72.09 -72.08 -72.07 -72.06 -72.05 -72.0441.26

41.28

41.3

41.32

41.34

41.36

41.38

41.4nantucket

10/17/2007 ILA 36 - Orlando, FL 32-72.11 -72.1 -72.09 -72.08 -72.07 -72.06

41.28

41.29

41.3

41.31

41.32

41.33

41.34

41.35

41.36

41.37

41.38

9960-Nantucket

10/17/2007 ILA 36 - Orlando, FL 33

0 2000 4000 6000 8000 10000 12000-0.9

-0.8

-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

Time into path

ASF

0.0025 by 0.0025 degree grid - Nantucket

σ fit error = 10 nsec

measuredmodeled

0 2000 4000 6000 8000 10000 12000-0.7

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

Time into path

ASF

0.0025 by 0.0025 degree grid - CarolinaBeach

σ fit error = 47 nsec measuredmodeled

0 2000 4000 6000 8000 10000 12000-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

Time into path

ASF

0.0025 by 0.0025 degree grid - Seneca

σ fit error = 21 nsec measuredmodeled

10/17/2007 ILA 36 - Orlando, FL 34

0 2000 4000 6000 8000 10000 12000-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

Time into path

ASF

0.0025 by 0.0025 degree grid - Seneca

σ fit error = 21 nsec measuredmodeled

0 2000 4000 6000 8000 10000 12000-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

Time into path

ASF

0.005 by 0.005 degree grid - Seneca

σ fit error = 22 nsec measuredmodeled

0 2000 4000 6000 8000 10000 12000-0.35

-0.3

-0.25

-0.2

-0.15

-0.1

-0.05

0

0.05

0.1

Time into path

ASF

0.001 by 0.001 degree grid - Seneca

σ fit error = 17 nsec measuredmodeled

Resolution ~meters Seneca Nantucket Carolina Beach0.0005 55 13 3 300.0010 110 17 7 400.0015 165 20 9 440.0020 225 21 10 470.0025 280 21 10 470.0050 560 22 10 48

Fit error in nsec

10/17/2007 ILA 36 - Orlando, FL 35-72.11 -72.1 -72.09 -72.08 -72.07 -72.06 -72.05

41.28

41.29

41.3

41.31

41.32

41.33

41.34

41.35

41.36

41.37

41.38

newH0025.mat

nantucket

9960-Seneca9960-Nantucket

9960-Carolina-B

CGA RefSta

10/17/2007 ILA 36 - Orlando, FL 36

15.26 15.27 15.28 15.29 15.3 15.31 15.32 15.330

5

10

15

20

25NL Harbor Test 10/16- Grid Performance

Positio

n Er

ror, m

UTC HH.h

20m bound

0 2 4 6 8 10 12 140

5

10

15

20

25

30

Error, m

Cou

nt

-10 -5 0 5 10 15-15

-10

-5

0

5

10

15

Error East-West, m

Erro

r Nor

th-S

outh

, m

95% err: 9.7645m

10/17/2007 ILA 36 - Orlando, FL 37

-74.1 -74.05 -74 -73.95 -73.9

40.46

40.48

40.5

40.52

40.54

40.56

40.58

40.6

40.62Seneca

9960-Nantucket

9960-Carolina-B

RefSta

9960-Seneca

ASF<=-1-0.8<ASF<=-0.75-0.75<ASF<=-0.7-0.7<ASF<=-0.65-0.65<ASF<=-0.6-0.6<ASF<=-0.55-0.55<ASF<=-0.5-0.5<ASF<=-0.45-0.45<ASF<=-0.4-0.4<ASF<=-0.351>ASF

10/17/2007 ILA 36 - Orlando, FL 38

16.6 16.7 16.8 16.9 17 17.10

5

10

15

20

25

30NY Harbor Test 2- Grid Performance

Posi

tion

Erro

r, m

UTC HH.h

20m bound

0 2 4 6 8 10 120

50

100

150

200

250

300

Error, m

Cou

nt

-15 -10 -5 0 5 10 15-15

-10

-5

0

5

10

15

Error East-West, mEr

ror N

orth

-Sou

th, m

95% err: 7.0103m

10/17/2007 ILA 36 - Orlando, FL 39

-76.4 -76.35 -76.3 -76.25 -76.2 -76.15 -76.1 -76.05 -76 -75.95 -75.9

36.9

36.95

37

37.05

37.1

NorfolkMay07H005.mat

Seneca grid

Nantucket

JupiterCarolina-B

Dana

Malone

Seneca

RefSta

17 17.01 17.02 17.03 17.04 17.05 17.06 17.070

5

10

15

20

25

30Norfolk Harbor Test March 2007- Grid Performance

Posi

tion

Erro

r, m

UTC HH.h

20m bound

10/17/2007 ILA 36 - Orlando, FL 40

0 5 10 15 20 25 300

5

10

15

20

25

30

35

40

Error, m

Cou

nt -30 -20 -10 0 10 20 30-30

-20

-10

0

10

20

30

95% err: 18.1326m

Error East-West, m

Erro

r Nor

th-S

outh

, m

10/17/2007 ILA 36 - Orlando, FL 41

-71.08 -71.06 -71.04 -71.02 -71 -70.98 -70.96 -70.94 -70.92

42.33

42.34

42.35

42.36

42.37

42.38

42.39

42.4

July07Boston_inner_Hgrid0025.mat

seneca

9960-Seneca

9960-Caribou

9960-Nantucket9960-Carolina-B

RefSta

10/17/2007 ILA 36 - Orlando, FL 42

14.84 14.86 14.88 14.9 14.92 14.94 14.96 14.98 150

5

10

15

20

25

30Boston Harbor Test July 2007- Grid Performance

Posi

tion

Erro

r, m

UTC HH.h

20m bound

0 2 4 6 8 10 120

10

20

30

40

50

60

70

Error, m

Cou

nt

-10 -5 0 5 10-10

-5

0

5

10

95% err: 7.3732m

Error East-West, m

Erro

r Nor

th-S

outh

, m

Loran error, Boston Harbor Test July 2007

‐‐ LDC ArchitectureLDC Architecture‐‐ Typical Spatial CorrelationTypical Spatial Correlation

10/17/2007 ILA 36 - Orlando, FL 43

10/17/2007 ILA 36 - Orlando, FL 44

Seasonal Monitor SitesSeasonal

Monitor SitesSeasonal Monitor SitesSeasonal

Monitor SitesSeasonal Monitor Sites

Seasonal Monitor Server wxTxmtr

• grab ASF values from current SM data file• Convert to offsets from reference value• write in LDC format to file• ftp file to server at LSU

LSUFTP Server

Loran TransmitterLoran

TransmitterLoran TransmitterLoran

Transmitter

LDC

Loran and GPS data at 1min intervals

Archived data

Each message is 45 bits and takes 24 symbols to transmit at 1 syEach message is 45 bits and takes 24 symbols to transmit at 1 symbol/groupmbol/groupAt 8970 takes 2.15sec/msgAt 8970 takes 2.15sec/msgTime: 5 every 64 messages or ~ every 27.5secTime: 5 every 64 messages or ~ every 27.5secASF data repeats every 2.3 minASF data repeats every 2.3 min

10/17/2007 ILA 36 - Orlando, FL 45

Mon-6Msg-0

Mon-6Msg-1

Mon-6Msg-2

Mon-6Msg-3

Mon-6Msg-4

Mon-6Msg-5

Mon-4Msg-0

Mon-4Msg-1

Mon-4Msg-2

Mon-4Msg-3

Mon-4Msg-4

Mon-4Msg-5Time Alm.

Mon-0Msg-0

Mon-0Msg-1

Mon-0Msg-2

Mon-0Msg-3

Mon-0Msg-4

Mon-0Msg-5

Mon-0Msg-0

Mon-0Msg-1

Mon-0Msg-2

Mon-0Msg-3

Mon-0Msg-4

Mon-0Msg-5Time Alm.

Mon-3Msg-0

Mon-3Msg-1

Mon-3Msg-2

Mon-3Msg-3

Mon-3Msg-4

Mon-3Msg-5Time Alm.

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repeats

‐‐ Prototype receiverPrototype receiver‐‐ Sample performanceSample performance

10/17/2007 ILA 36 - Orlando, FL 46

10/17/2007 ILA 36 - Orlando, FL 47

USCGA DDC Receiver• TOAs• demodulated LDC symbols• real-time ASFs (for comparison)

Matlab Script• Lookup ASF grid value• RS decode LDC symbols,• Interpret transmitted data• Apply transmitted temporal

correction and referencestation value

• Calculate position solution•Output position as NMEA string

Transview Display• Display position tracks of eLoran, Loran, and GPS systems

SatMate Receiver• Loran position

NovAtel Receiver• GPS position

10/17/2007 ILA 36 - Orlando, FL 48

Spatial ASF GridsSpatial ASF GridsNoise in the ASF measurements gets averaged out by the grid creaNoise in the ASF measurements gets averaged out by the grid creation processtion process500m grid spacing is typically sufficient500m grid spacing is typically sufficient

Smaller spacing only if dictated by physical size of HEASmaller spacing only if dictated by physical size of HEASmaller sizes just chase the noise in the measurementsSmaller sizes just chase the noise in the measurements

Harbor Survey procedure has been established and provenHarbor Survey procedure has been established and provenTemporal ASFTemporal ASF

Correct temporal value is critical to meeting HEA accuracyCorrect temporal value is critical to meeting HEA accuracyCurrently under investigation:Currently under investigation:

Frequency (and filtering) of corrections Frequency (and filtering) of corrections Monitor site spacingMonitor site spacingEndEnd‐‐state distribution architecturestate distribution architecture

eLoran ReceivereLoran ReceiverIn areas where geometry / signal strength are poor, receiver perIn areas where geometry / signal strength are poor, receiver performance becomes formance becomes criticalcritical<20m real<20m real‐‐time is difficult time is difficult –– even with ASF spatial (grid) and temporal corrections, even with ASF spatial (grid) and temporal corrections, requires a good receiver requires a good receiver 

10/17/2007 ILA 36 - Orlando, FL 49

Alion New London TeamAlion New London TeamChristian OatesChristian OatesRuslan ShalaevRuslan ShalaevMark WigginsMark WigginsKen DykstraKen Dykstra

USCG AuxiliaryUSCG AuxiliaryCaptain and crew of Launch #5 (New York)Captain and crew of Launch #5 (New York)Captain and crew of Myst (New London)Captain and crew of Myst (New London)Captain and crew of Halcyon Lace (Norfolk)Captain and crew of Halcyon Lace (Norfolk)Captain and crew of Three JCaptain and crew of Three J’’s (Boston)s (Boston)

USCG Loran Support UnitUSCG Loran Support UnitCDR Chris NicholsCDR Chris NicholsLT Chris DufresneLT Chris Dufresne

10/17/2007 ILA 36 - Orlando, FL 50

gwjohnson@alionscience.comgwjohnson@alionscience.comswaszek@ele.uri.eduswaszek@ele.uri.eduRichard.j.hartnett@uscga.eduRichard.j.hartnett@uscga.edu