International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 5

Number 4

December 2011

463

1 INTRODUCTION

Integrated Vessel Traffic Control System realizing

fusion of data received from shore based station of

the Automatic Identification System (AIS) and pulse

and Frequency Modulated Continuous Wave

(FMCW) radars and presenting information on Elec-

tronic Navigational Chart issued by the Polish Na-

tional Hydrographical Service – Hydrographical Of-

fice of the Polish Navy is described in other paper

presented on this conference. Described system was

designed, built and tested in the scope of research

work financed by the Polish Ministry of Science and

Higher Education as developmental project No

OR00002606 from the means for science in 2008-

2010 years.

This paper described results of the exploitation

test of the constructed system conducted in real sea

conditions using hydrographical vessels “Tukana”

and “Zodiak” owned by the Maritime Office in

Gdynia.

2 DESCRIPTION OF THE MEASUREMENTS

Measurements were conducted on 30

of September

and 24

of November 2010 using:

− Installed on shore in the radar laboratory of the

Gdynia Maritime University:

− Pulse radar Raytheon NSC 34;

− FM-CW radar built by the Przemysłowy Insty-

tut Telekomunikacji S.A.; and

− Class A ship borne AIS type R4 produced by

SAAB.

− Hydrographical vessel “Zodiak” equipped with:

− Receiver GPS RTK Trimble R7 L1L2 using

during the tests GPS reference station ID 745

situated in Gdynia; and

− Ship borne AIS R4 produced by SAAB.

− Hydrographical vessel “Tucana” equipped with:

− Receiver GPS RTK R7 using during the tests

the same GPS reference station; and

− Ship borne AIS R4 produced by SAAB too.

Basic parameters of utilized ships and radars are

described in Tables 1-3. Vessels are presented in

Figures 1 & 2.

Table 1. Basic parameters of the hydrographical vessels “Zo-

diak” and “Tucana”

___________________________________________________

Ship’s parameter Value

Zodiak Tukana

___________________________________________________

Displacement 751 71

Length 61.3 m 23.0 m

Breadth 10.8 m 5.8 m

Mean draught 3.3 m 2.2 m

Power 2 x 706 kW 2 x 280 kW

Maximum speed 14.0 knots 12.0 knots

Height of the radar scanner 16 m 6.5 m

above sea level

___________________________________________________

Fusion of Data Received from AIS and FMCW

and Pulse Radar - Results of Performance Tests

Conducted Using Hydrographical Vessels

“Tukana” and “Zodiak”

A. Krol, T. Stupak & R. Wawruch

Gdynia MaritimeUniversity, Gdynia, Poland

M. Kwiatkowski, P. Paprocki & J. Popik

Telecommunication Research Institute Ltd., Gdansk Division, Poland

ABSTRACT: Paper presents results of performance tests of the Integrated Vessel Traffic Control System re-

alizing fusion of data received from shore based station of the Automatic Identification System (AIS) and

pulse and Frequency Modulated Continuous Wave (FMCW) radars and presenting information on Electronic

Navigational Chart issued by the Polish National Hydrographical Service – Hydrographical Office of the

Polish Navy. Tests were conducted in real sea conditions using hydrographical vessels “Tucana” and “Zodi-

ak” owned by the Maritime Office in Gdynia.

464

During the measurements were good weather

conditions without rainfalls. There were sea waves

0.5-1m high.

The main goal of the test was assessment of the

accuracy of information about ship’s position,

course over ground (COG) and speed over ground

(SOG) received from both shore based radars and

AIS before and after their fusion in comparison with

values of these parameters indicated by ship borne

DGPS receiver. Due to that there were automatically

registered positions, COG and SOG of the vessel in-

dicated by:

Table 2. Basic parameters of the radar Raytheon NSC 34

___________________________________________________

Parameter Value

___________________________________________________

Output power 25 kW

Carrier frequency 9410±30 MHz

Range 0.25; 0.5; 0.75; 1.5; 3; 6; 12;

24; 48; 96 NM

Pulse length 0.06 μs, 0.25 μs, 0.5 μs, 1.0 μs,

Pulse repetition freq. 3600 Hz, 1800 Hz, 900 Hz

IF bandwidth 20 MHz, 6 MHz

Antenna length 2.1336 m

Beam width horizontal/vertical 1.0°/23° dB

Polarisation Horizontal

Gain 29 dB

Rotation speed min/max. 22/26 rpm

Display size 28 inch

Resolution 1600 × 1200 pixels

Acquisition automatic up to 40 targets

Tracking automatic of all acquired target

Range accuracy 0.3% of selected range or 6.4 m

(whichever is greater)

Angle resolution 0.3°

Bearing accuracy 1.0°

___________________________________________________

Table 3. Basic parameters of the FM-CW radar

___________________________________________________

Parameter Value

___________________________________________________

Output power 1mW-2W (switched)

Carrier frequency 9.3 – 9.5 GHz

Frequency deviation 54 MHz at 6 NM

switched according to 27 MHz at 12 NM

the required scale range: 13.5 MHz at 24 NM

Range scales 0.25 NM – 48 NM

Modulation DDS based linear FMCW

Sweep repetition period 1 ms

IF bandwidth 4 MHz

Frequency curve slope of 6 dB/oct; 12 dB/oct; 18 dB/oct

IF amplifier

Antenna length 3.6 m

Beam width 0.70°/22° dB

horizontal/vertical

Polarisation Horizontal

Gain 32 dB

Rotation speed min/max 12/30 rpm

FFT signal processing 8192-points FFT

Sampling frequency 8 MHz

Display size 22 inch

Resolution 1280 × 1024 pixels

Acquisition automatic up to 100 targets

Tracking automatic of all acquired targets

Range accuracy 1% of selected range or 50 m

(whichever is greater)

Angle resolution 0.1°

Bearing accuracy 0.7°

___________________________________________________

Figure 1. Hydrographical vessel “Zodiak”

Figure 2. Hydrographical vessel “Tucana”

− GPS RTK receivers onboard ships;

− AIS and radars Raytheon NSC 34 and FM-CW

installed onshore in radar laboratory; and

− Display unit of the integrated system after fusion

of data from above mentioned sensors.

Figure 3 presents complete track of the ship “Zo-

diak”. Dots indicate positions in ten minutes time in-

tervals.

Figure 3. Complete track of the ship “Zodiak” during the

measurements showing its positions received from onboard

DGPS MX 420 receiver.

In figure 11 is presented part of the “Zodiak”

track utilised for analysis presented in further part of

this paper.

Figure 4 shows track of the vessel “Tukana” dur-

ing the measurements received from onboard GPS

RTK receiver and from shore based radar Raytheon.

465

3 RESULTS OF THE MEASUREMENTS

3.1 Accuracies of the data available on shore from

AIS and radars

Tested integrated system performs fusion of data re-

ceived from two connected radars and AIS. Due to

that one of the main goals of the described tests were

measurements of the accuracies of data available

from shore based AIS station and radars and compu-

tation of their errors by comparison with data regis-

tered in onboard GPS receiver for the same moments

of time.

Figure 4. Track of the vessel “Tucana” during the measure-

ments received from onboard GPS RTK receiver and from

shore based radar Raytheon.

Figure 5 presents differences during the test be-

tween ship’s positions, course over ground (COG)

and speed over ground (SOG) available for the same

moments of time onshore from AIS station and

onboard “Zodiak” from DGPS receiver. They were

accounted as differences between data: last received

from onshore AIS and presented by onboard DGPS

receiver. Errors arise due to the time differences be-

tween receiving by AIS data from ship’s GPS re-

ceiver and its transmission according to the

SOTDMA time schedule mainly. Additionally not

all ship’s transmissions were received by the shore

AIS station. For ship’s speed during the test (approx-

imately 4.6 m/s) vessel’s way between two consecu-

tive AIS transmission was equal to 45 m (for pas-

sages with steady courses) or approximately 15 m

(for course and/or speed alteration). Any fault in re-

ceiving AIS message causes errors directly propor-

tional to this way.

Received results are compliant to conclusions

done on the base of measurements of the AIS data

accuracies conducted on the ship “Dar Młodzieży”

and described in [1].

Radars begun to track echo of „Zodiak” after

leaving by this ship port in Gdańsk and lost vessel at

the entrance to the port in Gdynia when they con-

nected its target with echo from coastline. Tracking

was resumed after leaving the port and continued

during ship’s passage back to the Gdańsk.

Figure 6 presents differences between values of

courses speeds and positions indicated onshore by

ARPA Raytheon NSC 34 and by onboard DGPS re-

ceiver.

Figure 7 shows accuracies of ship’s positions re-

ceived from FM-CW radar during the test conducted

with vessel “Zodiak” and calculated in relation to its

AIS positions. Errors distribution of these positions

indicated incompatibility of cartographical coordi-

nate systems used for calculation of ship’s positions

transmitted by AIS and received on the base of radar

measurements. It was eliminated by corrections in-

troduced to the radar coordinates (0.0049’ to the

North and 0.0016’ to the West). Corrected radar data

was used for its fusion with information received

through AIS system.

466

Figure 5. Differences between values of courses, speeds and positions available from onshore AIS and DGPS receiver onboard the

ship

467

Figure 6. Differences between values of courses speeds and positions available from onshore radar Raytheon and DGPS receiver

onboard the ship

468

Figure 7. Accuracy of positions of vessel “Zodiak” received from FMCW radar

3.2 Data fusion

Data after its fusion is presented in Figures 8-11.

Figure 8. Distances between ship’s positions indicated by particular radars and display unit of the integrated system (after data fu-

sion) and AIS or GPS receiver

Figure 9. Information about ship’s course over ground (COG) indicated by onboard DGPS receiver (RTK) shore based FMCW

(FMCW) and pulse (RAY) radars and integrated system (after data fusion - Fuzja)

469

Figure 10. Information about ship’s speed over ground (SOG) indicated by onboard DGPS receiver (RTK) shore based FMCW

(FMCW) and pulse (RAY) radars and integrated system (after data fusion – Fuzja)

Figure 11.Track of the vessel “Zodiak” during tests plotted on the base of data available from onboard DGPS receiver (RTK) and

shore based FMCW (FMCW) and pulse (RAY) radars and display unit of the integrated system after data fusion (Fuzja)

4 CONCLUSIONS

According to recommendation of the International

Maritime Organisation (IMO) integrated navigation-

al system (INS) shall, after checking that infor-

mation received from AIS and radar tracking facili-

ties concerns the same object, present for this object

AIS data only. Conducted tests proved that AIS data

may present inexact information about present vec-

tor of object’s movement. Main reasons of this fault

are problems with receiving AIS messages without

time delay. Fusion of AIS and radar data as present-

ed in this paper may be helpful in solving indicated

problem. Additionally fusion of radar data increase

reliability of radar data and its accuracy.

REFERENCES

[1] Król A., Stupak T: Dokładność rejestracji danych pozycyj-

nych statków w systemie nawigacji zintegrowanej. XIV In-

ternational Conference Transcomp 2010, Logistyka 6/2010

str. 1675 – 1681.