International Journal

on Marine Navigation

and Safety of Sea Transportation

Volume 5

Number 1

March 2011

1 BACKGROUND

The International Maritime Organization (IMO) [1]

adopted a “Strategy for the development and

implementation of e-Navigation” (MSC85-report,

Annexes 20 and 21).

In particular, IMO adopted the following defini-

tion of e-Navigation:

“e-Navigation is the harmonized collection, inte-

gration, exchange, presentation and analysis of mari-

time information onboard and ashore by electronic

means to enhance berth to berth navigation and re-

lated services, for safety and security at sea and pro-

tection of the marine environment”.

IMO has stated the driving forces and the conse-

quential goal for their e-Navigation concept as fol-

lows: << There is a clear and compelling need to

equip shipboard users and those ashore responsible

for the safety of shipping with modern, proven tools

that are optimized for good decision making in order

to make maritime navigation and communications

more reliable and user friendly. The overall goal is

to improve safety of navigation and to reduce errors.

However, if current technological advances continue

without proper coordination there is a risk that the

future development of marine navigation systems

will be hampered through a lack of standardization

on board and ashore, incompatibility between ves-

sels and an increased and unnecessary level of com-

plexity >> (IMO MSC 85, Annex 20, §2.1).

e-Navigation is therefore a vision for the integra-

tion of existing and new navigational tools, in a ho-

listic and systematic manner that will enable the

transmission, manipulation and display of naviga-

tional information in electronic format.

The paper is organized as follows. After the pre-

paring for e-Navigation in section 2, the initial e-

Navigation architecture is presented in section 3 fol-

lowed by the usage of radar to validate aids to navi-

gation including the identification of buoys by solid

state VTS / navigation radars in section 4. Conclu-

sion and future trends are reported in section 5 while

references in section 6 will close the paper.

2 PREPARING FOR E-NAVIGATION

IMO has invited IALA and other international or-

ganizations to participate in its work and provide

relevant input. IALA formed the e-Navigation (e-

NAV) committee for the purpose of developing rec-

ommendations and guidelines on e-Navigation sys-

tems and services. The committee aims to review

and develop related IALA documentation on issues

such as the impact of new radar technology on radar

aids to navigation, future Global Navigation Satellite

System (GNSS) and differential GNSS and the im-

pact of electronic ship-borne navigation aids on aids

e-Navigation and Future Trend in Navigation

F. Amato, M. Fiorini, S. Gallone & G. Golino

SELEX - Sistemi Integrati, Rome, Italy

ABSTRACT: The International Maritime Organization (IMO) adopted the following definition of e-

Navigation: “e-Navigation is the harmonised collection, integration, exchange, presentation and analysis of

maritime information onboard and ashore by electronic means to enhance berth to berth navigation and relat-

ed services, for safety and security at sea and protection of the marine environment”. A pre-requisite for the e-

Navigation is a robust electronic positioning system, possibly with redundancy. A new radar technology

emerged from the last IALA-AISM conference held in Cape Town, March 2010, where almost all the manu-

factures companies involved on navigation surveillance market presented –at various state of development-

solid state products for VTS and Aids to Navigation indicating a new trend for this application. The paper

present an overview of the systems for global navigation and new trend for navigation aids. The expected de-

velopments in this field will also be briefly presented.

to navigation systems. The committee also works

with other international organizations to develop the

overall e-navigation concept.

Concerning radars, a clear trend emerged from

the last IALA-AISM conference held in Cape Town,

March 2010, where almost all the manufactures

companies involved on navigation surveillance mar-

ket present –at various state of development- solid

state products for VTS and Aids to Navigation

[2][3][4]. The trend of events set the evolution from

the microwave tubes (klystrons and magnetron or

travelling-wave) [5] to the solid state technologies. It

starts from the IMO resolution 192(79) [6] who in-

tend to encourage the development of low power,

cost-effective radars removing (from July 2008) the

requirement for S-band radar to trigger RACONS

(radar beacons). Solid state radar may fulfill these

wishes making use of low-power and digital signal

processing techniques to mitigate clutter display that

are instead associated with high-power magnetron

based radars.

A full comparison magnetron versus solid state

VTS radars is provided in [7] including experimental

result with live data to show clutter filtering and

range discrimination of the solid state LYRA 50 ra-

dar. The advantage of solid state transmitted could

be summarized as long operational life and graceful

degradation, coherent processing, high duty cycle,

multi frequency transmission on a wide band, no

high voltage supply and compact technology.

Regarding GNSS and DGNSS, an overview of

the state of art is reported in [8] where also radio

aids to navigation are mentioned while an innovative

usage of radar to validate aids to navigation (AtoN)

is described later in this paper.

In short, based on the IMO definition, three fun-

damental elements must be in place as pre-requisite

for the e-Navigation. These are:

1 worldwide coverage of navigation areas by Elec-

tronic Navigation Charts (ENC);

2 a robust and possibly redundant electronic posi-

tioning system; and

3 an agreed infrastructure of communications to

link ship and shore but also ship and ship.

3 THE INITIAL E-NAVIGATION

ARCHITECTURE

In previous sections e-Navigation and its pre-

requisite were presented as a concept but in order to

implement such concept a technical architecture is

needed. It is shown hereafter (Figure 1) where the

shipboard entities, the physical link(s) and the shore-

based entities are included in this representation.

On the left side is represented, for simplicity’s

sake, a single “ship technology environment”. From

the e-Navigation concept’s perspective the relevant

devices within the ship technology environment are

the transceiver station, the data sources and the data

sinks connected to the transceiver station, the Inte-

grated Navigation System (INS) and the Integrated

Bridge System (IBS). The transceiver station is

shown as a single station for simplicity’s sake, alt-

hough there may be several transceiver stations. The

entities which are involved with the specifics of the

link technology are confined by the dotted line.

Figure 1. e-Navigation architecture Source: IALA e-NAV140

[9]

The shore-based technical e-Navigation services,

in their totality and by their interactions, provide the

interfaces of the shore-based user applications to the

physical link(s). They also encapsulate their tech-

nology to the whole of the common shore-based e-

Navigation system architecture. Encapsulation, used

as an Object Oriented Programming term is ‘the

process of compartmentalizing the elements of an

abstraction that constitute its structure and behavior;

encapsulation serves to separate the contractual in-

terface of an abstraction and its implementation’.

The encapsulation principle hides the technology’s

sophistication from the shore-based e-Navigation

system as a whole and thus reduces complexity. The

entities which are involved with the specifics of the

link technology are confined by the dotted line.

Amongst other benefits, it allows for parallel work

of the appropriate experts in the particular technolo-

gy of a given physical link, provided the functional

interfaces of the shore-based technical e-Navigation

services are well defined.

For the precise technical structure of the shore-

base technical e-Navigation services, the common

shore-base e-Navigation system architecture is under

development for a future IALA Recommendation.

It is also showed the World Wide Radio Naviga-

tion System (WWRNS), which includes GNSS, be-

ing presented as a system external to the e-

Navigation architecture providing position and time

information. The Universal Maritime Data Model

was also introduced as an abstract representation of

the maritime domain [9].

4 USAGE OF RADAR TO VALIDATE AIDS TO

NAVIGATION

The use of an additional source of information to

improve AtoN has been suggested by Barker in [10]

where he consider the vessel traffic routing infor-

mation providing by the Automatic Identification

System (AIS) as an improvement in the AtoN as-

sessment. On the contrary the on board radar of ves-

sels travelling around an AtoN device could be used

to assess and to check the position of the

buoys/beacons resulting in an almost real-time veri-

fication of the information provided by the Aids and

consequently alert for maintenance if needed. To

this end, new generation VTS / navigation radars [2]

provide a break-through for the task of target classi-

fication.

4.1 Identification of buoys by solid state VTS /

navigation radars

In this section an example of application of the de-

scribed system is shown.

Navigation buoys are often affected by drift or

malfunctioning. A method to detect the presence of

the buoy and the correct position is addressed, and

data are sent to ground base station, in order to veri-

fy the position and the presence of the buoy against

the navigation maps. The method described is used

also for maintenance purpose, in case of failure of

the device (i.e. low battery) and uses just the passive

reflector positioned on the top of the buoy.

Conventional VTS / navigation radars have poor

classification capabilities at long distance due to

their non-coherent receiver and the limited range

resolution. Navigation radars equipped with magne-

trons usually are set for medium-high range, to im-

prove safety in navigation, using medium-long puls-

es (i.e. 30-75 m) with the consequence of very poor

discrimination in range.

New generation solid state radars permits to un-

couple resolution from transmitted pulse length by

using a coherent receiver and long coded pulses.

High range resolution can be preserved by imple-

menting a pulse compression algorithm in the digital

processor. The radar “LYRA 50” for example can

provide a range resolution of 9 m for all ranges up to

24 NM making use of long compressed pulses

shown in figure 2.

Figure 2. Example of digital a compressed pulse with close up.

The long uncompressed pulse has a time length of

30 µs (4.5 km) and an instantaneous bandwidth of

22 MHz. Due to the digital pulse compression the

resulting pulse is severely deformed: it presents one

high peak lasting only 60 ns (9 m) and a series of

much weaker peaks (side lobes) lasting all together

60 µs (9 km); however the side lobes are more than

40 dB lower with respect to the main one and their

contribute to the received signal is usually negligi-

ble.

Range profile can be associated to a radar report

and stored for classification purpose by the radar da-

ta processor. Buoys can be considered small object

for a radar having range extension less than 1 m

which produce a narrow peak signal in the radar re-

ceiver, whose width equal to the range resolution.

Small vessels usually generate a broader peak and

sometimes even different discriminated peaks when

the length of the vessel is greater than twice the

resolution.

An addition contribute to the classification pro-

cess of the target can be derived by analysis of the

amplitude of the echoes. A study on the variation of

the amplitude of the target echo over different scans

has been conducted by the authors using live radar

data (examples are shown see figures 3, 4 and 5).

Figure 3. Example of amplitude distribution from an buoy (live

data).

Figure 4. Example of target echoes amplitude distribution from

a small anchored boat (live data).

Figure 5. Example of target echoes amplitude distribution from

a tanker (live data).

5 CONCLUSION AND FUTURE TREND

For someone in the short term e-Navigation should

remain a theoretical concept but it is indubitably an

overall concept to which all marine users have to

deal with from now on.

Electronic positioning system is a prerequisite for

the e-Navigation and position fixing using GNSS is

prevailing amongst commercial and leisure users. By

the way radars and traditional Aids to Navigation

(AtoN) will continue to be required, at least for re-

dundancy and/or terrestrial backup to satellite sys-

tems, or in many military scenarios. Co-operation

between complementary systems such as radar and

AtoN should become stronger and stronger to as-

sessing the data and improving reliability for more

informed decisions.

These analysis should be used to improve the fil-

tering and the recognition of buoys, not only based

on the expected position data: the recognition pro-

cess is helpful to distinguish the radar echo of a

buoy from other fixed targets such as ships in stand-

by or outcropping rocks.

Further work may include studies on the range

extension of the radar echoes.

REFERENCES

[1] Internationa Maritime Office (IMO) website, www.imo.org

[2] F Amato, M. Fiorini, S. Gallone, G. Golino, “New Solid

State frontier on radar technologies”, Proc. International

IALA-AISM Conference 2010, Cape Town, South Africa,

21-27 March 2010

[3] J C Pedersen “A Next Generation Solid State, Fully Coher-

ent, Frequency Diversity and Time Diversity Radar with

Software Defined Functionality”, Proc. International IALA-

AISM Conference 2010, Cape Town, South Africa, 21-27

March 2010

[4] N Ward, M Bransby “New Technology Radars and the Fu-

ture of Racons”, Proc. International IALA-AISM Confer-

ence 2010, Cape Town, South Africa, 21-27 March 2010

[5] Collin R.E. “Foundations for Microwave Engineering” 2nd

Ed., McGraw-Hill, 1992

[6] IMO MSC79 resolution 192(79) (IMO, 2004)

[7] F Amato, M. Fiorini, S. Gallone, G. Golino, “Fully Solid

State Radar for Vessel Traffic Services”, Proc. International

Radar Symposiums, IRS 2010, Vilnius, Lithuania, 16-18

June 2010

[8] M. Fiorini, “e-Navigation: a Systems Engineering Ap-

proach”, Proc. MAST 2010, 5th Maritime Systems and

Technology conference, palazzo dei congressi, Rome, Italy,

9-11, November 2010

[9] e-NAV 140 “The e-Navigation Architecture – the initial

Shore-based Perspective” Ed.1.0, IALA Recommendation,

December 2009

[10] R Barker “AIS Traffic Analysis / The Risk Assessment

Process for Aids to Navigation”, Proc. International IALA-

AISM Conference 2010, Cape Town, South Africa, 21-27

March 2010