m COMMISSION OF THE EUROPEAN COMMUNITIES 
C0MC91) 1 final 
Brussels, 21 January 1991 
Proposal for a 
COUNCIL DECISION 
on the LORAN-C radionavigation system 
$ÈM (presented by the Commission) 
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l . Introduct ion 
The enhancement of the standard of maritime safety in general and in 
Europe in particular is one of the concerns of the Community. While 
recognising the important role of international organisations, such as 
the International Maritime Organisation, for the establishment of 
worldwide safety rules it is nevertheless in the field of operations of 
the maritime industry that the European Community can best develop 
specific actions. With the objective of ensuring the safety of 
navigation in Europe and neighbouring areas, the development and 
improvement of aids to navigation is one of the actions which we are 
currently concerned with. 
Although the Commission intends to outline its view on maritime safety 
at a later date, recent developments have made It a necessity to 
consider the matter of radionavigation aids at this stage. 
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Il. Radionavigation Aids 
Under the Safety of life at Sea Convention (SOLAS 1974), as amended, 
especially regulation 14 of Chapter V "Safety of Navigation", dealing 
with aids to navigation, each contracting government has the obligation 
to arrange the establishment and maintenance of such aids to navigation 
as in their opinion the volume of traffic justifies and the degree of 
risk requires. In European waters, and especially in coastal areas, 
radionavigation aids have long been recognised as an Important element 
of the provisions made to meet the above mentioned international 
obligation to maintain maritime safety. 
Radionavigation aids are complemented by the visual aids of lights and 
buoys, of which a basic system will continue to be necessary to mark 
hazards and navigable channels and give visual confirmation of a ship's 
position. With the advance of technology, however, there is a growing 
wealth of choice of electronic aids to navigation. 
The existing radiopositioning systems can be divided into two 
categories, the space-based systems on the one hand and the 
terrestrial-based systems on the other. The systems can be further 
classified on the basis of the extent of their coverage extending from 
purely local to worldwide coverage. 
Two satellite systems offering worldwide cover to an intended accuracy 
of 100 metres for civil users are expected to be operational in the mid 
1990's.These are the U.S. Global Positioning System (GPS) and the USSR 
Global Navigation Satellite System (GLONASS). 
Due to similarities between the two systems it might theoretically be 
possible for users to have receivers that could work with either 
system. Unfortunately both systems are military systems. Many 
organisations within the International Maritime Organisation have 
expressed reservations about adopting either system as a worldwide 
civil navigation system. As stated in the U.S. Federal Radionavigation 
Plan, GPS signals will be available to serve the safety of navigation 
at all times except during a time of national emergency when only those 
radionavigation signals that serve the national interest will be 
available. The recent past has proved that despite the policy detente 
regional conflict cannot be ruled out. Thus total reliance on any 
single system would expose users to the risk of having no 
radionavigation aid. In addition there is uncertainty concerning the 
possible future introduction of user dues on the satellite systems. 
On the European level, GRANAS (Global Radionavigation System) and 
NAVSAT , developed by the European industries, funded by the European 
Space Agency, are global civil navigation satellite systems which have 
similar operational objectives to GPS. These are still in the planning 
phase. 
Technical specifications of these systems are given in annex B 1. 
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The satellite systems will provide three dimensional position 
determination. Satellite systems have an achievable accuracy of between 
2.4 and 24 metres according to whether the user is stationary or moving 
but for the civilian user the accuracy offered is in the order of 100 
metres. 
As terrestrial-based radionavigation systems suitable for general 
navigational .purposes the OMEGA, the DECCA Navigator System and the 
LORAN-C system can be identified. 
The OMEGA system provides position fixing of limited accuracy, it Is 
only usable for general navigation on routes followed by ships in the 
ocean phase and for aircraft. It Is likely to be replaced by GPS but 
may be retained for marine use until the turn of the century. 
The technical specifications of the DECCA system are given In annex 
B 1. Coverage by DECCA is adequate around the British Isles, extensive 
in western Europe from Norway to the English Channel including part of 
the Baltic, it is also provided in certain other sea areas around the 
Iberian Peninsula, Australia, Japan, South Africa, India and the 
Arabian Gulf, it has been estimated there are about 140.000 users 
worldwide; most are in Europe. In total about 80.000, rising to 90.000 
by the end of 1989, are fitted to vessels which use three UK chains. 
The Loran-C system is also a terrestrial-based radio hyperbolic 
position-fixing system. The system is based upon measurements In the 
difference in time of arrival of pulses of radio frequency energy 
radiated by a chain of synchronised transmitters which are separated by 
hundreds of miles. More technical information is given In annexes B 1 
and B 2. 
Although initially established to meet US defense requirements LORAN-C 
is widely available for civil use in the Northern Hemisphere to all 
using a commercially available receiver. In addition to the fourteen 
LORAN-C chains managed by the US Coastguard worldwide LORAN-C chains 
have been established in France, Egypt, Saudi Arabia, China, India and 
Korea. The Soviet Union operates a similar radionavigation system 
caI led Chayka. 
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III. INTERNATIONAL DEVELOPMENTS 
The US Coastguard has stated its intention to cease funding and 
manning all Loran-C stations outside of the US at the end of 1994. The 
US Coastguard has also offered to transfer all or part of Loran-C 
station equipment to interested host nations when these are no longer 
needed by the U.S. 
A working group comprising representatives from Canada, Denmark, the 
Federal Republic of Germany, France, Iceland, Ireland, Norway the USA 
and IALA (the International Association of Lighthouse Authorities) 
started discussions about the future of Loran-C In 1983. 
In 1985 France introduced a Loran-C chain at Its own expense which is 
operated with two stations. 
From 1 January 1987 the RACAL DECCA Company ceased to be responsible 
for the management of the DECCA navigator chains around Great Britain 
and Ireland and the responsibility for them has been assumed by the 
Lighthouse Authorities. 
in March 1987 a special radionavigation Conference of IALA presented 
seven conclusions on Loran-C. The most important conclusion undoubtedly 
was that whereby Denmark, France, the Federal Republic of Germany, 
Ireland, the Netherlands, Norway and the United Kingdom agreed to enter 
into direct negotiations with each other to consider the possibility of 
extending Loran-C coverage in N.W. Europe. The conference concluded 
that in appropriate national and Regional areas terrestrial 
radionaviagtion systems should be maintained after the introduction of 
new satellite navigation systems for the foreseeable future. 
Another conclusion reached by the conference was that the IALA will 
continue to pursue the possibility of extending Loran-C coverage along 
the Iberian Peninsula and in the Mediterranean until such time as the 
governments concerned are in a position to enter into direct 
negotiations with each other. 
Discussions between the Mediterranean countries started In 1989 in IALA 
with the participation of the Commission of the European Communities to 
examine the need to maintain or even extend Loran-C in the 
Mediterranean area. 
in 1989 the USA and the USSR signed an agreement for a Joint Loran-
C/CHAYKA radionavigation system to facilitate improved marine and air 
navigation in the North Pacific Ocean and the Bering Sea areas. 
in April 1990,the UK decided in principle, on technical and cost 
grounds, to join the international civil Loran C system currently 
proposed for N w Europe and the North Atlantic. Implementation of this 
decision is dependent upon a satisfactory International agreement being 
achieved by early/mid 1991 with the other interested states, with the 
new Loran c system in place and operational before the end of 1993.The 
existing contractual arrangements for the UK Decca Navigation system 
extend to February 1997. 
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in May 1990 the French, Portuguese and Spanish governments begun expert 
level discussions on the establishment of a Loran-C chain for the 
Atlantic with sufficient coverage to link the Mediterranean and North 
Atlant ic cha ins. 
in September 1990 IALA chaired a first meeting, In Tokyo, between 
Japan, USSR, China and Republic of Korea with a view to seeking the co­
operative operation of the Loran-C in these countries. 
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IV. ADVANTAGES AND POSSIBILITIES POSED BY THE LORAN-C 
Loran-C satisfies the mariners needs for accuracy. It meets the 
requirements of IMO Resolution A 529 (13) and provides an accuracy 
level at least equal to, and in many cases better than, the existing 
DECCA system. 
The existence, of operational Loran-C stations, and others coming into 
operation, facilitates the development of a European Network In the 
short term. 
The handover of existing facilities without charge has an obvious cost 
advantage and Loran-C is considered to be markedly less costly than 
the existing DECCA system. 
Loran-C is capable of being extended to provide coverage of all 
European and neighbouring waters without major difficulty. Existing 
projects will offer coverage of blind radionavigation areas which is 
not possible with existing DECCA (especially in Irish waters, and the 
Bay of Biscay). Furthermore the co-operation with the USSR Chayka 
Chains will oe possible. 
The existing Loran-C charts would continue to apply thus minimising 
inconvenience and costs to mariners. 
The Loran-C system has proved to have an acceptable level of 
reliability of operation which is vital for the mariner. 
Loran-C technology is already developed and transmitters/receivers are 
commercially available. A large number of receiver types are available 
without restrictive systems patents. This provides considerable scope 
for lower unit costs and hence lower selling prices of receivers as the 
system is extended. 
Confidence is lacking in the continuing availability of essentially 
military satellite systems and Loran-C would be a terrestrial-based 
alternative civil system under the control of contracting governments. 
The chain configuration of Loran-C facilitates phased implementation 
for programmed growth and utility in the coverage area. 
As there is no limit to the number of receivers that can use Loran-C 
simultaneously future capacity considerations are accommodated. 
Applications of Loran-C are not confined to maritime use. It can also 
be extended for land and air use. There has been a significant Increase 
in the number of users in the US civil aviation community in recent 
years. The US has established new stations to complete coverage of the 
entire continental US. 
Combined Sate I Iite/Loran-C coverage will offer the highest degree of 
system verification and continuity of radionavigation coverage for the 
benefit of maritime safety and environmental protection. 
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V. State of the discussion on international level 
1. North West European chain : 
The governmental representatives of Denmark, The Federal republic of 
Germany, France, Ireland, the United Kingdom, Canada, Iceland and 
Norway, members of the Loran-C Policy Group, will finalise an 
agreement bas,ed upon the Policy-Group report before the end of this 
year. Since July 1990 the E.C. Commission has attended the meetings of 
the Group as an observer. 
The governments participating in the Loran-C Policy Group will be 
invited to establish a Loran- C system for North West Europe and the 
North Atlantic. An agreement has and already been reached on the 
configuration (Annex B 2) and on the technical requirements of the 
System (Annex B 3). 
it will be noted that in the current stage of the discussions the 
Benelux countries are not envisaged to be involved in the foreseen 
agreement. 
The Netherlands initially participated in the policy group but decided 
not to participate in the agreement. Their reasons are that the two 
DECCA navigator chains controlled by the Dutch authorities still meet 
the requirements regarding maritime traffic In their coastal waters. 
Despite the opinion of all other Member States involved, the 
Netherlands considers that putting Loran-C into operation in Dutch 
coastal waters would be a superfluous interim step in the global 
changeover from terrestrial navigation systems to satellite based 
systems. 
Denmark has already agreed to maintain the Loran-C stations in Ejde and 
Angissoq but will not be able to take a final decision regarding Its 
participation in the final agreement before the end of this year. It is 
the intention of the Policy Group to finalise the agreement before the 
end of the year even if the Netherlands or Denmark will not participate 
in an agreement. 
Germany supports the NWE chain. That results from the inclusion of the 
Sylt station in the chain. Germany is prepared to support an 
enhancement of the Loran-C system in the Baltic with possible new 
stations in the eastern part of Germany or the Polish area. The 
International Telecommunications Unions has already been asked to 
allocate frequencies for an East European Chain. The Soviet Union is 
prepared to co-operate In this respect. 
The United Kingdom, Ireland and Iceland support the agreement with the 
largest coverage area. The UK emphasised that an acceptable 
international agreement on Loran-C is a prerequisite for the UK for 
changing from its DECCA system to the Loran-C. 
France is prepared to bring its two stations built on its own account 
into the system. France is supporting the chain with the largest 
coverage to ensure the link with the foreseen Atlantic chain. Therefore 
France is prepared to make signals from its two stations available for 
hyperbolic use of the system with other stations. 
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Canada is participating in the chain because of its interest In the 
Loran-C station at Angissoq which is dualrated as part of the Labrador 
Sea chain. 
it is important to emphasise that the decision of the Netherlands or 
Denmark not tp participate in an agreement will probably not affect the 
configuration and coverage of the foreseen N.W. European Chain. 
Although a revision of the costsharing agreement could have an 
influence on some technical aspects such as the power of the stations. 
The agreement will be finalised in the January meeting of the Policy 
group. 
The Mediterranean chain 
The IALA took the initiative to bring the interested parties of the 
Mediterranean area together with the aim of setting up a similar 
agreement to the NWE agreement. Representatives of Italy, Greece, 
France, Spain, Portugal, Algeria, Egypt, the US Coast Guard and the 
Commission of the E.C. have met each other since January 1989. 
There is a general consensus in the Mediterranean working group in 
favour of maintaining the existing Loran-C stations In Italy and Spain 
and maintaining the existing coverage In the Mediterranean for the 
benefit of merchant ships, fishing vessels, pleasure craft and 
hydrographie surveys after the US Coastguard cease to operate the 
stations in 1994. The latest meeting in Paris confirmed the need for a 
terrestrial navigation system in the Mediterranean Sea and that the 
Loran-c was the only feasible system meeting the maximum service 
requirements of coverage in the most cost-effective way. 
A subcommittee, coordinated by Italy, will study the technical and 
administrative matters concerning the existing Loran-C stations. 
To ensure a coverage equivalent to or even better than the actual chain 
it is vital that a solution for the re-sltlng of the Turkish Station 
of Kargaburun be found if the Turkish government maintains its decision 
not to take over the US Coastguard station on its territory. One 
solution could be to site a new station on Greek territory. The final 
objective of the group is to facilitate as soon as possible the setting 
up of a Mediterranean MOU for the Mediterranean Loran-C with 1994 as 
the operational target date. 
Iberian (Atlantic) chain 
The French, Spanish and Portuguese representatives participating In the 
Mediterranean Loran-C group, confirmed their intention to extend Loran-
C coverage into the Atlantic Ocean, including the Azores and the Canary 
islands and improve coverage in SW Mediterranean area. 
As a result, preliminary discussions started in Madrid in May 1990 
between experts of those countries. It Is the Intention to find an 
agreement on the configuration and the technical requirements of the 
chain thus ensuring a link with the NW European and Mediterranean 
cha ins. 
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VI. Community interests in the Loran-C chain 
The countries participating in the N.W. European Loran-C Policy group 
and in the Mediterranean Loran-C group consider It advisable that the 
goal should be to have a single terrestrial based radionavigation 
system, stretching from North Europe to the Mediterranean and through 
the Atlant ic. 
Without prejudice to the development of satellite navigational systems, 
the Commission supports the development of a European Loran-C coverage 
composed of three regional chains. A possible configuration of the 
Furopean chain is given in annex B 4) 
Taking account of the achievements of the discussions on a NW European 
chain and the intention of the Mediterranean countries regarding the 
Mediterranean and Iberian chains, the Commission supports the 
<.k:ve lopment of regional chains with the largest coverage area. 
As safety is an integral part of the Common Transport Policy it is the 
role of the Community to develop initiatives in the field of maritime 
safety with special regard to the maintenance of high safety standards. 
Having regard to the achievement of the objectives of the Treaty it Is 
the role of the Commission to base its proposals to the Council upon a 
high level of protection. 
Radionavigation systems are part of the safety environment of ships. 
The withdrawal of existing systems without any replacement by another 
reliable and accurate system will affect the level of safety of ship 
operations in Community waters. The development of regional Loran-C 
chains is, for the immediate future only, a suitable alternative for 
existing terrestrial systems which are being phased out, It will result 
m an improvement of the actual accuracy of radioposit Ioning. In the 
future Loran-C, as an essential and economical verification system for 
satellite navigational aids will contribute to the enhancement of 
maritime safety in Europe on a large scale. 
Recognising that Loran-C is an accurate radiopositioning system that 
can be developed on the European level in the very near future, the 
Commission, with the purpose of maintaining and developing the high 
standard of safety for ship operations In European waters, proposes 
to the Council that it supports the achievement of regional Loran-C 
chains in the European area. This will, through its operation, 
contribute significantly to the preservation and protection of the 
marine envirionment. 
Considering the need for the compatibility of the aids to navigation 
systems introduced or foreseen on the regional level in Europe it Is 
important that the Commission acts so as to ensure such compatibility. 
it must be noted that the withdrawal of any involved party from the 
envisaged agreement will seriously jeopardise the development of the 
European network. 
Following an agreement between the USA and the USSR on Loran-C the 
development of a European Loran-C chain will extend Loran-C coverage to 
the entire northern hemisphere. 
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As soon as the European interest in the Loran-C chains is recognised it 
win be necessary to improve the accuracy of the system and to develop 
the most suitable receivers, with regard to future developments 
espec ialy by satelIi te. 
Taking account of the decision of some Member States to cease operating 
the DECCA system appropriate measures have to be found to ensure the 
transition frpm one radionavigation system to another is achieved at 
the lowest cost for the users. 
The Commission is prepared to start investigation In this field. 
For all the above mentioned reasons there now exists a unique 
opportunity to provide a low-cost radionavigation system to cover 
European waters thus enhancing maritime safety and protection of the 
maritime environment. It is vital that this opportunity is seized. The 
Commission proposes to the Council the adoption, as soon as possible, 
of a Decision, based upon the proposal in Annex A. 
- 12 - ANNEX A 
Proposal for a 
COUNCIL DECISION 
on the LORAN-C radionavigation system 
THE COUNCIL OF THE EUROPEAN COMMUNITIES, 
Having regard to the Treaty establishing the European Economic 
Community, and in particular Article 84 paragraph 2 thereof, 
Having regard to the proposal from the Commission, 
Having regard to the opinion of the European Parliament, 
Having regard to the opinion of the Economic and Social Committee, 
Whereas the international Maritime Organisation (IMO) requires the 
contracting governments to the SOLAS Convention to undertake to arrange 
for the establishment and maintenance of such aids to navigation as the 
volume of traffic Justifies and the degree of risk requires; 
Whereas it is a concern of the Community to ensure the highest degree 
of safety of navigation and protection of the marine environment; 
Whereas the United States Coastguard has decided to terminate its 
LORAN-C commitments outside the USA before 1994 and has the intention 
to offer the LORAN-C facilities to the relevant host nations; 
Whereas the international Association of Lighthouse Authorities (IALA) 
supports the need for a terrestrial radionavigation system to meet the 
needs of maritime navigation; 
Whereas certain Member States intend to participate in one or more 
regional agreements on the establishment of LORAN-C chains covering 
North West Europe and the North Atlantic, the Mediterranean, the 
Iberian Peninsula and the Baltic; 
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Whereas the LORAN-C system satisfies the international requirements and 
the more general utilisation of the LORAN-C system does not prejudice 
the development of satellite aids to navigation; whereas, furthermore, 
combined coverage by satellite and LORAN-C will offer the highest 
degree of system verification and continuity of radionavigation 
coverage for the benefit of maritime safety and environmental 
protection; 
Whereas the establishment of regional LORAN-C systems must ensure, a 
coherent and complete coverage of the European maritime area, avoiding 
as much as possible the imposition of additional costs upon the users 
of existing terrestrial radionavigation systems; 
HAS ADOPTED THIS DECISION : 
Article 1 
1. The Member States shall participate in or Join regional agreements 
on LORAN-C as far as necessary to realise the international 
objectives. 
2. With regard to their participation in regional agreements the 
Member States shall seek to achieve the LORAN-C configurations 
which cover the widest possible geographical area in Europe and in 
neighbouring waters. 
Article 2 
The Commission: 
shall ensure coordination between the Member States 
participating in regional agreements with a view to 
ensuring compatabiIity between the LORAN-C chains 
introduced on the regional level, 
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shall encourage the development of LORAN-C receivers, 
taking account of the ongoing development of satellite 
systems and the enhancement of the present LORAN-C 
system, 
and shall propose, where necessary, to the Council the necessary 
measures. 
Article 3 
In their role as member or observer within the International 
Association of Lighthouse Authorities the Member States and the 
Commission shall strive to obtain the participation of the greatest 
possible number of countries in the European regional LORAN-C chains 
with the purpose of enlarging the coverage of LORAN-C worldwide in 
order to improve safety of navigation and protection of the marine 
env i ronment. 
Article 4 
This Decision is addressed to the Member States, 
Done at Brussels, For the Council 
The President 
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AJUiEJL-ai/... 
TECHNICAL SPECIFICATION OF AIDS TO NAVIGATION SYSTEMS 
1. GLOBAL POSITIONING SYSTEM (GPS) 
GENERAL 
The Global Positioning System (GPS) Is a space-based, radio 
positioning, navigation and time-transfer system having free major 
segments: space, control and user. The GPS space segment, when fully 
operational, will be composed of 21 satellites, plus three operational 
spares In six orbital planes. The satellites will operate In circular 
20,200 km orbits at an inclination angle of 55' and with a 12-hour 
period. The spacing of satellites in orbit will be precisely arranged 
so that a minimum of four satellites will be in view to any user, 
thereby ensuring world-wide coverage. Each satellite will transmit L1 
and L2 signals. L1 will carry a precise (P) signal and a 
coarse/acquisition (C/A) signal. L2 will carry a P signal only. 
Superimposed on these signals will be navigation and atmospheric-
propagation correction data, and satellite clock-bias information. 
The control segment will Include a number of monitor stations and 
ground antennas located throughout the world. The monitor stations will 
use GPS receivers to track passively all satellites In view, and 
thereby accumulate ranging data from the satellite signals. The 
information from the monitor stations will be processed at the master 
control station (MCS) to determine the satellite orbits, and to update 
the navigation message of each satellite. This updated information will 
be transmitted to the satellites via the ground antennas, which will 
also be used for transmitting and receiving satellite control 
Informat Ion. 
The user segment will consist of antennas and recel verprocessors that 
will provide positioning and navigation data to the user. 
PURPOSE 
GPS is a position-fixing system which will be used for general 
navigation on land, sea and air. It will also have survey and timing 
appiicat ions. 
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A2fiiEjL_Bl/ 
SIGNAL CHARACTERISTICS 
The GPS concept depends upon having accurate and contlnous knowledge of 
the spatial position of any satellite in the system, In terms of the 
time and distance of the satellite from the user. Each satellite 
transmits its own ephemeris data. This data Is periodically updated by 
the control station, and is based upon information obtained from five 
widely dispersed monitor stations. 
The GPS receiver automatically selects appropriate signals from three 
or four of the satellites that give the best view as based on the 
optimum satellite-to-user geometry. It then solves tlme-of-arrI va I 
difference quantities to obtain the distances between the user and the 
satellites. This information establishes the user's position with 
respect to the satellite system. A timecorrection factor then relates 
the satellite system to earth co-ordinates. Each satellite continuously 
transmits a composite spread-spectrum signal at 12227.6 (L2) and 
1575.42(H) MHz that contains a precise navigational signal, a coarse 
navigational signal, satellite ephemeris data, atmospheric-propagation 
correction data and clock-bias Information. The user equipment measures 
four Independent pseudo-ranges and range rates, and translates these to 
a three-dimensional position, a velocity and a system time. 
ACCURACY 
Reference System. The geodetic reference system selected for use by the 
Global Positioning System (GPS) is the World Geodetic System (WGS). The 
GPS currently uses the 1984 version, which Is designated as WGS 84. 
Datum transformation will permit coordinates to be transformed between 
WGS 84 and most of the major and local datums in the world. 
The GPS provides two services for position determination. 
The Precise Positioning Service (PPS) will provide predictable 
positioning accuracy of 17.8 m (2dRMS) horizontally and 27.7 m (2 
sigma) vertically, velocity accuracy of 0.2 m/sec (2 slgma) In each of 
the three dimensions, and timing accuracy. The PPS will be limited to 
the US and allied military and federal government users. Limited civil 
use may be authorised to those who can demonstrate a need for the 
accuracy that cannot be obtained by other means, Is in the US national 
interest and can satisfy US national security requirements. 
The Standard Positioning Service (SPS) will provide a lower level of 
accuracy than the PPS. The SPS will be made available to civil, 
commercial and other users at the highest level of accuracy that Is 
consistent with the national Interests of the USA. The current policy 
of the American Department of Defense (DOD) Is to provide the SPS at an 
accuracy of 100 m (2 dRMS). 
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2. GRANAS/NAYSAT AiJNJEJLBl/ 
GENERAL 
The GRANAS (Global Radio Navigation System) Is a planned civil, 
satellite-based radio navigation system with the capability of 
additional communication services. NAVSAT is a planned global civil 
navigation satellite system which has similar operational objectives to 
the GPS. 
GRANAS has been investigated by Standard Elektrlk Lorenz, (SEL) funded 
by the German Ministry of Research and Technology. NAVSAT has been 
developed by European industries, funded by the European Space Agency 
(ESA). 
Both systems reveal more similarities than differences. In order to 
enhance the prospect of a future system realization, ESA decided to 
release a study which aims at the harmonization of the GRANAS and 
NAVSAT systems. It was the objective of the study to Identify the best 
features of the original concepts and to merge them Into a single 
consolidated system. 
For the method of satellite position determination the principles of 
GRANAS and NAVSAT are taken as two parallel options. One of these will 
be selected at a later stage, when some realization aspects are 
considered in more detail, e. g. by means of an experimental validation 
system. 
The new system Is characterized by the composition of the following 
features : 
SPACE SEGMENT 
The configuration of the space segment Is characterized by 6 equally 
spaced geostationary satellites (GEO) supplied by 12 satellites in 6 
inclined highly-elliptic orbits (HEO) with 12-hour periods. These 
orbits are arranged within 3 orbital planes mutually separated by 120 X 
in right ascension of ascending nodes and incline by 63.4 with regard 
to the equator. Each plane Includes two orbits, one with its apogee in 
the Northern, the other with its apogee In the Southern hemisphere. 
During 5/6 of a HEO period the ground track is concentrated on a 
relative small area providing good visibility conditions and making 
this type of orbit comparable to GEO satellites. Only the altitude of a 
HEO satellite is changing considerably increasing up to 39,000 km. To 
avoid problems of high Doppler frequencies each HEO satellite becomes 
operational only above an altitude of about 10,000 km. Nevertheless, 
this constellation guarantees, that during 96,2 X of the time at least 
4 satellites (GEO as well as HEO) are visible. 
The communication function (e.g. for the purpose of position reporting 
in case of SAR) may be realized according to INMARSAT standards. 
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ANttHLfii/... 
GROUND SEGMENT 
in the case of autonomous satellite position determination 16 ground 
stations are proposed which are equipped with simple transponders to 
respond to the interrogation signal. The monitor function is performed 
simultaneously. 
For the ground based position determination 6 Regional Centres are 
needed, one of which provides the service of the Mission Centre. 
However, about 10 additional monitor and tracking stations are 
required. For these the same locations as above can be used. 
USER SEGMENT 
The harmonized navigation system offers two navigation modes : dual 
frequency and single frequency. The dual frequency mode permits 
correction for Ionospheric delays to be made and hence provides higher 
accuracy than the single frequency mode of operation. 
PURPOSE 
GRANAS/NAVSAT would be a general navigation system for position-fixing 
by air, land and sea users. 
SIGNAL CHARACTERISTICS 
The determination of the user position is similar to that of GPS In 
making pseudorange measurements to at least 4 satellites. However, the 
new system bases on a time-devlsion multiplex (TDMA) approach using 15 
time slots within a frame length of 2.4 s. Each navigation burst 
consists of a synchronization preamble (24 ms), 5 data words (100 ms 
and a postamble 16 ms). The latter Is transmitted at another frequency 
(1228 MHz compared to 1575 MHz) in order to compensate for Ionospheric 
delays. 
The data part of the burst includes system time, satellite position 
coordinates as well as an additional word Indicating the health status 
of the system. 
ACCURACY 
Due to the chip rate of 4 MHz and the dual-frequency method, the 
accuracy of user position is comparable to that of the GPS P-code. 
According to whether a user is stationary or moving an accuracy of 2.4 
or 24 m (2dRMS) respectively Is achievable. 
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AitiEJL_ûl/... 
3. GLOBAL NAVIGATION SATELLITE 
SYSTEM (GLONASS) 
GENERAL 
The Global Navigation Satellite System (GLONASS) Is a space-based, 
radio positioning system that is being Introduced In the USSR for 
world-wide use by aircraft, but it could also be used at sea level. The 
system will start operation with between 10 and 12 satellites, of which 
5 or 6 will be positioned in each of two orbital planes having an 
inclination of 65*. The satellites will operate In nearly circular 
orbits at an approximate height of 19,100 km, and with a period of 
11.25 hours. The system is finally intended to contain 24 satellites, 
of which 3 will normally serve in a standby mode, three orbit planes 
120' apart will each contain seven to eight satellites. 
The user will establish his position by receiving signals from three 
satellites and thereby calculating the distances to the satellites. A 
signal that will give a very precise fix of position will be provided 
to users who are allowed the means to decode It, while a different 
signal that will give a less accurate fix will be generally available. 
The former signal will be carried by two frequencies in the L band (L1 
and L2), while the latter will be carried by only one of these 
frequencies. This arrangement is similar to the P and C/A signals of 
the GPS. it might be possible, because of similarities between the 
GLONASS and GPS, for users to have receivers that could work with 
either system. 
PURPOSE 
Glonass is a position-fixing system which will be used for general 
navigation by aircraft and ships. 
SIGNAL CHARACTERISTICS 
A master station monitors the satellites In order to keep the 
ephemeris, or positional, data of each one up to date. The satellites 
transmit their data over separate channels using a spread-spectrum 
technique. The L1 and L2 frequencies are respectively 1597-1617 MHz and 
1240-1260 MHz. 
ACCURACY 
100 m horizontal, 150 m vertical and 15 cm/s velocity (all 95 X 
probability). 
- 20 -
A2JN£L_B1/ 
4. DECCA 
GENERAL 
The Decca Navigator System, generally known as Decca, Is a hyperbolic 
radio navigation system, operating in the 70-130 kHz frequency band, 
using groups of at least three ground transmitter stations, each group 
making a system unit known as a chain. A Decca chain consists of one 
Master, and two or three Slave stations, 80-110 km from the Master, 
designated as Red, Green and Purple. The signals can be received by 
surface craft and by aircraft at all altitudes down to ground level at 
distances of several hundred kilometres from the transmitters. The 
characteristic high accuracy of Decca results from Its combination of 
hyperbolic geometry, and the phase comparison method of time-difference 
measurement. 
PURPOSE 
The Decca Navigator System Is used for position-fixing principally by 
maritime and aviation users. 
SIGNAL CHARACTERISTICS 
Transmitter signals are continuous unmodulated radio waves, the Slave 
signal is phase-locked to the Master. The frequencies of the 
unmodulated continuous radio waves transmitted from the Master and 
Slaves are harmonically related to a fundamental value "f" which is not 
transmitted but which is roughly 14 kHz, the exact value varying from 
chain to chain. 
Phase synchronisation of Master and Slave transmissions creates a 
pattern of hyperbolic position lines along which the phase difference 
between Master and Slave is constant. Position fixing carried out by 
the Decca receiver consists basically of identifying position lines by 
phase comparison carried out with a multiple frequency. 
in receivers, the transmitted frequencies are multiplied in order to 
produce comparison frequencies of 24f (Red), 18f (Green) and 30f 
(Purple). 
Taking the Red comparison frequency as an example, 24f equals 
approximately 340 kHz corresponding to a wavelength of about 880 
metres. By travelling 440 metres (half a wavelength) along the Master-
to-Slave baseline a phase change of 360* is produced, and this distance 
is designated as a lane and Indicated by a complete revolution of the 
phasemeter pointer of Deccometer receivers and by counting up or down 
100 divisions of one lane, at the displays of receivers with a digital 
performance. 
However, on the latest receivers the position is usually displayed In 
geographical coordinates. 
- 21 -
AHO-fil/-. 
Off the inter-statIon baseline, the lane widths expand In accordance 
with the hyperbolic geometry but the Instrinslc accuracy of the system 
is indicated by the fact that phase Is measured to within one or two 
hundredths of a lane, corresponding to a few metres In distance. 
Lanes and zones (groups of 24 Red, 18 Green and 30 Purple lanes) are 
counted by either a geared pointer on the Deccometer or on a digital 
display of a modern microprocessor based receiver. 
Once every 20 seconds lane identification signals known as multipulse, 
are transmitted from each station in turn. Their prime purpose Is to 
provide a check on the lane settings, however, because these signals 
are formed from a 1 f pulse syntheslsed from all four radiated 
frequencies, they are much less susceptible to skywave errors at night 
than those that may be experienced using the normal patterns, it can be 
shown that variable errors, particularly at longer ranges from the 
chain, are significantly smaller at night using multipulse - and can be 
up to 2:1 better. In the current generation of Decca receivers, the 
multipulse signals can provide the primary fixing information, being 
rate-aided between transmissions by the normal or continuous patterns. 
ACCURACY 
The accuracy of Decca is specified in some metres at positions on or 
near the baselines between two stations, but this accuracy decreases as 
the distance from the baseline Increases. Due to sky-wave Interference 
Decca is susceptible to night effect which generally reduces the 
accuracy by a factor of 6 to 8. 
In daylight at a distance of 240 km the accuracy will be better than 
440 metres; this figure deteriorates to approximately 2.4 km at night. 
Within 80 km of the Master station the accuracy Is approximately 25 
metres by day and 190 metres at night. 
All accuracies quoted are at 2 dRMS. 
In areas of fringe cover, a single line is used for homing purposes by 
mariners. The high order of repeatability of the Decca system Is also 
particularly significant. For example, if the Decca co-ordinates of a 
particularly good fishing area are known, a vessel can subsequently 
return to the position by referring solely to the Decca readings. 
Similarly, any user can be directed to a precise location by using 
Decca coordinates. 
In certain areas the hyperbolic patterns are distorted, mainly owing to 
the signals passing over ground of low electrical conductivity. These 
distortions, known as fixed errors, should be taken Into consideration 
when fixing the ship's position. This Information is published In the 
form of Pattern Correction Charts in the Chain Data Sheets. 
- 22 -
AifiEJL_Bl/ 
5. LORAlh£ 
PURPOSE 
LORAN-C is a general navigation system for air, land and sea users. In 
addition to its position fixing capability It can be used for timing 
purposes. 
SIGNAL CHARACTERISTICS 
LORAN-C is a hyperbolic system operating In the 90-110 kHz frequency 
band. Each station of a chain is separated by several hundred miles 
with each transmitting a series of eight precisely timed RF pulses. 
Chain differentiation Is provided by Group Repetition Interval (GRI). 
Selection of specific GRI may be coordinated with the US Coast Guard to 
avoid Interference. 
The system is based on the measurement of the differences In the time 
of arrival of signals from the stations In a chain. The measurements of 
the Time Difference (TD) are made in a receiver which achieves high 
accuracy by comparing a specified cycle zero-crossing within the 
transmitted pulses of the master and secondary stations of a chain. The 
comparison is made at the 30 us zero crossing to avoid sky-wave 
interference. Additionally, the phase of the pulses is alternated In a 
predetermined pattern over two groups of eight pulses to limit the 
effects of long delayed sky waves. Precise control over the pulse shape 
ensures the proper comparison at the 30 us zerocrosslng. 
ACCURACY 
Within the defined coverage area, Loran-C provides the user using an 
adequate receiver with a predictable accuracy of 0.25 m (2dRMS) or 
better. The repeatable and relative accuracies range between 18 and 90 
m. Accuracy Is dependent upon the Geometric Dilution of Precision 
(GD0P) at the user's location, the measurement error (slgnal-to-nolse 
ratio) and chart or local area calibration. The Loran-C ground wave Is 
primarily used for navigation; precise time measurement and time 
Interval dissemination are also derived from the Loran-C signal. 
Sky-wave navigation is feasible, but with a significant loss In 
accuracy. Like ground waves, sky-waves to some extent may also be used 
for time dissemination. Loran-C was originally designed to be primarily 
a hyperbolic navigation system. However, with the advent of the highly 
stable frequency standards, Loran-C can also be used In the range-range 
(rho-rho) mode of navigation. This is accomplished by a comparison of 
the received signal phase with a known time reference to determine 
propagation time and, therefore, range from the stations. It can be 
used In situations where the user is within reception range of 
individual stations, but beyond the hyperbolic coverage area. The rho-
rho method using Loran-C requires that the user has a very precise and 
stable time reference. The high cost of equipment limits the use of 
this mode. 
- 23 -
AlHEJL_ai/... 
The accuracy of the Loran-C system makes It a suitable candidate for 
many land radiolocation applications. Loran-C can be received In 
mountainous areas where VHF and UHF systems are terrain limited. Some 
distortion of the hyperbolic grid Is to be expected since the 100 kHz 
signal's time of arrival and strength are affected by the soil 
conductivity and terrain. Propagation anomalies may be encountered In 
urban areas where the proximity of large man-made structures affect the 
signal. The existence of these anomalies Is predictable and can be 
compensated for, usually by surveying the area. The long range of the 
Loran-C system makes it particularly desirable for application to 
remote areas, or where the user population Is too low to Justify the 
cost of a large number of short-range facilities. 
- 24 -
Proposed configuration NW-Europe and Atlantic ANNEX B2 
- 25 -
AHJBLB2/ 
SYSTEM DESCRIPTION 
Genera 
1. The North West European Loran C system shall comprise the eight 
existing stations of the Icelandic, Norwegian and French chains, with 
the addition of two new stations In Norway and one each In Ireland and 
the Uni ted Kingdom. 
2.The coverage of the new system Is shown In annex 2. The area shaded 
is limited either by accuracy (maximum error .25 n. mile 2drms) or by 
signal strength (minimum SNR - 10db noise 6ldB above luV/m). 
Transmitted Signal 
3. The signal from all the transmitters shall conform to the 
requirements of the "Specification of the transmitted Loran C signal" 
(USCG-USDOT COMDTINST M 16562. 4 July 1981). 
Transmitting Equipment 
4.The transmitters shall be of modular construction and shall consist 
of a prime power unit, timing and control units, pulse generating 
assemblies, a coupling network, output cabinets, switch network and 
antenna fenders. 
5.New transmitting equipment shall be required at all sites except 
those In France. Gamvlk, FedJe, South West Ireland and North East 
England are new sites. The existing stations In Norway (Boe and Jan 
Mayen) shall be dual-rated In the new system, but the existing 
transmitting equipment is unsuitable. The present valve transmitters on 
the other four sites (Anglssoq, Sandur, EJde and Sylt) shall be 
replaced with solid-state equipment. 
6. Power reqlrements vary depending on the ranges and types of terrain 
to be covered. Transmitters of different peak radiated power (p.r.p.) 
can be provided using the same components but increasing the number of 
pulse generating assemblies. 
Antenna 
7. The antenna is a top-loaded, guyed, steel lattice tower, fully 
Insulated from the guys and foundation with the exception of the feed 
from the antenna coupler. The antenna may be 200 m to 400 m high. 
- 26 -
AUUBLfia 
Monitoring and control 
8. Time of transmission (TOT) control will probably be used for the 
complete system eventually, although existing USCG stations will be 
controlled via System Area Monitors at least until the proposed 
handover date (1994). 
9. Under TOT, times of transmission are fixed relative to an external 
standard such as Universal Co-ordinated Time (UTC). Propagation time 
along the baselines Is measured by monitor receivers located at or near 
the transmitter sites. Data from these monitors is automatically sent 
to a control centre from which commands such as timing adjustments are 
sent, again by data link. 
10. The standard deviation of TOT, with respect to UTC, for each 
transmitter shall be kept below a pre-determined value, probably 50-100 
nanosec. The standard deviation of time differences between masters and 
secondary shall be less than 30 nanosec. 
11. The system shall be controlled from two centres : Boe In Norway for 
the Iceland and Norwegian Sea chains and Brest in France for the North 
Sea and Biscay chains. 
12. The principal maintenance centres and stores shall also be at these 
control centre locations, together with a maintenance centre at Sandur. 
- 27 -
ANNEX B 4 
EXISTING LORAN C COVERAGE 
PROPOSED COVERAGE 
N-W EUROPEAN LORAN C 
-5 o 5 'O 
^3 ENVISAGED LORAN C 
COVERAGE IBERIAN PENINSULA 
AND MEDITERRANEAN SEA 
- 28 -
COMPETITIVENESS AND EMPLOYMENT IMPACT STATEMENT 
1. What Is the main reason for introducing the measure ? 
The simultaneous withdrawal of the DECCA RACAL company and the US 
Coastguard from the provision of radionavigation signals In Europe 
and the on-going development of new radionavigation systems In the 
Iberian Peninsula and the Mediterranean poses the potential major 
problem of piecemeal, uncoordinated, and hence uneconomic 
development of radionavigation signal systems In Europe. The 
proposal alms to secure the commitment of the Member States and 
Inter alia third countries to the introduction of the LORAN-c 
radionavigation system as the European standard for the medium 
term. 
2. Faaturea of the business In question 
All enterprises which use radionavigation signal systems. 
3. What obligations does this measure Impose directly on business ? 
No additional obligations. 
4. What Indirect obligations are national, regional or local 
authorities likely to Impose on business ? 
Authorities are likely In-due course to require vessel owners to 
adapt or replace existing receiving equipment to ensure the 
maintenance of high safety standards. 
5. Are there any special provisions In respect of SME's ? 
None. 
- 29 -
6. What la the. M Ko I Y effect on ; 
a) The, competitiveness of the business 
The competitiveness of Community vessel operators will be 
enhanced through the avoidance of the necessity to equip 
vessels with multiple receivers to Interface with different 
radionavigation signal systems. 
b) Employment 
PosItive. 

ISSN 0254-1475 
COM(91) 1 final 
DOCUMENTS 
EN 15 
Catalogue number : CB-CO-91-022-EN-C 
ISBN 92-77-68909-9 
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