The Swedish Maritime Administration Sjöfartsverket is equipping ten beacons with radar answering beacons. The first system went into operation on Öland in December. The background to this is persistent GPS interference in the Baltic Sea.
With the installation of response barges, so-called radar beacons or racons, the Swedish Maritime Administration is utilising a proven but largely forgotten navigation technology. Unlike GPS, racons are completely ground-based: They receive radar signals from ships and send back a characteristic Morse code signal that appears on the ship's radar screen. The position can be determined from the bearing and distance to the beacon - independently of satellite signals.
Reaction to massive GPS interference
The measure is a reaction to the GPS failures in the Baltic Sea, which have persisted for months. The Swedish Maritime Administration justifies the move with the growing need for alternative navigation systems as a result of the GPS failures. According to statistics from Swedish Transportstyrelsen, the number of reported GPS incidents in air traffic has risen by 2,000 per cent within two years. Unfortunately, no figures are available for shipping, but it is assumed that the failures also pose an increasing risk in the maritime sector.
The first Racon system was installed on Kapelludden-Fyr on Öland in December. A further nine locations on the southern Swedish coast are to follow. The choice fell particularly on coastal stretches where shallow shores and a lack of prominent landmarks make visual navigation difficult.
Back to the future
The initiative came from Sjöfartsverket's general manager Erik Eklund, who himself learnt to navigate using radar, paper nautical charts and a magnetic compass. At that time, radar beacons provided him with orientation points for bearing and distance on flat coasts. The Racon systems are mounted on high beacons. They emit a Morse code signal that appears on the ship's radar as soon as the radar beam reaches the beacon. The position can be determined using the bearing and distance to the signal - even in daylight and poor visibility, when optical beacons cannot be recognised.
Crisis-proof and easy to implement
At a meeting of the international organisation IALA for maritime aids to navigation, Johan Winell, Head of Construction and Technology at Sjöfartsverket, reported on the Swedish initiative. Several member countries reacted favourably and described the approach as innovative; some had not thought of this simple solution, which is also difficult to disrupt. It is also easy to implement and, unlike alternative navigation systems such as R-Mode no special receivers. The response beacons react not only to the S-band systems commonly used in commercial shipping, but also to X-band radar systems such as those used on yachts.
More articles on this topic:
- Baltic Sea: Sweden warns of large-scale GPS interference
- Sweden: Investments in navigation marks - due to GPS interference
- Back to map and compass due to GPS malfunctions
- GPS disruptions: Backup navigation system for the Baltic Sea enters next phase
- Navigation without GPS: classic methods you should know
