IMO MSC79 approved new radar performance standards in Resolution 192(79) which removed the requirement for S-Band Radars to trigger racons. This was intended to facilitate the introduction of "new technology" (*NT) to enable future radars to meet the more stringent limits being imposed on spurious and out of band emissions.
It is expected that the new technology will improve target detection in clutter and therefore safety, but these radars will probably not trigger racons.
The GLAs consider Racons a very important Aid-to-Navigation, since they provide an independent means of identifying and locating marks in poor visibility and without reliance on GNSS. S-Band is particularly useful in heavy rain clutter conditions. It is generally recognised that S band radar is preferred as the ARPA / collision avoidance radar due to its detection and display properties.
Racons that are compatible with the new radar technologies could be developed, but there are currently no industry standards or recommendations for these new technologies.
R&RNAV is coordinating work within the GLAs to assess the effectiveness of existing racons with New Technology (NT*) radars. This involves trials on a GLA vessel (CILT Granuaile) fitted with an NT radar, observing responses from different types of racon. The trials were conducted in the Dublin Bay and Codling area of the Irish Sea, where a number of fixed and floating CIL AtoNs fitted with Racons were used.
Trial results showed that:
- the NT radar tested did trigger Racons but at a significantly reduced range;
- there were gaps in the Racon response;
- short proportional responses can be obscured in clutter;
- some Racons responded with a portion of the "paint" in front of the actual position of the Racon;
- one Racon gave a response which was offset in azimuth and range from the actual Racon position.
This report proposes that consideration be given to modifying existing Racons to improve their response to NT radars. Further trials should also be arranged to clarify the results and test the effects of any modifications to existing Racons. A forward strategy is being developed for racons within the GLA and the results of this work are being shared with other IALA Members to ensure there is awareness of the potential effect of NT radars on Racon performance and of the strategic options available.
* NT Radars:
New Technology radars use coherent, FM/CW, low-power, solid-state technology to enhance target detection in clutter, increase reliability and improve spectrum efficiency. The IMO has removed the requirement for S Band radars to trigger racons, to encourage these developments. However, there is still a significant navigational benefit from S Band racons and there are various ways of ensuring that the service can be maintained.
