Radar transponders.doc

Radar transponders (Racons) for the future Author: Dr. Nick Ward Background IMO Maritime Safety Committee (MSC) of the 79th meeting in section 192 / (79), which adopted the new standards of the radar,from 2008 on the abolition of S-band radar transponders trigger requirements. The measures aimed at promoting the introduction of new technologies (such as coherent modulation), to facilitate future improvements in radar clutter in the ability to detect targets, thus improving security. These technologies can also reduce distortion launch and band launch and promote the efficient use of spectrum. From 2008 , these technologies can be applied to the new S-band radar. S-band is particularly useful in the worst rain and snow clutter environment. Because of its ability to detect and display advantages, S-band radar is generally considered better suited as APRA (automatic radar plotting devices) / collision avoidance radar. Although the new technologies aimed at enhancing security, the use of this technology almost do not trigger the radar of existing radar transponder. Radar transponder was considered a very important navigational tool, because they can be very poor visibility in the case of recognition rather than rely on buoy positioning and GNSS. Overall, the new radar technology compatible with the radar transponder to research and development, but at present these new technologies not related to industry standards or recommendations. At present the application of new technologies for the S-band radar of the mandatory requirements of loading also did not mention on the agenda. Similarly, the existing S-band radar phase-out schedule has not planned. New radar technology will have some new characteristics of the operation, the need for operator training. X-band radar on the request has not changed. In the foreseeable future, still require X-band radar trigger and search and rescue vehicle radar transponder radar transponders (SART). New technologies in the S-band radar will be decided X-band radar future development plans as a factor, therefore, it was suggested that the IMO to amend the requirements of SART, will change it from radar-based based AIS or other techniques. New radar technology International Maritime Radio Committee (CIRM), Professor of Norris explained that the radar technology constantly changing, and for the identification of the Clutter offers the potential for increase - the user that the current marine radar performance in this regard can not meet the requirements. More effective control of bandwidth and can also improve the compatibility of other users RF (radio frequency interference lower). Hope that a solution to reduce the use of high-pressure components in volume, thereby enhancing reliability, and hope that the eventual lifting of restrictions on a life of the components. This will be able to achieve higher electronic integration, further improve the reliability (components to reduce dependence) and ultimately reduce costs. It is possible to achieve the future with affordable prices, the radio beam of the sensitive phase-array antennas and feasible static (non-rotating) antenna systems compatible, given a high price. Coherent use of radio frequency signal modulation can increase clutter recognition performance - the non-navigational radar magnetron coherence modulation. These reservations to receive the radar signals in the frequency and phase information, this information will be used after the process, the better the target from the clutter distinguish. General, it is with different goals and clutter of the spectrum. After a few years, improving the processing algorithms and faster processor speeds will gradually improve the identification of targets from the clutter of the capacity. The short term, will improve the signal to noise ratio of dozens dB is possible. The long run, the potential for improvement may be even greater. Schedule changes Microwave devices handle the advances in technology and the improvement of cost-effective, these changes have already began to appear. IMO has endorsed these changes and amendments to the marine radar standards to allow in July 2008 after the S-band radar of the non-magnetron. At present, some documents have pointed out that the type of proven solutions in 2010 before there can be certain, but there is also considerable technical difficulties, this assertion may be too optimistic. And some solutions may be related to national defense export restrictions on the issue. On the impact of the radar transponder Most of the new technology solutions rely on low-peak power performance ( 10 W-1kW). Some solutions have similar wave of noise, causing other system can not effectively monitor (such solution is the elimination of radar / radar jamming advantage). To request a new radar technology with the existing radar transponder compatible with the clutter to get a higher recognition performance is a major part of innovation, and IMO has agreed that from July 2008 onwards, S-band radar and navigational radar transponder do not compatible . However, radar and X-band radar system compatibility requirements not relax. The expected changes in the radar In order to obtain better Clutter / target resolution, needs 20 MHz or even higher bandwidth. Any pulse duration, and other sites to wave in theory, are feasible; can use pulse compression technology acquisition from the differential. With frequency, phase modulation, or AM (if possible) pulse. Continuous pulse may not be the same. If you use a fixed phase-array antennas, may not be able to produce a continuous beam azimuth flyback - even with the rotating antenna to antenna pointing before or backward direction of ancillary facilities. Alternative technologies Understandably, in a highly competitive environment, manufacturers do not want to talk about them is still in the development process solutions. Each vendor solutions may be totally different, and not all companies are the most important new technology programmes. May become an alternative technologies, including in the short coherent, such as pulse rate and the wave (CW). Coherent short pulse is given to minimize the handling of the inherent good distance resolution, and do not have a distance sidelobe (from the sidelobe Luanzhen distance in the real targets of redundancy echo, may have a pulse compression process) . This will be a better short-term performance, and that the solution to the existing S-band radar transponder compatible. However, it needs high peak power pulses, may also need to use coherent magnetron, due to the need for high-voltage, but also in a very short pulse in the maintenance phase and frequency stability is very difficult, the technology more expensive. Medium coherent pulse width can be relatively easily in a pulse of a better frequency / phase stability, but also is likely to pulse shape the design, which were optimized short-range, medium-range and long-range performance. These technologies can be part of that with the existing S-band radar transponder compatible. However, the technology requires a traveling wave tube (TWT), or related to high power semiconductor amplifier (a few hundred watts of peak power), there may be relatively expensive. The availability of sufficient distance from the low side lobe is also a problem. , And other pieces of radar (CW Radar) peak power needs of the relatively low (10 W of power may be sufficient), you can use prices affordable and stable performance of semiconductor technology. At present a possible modulation, FMCW, is the one already exists, we all fully understand the Navys radar navigation technology. Based on the choice of noise modulation can remove all the radar of radar interference effects (of the technology has been used for military radar on the LPI). Radar and other pieces of the shortcomings is that it may need to separate the launch / reception antenna to get the necessary isolation, short-range, long-range optimization problems, but also difficult to obtain sufficient distance from the low side lobe. The method can with the existing S-band radar transponder compatible with any noise modulation system transponders, are not compatible. Navigation the first choice In a decision before the IMO, the Maritime Academy on S-band radar transponder compatibility of the potential loss of a user survey. The results of the survey is some reluctantly agreed that the radar transponder to the decline in performance at the cost of S-band clutter of the improvement is the identification of the current situation an improvement. IMO has taken note of this priority choice. Sea to be familiar with and prefer to use radar transponder, because the radar transponder to the radar on the natural way, and is directly opposed to ship as the center of the world data. AIS on their radar as a substitute for the proper lack of confidence, because AIS is not to ship as the center, it is not directly given the relative position and distance. Radar transponder alternative to One worth considering alternative methods are independent of the distance / position transponder system, which use a simple ship-based Information System. But this method also has many problems. It will increase the owner, additional costs, and navigation display system specifications, such as radar and ECDIS, need to be changed accordingly to accommodate the new data. In some ships identified the other major antenna installation location may be very difficult, because of the need 360-degree angle, there may need to rotate. With the future design of the highly specialized and not the same as the radar antenna and radar will make it more difficult for co-location, although a special transponder antenna system may be than a typical X-band radar antenna the size of a small number And at the same time retain the current position accuracy. Conclusion of the S-band radar transponder application should be suspended until the new radar technology of the early development of a better understanding. But IALA should consider the single-S-band radar transponder installation is recommended. farther in the future (that is, in the S-band radar NT confirmed the superiority of their 7-10 years), X-band radar may not be limited to the magnetron technology, it may be suitable for the new distance / Position transponder system to develop and replace the radar transponder. CIRM will be happy with the IALA together to develop solutions for the future, and their development of the NT solutions to provide further information. New technology of radar and radar transponder compatibility We all know that the existing radar transponder can not be compatible with the new technology of radar. And the question of whether signal modulation, the existing radar transponder lack of monitoring of new technologies required by the radar signal sensitivity. This is because the existing radar transponder must be all-band radar frequency radar signals to respond (Remember, bandwidth and sensitivity is inversely proportional relationship). The main issues to be considered If you need a new type of radar transponder, a list of the main views and limitations: new technology of radar may use digital modulation technology and digital synthesis transmitter; magnetron transmitter and a typical high-power short-pulse different, the new technology of radar may need more time to send low-power cycle modulation pulse; new technology of radar may need to use digital receiver; agreed to narrow the frequency bandwidth to receive the radar transponder can be a high sensitivity, and to monitor low-power long pulse radar signals; aviation beacons radar should work in different band; individual manufacturers to use the new technology of radar modulation type, the radar transponder may not be able to copy the correct demodulator, resulting in radar discarded radar transponder response; different manufacturers may use their own patents modulation technique; As different modulation technology, radar transponder may not be able to monitor from a specific new technology of radar, asked. Conclusion to monitor and to manufacturers of all the new technology of radar had been successful response to the radar transponder is almost impossible, if not impossible, to create to monitor and respond to the success of all brands of new technology of radar radar transponder is also extremely difficult; Since the radar transponder can not be made complicated enough, then the radar must be complex enough; Radar / radar transponder system on the recommendation of radar should be recognized in the frequency, periodically (perhaps every few seconds) launched the internationally accepted codes, modulation of the signal (the use of digital technology to the process is relatively simple); radar transponder should receive these signals, and the known frequency (preferably with the different frequency) and the use of special coding to respond to the signal modulation; rotating radar should have been authorized to receive the encoded signal (repeat, the use of digital technology can make the process relatively simple), and on the display show the right information. Milestone international organizations should agree that the new technology of radar and radar transponder use, or expectations are mandatory; international organizations should be adopted on the radar / radar transponder system of technical standards mentioned above on the recommendation of the choices in only one; radar and radar transponder manufacturers must agree to cooperate. CIRM Working Group In order to promote the progress of the case, CIRM has proposed that the radar / radar transponder system standards organization of a working group. Part of the radar manufacturers have some resistance, they are worried about losing their own patented technology, or that they lack the mandatory use of advanced technology mandatory, it is also understandable. These two proposals to avoid this situation. AIS as a radar transponder as a substitute for On the surface, the AIS to use the radar transponder from quite attractive, because AIS more powerful and more low cost. However, AIS relie