LOGBOEK  - JOURNAL DE BORD

SharpEye solid-state radar  sees an end to the magnetron

Kelvin Hughes has delivered economically competitive solid-state radar well in advance of market expectations, and says it has 'futureproofed' the technology to meet further regulation requirements

by Alan Welcome

It is not often that a commercial marine electronics manufacturer pushes itself well ahead of the field, but with the introduction in

September of the new SharpEye radar at SMM in Hamburg, Kelvin Hughes appears to have donc just that. The company describes its SharpEye radar as the most revolutionary innovation in the marine navigation market since the introduction of commercial radar, and — satellite navigation notwithstanding — it has a point.

Currently available in S-band, SharpEye dispenses with the magnetron and high voltage modula tor, employing instead a monostatic pulse doppler solid-state transceiver. This enables more information to be extracted from the radar returns, employing detection techniques so far confined to military systems.

Doppler shift is used to calculate the velocities of targets. Pulse compression improves the signal-to-noise ratio and restores fine range resolution, doppler filtering sorts the received echoes into velocity bands enabling the separation of targets and clutter. Kelvin Hughes says that SharpEye target detection in clutter is much better than conventional radar.

Magnetron-based radars have provided good service, but now seem to have reached a development plateau. Overall performance is generally acceptable, but there are aspects that still leave much to be desired, particularly the detection of small targets in clutter. Magnetrons are greedy in terms of power, and more importantly, frequency spectrum. Historically this was not a problem, but the increase in communication devices operating in the same spectrum makes this a growing issue.

Solid-state alternatives to magnetron technology exist, and are generically known as 'new technology' (NT) radars. They have been available to the military for some time, but at a price prohibitive for commercial operators.

 

It was also accepted that NT radars would not be able to trigger racons and similar devices, a requirement of current radar regulations. Consequently, new radar regulations adopted in 2004 — and coming into force in July 2008 — removed the requirement for S-band radar to detect radar beacons, sarts and radar target enhancers.

Nevertheless, there was some doubt whether this would be enough to prompt NT radar development, and some felt that ultimately there would need to be stricter frequency spectrum and interference requirements to effectively outlaw the magnetron.

Kelvin Hughes says the cost of the new system will be comparable to that of the present magnetron system. This may be interpreted as a higher initial cost, offset by the absence of items requiring periodical replacement, such as the magnetron every two to three years. The graduai fall off in performance associated with magnétrons is also eliminated. Kelvin Hughes promises high levels of reliability and minimal maintenance requirements. It backs up these daims by providing a lifetime guarantee, subject to terms and conditions, in support of SharpEye technology, which it describes as "fit and forget".

With regard to radar beacons, Kelvin Hughes says that the patented SharpEye technology allows the radar to trigger existing racons and sarts. Kelvin Hughes is not prepared to disclose how this is achieved, but says that the technology will be made available to other manufacturers under licence. Thus the new radar can be installed and operated now, with no need to wait for the 2008 rule changes. Kelvin Hughes says that operators

will not see any dramatic change in the controls and that most of the functions expected by bridge operators have been automated, significantly simplifying the watchkeeper's task.

The SharpEye solid-state power amplifier has a peak output power of 170W, while that of marine magnetron-based systems is in the region of 30kW. Nevertheless, Kelvin Hughes says the more efficient use of transmitted power allows SharpEye to deliver target detection performance superior to conventional radar.

Periodic performance checks are not required as SharpEye continuously measures the main performance indicators including RF output power, voltage standing wave ratio, oscillator frequencies and receiver sensitivity, confirming to the operator that the radar is operating within its parameters, highlights the company. The system has an alarm to indicate if there is any degradation in radar performance.

With regard to type approval, SharpEye is currently being tested against the existing radar regulations, and Kelvin Hughes expects to achieve approval by January 2007. However, the SharpEye radar system has been designed to meet both the existing and the new regulations when they tome into force. Furthermore, Kelvin Hughes says SharpEye is very 'futureproof', having been designed with future enhancements in mind.

The company added that the SharpEye radar sensor can be retro-fitted to existing Kelvin Hughes Nucleus 3 and Manta systems. Also, an X-band system should be available in 2007, and I- and F-band systems are planned for naval applications. FT