Marine Radar Product

Overview

Marine radar is the primary collision-avoidance and pilotage sensor on vessels from sport-fishing boats to ULCCs. It measures the range and bearing of targets — ships, buoys, coastline, rain — by timing microwave echoes and noting where the antenna pointed when each echo returned. Small-craft units operate in X band around 9.4 GHz, where a compact antenna still achieves a narrow beam and small targets reflect well; large ships add an S-band (3 GHz) set for better rain penetration.

This unit is the modern solid-state type. Instead of a magnetron firing kilowatt pulses, a GaN Power Amplifier built on gallium nitride transmits long, frequency-swept chirps of only 25 W peak. Pulse compression in the receiver recovers the range resolution of a short pulse with the energy of a long one, so detection performance matches a 4 kW magnetron set while eliminating warm-up time, magnetron ageing, and most of the radiation hazard near the antenna.

How it works

Each trigger, the Chirp Exciter synthesizes a linear-FM chirp — 80 ns for close ranges up to 18 µs offshore — which the GaN amplifier raises to 25 W. The Ferrite Circulator steers this pulse through the RF Rotary Joint into the rotating Slotted Waveguide. The array's milled slots form a fan beam 1.8° wide in azimuth and 22° tall; the width sets how well two adjacent targets are separated in bearing, while the generous height keeps the beam on the horizon as the vessel rolls.

Returning echoes re-enter the same waveguide and the circulator routes them to the receiver, where the Receiver Protector / Limiter protects the Low-Noise Amplifier from transmit leakage. After the Receive Downconverter shifts the signal to IF, the High-Speed ADC digitises it and the Radar FPGA applies the matched filter: correlating the received chirp against the transmitted one compresses an 18 µs pulse to an effective ~30 ns, giving roughly 5 m range resolution. The FPGA also runs constant-false-alarm-rate thresholds and the sea and rain clutter filters, and because the chirped waveform preserves phase, it extracts Doppler: echoes from closing targets are colour-coded differently from opening ones, an immediate visual collision cue.

Bearing comes from the Pedestal & Rotation Drive. The Scanner Drive Motor spins the Antenna Turntable at 24 rpm (48 rpm on short ranges for faster updates) through a final Helical Gear Pair, while the Encoder reports azimuth continuously and the Heading-Line Sensor pulses as the beam sweeps past the bow, anchoring the picture to the vessel's heading.

Display and tracking

The Signal Processor Board's Compute SoC Module assembles compressed, filtered echoes into the familiar PPI picture and streams it as Ethernet packets down the Scanner Interconnect Cable to the Display Unit. The 12-inch LCD Panel runs about 1200 nits for sunlight viewing, with a Touch Digitizer for chart work and the Keypad & Rotary Control rotary knob for gain and range when spray makes touch unreliable. The tracker maintains up to 50 ARPA targets, computing each one's course, speed, closest point of approach (CPA), and time to CPA from successive plots; CPA violations and guard-zone intrusions sound through the Speaker. Radar video can be overlaid on the electronic chart, with heading input from the vessel's compass aligning the two.

Installation

The pedestal mounts on the Mast Mounting Platform high enough to clear crew sightlines and extend the radar horizon, which scales with the square root of antenna height — at 5 m the horizon for a surface target is roughly 8 nm. The Pedestal Casting seals the drive and Transceiver Module to IPX6 against green water and driving spray, and the Scanner Power Module with its EMI Input Filter keeps switching hash off the vessel's DC bus, where it would otherwise leak into VHF and AIS receivers. Total draw while transmitting is near 35 W, modest enough for sailing yachts to run radar continuously at night.

Operating considerations

Solid-state sets transmit on the instant — no three-minute magnetron warm-up — and their low peak power makes the mandated safe-distance circle around the open array a matter of centimetres rather than metres, though crew are still kept clear of the rotating antenna. Routine maintenance is limited to washing salt off the Array Fairing, checking the RF Rotary Joint and azimuth bearings at refit, and confirming heading-line alignment, since a misaligned heading pulse skews every bearing the radar reports.