Digital Radar Processing and the New Low Power Radars

Navico BR24 Radar

Odin SlettenTechnical Sales EngineerNavico Denmark

© Navico Company Confidential2

A Short History of Radar

• In 1917, Nikola Tesla first established the principles for primitive radar units

• In 1935, The British invented and patented the first radar for aircraft defence

• In 1950, Decca introduced the first marine pulse radar utilising a magnetron, which eventually trickled down into recreational boats…


60 Years of Development


Weaknesses of Traditional Radar• User expertise required

– Blurs and distorts objects, making it difficult to interpret surroundings and navigate safely

– Obscures objects closest to the boat, where visibility is most important for collision avoidance

– Difficulty distinguishing targets from clutter - requires experience to safely operate

• Inconvenient installation and operation– Magnetron takes several inconvenient minutes to warm up– Magnetron has a limited life, and is expensive to replace– Large cables and connectors – Power consumption is impractical for small boats and most sailboats– Emissions require mounting away from humans and other electronic

equipment. Most small boats have no room at all


First X-band Radome Radar


Navico’s BroadBand Radar• “Revolutionary improvement in situational awareness” - the best short-

range resolution and target discrimination of any X-band marine radar

– Radar is finally easy enough for a novice – identifies targets clearly with no ‘tune control’, as sea and rain clutter rejection is 5-10 times better than a pulse radar

– Navigation is truly easy, even at an unprecedented 1/32 NM range,

with unparalleled resolution and clarity within two metres of the dome, with no ‘main bang’, ‘zero range adjust’, or close-range sidelobe distortion


Close Range Performance


Comparison and Main bang

4 kW HD pulse radar, 1/8 NM range BroadBand Radar, 1/16 NM range

main bang


Comparison and Main bang

4 kW HD pulse radar, 1/8 NM range Broadband Radar, 1/16 NM range

main bangsuppression




Moored boat

4 kW HD pulse radar Broadband Radar

Approximate position of boat


Foot bridge


Superb Resolution

4 kW HD Pulse Radar BroadBand Radar

Pile moorings

Moored boat


Seaclutter Performance

4 kW HD pulse radar, 1/2nm

Sea clutter rejection 50%

Two boats, towing into the harbour

BroadBand Radar ¼ NM

No sea clutter rejection applied

What makes the difference?


Traditional Radar

• The radar transmits a powerful, but very short pulse, at a fixed frequency.• The pulse propagates outwards in a direction determined by the angle of the

rotating radar antenna at the time of transmission.• The radar then switches to receive mode to listen for reflections. • If the pulse reflects off an object, it will return to the receiver with a delay

proportional to the distance of the object from the transmitter.• The antenna angle at the time of pulse transmission equals the direction of

the object.

Power

Time

100nsec

Object

Transmitted

ReflectedRadar

Fixed Frequency:9.4GHz


BroadBand Radar

• FMCW = Frequency Modulated Continuous Wave• Transmits a ‘rising tone’ (Tx wave) with linear increasing frequency• The wave propagates out from the transmitter retaining the frequency it

had when it was transmitted• If it reflects off an object, it will return to the receiver, still at the frequency

it had when originally transmitted• Meanwhile the transmitter continues to output an increasing frequency

Frequency

Time

1ms 4ms

9.41GHz9.4GHz


BroadBand Radar

Frequency Difference in Transmitted and Received Signals

The difference in the currently transmitted and currently received frequencies, coupled with the known rate of frequency increase, allows a time of flight to be calculated, from which we can calculate distance.

Frequency

Time

At any instant in time, Tx freq is higher than Rx freq

Tx Rx – retains same frequency it had when it was transmitted

Time delay

Unique Advantages


Solid State – No Magnetron“Start faster, go longer” - 100% solid state RF design – no

magnetron! Provides InstantOn™ power up and low power consumption

– Eliminates 2-3 minutes warm-up time typical of magnetron pulse radars

–Conserves power; operating power drain is ~30% less than the best 2 kW radar (<1/20 in standby mode) – extremely beneficial for sailboats and smaller power boats –No limit on transmit usage lifetime – typically 2-3,000 hours

for a magnetron pulse radar


Two Antenna Arrays

RX

TX


Totally Safe“Incredibly approachable” - Totally safe RF transmitted

emissions and flexible installation setup allows you to mount the radome anywhere

– Extremely low power - less than 1/10th of the transmitted emissions of a mobile phone; install in any position, even on the smallest of boats


Proven Safety

Page 22

Conclusion: Human exposure level to radiation outside the radome is 0.45 W/m2, well below the general public safety emission level of 10 W/m2. Included is the possible case of mechanical failure of the motor or drive belt with the antenna pointing into a fixed direction.

2,8 m (9.3 ft)Standard 4 kW pulse radar

0 m (0 ft)New Navico Broadband radar

1,4 m (4.6 ft)Standard 2 kW pulse radar

Safe DistanceRadar Type


Easy Installation “Incredibly approachable” - Totally safe RF transmit emissions and flexible

installation setup allows you to mount the radome anywhere


– Super small custom 13.5 mm RJ45 connector and round 9 mm pre-connected radar cable allows simple bridge tube installations


Radar Interface

Radar Interface Box Fully watertight Small RJ45 connector


Connector

Radar Dome Connection External watertight connector

Same footprint as today’s 2 kW scanner


Mutltiple Displays“Incredibly approachable” - Totally safe RF transmit emissions

and flexible installation setup allows you to mount the radome anywhere


– Super small custom 13.5 mm RJ45 connector and round 9 mm pre-connected radar cable allows simple bridge tube installations

–Compatible with a wide range of Navico multifunction displays and heading sensors


Multiple Displays

HDS-5

HDS-5m

HDS-5x

HDS-7

HDS-7m

HDS-8

HDS-8m

HDS-10

HDS-10m

GB40

NX45 12”

NX40 8”

NSE8

NSE12


Super high resolution No blind spot at center (mainbang) Totally safe, 0.1 W TX – install anywhere InstantOn – no warm up time Lower power consumption, no standby power Five times better sea and rain clutter performance Easy to install – very small connector

The Highlights


The Differences Between Pulse and FMCW Radars

Inherent Differences between the technologiesCharacteristic Broadband (FMCW) Pulse

Short range target detection Better Worse

Long range target detection Worse Better

Visibility of close in targets Better Worse

Target resolution in azimuth Same Same

Target resolution in range Better Worse

Sea clutter suppression Better Worse

Power requirements Similar Similar

Requires standby period No Yes

Vulnerability to interference from other radars Difficult to solve Easy to solve

Vulnerability to onboard reflectors Potentially a problem Not a problem

Potential for future development Only just begun Mature technology

Summary from a Technical Briefing by Bill Mullarkey from Navigate-us.comN.B This was purely from theoretical analysis, no practical testing was made


Long Range Performance

Maximum range for any radar under ideal circumstances:

Scanner height

Target Object at sea level Small boat (2 m high) Big launch (6 m high)

2 metres 3.1 miles 6.3 miles 8.5 miles3 metres 3.8 miles 7.0 miles 9.2 miles4 metres 4.4 miles 7.5 miles 9.8 miles

__________________________________________________________________________

So….. there is no possible way a radar on a small/medium boat can see a large launch at more than 10 miles

But… It may be possible to see rain or high land features beyond 10 miles.


Further Enhancement

• Navico’s R&D teams have developed technologies, which bring interference from other radar and onboard reflectors to a minimum or even totally eliminates them.

•This also means we are not depending on already patented technologies, which would have influenced the price of the radar.


Power Requirements

Power consumption transmitting is only 17 W

• 30% less than a 2 kW radar

• 50% less than a 4 kW radar

• Power consumption in standby is only 1.6 W

• The BroadBand radar has no magnetron to heat!


Not Considered in the Report

The very low TX power of the BroadBand radar will often not trigger Racons and SARTs.

Racons are ’active radar reflectors’ on some major buoys used mainly by commercial vessels for long distance radar navigation.

The BroadBand radar cannot be used as the primary radar for rescue vessels, but serves as an outstanding no. 2 radar for close range search.


Additional Benefits

• No 30 m blind spot at centre (mainbang)• Easy to operate. No tuning or adjusting required• Very low sidelobe effects • Totally safe, 0.1 W TX – install anywhere• No magnetron that wears out over time• Easy to install – 9 mm cable and very small connector• Easy to dismantle – external connector at radome

Thank you

Questions?

Technology

Digital Radar Processing and the New Low Power Radars