Radar / Collision Avoidance / Navigation for Boaters

Radar / Collision Avoidance /

Navigation for Boaters

By David Vacanti

Sr Fellow Advanced Technology Emeritus

Honeywell Aerospace

2/2019 Copyright Vacanti Yacht Design LLC 2019

Gee Martha, that radar is not

working worth a darn today…

Copyright Vacanti Yacht Design LLC 2019

• Value and Purpose of Radar

• AIS Vs Radar

• Radar Basics

• Radar Types

• Radar Image Displays

• Radar Installation

• Safety

• Doppler Vs Standard Radar

• Radar Operation Examples

• Radar Collision Avoidance Examples

• Radar Settings and Controls

• What Radar Can and Cannot Do

• Summary

Agenda – Todays Presentation


Purpose and Value of Radar • Collision Avoidance

• Above Surface Rocks, Markers, Navigation Buoys

• Other Vessels, Shorelines, Towed Barges behind AIS Tug

• Works in Conjunction with AIS (Automatic ID System)

• Finds true target location with no delay

• Corrects transmitted AIS GPS Location Errors

• Shows non-AIS equipped Targets

• Weather Detection • Detect Rain Squalls

• Navigation • Verify Plotted Chart position Vs Terrain / Navigation Objects

• Flags GPS Location Errors (Spoofing, GPS RX Errors)

• Radar can Measure: • Range

• Angle

• Velocity (Consecutive Scan or Doppler)

• Rain Rate


If I have AIS why do I need Radar?

AIS is not installed on all vessels – Only Radar can see all vessels

regardless of AIS equipage

AIS transponders can transmit erroneous data if not correctly installed

AIS transponders can be set to Silent Mode (No transmissions)

AIS cannot be used for Navigation in Fog to validate position

Only Radar can see through fog and moderate rain

All Optical sensors are obscured by any atmospheric aerosol

AIS TRANSMIT is generally not installed in 30Kt fishing vessels!!

AIS cannot validate locations of Navigation Buoys in limited visibility

AIS = Automatic

Identification

System

Vessel #1

AIS Xmit

GPS

Transmit Vessel

Name, Location,

Course and Speed

Vessel #2

AIS Receive

Chart Plotter Display Vessel

Name, Location,

Course and Speed Copyright Vacanti Yacht Design LLC 2019

Radar Principals of Operation

Object

Object

Radar cannot see through or around objects.

Therefore objects at short range can mask or

hide objects at longer range.

Radar systems MUST be mounted well clear

of all obstacles to avoid “blanked regions”

and false angle reporting

Object is hidden

from radar by

object in front.

Radar measures

range by time of

flight of transmitted

signal as it returns

to the receiver.

Range resolution

depends on pulse

length or pulse

“chirp” bandwidth

Radar measures

Angle by position of

antenna rotation

angle. Angle

Resolution depends

on antenna size

(beam width).

Wider antennas

provide better

Azimuth angular

resolution


Marine Radar Antenna Pattern

Radome Antenna System Open Array Antenna System

Horizontal Pattern

(Top Down View)

Vertical Pattern

Elevation View

Antenna Sidelobes and Backlobes can

cause false target detection or angular

extension of targets


Types of Marine Radar Systems High Power Pulse

Magnetron Transmitter

2,000 to 25,000 Watts Peak Transmit Power

0.2 to 18 Watts Average Transmit Power

Eye / Brain Damage possible at short range

Pulse Compression “CHIRP” Radar

Solid State (Transistor) Transmitter

20 to 80Watts Peak Transmit Power

2 to 8 Watts Average Transmit Power

Pulse Compression – Doppler Radar “CHIRP” Radar


20 to 80Watts Peak Transmit Power

2 to 8 Watts Average Transmit Power

FMCW (Broadband Radar – Navico) Frequency Modulation – Continuous Wave

“CHIRP” Radar


0.2 to 0.4Watts Peak Transmit Power

0.2 to 0.4 Watts Average Transmit Power


Radar Modulation Schemes

Standard Pulse Radar (Magnetron 25,000 Watts Peak, 18Watts Average or 0.072% On Time)

Pulse Compression (Solid State Transistors – 50Watts Peak, 5 Watts Average, 10% On Time)

8,200Volt Power Supply

“Tube” technology that

slowly drops in output

power over time, Noisy

Transmit Spectrum –

High Power Oscillator

70Volt Power Supply

with Constant Power

Over Time, Pure

Transmit Spectrum,

Power Amplifier

1.5”

2.6”

0.001Sec

0.72uSec or 354ft Range Resolution

0.001Sec

100uSec with 50MHz Chirp or 10ft

Range Resolution

50MHz of

Frequency

Change

Constant Frequency


Radar Modulation Scheme - Completed

FMCW(Solid State Transistors – ~1Watt Peak, ~1Watt Average, 100% On Time)

5Volt Power Supply with

Constant Power Over

Time, Pure Transmit

Spectrum, Power

Amplifier

0.001Sec

0.001Sec with 65MHz Chirp or 7.5ft

Range Resolution

65MHz of

Frequency Sweep <1” Per Side

FMCW (Broadband Radar) = Frequency Modulation, Continuous Wave

Resolution:= Speed of Light /(2 x Chirp Bandwidth)

300,000,000/ (65,000,000 x 2) = 2.3m or 7.54ft


Range and Angle Resolution of Marine Radar Systems

Range Cell

of Length “d”

Range Cell “a’

Degrees wide

Pulse

Length

uSec

Pulse

Bandwidth

in MHz

“d” Cell

length

Antenna

Width

Angular Resolution

“a”

1uSec 1MHz 500ft 2ft 3.4Deg / 326ft at 1Nmi

0.2uSec 5MHz 100ft 3ft 2.3Deg / 221ft at 1Nmi

0.03uSec 33.3MHz 15ft 4ft 1.7Deg / 163ft at 1Nmi



1 uSec = 1millionth of a

second or 0.000,000,1

Seconds

Pulse

Radar

Pulse

Compression or

FMCW Radar

Type of Radar Transmitted

Signal

Type and Size of Radar

Antenna


Radar Horizon Or Max Useable Range

Radar Height

H1

Target Height

H2

Max Radar Range

D in Nautical Miles

5ft 5ft 5.45Nmi

15ft 15ft 9.45Nmi

50ft 50ft (Large Ship) 17.25Nmi

20ft 626ft (Hill Side) 36Nmi “Spec”

20ft 5508ft (Mountain!) 96Nmi “Spec”

Typical Useful Range for Marine Radar is <20Nmi for

Target / Navigation Buoy Detection. Rain Storms can

be detected at longer ranges

Runabout

Trawler

Trawler /

Sailboat

SHIP


Effects of Antenna Sidelobes Object 1

Range 1

Object 2

Range 2

Object 1 is shown at same

angle as mainbeam

position Object 1 shown at true

angle location when

mainbeam passes over it

The radar can only report target

positions according to the rotation

angle of the antenna. It does not

“know” signals are arriving from

sidelobe locations and reports them

at the angle of the mainbeam

Only very “bright” or highly reflective objects or

bright objects at short ranges cause false angle

locations for targets.


Examples of “Sidelobes” in Light Illumination

Sidelobe examples Mainbeam examples


Sidelobe Detection Example

Sidelobe

detection of

bright object

on shore.

Antenna

location is

blue line –

sidelobe

location is

dashed red

line

Sidelobe Detections Copyright Vacanti Yacht Design LLC 2019

Safe and Effective Radar Installation Radar is LINE OF SIGHT – ANY Obstruction in the path of the antenna will

result in some form of degraded performance

Mounting Position

Highest Possible on the vessel with 360 degree clear line of sight

Sailboat installations are always limited by Mast

High Power Magnetron Radars MUST be mounted ABOVE height of all

crew positions

Damage to eye sight can result from high power pulse radars

Least Possible Obstructions

No more obstruction than standard “mast” mounting if at all possible

Install well above a Bimini with metal supports

Do not place kayaks, dinghies, Crab pots or other gear in way of the

radar

NEVER install BELOW windscreen of Flybridge

Dangerous to crew

Severe obstruction to the side and aft directions

High Sidelobe levels with false target detections

Non-Line of sight to GPS Antennas

High Power Radar Microwave Radiation may cause damage to GPS

receiver in the antenna module

Radar radiation may jam or cause intermittent operation of GPS receiver


Do’s and Don’ts for Radar Installation

As installed new by the

builder! What were they

thinking? Green: Clear of obstructions and away

from people to prevent exposure to harmful

microwave radiation

Orange: May cause interference with other

electronics or second radar

Red: Major obstructions and danger to

people from Microwave radiation


Example System Integration

Wind Display

@

Helm

Satellite

Antenna

Satellite

Receiver

Depth

Sounder

Ethernet Switch

Camera Display

at

Flybridge

Quantum

Radar

Auto

pilot

Auto

Pilot

Computer

Heading

Sensor

AIS

Xponder

Rudder GPS

VHF 1

VHF 2

Ray STNG /

NMEA 2000 Bus NMEA 0183 Bus

GPS Location Fusion

Stereo VHF Radios may provide AIS

receive only or transponder

capability that can be sent to other

systems via NMEA bus systems

Dedicated AIS

Transponder


Two Forms of Radar Display / Control

Dedicated Radar Display

Multi-Function Display – Chart Overlay

or Dedicated View


Doppler Vs Standard Radar Standard Radar – No Doppler

Doppler

Approaching

Target

Doppler

Receding Target

Doppler capability is only possible with solid state

pulse compression or FMCW radar systems that

provide required frequency stability

Additional Signal processing is required to provide

measurement of target velocity and direction of

travel

Doppler immediately shows moving vessels in a

cluttered radar image

Overlay of AIS and Radar

Detection with AIS direction and

speed of travel shown graphically


Multiple Vessel Crossing Situation

• Radar and AIS

Targets

• AIS Vs Radar

• Barge

• Antenna

Sidelobes

Note that the presence of a

barge is NOT provided by

AIS – it can only be seen by

radar!!

Non AIS

equipped

trawler


AIS Target List


New Collision Avoidance Graphics for Radar

Settings for Automated Collision

Avoidance for Radar Targets


Collision Avoidance Example

1

2 3

4

History of

target Motion Beginning of

Track

TCPA = Time to

Closest Point of

Approach


Radar Track Vector of Nearby Vessel

Radar detection and

estimate of speed

and direction of

travel using manual

detection and ARPA

ARPA = Automatic Radar Plotting Aid – For Tracking Targets Copyright Vacanti Yacht Design LLC 2019

Close Up of Tracked ARPA Target and Shoreline

Radar

Reflection is

blocked by

Armitage

Island

Tracked Target with 3 minute Direction and position vector Copyright Vacanti Yacht Design LLC 2019

Vessels in Harney Channel

Two vessel

detections, currently

not being tracked


A few minutes later


Approaching Vessel being Tracked


Track has been dropped


Target Crossing at 90 Degrees


Vessel approaching narrow channel


Target Intent??


RADAR Settings and Controls

Sea Clutter Sea Clutter is radar reflections from Wave Tops in Windy Conditions

Fixed Sea Clutter Settings

“Harbor”, “Coastal” and “Open Sea”

Variable Sea Clutter Control

Rain Attenuation Reduce wide area reflections from rain fall

Mitigates saturation of display by wide area reflections from rain fall

Receiver Gain Settings Allow selective detection of highly reflective or low reflectivity targets

Adjust overall sensitivity of the radar

Color Gain Settings Allows indication of Radar Reflectivity of Targets


Example of Sea Clutter on Radar Screen

Sea Clutter (Reflections from Wave

Tops) Overwhelms Sea Targets

Sea Clutter Reduction Via

Attenuation Setting


Preset Radar Sea Clutter Settings

“Harbor” “Coastal”

“Offshore”

• Harbor – Minimum Attenuation –

small targets are visible

• Coastal – Moderate Attenuation of

Sea Clutter, some targets are

removed

• Offshore – High Attenuation of Sea

Clutter, small targets are removed


Sea Clutter Reduction

“Offshore” Sea

Clutter Setting

48% Sea Clutter

Attenuation

0% Sea Clutter

Attenuation


Radar Rain Clutter Example

Rain Clutter

Attenuated

Rain Clutter

Overwhelms

Sea Targets


Rain Clutter Adjustment

Zero Rain

Attenuation 51% Rain

Attenuation

84% Rain

Attenuation

Note Blue tracks of

targets that have

been lost with

added attenuation

for rain clutter

suppression

Blue detections are

“trails” or histories of

past detections. It is

also useful to indicate

the motion of a moving

target

Use Care when adding

rain clutter

suppression to avoid

losing too many

targets


Receiver Gain Adjustment

Normal

“auto” setting

Minimum

Receiver Gain

Maximum

Receiver Gain


What Radar Cannot or May Not Do Cannot see through or around obstacles

Causes “shadowing” or blank spots

Radar image will not directly correspond to shorelines

on a chart – making dedicated radar displays difficult to

use in many conditions

Chart Overlay is a big help in validating targets and

navigation position

Cannot see floating debris on the water

Cannot see small targets in heavy rain conditions

Rain attenuates signal and causes “display saturation”

Cannot see small targets in Heavy Seas

Reflections from waves obscure targets

Marine Radar may produce target “fading” in smooth

conditions

This is a physics phenomenon and not a short coming of

the radar itself. Continued motion of at least one vessel will

cause the target to eventually reappear Copyright Vacanti Yacht Design LLC 2019

Latest Radar / AIS / GPS Technology Automated On Screen Collision Avoidance Plotting

When engaged it provides direct information on how to steer or change speed

to avoid a collision or near collision

AIS – Aids to Navigation – Virtual Buoys that are not physically on the water but are

observed on electronic charts

Doppler Radar

Where radar is going:

Low power, transistor based radars with complex waveforms

Electronic Beam Steering with no mechanical rotation

High Speed updates, simultaneously observe 3 or 4 zones at the same

time

Doppler Processing to reduce sea clutter, enhance target detection

Automated collision avoidance capabilities

GPS Rollover Date April 6 2019!!!

Older (<2005) GPS Receivers or Chart Plotters may have problems with

GPS functionality. Check with your Manufacturer. Last Rollover was in 1999.


Summary and Suggestions Strongly Encourage installing AIS and Radar together

AIS Receive and display capability on your display allows calling a vessel on

Channels 13 or 16 By Name of Vessel – rather than “ Large vessel in San

Juan Channel heading north”

Encourage installing AIS Class B Transponder in addition to Radar

Helps make sure that commercial vessels can see you well in advance

A big help with avoiding Ferry, Tug, Ship and Transport Traffic

They know who you are and can see you on their commercial displays

AIS does NOT show barge Tows!!! Only Radar will show you that there are

TWO vessels involved and you MUST not pass astern of a tug with a tow!!

AIS does not show vessels that are not equipped with a transponder or

vessels with transponders turned off or in Silent mode

Navy and Coast Guard Vessels Frequently do NOT actively transmit on

AIS for security reasons

ONLY Radar will detect these large vessels in low visibility

conditions

Consider Upgrade to new Doppler Capable Radars

Automatically locates targets and shows Approaching or Receding motion with

no manual interaction with the radar

Very critical in foggy conditions with high speed fishing boats or dense

traffic areas


Radar / Collision Avoidance / Navigation for Boaters

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