Peter Selwyn Gps Technologies in Ppus Claryfing Some Misunderstandings

7/27/2019 Peter Selwyn Gps Technologies in Ppus Claryfing Some Misunderstandings

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Photoc

ourtesyofFlindersPorts

GPS Technologies in PPUs

Clarifying some misunderstandings


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Our staff:

Experienced mariners

Marine electronics experts

PPU experts

Our customers:

Government Marine Departments

Port Authorities

Terminal operators

Pilotage companies

Independent pilots

Large oil & gas corporations

Coast Guards

In over 25 countries

Our Company


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Producing PPUs since 2003

Supported by world-leading software, electronics and GPS experts

Presented and published a wide variety of industry papers

Industry members of bodies such as IHMA

Experience


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What is a PPU (Portable Pilot Unit)?

Is it the display? (Laptop, Tablet, iPad, etc)

Is it the Software? (Basic, Advanced)

Is it the sensor equipment?

Ship-based (normally via AIS interface)

Wired (AIS Cable)

Wireless (AISPilot)

Independent GPS

Single GPS antenna

Without gyro assistance (LightPilot)

With gyro assistance(ChannelPilot)

Semi independent heading/ROT

Dual GPS antenna (HarbourPilot)

Fully independent heading/ROT


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Wired and Wireless AIS

connectors


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Single antenna GPS with and

without gyro assistance

LightPilot

(no gyro)

ChannelPilot

(with gyro assistance)


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Dual antenna

(fully independent system)

HarbourPilot


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Only as good as the data from the sensors

Only as good as the software being used

Only as good as the chart on which its displayed

Only as good as the level of training of the user touse it

This presentation will concentrate on the datageneration aspects

A lot of confusion over accuracy and terminology

The PPU is the combination of all the above


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Basic GPS (iPhone/Android/handheld GPS)

15-30m

Basic GPS with DGPS corrections

10-15m

High quality GPS

2-3m

High quality GPS with DGPS corrections


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Any GPS will give you a position

But knowing the position only tells you where the

antenna is

It doesnt tell you where the bow or the stern are

The most important factor is:

HEADING

(Proa)

But - whats the most important factor?


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Ship points in wrong direction on screen

Position showing with 15m error circle

What happens if we dont know heading?


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Position with 2m error



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If ship is moving, the heading will follow COG, not true

heading



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If we add the true heading, with ROT as well, we get a

much better image of what is happening



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Ships gyro via AIS Pilot Plug

Gyro error

Whole-degree rounding

Gyro-assisted PPU

Single-antenna system with gyro assistance

Eg ChannelPilot

Fully independent PPU

Dual antenna system

Eg HarbourPilot

Where does heading come from?


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Antennas 1.6m apart = 0.1 deg error (95%)

Error at bow (250m distance) =


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GNSS (Global Navigation Satellite System) GPS American System

GLONASS Russian System

Beidou (Compass) Chinese System

Dual Frequency

L1/L2

Making Position more accurate

DGPS (Ground-based)

SBAS (Space-Based Augmentation Systems)

(WAAS/EGNOS/MSAS/GAGAN)

RTK (Real Time Kinematic)

A little about terminology?


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For position accuracy absolutely NO! Glonass by itself is less accurate than GPS

GPS + GLONASS is not possible (clock systems areincompatible)

Only advantage is it gives an alternative system whenGPS reception is poor

For heading accuracy Yes.

More data for heading computer to use

Heading is calculated quicker and more reliably

Allows for greater antenna separation (dual antennasystems)

Single antenna systems

Glonass does very little except provide redundancy

Do I need GLONASS as well as GPS?


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For position accuracy a qualified yes, but notmuch

Civilian users cannot use the all the data from the L2 freq

Addition of L2 data helps to reduce Ionospheric errors

For heading accuracy Yes.

More data for heading computer to use

Heading is calculated quicker and more reliably

Allows for greater antenna separation in dual antennasystems

Single antenna systems for pilotage

Dual frequency is not so important

Do I need Dual Freq (L1/L2)?


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Yes but not so much for the absolute positionalinformation itself

How accurately do you measure your antenna offsets?

How accurate is the chart?

Pilots use their eyes

Velocity data is improved if position is moreaccuracy

Do I need better posit ion accuracy?


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Dont rely on AIS (notoriously poor data) Single antenna PPU

Make sure its gyro integrated (eg ChannelPilot)

Dual antenna systems

By putting the antennas further apart

Add GLONASS for more data

Add L2 frequency for more data

How do I make heading more accurate?


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Dual antenna systems

For Position accuracy

DGPS is fine.

RTK adds a little but really only to velocity

For Heading accuracy

Glonass and dual freq allow greater antenna separation hence moreaccurate

Single antenna systems

Get the best you can

Be gyro-integrated

In summary 1


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Most important of all..

Dont forget to look out the window

This is not a video game!!!

Its just an aid no different from any other aid

In summary 2


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MUCHAS GRACIAS

MUITO OBRIGADO

THANK YOU

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Peter Selwyn Gps Technologies in Ppus Claryfing Some Misunderstandings