Implementing the Multi-Source Positioning

Service: The Multi-Source Receiver

Dr. Paul WilliamsGeneral Lighthouse Authorities

United Kingdom and IrelandACCSEAS Conference

Rotterdam 16th - 19th February 2015

ACCSEAS Resilient PNT: Two Important and Novel Results!

ACCSEAS receiver

- We’ve built the world’s first prototype Multi-Source Resilient PNT Receiver!

- Based on GNSS as primary PNT source, integrity algorithms and a terrestrial (frequency and system diverse) backup

R-Mode- Investigated a way of adding ranging signals to already existing

IALA DGPS radio-beacons and AIS VHF base-station transmissions

- Michael Hoppe – WSV – Feasibility Study and Trial

Ship-side Resilient PNT With Data Processing Element

terrestrial

Resilient PNT Options

• Harden existing systems– Adaptive antennas– Plausibility checks

• Inertial Navigation Systems

• Use dissimilar services– Radar Absolute positioning– Ranging mode (R-mode)– eLoran

• Only need one fully working system to demonstrate the principles

Resilient PNT receiver/engin

e

Resilient PNT receiver/engin

e

terrestrialOther PNT

source

Resilient PNT solution

GNSS GNSS

RADAR Absolute Positioning: Results of Static Tests

• Derive Latitude and Longitude from one or more RADAR returns

• Single racon accuracy 40 m within 5 M, 100 m at 12 M

• With two racons, 2 m accuracy achieved

• Availability of single racon fix at under 5 M was 98%

• Availability of two-racon fix dictated by more distant racon at 87%

R-Mode Feasibility Study

• Add a ranging signal to the broadcast of IALA DGPS radio-beacons

• Also AIS base stations

• Feasibility study and experimental transmissions performed

• More detail in the presentation from Michael, coming next

eLoran in the NSR

Runs continuously; available since May 2010; 10-20m accuracy in ports with differential service (green area)

ACCSEAS: Planned Multi-Source Receiver Architecture

ACCSEAS Multi-Source Positioning Receiver

Multi-Source Positioning Receiver

Resilient PNT Data Processor Computes a position solution based on TOA measurements from eLoran receivers, as

required (also RMode as a future expansion)

Stores and applies propagation data corrections (e.g. eLoran ASFs)

Applies differential correction data to the pseudorange measurements of terrestrial PNT services

Computes and maintains the Horizontal Protection Levels (HPL) for complementary PNT services and the primary DGPS service – independent performance monitoring

Detects incidents of GPS interference and jamming, and monitors the interference level

Automatically and seamlessly switches the main PNT output of the service to the best available backup source given the prevailing interference/jamming/outage conditions

Generates alarms for the purposes of notifying the mariner and shore-based stakeholders

Early version PNT Data Processor

Vessel Installations – P&O Pride of Hull• Ro-Ro Cargo and Passenger

- 59,925 Gross Tons- Length: 215m- Beam: 32m - Draft: 6m

• ACCSEAS receiver installed in equipment room for trial

• Video available!

ACCSEAS Resilient PNT Portrayal

ACCEAS: Resilient PNT Portrayal

Vessel Installations – MV Palatine• Ro-Ro Cargo

- 25,500 Tons- Length: 194m- Beam: 26m - Draft: 6.4m

• ACCSEAS Receiver integrated into ECDIS’ second input

• NMEA GLL, GGA, VTG, ZDA, DTM

Vessel Installations –THV Patricia• Buoy Tender

- 2639 Tons- Length: 86m- Beam: 14m - Draft: 4.4m

• ACCSEAS Receiver integrated into Sperry ECDIS’

• Receiver EMC tested- MCA- Lloyds

Use of GPS in the Maritime Sector

GPS has become the normal means for maritime positioning, navigation and timing.

The level of integration onboard is different for each vessel depending on equipment fitted.

But GPS is everywhere!

Receiver StandardsIMO: NCSR

• Developing Multi-Source Receiver Performance Standard• Not stipulating what systems to use, but calls for system diversity in terms of

frequency, systems and resilience. • Hope to be completed by March 2015, whereupon final draft will be sent to

MSC later in the year

IEC• Receiver test standards• Generally waits for IMO approval and works to their standards, but can start

earlier• RTCM SC-131 is drafting test specification • IEC will likely take 2 years to complete specification

RTCM• Starting point for technical specifications• SC-131 – MSRX, SC-127 – eLoran, SC-104 – DGPS (MF R-Mode)

Likely not going to be mandatory carriage requirements, but ship owners will upgrade as part of their normal equipment replacement schedules.

Thank You!Dr. Paul Williams

paul.williams@gla-rrnav.org

The General Lighthouse AuthoritiesTrinity House

The QuayHarwich

EssexCO12 3JW

United Kingdom

http://www.gla-rrnav.org

Tel: +44-1255-245146