bpa regional meetings the use of gps in cpe...•rtk gps systems positional location of signs &...

BPA Regional Meetings

The Use of GPS in CPE

by Gary Smith BEng PGDip MSc CEng MCIHT MILT MIPP

Technical Details Supplied by Korec & Trimble

www.garykaysmith.co.uk

Presentation Outline

We Will Cover:

• Principles of GPS

• CPE Applications

• Planning

If Time Permits We Will Also Cover:

• Sources of Error

• Accuracy Factors

• Differential GPS

Principles of GPS

Introduction to GPS

?

The Global Positioning System (GPS)

• Developed by the American Department of Defence (DoD)

• ALL WEATHER, 24 Hour, worldwide time and positional information service

• Minimum of 4 Satellites required for a position

• 3 Segments: Control; Space: User:

Control Segment

Space Segment

User Segment

Segments

Control Segment

• Monitors and controls satellite orbits

• 1 Master control station ( Colorado Springs USA )

• 12 Monitoring Stations

The Global Positioning System

Space Segment

• 28 Satellites• 22,000km above the

earth• 12 Hour Orbits

How does GPS Works ?

4 or more satellites required Travel time of GPS

Distance= Speed x Time

Principle of Trilateration

The Global Positioning System

User Segment• Receive signals from Space

Segment• Information is used to

determine our position• CPE Applications ???

CPE Applications

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CPE Applications• CCTV Smart Car

Enforcement of Bus, Parking & Traffic Contraventions using either:

Attended or Un-Attended Mode

• Digital GPS Camera

Positional Condition Survey

Enforcement of Parking Contraventions

• XT / XH DGPS systems

• RTK GPS Systems

Positional Location of Signs & Lines (& Any Asset)

CPE Applications

• Autonomous (10-15m)

E.g. GPS Sat Nav

• DGPS (Differential)(0.5 - 3m)

E.g. CCTV Smart Car & Digital GPS Camera

• “Float” (Meter to decimeter)

E.g. GPS Handheld Systems

• “Fixed” (1-3cm)

E.g. R8 GPS/GNSS System

CCTV Smart Car

Digital GPS Camera

Digital GPS Camera

Digital GPS Camera

Digital GPS Camera

XT / XH DGPS systems

RTK GPS Systems

GPS Surveying

Google Earth View of Surveying

Google Earth View of GPS Surveying

GPS Surveying Transferred to FastMap

GPS Surveying Transferred to MapInfo

MapInfo Transferred to ParkMap

Planning

?

Planning GPS

Planning GPS & GNSS

Sources of Error

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Sources of Error

These factors cannot be controlled!

• Obstructions

• Multipath

Obstructions

Multipath

Accuracy Factors

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Accuracy

These factors can be controlled by the GPS receiver:

• Satellite Geometry

• Elevation Mask

Satellite Geometry (DOP)

• A measurement of satellite dispersion relative to each other

• Often measured in DOP (Dilution of Precision) –Standard deviational spread of satellites.

• Lower the DOP the more spread out the satellites are relative to each other

• Lower the DOP the greater the accuracy• To obtain sub meter accuracy, a Positional DOP

(PDOP) of 6.0 less is requiredAccuracy Factors

Good Satellite Geometry (DOP)

Accuracy Factors

Poor Satellite Geometry (DOP)

Accuracy Factors

Elevation Mask

15 Degrees above the horizon

Atmosphere

Accuracy Factors

Controlling Accuracy Factors

• DOP value of less than 6.0

• Signal to Noise Ratio greater 4.0

• Elevation mask of 15o

Speed or Accuracy…?

Accuracy Factors are controlled by a simple Slider Bar in FastMAP

Differential GPS

?

Differential GPS (DGPS)

• GPS Positions on their own are often referred to as Autonomous (uncorrected).

• Autonomous GPS will give you typically 10-15m

• To improve this we need to perform some form of Differential correction to our GPS positions (DGPS)

Real Time DGPS

• A means of applying differential corrections whilst collecting GPS positions at the Rover

• Requires direct communication to a base or ground control station

Correction onlyRover Base

VRS – (Virtual Reference Station)

Trimble VRS NOW

– Real-time RTK / DGPS correction service provided by Ordnance Survey & Trimble’s Network of Base stations.

– Corrections provided by GPRS/3G– Requires a subscription fee & mobile

phone costs– 30cm accurate with XT / XH DGPS

systems– cm accurate with RTK GPS Systems

VRS – How it works – 3 Steps• 1) Rover receiver sends VRS

server its location from 5 or more satellites

• 2) VRS finds 3 nearest base stations and creates virtual base station within 10km of the Rover

• 3) VRS Server sends back DGPS corrections the Rover

Any Questions?

Company ProfileGary Kay Smith Ltd was established in 2005 to match the Key Skills of its founders as Business Management Consultants with Specialist Aspects including:

Business Management

Consultancy

Communications

Training

Consultancy Services

Business Management

Financial Management• Change Control• Financial Analysis• Benchmarking• Value Engineering• Business Case Preparation, Monitoring & Review

Project Management• Prince2 Philosophy• MS Project & MS Excel Project Plans

www.garykaysmith.co.uk

Consultancy Services

Consultancy

Highway Development• Planning application assessments• Transport impact assessments• Parking accumulation surveys• Asset surveying & mapping (inc Landscaping, Street Furniture & Trees)

Parking• Traffic Management Act 2004 specialist advice• Business case preparation• CPE feasibility business plan and implementation• Review of Parking Controls (inc GIS mapping of asset data)

Traffic and Transportation• Accident analysis• Junction design• Road space solutions• Traffic Sign Design and Traffic Regulation Orders• Public Consultation including statistical analysis of results www.garykaysmith.co.uk

Consultancy Services

Communications

Analysis• Spatial Analysis• Demographic Analysis• Equality & Diversity Analysis• Response Analysis• Customer Feedback

Consultation• Presentations• Workshops• Workgroups• Mystery Shopper• Postal Surveys• Door to Door Surveys• One to One Interviews

www.garykaysmith.co.uk

Consultancy Services

Training

City & Guilds & Edexcel Approved Centre• CCTV• Civil Enforcement Officers (plus Notice Processing & Supervisors)• Community Wardens (plus Accredited Persons)• Conflict Management• Customer Service• Health & Safety in the Workplace • ILM Centre (Team Leading, Leadership & Management)• NVQ Centre • Security Guarding

City & Guilds GOLA Centre• Mobile testing facilities using our suite of laptop computers

One Day Technical Courses• In house course tailored to our Clients Needs

www.garykaysmith.co.uk

Introduction To Key Staff

Gary Smith is the Managing Director of Gary Kay Smith LtdGary is a former Parking ManagerHe is a Chartered Engineer, Masters Qualified with over 25 yearsIndustry related experience in Highways, Parking, and Traffic & TransportationIn both Public and Private Sectors

Kay Smith is a Director of Gary Kay Smith LtdKay is a former Assistant Parking ManagerShe is a Degree Qualified Engineer with over 15 yearsIndustry related experience in Highways, Parking, and Traffic & TransportationIn both Public and Private Sectors

Danny Purton is the Business Manager & Quality Co-ordinatorDanny is a former Head of ServiceHe is a Chartered Engineer with over 40 years Industry related experience in Business Management, IT and Quality Systems

Peter Matthews is the Office & IT ManagerPeter is a former IT SpecialistHe has over 20 years industry related experienceIn the GIS/GPS Surveying, IT and Parking Sectors www.garykaysmith.co.uk

Contact Us

W: www.garykaysmith.co.uk

E: garykaysmith@btconnect.com

T: (01279) 417148

F: (01279) 417250

M: 07939337355

A: Allen House 1st FloorEdinburgh WayHarlowEssex CM20 2HJ

www.garykaysmith.co.uk