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HODSB Speedometer - UK Government Web Archive
The Speedmeter Handbook
(Fourth Edition)
A Guide to Type Approval Procedures for Speedmeters
Used for Road Traffic Law Enforcement in Great Britain
Dr S R Lewis
Publication No. 15/05
The Speedmeter Handbook
(Fourth Edition)
A Guide to Type Approval Procedures for Speedmeters
Used for Road Traffic Law Enforcement in Great Britain
Dr S R Lewis
Publication No. 15/05
HOME OFFICE SCIENTIFIC DEVELOPMENT BRANCH
i
THE SPEEDMETER HANDBOOK (FOURTH EDITION)
DR S R LEWIS
FIRST PUBLISHED 2005
© CROWN COPYRIGHT 2005
The text of this publication may not be reproduced, nor may talks or lectures based on material
contained within the document be given, without the written consent of the Director, Home Office
Scientific Development Branch.
Published by:
Home Office
Home Office Scientific Development Branch
Woodcock Hill
Sandridge
St Albans
Hertfordshire AL4 9HQ
United Kingdom
ii
Management summary
Proposed changes to road traffic law will facilitate the introduction of new methods of
speed detection, especially those that permit automatic and unattended detection by
using a camera to record the offending motorist. This handbook contains a description
of the technical requirements to be met for consideration of type approval of certain
types of speedmeter which are prescribed devices for the purposes of the road traffic
legislation. The handbook is intended to be a reference for manufacturers wishing to
develop or sell existing products to the Police Service in Great Britain. The handbook
contains not only a list of technical requirements but also guidance on methods of
measurement, and the procedures to be followed in seeking type approval.
Type approval has been necessary for radar speedmeters since 1984, but the approval
procedures previously covered only hand-held and across-the-road models, which were
neither capable of taking photographs nor of operating unattended. The opportunity
has been taken to reassess the technical parameters and to expand the requirements to
cover the use of photography and video to permit automatic and unattended
operation. Speedmeters using road surface sensors have also been included.
Preface to the second edition
The second edition of the handbook has been broadened in scope to include
speedmeters using sub-surface sensors and optical systems. Previous requirements for
radar and sensor speedmeters have not been changed, but the opportunity has been
taken to clarify the text in some places.
Preface to the third edition
The third edition of the handbook has been broadened in scope to include controlled
motorway over-the-road radar speedmeters, which operate with variable speed limit
signs, and the use of cameras producing electronic images. It also covers requirements
for the storage of electronic data necessary for its acceptance as evidence by the courts.
Preface to the fourth edition
The fourth edition of the handbook includes amendments to the requirements for
over-the-road radar speedmeters that will be operated on motorways with active traffic
management where the hard shoulder is temporarily used as a running lane. The
electromagnetic immunity tests have been updated, the frequency range and levels
amended, and a new simulated TETRA immunity test introduced to test for
immunity from police TETRA radios. The new test is not required for automatic
systems designed to be operated unattended. The permitted positive speed error has
been reduced to be close to the level recommended in Organisation Internationale de
Métrologie Légale recommendation 91. The requirements for sensor speedmeters
using inductive loop sensors and for systems that combine speed and red light
enforcement are now included. Legal advice is that it is not necessary to continue to
require evidence from systems using digital imaging to be recorded at the roadside,
and reference is now made to separate requirements for the remote recording of this
evidence and control of the device.
Publication No. 15/05
iii
Contents
1
Page
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
2
Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
3
Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3.1
3.2
3.3
3.4
3.5
3.6
3.7
3.8
3.9
3.10
3.11
3.12
3.13
3.14
3.15
3.16
3.17
3.18
Attended actively operated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Automatic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3.2.1 Unattended operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
3.2.2 Supervised operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6
Beam width . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.5.1 Hand-held radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.5.2 Across-the-road radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.5.3 Variable speed limit above-the-road radar . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Surface pressure sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Sub-surface pressure sensors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Speedmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Optical speedmeter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
3.9.1 Hand-held . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
3.9.2 Across-the-road . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Camera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Measuring zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Vehicle detector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Recording zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Start image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Stop image . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Recording counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8
Inductive loop sensor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
Combined traffic light and speed camera . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
4
General requirements for eligibility for type approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9
5
Operational requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1
5.2
5.3
5.4
5.5
5.6
5.7
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Test signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Segmented display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Manual reset . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Sensor systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.5.1 Pressure sensor systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.5.2 Inductive loop systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Hand-held radars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Automatic systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.7.1 Second method of speed measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.7.2 Offence data storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.7.3 Analogue video tape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Publication No. 15/05
1
5.8
5.9
6
Constructional requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.1
6.2
7
Optical hand-held speedmeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Variable speed limits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Components . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Power supply . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.2.1 Battery operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.2.2 Vehicle fitting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.2.3 Mains operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Performance requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.1
7.2
7.3
7.4
7.5
7.6
Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Working temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Robustness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Electromagnetic immunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Electrostatic discharge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Measuring accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.6.2 Radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.6.3 Direction-sensing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.7 Radar operating frequency and power output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.8 Radar antenna characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.8.1 Across-the-road radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.8.2 Hand-held radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.8.3 Variable speed limit above-the-road radar . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.9 Laser power output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.10 Camera timing accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.10.1 Photographic and digital cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.10.2 Video cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.11 Vehicle detector speed threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.12 Inductive loops . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8
Measuring methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
8.1
8.2
8.3
8.4
8.5
8.6
General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Speed measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Second method of speed measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.3.1 Photographic and digital cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.3.2 Video cameras . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Speed simulators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.4.1 Radar speedmeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
8.4.2 Pressure sensor speedmeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.4.3 Optical speedmeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.4.4 Inductive loop sensor speedmeters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Environmental tests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Electromagnetic immunity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.6.1 General test arrangements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
8.6.2 Device specific test arrangement aspects . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.6.2.1 Hand-held radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.6.2.2 All radar . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
8.6.2.3 Vehicle mounted devices . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
2
Publication No. 15/05
8.7
8.8
8.9
9
8.6.3 Modulation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8.6.4 Speed simulators test arrangements and set-up . . . . . . . . . . . . . . . . . . . . . 22
8.6.5 Conducted immunity test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8.6.6 Test limits and frequencies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
8.6.7 Simulated TETRA immunity test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Variable speed limit signs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Stop/start and door alarm frames . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Vehicle detector speed threshold . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Type approval procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Figures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27–30
3
Publication No. 15/05
4
Introduction
1
INTRODUCTION
1.1
Section 20 of the Road Traffic Offenders Act 1988, as originally enacted, provides
that evidence from a radar speed detection device is admissible in a prosecution for
exceeding the speed limit only if the device is of a type approved by the Secretary of
State. This provision was previously laid down in section 90 of the Road Traffic
Regulation Act 1984. In practice, this means that all radar speedmeters used by the
police for speed enforcement in Great Britain need to be of a type approved by the
Home Secretary. To obtain such approval, a model speedmeter must, among other
things, meet specific technical requirements laid down by the former Police Scientific
Development Branch (PSDB), now the Home Office Scientific Development Branch
(HOSDB). The first type approval specification documents for hand-held and acrossthe-road radar devices were published by PSDB (now HOSDB) in 1983 and
1984 respectively.
1.2
In the White Paper, The Road User and the Law, published on 7 February 1989, the
Government set out proposals for enabling more effective use of automatic detection
devices in the enforcement of road traffic law, particularly speeding and traffic light
offences. Statutory provisions to implement these proposals were included in the Road
Traffic Act, which received Royal Assent on 25 July 1991. Following this legislation,
PSDB published the first editions of the Speedmeter Handbook and the Red Light
Camera Handbook to provide guidance on the type approval requirements for a
range of speedmeter devices and red light cameras. These took into account
recommendations made by the Organisation Internationale de Métrologie Légale
(OIML), and were expanded to include equipment incorporating photography and
designed for unattended and automatic operation.
1.3
A second edition of the Speedmeter Handbook was published by PSDB in 1992 and
included technical requirements for speedmeters using optical methods and road
surface and sub-surface sensors. A third edition, published in 1997, introduced
requirements for the use of electronic images and their storage with other electronic
data in ways necessary for their acceptance as evidence by the courts. The opportunity
was also taken to include additional requirements that were previously established for
controlled motorway over-the-road radar speedmeters which operate with variable
mandatory speed limit signs. This fourth edition amends these for use on roads
subject to Active Traffic Management where the hard shoulder can be temporarily
used as a running lane. It also introduces updated electromagnetic immunity tests and
a new simulated TETRA test for testing immunity against police TETRA radios. The
positive speed accuracy is amended to be closer to the limit recommended by OIML.
Included are the requirements for sensor speedmeters using inductive loops and
systems that combine speed and red light enforcement. Reference is made to
requirements for the remote recording of digital evidence and for the control of type
approved devices.
1.4
The type approval procedure consists of a number of technical performance tests
which are carried out on a single production model of the type of speedmeter offered
for approval by the manufacturer or their appointed agent. The actual testing is
carried out by an independent testing laboratory, and is paid for by the manufacturer
or their agent. The formal steps necessary to seek approval are described later in
section 9 of this guide.
Publication No. 15/05
5
Speedmeter Handbook (Fourth Edition)
1.5
The technical procedures described in this document replace previous requirements.
They are intended as a guide to manufacturers and their agents. The procedures will
be updated from time to time and amended versions of this guide will be issued
subsequently.
2
SCOPE
2.1
The test procedures described here are applicable to road traffic speed measuring
equipment, including that combined with traffic light cameras, used for law
enforcement. The scope of the procedures covers Doppler radar, systems using sensors
placed upon the surface of the carriageway, sub-surface sensors, including inductive
loop and piezo sensors, and light beams. Equipment may be designed for attended
actively operated use or for automatic use, either unattended or supervised and used
with a camera or video recorder to record a speeding vehicle.
2.2
These requirements may be updated and supplemented by HOSDB and further
editions may be published in the future.
3
TERMINOLOGY
3.1
Attended actively operated
Equipment designed to be set up and actively operated by a trained user. The accuracy
of the evidence from such equipment is verified by the operator in every case at the
time of the offence. Such equipment may or may not record an image of an offending
vehicle, but its operations are at all times supervised and controlled by the operator,
whose evidence of the offence is crucial.
3.2
Automatic
A speedmeter which, once set up, works by itself without direct and continuing
human intervention and operates with an approved secondary check (see 5.7). Such
equipment shall record an image of a speeding vehicle together with the time, date
and speed, and, if operated with a variable speed limit sign, direct evidence of the
speed limit in force and displayed at that time.
3.2.1
Unattended operation
Equipment mounted in an appropriate housing and designed to operate automatically.
3.2.2
Supervised operation
Equipment designed to operate automatically but supervised to protect the equipment
and the integrity of the evidence.
6
Publication No. 15/05
Terminology
3.3
Beam width
The beam width of an antenna is the total angle between the half-power points of the
main lobe measured for a stated plane of polarisation.
3.4
Failure
A speedmeter will be considered to fail a type approval test if it displays an incorrect
reading of speed outside the tolerance range of error or if it displays a speed when no
measurement should be possible. The display of a blank screen or defined symbol in
recognition of an incorrect reading is acceptable.
3.5
Radar
A speedmeter employing a continuous wave microwave transmitter and receiver
operating on the doppler principle. There are three main types of this device as
defined below.
3.5.1
Hand-held radar
A radar in which the microwave beam is directed along the road at the target vehicle.
3.5.2
Across-the-road radar
A radar in which the microwave beam is directed at a known angle across the road.
3.5.3
Variable speed limit above-the-road radar
A radar in which the microwave beam is directed from a fixed installation at a known angle
above the road along a specified lane and is operated with a variable speed limit sign.
3.6
Surface pressure sensors
A cable or other device which is intended to be placed upon the road surface such that
when a vehicle passes over it some change in its physical properties is produced, e.g.
sensors may work by piezo electricity or changes in air pressure.
3.7
Sub-surface pressure sensors
As 3.6, but the sensor is fixed into a slot cut into the road surface.
3.8
Speedmeter
A stationary device for measuring the speed of road traffic vehicles.
3.9
Optical speedmeter
A speedmeter which uses a beam of light in the visible or infrared region of the
electromagnetic spectrum. There are two main types of this device as defined below.
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3.9.1
Hand-held
An optical speedmeter which consists of a single beam aimed along the road at a target
vehicle. The energy reflected is detected and processed to determine the vehicle speed.
3.9.2
Across-the-road
A system of two or more beams of light aimed across a road and detected by separate
sensors, or reflected by the road surface, vehicle body or a purpose-built reflector.
The speed is determined by the measurement of the time intervals between the
interruption of the beams caused by the passing of the target vehicle.
3.10
Camera
A photographic, digital or video camera.
3.11
Measuring zone
A length of road which includes the area within which both the primary speed
measurement and the second speed measurement are made (see 5.7.1).
3.12
Vehicle detector
A device or method for detecting the presence of a vehicle approaching the measuring
zone above a set speed threshold and automatically triggering an analogue video
recorder to begin recording.
3.13
Recording zone
The length of road within which a video camera records on an analogue video
recording a vehicle passing through the measuring zone from the vehicle detector to a
position beyond the measuring zone.
3.14
Start image
A start image is inserted into an analogue video recording at the beginning of each
recording started automatically by the activation of a vehicle detector at the beginning
of the recording zone.
3.15
Stop image
A stop image is inserted in to an analogue video recording at the end of each
recording started automatically by the activation of a vehicle detector at the beginning
of the recording zone and stopped automatically by the expiry of the required
recording time (see 5.7.3.2).
3.16
Recording counter
A sequence counter for each recording on an analogue video recording which has been
automatically started and stopped since the equipment was turned on.
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General requirements for eligibility for type approval
3.17
Inductive loop sensor
A number, typically three, turns of an insulated conductor laid in the carriageway
which, when connected to a detector unit, forms a vehicle sensor.
3.18
Combined traffic light and speed camera
A safety camera system that automatically switches between operating as a red light
camera or as a speed camera depending on the state of the traffic signal.
4
GENERAL REQUIREMENTS FOR
ELIGIBILITY FOR TYPE APPROVAL
4.1
The supplier shall provide free of charge a written technical description of the
speedmeter, its operation and intended use, and full circuit diagrams to HOSDB
when the device is accepted for the practical assessment described in section 9. They
shall also provide free of charge a copy of this information together with a speedmeter
of the type intended for sale to the testing laboratory carrying out the type approval
before the laboratory commences its testing.
4.2
No liability for breakage or damage will be accepted by the Home Office or its agents.
4.3
The model type shall be indelibly marked on the outside of the meter, together with a
serial number which shall be unique to that instrument.
4.4
All models, if approved, shall be numbered consecutively.
4.5
Any system software or firmware shall be labelled with a version number, and a copy
of the program, along with a sample of the memory, shall be left with the Home
Office.
4.6
Once type approval has been granted, the manufacturer or their agent shall not
change either the value or type of the components used, or alter the circuit or the preprogrammed memory of the speedmeter, without permission of the Home Office.
4.7
The speedmeters shall be calibrated annually, and a certificate should be issued to this
effect and held by the police. A visible sticker showing the date of calibration should
be fixed to the meter.
4.8
Any repair or calibration shall be carried out by the manufacturer, their appointed
agent or a suitably qualified technician offering appropriate evidence of technical and
professional competence. Such persons shall keep accurate records which shall be open
to inspection by the Home Office.
4.9
All equipment used for calibration (but not for repair) shall be certificated annually by
a competent body with equipment traceable to national standards.
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4.10
A handbook or a set of written instructions for the use of the operator shall be provided
with the instrument when it is accepted for the practical assessment described in section
9. A copy will be provided to HOSDB. The instructions shall be dated and any
subsequent changes agreed with HOSDB sent to all users, including the Home Office.
4.11
Any requirement for goods or materials to comply with this specification shall be
satisfied by compliance with:
1
10
a relevant standard or code of practice of a national standards body or
equivalent body of any member state of the European Community;
or 2
any relevant international standard recognised for use in any member state in
the European Community;
or 3
a relevant technical specification acknowledged for use as a standard by a
public authority or by any member state of the European Community;
or 4
traditional procedures of manufacture of a member state of the European
Community where these are the subject of a written technical description
sufficiently detailed to permit assessment of the goods or materials for the use
specified;
or 5
a specification sufficiently detailed to permit assessment of goods or
materials of an innovative nature (or subject to an innovative process of
manufacture such that they cannot comply with a recognised standard or
specification) and which fulfil the purpose provided by the specified standard,
provided that the proposed standard, code of practice, technical specification
or procedure of manufacture provides in use equivalent levels of safety,
suitability and fitness for purpose.
5
OPERATIONAL REQUIREMENTS
5.1
General
5.1.1
If a camera is used to record a speeding vehicle, it shall have an angle of view sufficient
to ensure that the speeding vehicle is clearly identified in relation to the measuring
position and other vehicles that may be nearby.
5.1.2
Every image of the offence shall show, in addition to the speeding vehicle, in the
following order: the date in day, month and year; and the time in hours, minutes and
seconds. In the case of a video recording made in an unattended operation, it shall
also include a frame count from the beginning of the recording (see 5.7.3.2). When
inductive loop sensors are used, the lane number shall also be included. The
indication of the time to the nearest minute is acceptable. If operated with a variable
speed limit sign and an enforceable speed limit has been set, the time elapsed since it
was set, in hours, minutes and seconds, and direct evidence of the speed limit
displayed shall also be shown. A code representing the location of the measurement
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shall also be shown. This data shall be imprinted on the image at the time of the speed
measurement. If digital images are used, the data shall be recorded with the image at
the time of the offence as part of the same offence record. Only complete offence
records shall be displayed or output.
5.1.3
The speedmeter may be so designed that speed may be measured in either direction,
but not in both directions at the same time, i.e. once a measurement has commenced,
enforcement in the other direction shall be disabled until the measurement has
completed (hand-held devices excepted). Speedmeters designed to record an image of
a speeding vehicle shall show the direction of measurement on the image at the time
of the speed measurement.
5.1.4
The speedmeter shall be provided with an on/off switch and with ‘power on’ and, if
powered by battery, ‘battery low’ indicators.
5.2
Test signal
The instrument shall be provided with an inbuilt test signal to simulate a
measurement. The test signal shall be independent of the measuring circuits, and shall
be capable of checking the function and accuracy of all circuits from the sensor input
or radar head output onwards. The test signal may operate automatically when the
equipment is switched on, but it shall also be available for manual operation. When
the test signal operates a camera, the image shall clearly show that a test signal has
been generated.
5.3
Segmented display
If a segmented display is used, there shall be a means of checking that all segments are
functioning.
5.4
Manual reset
During attended operation, the last speed measured shall remain visible on the display
until manually reset. When the display is reset, it shall not be possible to recall to the
display any previous reading unless recalled with a displayed image recorded by an
approved camera attachment.
5.5
Sensor systems
5.5.1
Pressure sensor systems
All speedmeters incorporating pressure sensors shall be designed to make two
measurements by comparing signals from at least three sensors. The two speeds shall
then be compared and, if they are within 2 mph, the lower speed shall be displayed.
5.5.2
Inductive loop systems
All speedmeters using inductive loop sensors shall be designed to make two or more
measurements which shall be compared, and if they are within 2 mph, the lowest
speed displayed. At least two sensors shall be used. If only two sensors are used, the
system shall be designed to include at least two measurements from the detection of
both vehicle entry and exit times at both sensors.
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5.6
Hand-held radars
If audible doppler is provided, it shall be via a loudspeaker built within the body of
the device, and shall provide a sound output representative of the doppler signal.
A volume control shall be fitted.
5.7
Automatic systems
5.7.1
Second method of speed measurement
A second method of speed measurement involving a different principle (such as two
photographs or video frames taken a known time apart) shall be used to verify the
primary speed measurement. The accuracy of the second method shall be within 10%
of the speed recorded by the primary measurement. The speedmeter shall be set up in
traffic and sufficient readings taken to be able to make a valid statistical comparison of
the two speed measurements. A test track may be used for this purpose.
5.7.2
Offence data storage
The data to be used as evidence of an offence shall be recorded on either:
i
photographic film;
or ii a removable digital storage medium which provides a physical record of the
data and, once written, cannot be amended with new data;
or iii analogue video tape on which start and stop images are recorded in accordance
with 5.7.3.2 and alarm frames recorded in accordance with 7.3.
If the equipment is constantly supervised to maintain the integrity of the evidential
chain then the data may also be recorded on:
iv removable read writable digital storage media, provided that two copies are
made simultaneously;
or v analogue video tape.
For unattended equipment, all digital data shall be stored with security codes
generated using PSDB published standards for data protection. It shall be recorded at
the roadside or requirements published by PSDB for the remote recording from and
control of unattended type approved devices complied with. The data protection shall
be applied immediately after capture within the tamper-proof cabinet. There shall be
no external means of accessing the data without the protection being applied.
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5.7.3
Analogue video tape
5.7.3.1
When an analogue video recording is made from automatic equipment in an
unattended operation, the camera shall record continuously from when it is switched
on until it is switched off or has filled its recording capacity, unless it is automatically
controlled by the speedmeter.
5.7.3.2
If it is automatically controlled by the speedmeter, the camera shall insert one or more
start frames into the video recording before starting to record when it detects a vehicle
at the start of the recording zone above the set speed threshold. In addition to the date
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in day, month and year, the time in hours, minutes and seconds, location code and
frame count from the beginning of the recording, the start frame shall indicate that it is a
start frame and show a recording counter. The camera shall record until no more vehicles
are detected entering the recording zone and at least 10 seconds has elapsed since the last
vehicle was detected entering the recording zone. Whenever the recording is stopped, the
camera shall automatically insert one or more stop frames into the recording. In addition
to the date in day, month and year, the time in hours, minutes and seconds, location code
and frame count from the beginning of the recording, the stop frame shall indicate that it
is a stop frame and show the same recording counter as that in the start frame.
5.7.3.3
The recording counter shall provide a count of the sequence of recordings from when
the equipment was turned on.
5.7.3.4
The recording zone shall commence with sufficient distance before the measurement
zone to ensure that the entry of all vehicles into it is captured.
5.8
Optical hand-held speedmeters
The instrument shall be provided with a means of checking the sighting device with
the true alignment of the light beam.
5.9
Variable speed limits
5.9.1
When used to enforce variable speed limits, the speedmeter shall provide separately an
adjustable enforcement threshold for each speed limit that can be displayed and for
the National Speed Limit when no speed limit is displayed. The speedmeter shall
automatically select the correct enforcement threshold depending on the speed limit
displayed or the National Speed Limit when none is displayed.
5.9.2
The speedmeter shall enforce the displayed speed limit (or the National Speed Limit
when none is displayed) only when:
i all the speed limit signs connected to it are correctly displaying the same
speed limit, except when the hard shoulder of a motorway is actively
managed and that lane may show either the same speed limit or a red X;
and ii the speed limit has been displayed for one minute or longer. This delay shall
be variable to at least five minutes.
The speedmeter shall not enforce speed in the actively managed hard shoulder when
the red X is displayed. It shall operate with, and only with, all speed limit signs
mounted on the same gantry, facing in the same direction and over the same
carriageway, and every one of these signs fully operational.
5.9.3
Whenever the speed limit is changed, a single photograph shall be taken which will
show the date in day, month and year and the time in hours, minutes and seconds
when the display changed, the new speed limit set and the location code.
5.9.4
Within a variable speed limit, the time shown in photographs shall be within 10
seconds of a broadcast radio clock signal. On power up, the speedmeter shall not
commence enforcement until this synchronisation has been established. Enforcement
shall stop whenever synchronisation is not maintained or is not confirmed with the
radio clock within 14 days.
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6
CONSTRUCTIONAL REQUIREMENTS
6.1
Components
The speedmeter shall be constructed of good quality components which shall be
clearly marked with their type number or value, either in writing or by a recognised
code. Any sensor cables shall also be marked with an identifying mark.
6.2
Power supply
Any part intended to connect to the mains supply shall conform with electrical safety
regulations currently in force.
6.2.1
Battery operation
When the speedmeter supply is set at the normal voltage and the supply is gradually
reduced below the minimum working voltage, no erroneous reading shall appear.
Speed indication shall be inhibited when the power supply voltage varies beyond the
design limits.
6.2.2
Vehicle fitting
Equipment operating from a vehicle shall use a separate battery to power the
speedmeter, and any charging circuit from the vehicle power supply shall be
disconnected when the speedmeter is switched on.
6.2.3
Mains operation
This section shall apply only to speedmeters intended to operate from the public
mains supply, and does not relate to safety legislation which is covered by the
provisions of Directive 73/23/EEC (Electrical Safety). No erroneous reading shall
appear when the following disturbances are applied:
a
variation of power supply voltage from minus 15% to plus 20% of nominal value;
b
variation of power supply frequency from minus 2% to plus 2% of the nominal
value;
c
power supply interruptions to any level down to and including:
i
zero voltage for 10 ms or less;
ii 50% of nominal voltage for 20 ms or less;
iii 80% of nominal voltage for 50 ms or less;
d
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repetitive electrical fast transients to test level 3 of EN 61000-4-4: 1995.
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7
PERFORMANCE REQUIREMENTS
7.1
Storage
7.1.1
The speedmeter control unit and any electronic parts of the sensors shall, when out of
service, be capable of storage in adverse conditions.
7.1.2
They shall be held for at least three hours at –25 °C and then +70 °C, with low
humidity. The units shall then be allowed to return to room temperature and tested to
ensure correct operation.
7.2
Working temperature range
7.2.1
Equipment shall function within specification over a temperature range of at least
–10 °C to +50 °C, with 80% humidity above 20 °C. Hand-held devices shall be
tested over the range –10 °C to +35 °C. The temperature shall be varied in 5 °C steps,
and the equipment left for 30 minutes or longer to obtain thermal equilibrium; the
equipment shall function correctly at each temperature step. For radar devices the
frequency of the microwave oscillator shall be checked at each temperature step.
7.2.2
Unattended equipment shall have some form of sensor to prevent the equipment
operating beyond the working temperature range.
7.3
Robustness
7.3.1
Equipment shall be constructed so as to be fit for its purpose; in particular, equipment
designed for unattended use shall be tamper-proof and, if recording to analogue video
tape, opening the enclosure while the equipment is on shall immediately generate the
recording of one or more door alarm frames. In addition to the date in day, month
and year, the time in hours, minutes and seconds, location code and frame count from
the beginning of the recording, the door alarm frame shall indicate that it is a door
alarm frame and the equipment shall be able to operate with the door open only if a
valid key is inserted into it.
7.3.2
All parts of the equipment which may be exposed to the weather shall comply with
the requirement of BS EN 60529 (1992), classification IP 55, for water ingress and
dust protection.
7.4
Electromagnetic immunity
7.4.1
The equipment shall be capable of operating without indicating an erroneous reading
as follows:
a
in fields of at least 10 V/m from 80 MHz to 2,000 MHz;
b
in the presence of common mode currents from 27 MHz to 100 MHz to level 2
of EN 61000-4-6;
and, if designed for attended, actively operated or automatic supervised use
c
in the simulated TETRA fields defined in section 8.6.7 at the levels defined in
table 1 of section 8.6.7.4.
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7.4.2
For a and c, the basic test procedure defined in EN 61000-4-3 and, for b, the basic
common mode injection test procedure defined in EN 61000-4-6 shall be used. Some
of the requirements may be met by complying with the provisions of Directive
2004/108/EC (Electromagnetic Compatibility). Under these circumstances,
equipment complying with the directive and which has already been granted the
certificates of conformity provided for therein shall be exempt from the parts of the
type approval procedure covered by the directive.
7.5
Electrostatic discharge
7.5.1
The speedmeter shall be tested in accordance with EN 61000-4-2: 1995. At least 10
single discharges shall be applied to the exposed surface of each separate part of
the meter.
7.5.2
For permanent installations, tests may be performed in the final installed position.
A maximum test voltage of 4 kV shall be employed, i.e. at level 2.
7.6
Measuring accuracy
7.6.1
General
The speedmeter shall be assessed by comparing its readings with a vehicle fitted with
a speed measuring system having an accuracy of at least ±1 mph. Measurements at
different speeds up to the maximum stated by the manufacturer shall be made.
Simulated speeds may be used for speeds above 120 mph. The speedmeter shall give a
positive error no larger than 2 mph (or 3% above 66 mph) and a negative error of no
greater than 5 mph or 10% above 50 mph (see 8.2). For combined red light and
speed cameras, the requirements in the latest edition of the Traffic Light Camera
Handbook shall apply when a red signal is displayed and being enforced. At other
times whenever the speed limit is being enforced, the requirements of this handbook
apply.
7.6.2
Radar
In the laboratory, the speedmeter shall measure a simulated speed to within ±1 mph in
10 mph increments from 20 mph to the maximum measuring speed stated by the
manufacturer.
7.6.3
Direction-sensing
The equipment while set up at the roadside shall be observed while measuring traffic
in alternately the overtaking and receding modes against the direction of traffic; a total
of at least 500 vehicles shall pass in each direction. No readings of traffic flowing
against the selected direction should be recorded.
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7.7
Radar operating frequency and power output
7.7.1
The microwave operating frequency shall be 24.10 GHz ± 25 MHz over the working
temperature range. However, alternate frequencies may become available.
7.7.2
At no distance from the aperture of the antenna shall the power density exceed
5 mW/cm2.
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7.8
Radar antenna characteristics
7.8.1
Across-the-road radar
7.8.1.1
In the horizontal plane, the –3dB beam width shall be no greater than 5 degrees (±1°).
Any sidelobes shall be at least –15dB relative to the maximum value of the main lobe.
In the vertical plane, the –3dB beam width shall be no greater than 20 degrees, and
the front to back ratio shall be at least 30dB.
7.8.1.2
The angle of the radiated beam shall be set by the manufacturer to any angle between
15 and 25 degrees to the direction of the traffic and shall be clearly marked on the
antenna. The camera shall be fixed so that its optical axis cannot be changed from the
manufacturer’s setting without inhibiting the speed measurement.
7.8.1.3
Where equipment is fitted within a vehicle for use in the stationary mode, the
manufacturer shall provide a means of checking that the camera and antenna are
properly aligned.
7.8.2
Hand-held radar
The half-power beam width shall be no greater than 24 degrees. The first side lobes
shall be at least 20dB below the main beam. The front to back ratio shall be at least
30dB.
7.8.3
Variable speed limit above-the-road radar
7.8.3.1
In the horizontal plane, the –3dB beam width shall be no greater than 6.5 degrees (±1
degree). Any side lobes shall be at least –20dB relative to the maximum value of the
main lobe. In the vertical plane, the –3dB beam width shall be no greater than 6.5
degrees (±1 degree), and the front to back ratio shall be at least 30dB.
7.8.3.2
The angle above the road shall be set to between 20 and 35 degrees.
7.8.3.3
The equipment, while set up above the middle lane of a three or more lane section of
motorway, shall not be observed detecting any vehicle passing the measurement point
in an adjacent lane; a total of at least 500 vehicles shall pass in each lane.
7.9
Laser power output
The output power of laser(s) used on optical speedmeters must not exceed Class 1
(eye-safe) recommendations as given in British Standard BS EN 60825-1: 2001.
7.10
Camera timing accuracy
7.10.1
Photographic and digital cameras
7.10.1.1
If two images taken of the same vehicle, with a known time interval, are used to
confirm the measurement, the timing accuracy of the camera shutter shall be
measured. At least 10 measurements shall be made in accordance with 8.3.1, and all
measurements shall be within ±1% of the indicated time.
7.10.1.2
Where different intervals may be manually selected, the accuracy shall be measured
for the minimum setting.
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7.10.1.3
If the interval is varied automatically with the speed of the vehicle, the accuracy shall
be measured at various speeds between 30 mph and the manufacturer’s stated
maximum, the interval commencing at the trigger point of the sensor signal used.
7.10.2
Video cameras
7.10.2.1
Video cameras linked to the speedmeter shall conform to CCIR standards. If the
time between two video frames taken of the same vehicle is used to confirm the
measurement, then the time displayed in each frame shall be in hours, minutes and
seconds with either:
i
seconds shown to one hundredth of a second;
or ii a frame count.
If the video frames are taken from different cameras, then the cameras shall be
synchronised and use overlapping fields of view to provide common measurement
points.
7.10.2.2
The interval used shall always exceed 0.5 seconds (i.e. 13 or more frames). Ten
measurements of the time interval shall be made in accordance with 8.3, and all
measurements shall be within ±1% of the interval indicated by the displayed time or
the frame count, assuming a frame interval of 40 milliseconds.
7.10.2.3
When the frame rate is used, an error message shall be displayed in the image
whenever the frame interval does not remain within 1% of 40 milliseconds.
7.11
Vehicle detector speed threshold
The accuracy of speed measurement used by the vehicle detector to determine if
vehicles approaching the measurement zone are exceeding the set speed threshold shall
be within 10% of the primary speed measurement.
7.12
Inductive loops
When used for speed measurement, the manufacturer shall specify minimum loop
spacing. The width of each loop shall be sufficient to cover a single lane of road. The
dimensions of each loop shall be the same and all leading edges parallel to within 25 mm.
8
MEASURING METHODS
8.1
General
This section describes suitable methods of measurement for carrying out the tests
described in previous sections. It is recommended that the methods are followed to
ensure uniformity and repeatability of testing, in particular the method of EMC
testing for sensor speedmeters shall be followed. All measuring procedures shall be
recorded in the test report.
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8.2
Speed measurement
A road or track test shall be performed by driving a car fitted with a speedometer
calibrated to within 1 mph (1% above 100 mph) past the speedmeter under test at
various speeds between 20 mph and the manufacturer’s stated maximum, or 120 mph
if less. Across-the-road radars shall be set up at a distance of no more than 3 m from
the kerb. Sensor systems using inductive loop sensors shall be tested using the
minimum loop spacing specified by the manufacturer. If a range of loop dimensions is
specified, it shall be tested using loops of both minimum and maximum dimensions.
At least 100 measurements shall be taken in each direction.
8.3
Second method of speed measurement
8.3.1
Photographic and digital cameras
8.3.1.1
If two photographs taken of the same vehicle, with a known time interval, are used to
confirm the measurement, the timing accuracy of the camera shutter shall be checked.
8.3.1.2
The following measuring method may be used. A light source should be placed in front
of the lens, and a light sensor (for example a biased photodiode) placed inside the camera
body at the film plane. When the system is operated, a pulse is generated by the sensor
each time the shutter opens. This signal can be connected to a suitable counter/timer set
to measure the time difference between the two shutter events (figure 1).
8.3.2
Video cameras
The measuring method used may be to video record the display of a suitable
continuously running counter/timer to measure the time difference between 13 frames.
If frame counts are used to measure the interval, then a further test shall be carried out
to show that the system displays an error message whenever the frame interval does
not remain within 1% of 40 milliseconds. This may be demonstrated by
synchronising the camera to a signal from an external signal generator and varying its
frequency to determine the limits at which an error signal is displayed.
8.4
Speed simulators
8.4.1
Radar speedmeters
Simulated speed in the laboratory shall be carried out by generating the Doppler
signal at the operating frequency. This may be achieved for non-directional hand-held
radars by using a simple modulator consisting of a loudspeaker cone covered with
metallic foil and excited with an appropriate frequency Fd. The cone should be placed
a few inches in front of the device under test (figure 2). Directional radars require
either a single sideband modulator (figure 3) or equivalent mechanical device
(figure 4). The appropriate test frequency (Fd) can be calculated from the equation:
Fd=2vf.Cos0–
3 x 108
Where Fd= frequency of Doppler signal (Hz)
f = measured frequency of transmitted signal (Hz)
v = speed of vehicle (m/s)
θ = angle of beam to direction of movement
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8.4.2
Pressure sensor speedmeters
Pressure sensor devices, require a special speed simulator: for electrical cable sensors, a
suitable signal simulator capable of generating repetitive pulses equivalent to about 30
mph shall be connected in parallel with the sensor cables at the point where they enter
the impedance transformer; speedmeters employing air tubes shall be replaced by an
appropriate air-driven speed simulator.
8.4.3
Optical speedmeters
For hand-held devices, the range measurement of a target may be used instead of a
speed simulator. Manufacturers shall supply an appropriate simulator for across-theroad devices.
8.4.4
Inductive loop sensor speedmeters
For systems employing inductive loops, laboratory tests may be carried out using
substitute inductance instead of full-size loops.
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8.5
Environmental tests
8.5.1
At each temperature step in the working temperature range, the equipment shall be
checked by performing an internal calibration check and a simulated speed
measurement. If the speedmeter is operated with a variable speed limit sign, for the
simulated speed measurement it shall be connected to a sign, or a simulator of the
sign, with a correct speed limit displayed. After a speed measurement exceeding the
enforcement threshold is simulated, further simulations of the same speed
measurement shall be made after the displayed speed limit is lowered until
enforcement is again enabled. No enforcement shall occur for at least one minute after
the displayed speed limit is changed.
8.5.2
Care shall be taken to ensure that any fans, thermostats, or other electronic control
devices associated with the environmental chamber do not cause spurious readings
during the testing cycle.
8.6
Electromagnetic immunity
8.6.1
General test arrangements
8.6.1.1
The test arrangements are applicable to both radiated and conducted tests. The object
of the test is to confirm that the speedmeter is capable of operating in the presence of
electromagnetic fields without recording an erroneous speed reading.
8.6.1.2
The layout of the speedmeter shall be representative of the normal operating
conditions, in so far as this will permit a repeatable measurement. The measurement
shall be carried out in screened test facilities described in EN 61000-4-3, with the
equipment set up as intended for use. The field uniformity criteria of EN 61000-4-3
apply for the radiated immunity tests.
8.6.1.3
The speedmeter to be tested is placed centrally in the calibrated test area. The device
and its wiring are mounted on a non-conducting bench 0.8 m above the ground plane
(figure 5). Devices designed to operate on a tripod shall be adjusted to be 1 m above
the ground.
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Measuring methods
8.6.1.4
Any associated cable bundles/wiring shall be arranged in general accordance with
EN 61000-4-3. At least 1 m of the cabling from the device to the test facilities’ power
supplies must run in the calibrated area. Any interconnecting, remote control, camera
or sensor cabling will be treated as follows:
•
the manufacturer’s specified cable types and connectors shall be used;
•
when the manufacturer’s specification requires a wiring length of less than
3 m, then the specified length shall be used. The wiring shall be bundled lowinductively to 1 m in length;
•
when the specified length is greater than 3 m, then the illuminated length
shall be a minimum of 1 m. The remainder shall be run outside the calibrated
area on the floor, decoupled at the 1 m point by the use of lossy tubes.
However, in the case of remote control cables, the remote control unit must
be in the calibrated area as shown in figure 5. Therefore the cable length excess
greater than 1 m shall be zig-zagged on the floor parallel to and behind the
remote sensor cables. The remote control shall be placed as shown in figure 5.
8.6.1.5
In at least one orientation of the device, the wiring shall be arranged parallel to the
calibrated uniform area of the field.
8.6.1.6
The exposed wiring shall be run in a configuration that simulates as closely as possible
the manner in which it is run in operation.
8.6.1.7
All wiring running on the floor in the calibrated test area shall be spaced 0.1 m from
the floor by means of low dielectric spacers.
8.6.1.8
Any changes found necessary in the layout shall be recorded in the test report.
8.6.1.9
The device under test shall be irradiated by both horizontal and vertical polarised
fields from four orthogonal illumination angles. Figure 6 shows a plan view of a
typical test arrangement.
8.6.2
Device specific test arrangement aspects
8.6.2.1
Hand-held radar
If the device is fitted with radio frequency detection such that the display is disabled
and an indication shown that interference is present, it shall not come into operation
at fields below 3 V/m.
8.6.2.2
All radar
The radar target simulator shall be adjusted so that the radar return signal at the
device under test is 10dB above the threshold for reliable operation of the device.
8.6.2.3
Vehicle mounted devices
For devices mounted in a vehicle, the device under test shall be connected to simulate
the vehicle installation and mounted on the non-conducting test bench. The power
supply lines shall be 1 m long and connected to a 12 volt lead acid battery also placed
on the bench.
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Speedmeter Handbook (Fourth Edition)
8.6.3
Modulation
8.6.3.1
All test signals shall be 90% amplitude modulated with an appropriate signal
depending on the device. During these tests, a speed simulator shall be used to monitor
the correct operation of the equipment under test. For radar devices, sinusoidal
modulation shall be used and the frequency calculated from the equation given in
section 8.4.1. If the speedmeter is operated with variable speed limit signs, a sign shall
be connected to it and the speed simulation procedure described in section 8.5.1 used.
8.6.3.2
Pressure sensor systems shall employ a modulation frequency equivalent to the timing
period to be expected from pulses generated by a passing vehicle. Square wave
modulation of more than 90% shall be used.
8.6.4
Speed simulators test arrangements and set-up
8.6.4.1
Care shall be taken to ensure that the connection of the simulator does not degrade
the immunity of the equipment under test.
8.6.4.2
The speed simulator shall be set to a different speed to that of the modulation
specified in section 8.6.3 (e.g. 30 mph for the simulator and 40 mph for the test
signal). The display of the device shall be monitored throughout the test period, and
any erroneous readings or inconsistency in behaviour noted together with the
appropriate test frequency and field intensity.
8.6.4.3
For hand-held optical speedmeters, target range may be displayed as a substitute for
speed simulation.
8.6.5
Conducted immunity test
The test is conducted in basic accordance with EN 61000-4-6, with the following test
method deviations:
22
•
The clamp injection procedure is to be used with the signal being applied to
the total cable bundle, i.e. common mode injection. The signal is injected at
each electronic unit of the device under test connector by connector. The
current probe monitoring the injected current is placed 0.05 m from the
device’s connector on the bundle under test. The injection clamp is placed
0.05 m from this.
•
The modulation and limits are as defined in sections 8.6.3 and 7.4.
8.6.6
Test limits and frequencies
8.6.6.1
The test limits defined in section 7.4 for a) the standard radiated immunity test and
b) the standard conducted immunity test are in terms of the cw value of the signal,
the modulation being applied on top giving peak readings 90% higher than the cw
limit.
8.6.6.2
The RF signal shall be applied at each test frequency at the test limit for a time long
enough to fully operate the device under test. The frequencies shall be stepped
incrementally across the test range with a step size not exceeding 1% of the previous
frequency. If any effect is observed, the applied signal shall be reduced by 12dB and
increased in steps of 3dB until the required test level is reached. The level at which the
threshold of any effect is observed shall be logged and recorded in the test report.
Publication No. 15/05
Measuring methods
8.6.7
Simulated TETRA immunity test
8.6.7.1
The device under test shall be irradiated with both horizontal and vertical polarised
fields from four orthogonal illumination angles in turn.
8.6.7.2
The device shall be tested at each of the test frequencies specified in section 8.6.7.3 by
increasing the field, at each test frequency, from a minimum level of 12dB down from the
appropriate test limit in steps of 3dB until the test level is achieved. The level at which the
threshold of any effect is observed shall be logged and recorded in the test report.
8.6.7.3
The test frequencies to be used for this test are: 380, 385, 390, 395, 400, 405, 410,
415 and 420 MHz. The tolerance on these frequencies is ± 0.1 MHz.
8.6.7.4
The test limit is in terms of the peak value of the modulated signal as measured using
a peak detector calibrated in terms of the equivalent rms sine wave value that would
give the same reading. This is the standard calibration for all peak detector functions
on EMC receivers or spectrum analysers.
The test limits are specified in table 1 for the device categories defined in the table and
the minimum permitted operating distance from police TETRA radios.
Table 1
Simulated TETRA immunity test levels for device categories A to D
Category
Definition
Field strength
V/m
Comment
A
Hand-held attended
actively operated devices
and not operated within
vehicles
65
Can be operated to within
0.2 m of a personal 1 W TETRA
radio antenna and 1.5 m of a
3 W vehicle mounted TETRA
radio antenna
B
All other (non-category A)
attended actively
operated devices and
automatic supervised
devices not operated
within vehicles
20
Can be operated to within 1 m of
a personal 1 W TETRA radio
antenna and 4 m of a
3 W vehicle mounted TETRA
radio antenna.
C
Hand-held devices
operated within vehicles
and not connected to the
vehicle
x(1)
Field enhanced by internal
vehicle reflections
Vehicle mounted devices
with an external antenna
x(1)
D
One operator carried 1 W TETRA
radio operating inside the vehicle
with its antenna at least 0.2 m
from the device
No operator carried TETRA
radios operating inside the
vehicle
Can be operated to within
1 m (line of sight) of the antenna
of a 3 W vehicle mounted
TETRA radio
Note 1
Level as set by HOSDB
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Speedmeter Handbook (Fourth Edition)
8.6.7.5
The modulation to be applied shall be an 18 kHz square wave modulation with a
depth greater than 98% additionally gated on and off at 17 Hz. The duty cycle shall
be 50%. This is shown in figure 7.
8.6.7.6
The test limits are in terms of the peak value of the signal when measured using the
peak detector function of the measuring receiver/spectrum analyser. This is calibrated
in terms of the equivalent rms value of a sine wave as defined by:
“When measuring a modulated signal, the bandwidth of the measuring receiver
should be set wide enough to capture the total energy of the signal. The amplitude
reading as measured by the peak detector function is noted. The unknown signal is
disconnected and a sine wave signal at the same frequency fed in. Its amplitude is
adjusted until the same reading is produced on the measuring receiver. This amplitude
is expressed in terms of the rms value of the sine wave, e.g. a 1 volt rms sine wave
input will give an indicated measurement of 1 volt. This will not change if the signal
is switched on and off: the peak reading will still be 1 volt, hence the term peak rms.”
8.6.7.7
24
The characteristics of the equipment to be used to measure the amplitude of the
applied susceptibility test are:
•
The amplitudes associated with the test limits are based on the peak of the
rms envelope over the complete modulation period.
•
Amplitude measurements shall be made in a manner that clearly establishes
the peak amplitude of the modulated waveform.
•
The measuring instrument must have a fast enough time response to respond
to signal amplitude variations. A spectrum analyser may be used.
•
The detection, resolution and video bandwidths of the measuring instrument
must be wider than the modulating frequency.
•
The measurement bandwidth shall be increased until the amplitude of the
measured signal does not change by more than 1dB for a factor of three
change in bandwidth. This bandwidth setting shall then be used for the test.
At the proper setting the individual modulation side bands will not be resolved.
8.6.7.8
It is important to meet these requirements, especially when measuring modulated
signals. The use of a spectrum analyser for signal measurement during susceptibility
testing provides advantages over power meters or receivers as it allows a more direct
visual check on the quality of the applied signal during the testing. It provides direct
indication if the signal source is becoming non-linear or generating spurious signals.
Sometimes, when mismatched, TWT amplifiers have been found to produce parasitic
high power oscillations even with no input drive at a frequency that may be well
removed from the required test frequency. Regular checks should be made on the
quality of the test signal and on the presence of spurious signals.
8.7
Variable speed limit signs
8.7.1
When using a variable speed limit sign or a simulator of the sign connected to the
speedmeter, the following fault conditions shall be simulated while a speed
measurement of 90 mph is simulated:
Publication No. 15/05
Type approval procedures
i failure of any bulb used to illuminate any part of the speed limit aspect;
and ii power up of any extra bulb or bulbs used to illuminate other speed limit
aspects and not used in the correct display.
No enforcement shall occur while these fault conditions are simulated.
8.8
Stop/start and door alarm frames
For automatic equipment which records on analogue video tape and is to be used in
unattended operations, recordings shall be made to test that the requirements in 5.7.3
and 7.3 have been met. A sequence of at least 10 recordings automatically started by
simulating a stream of vehicles detected at the start of the recording zone above the
enforcement threshold shall be made. Vehicle gaps above and below 10 seconds shall
be simulated. A further recording shall be made by manually commencing recording
without the detection of any vehicles being simulated. During the recording, the door
shall be opened to generate a door alarm frame and then closed again to allow the
recording to continue. The recording may then be stopped manually or by filling the
recording capacity. The recordings shall be examined to determine whether the
requirements have been met.
8.9
Vehicle detector speed threshold
The accuracy of the speed measurement used by the vehicle detector shall be tested for
speed thresholds set at various speeds between 30 mph and 90 mph. At each threshold
setting, the lowest speed at which the video recording is triggered shall be measured by
simulating different speeds in increments of 1 mph.
9
TYPE APPROVAL PROCEDURES
9.1
Manufacturers or their appointed agents seeking type approval should first arrange for
the equipment to be demonstrated to the ACPO Roads Policing Enforcement
Technology Committee, which will arrange for a practical assessment by one or more
police forces. Enquiries should be made to:
The Secretary
ACPO Roads Policing Enforcement Technology Committee
Essex Police
Burghstead Close
Billericay
Essex
CM12 9JZ.
Only when this assessment has been satisfactorily completed, and any necessary
modifications made to the speedmeter, should the device be offered for formal type
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25
Speedmeter Handbook (Fourth Edition)
approval. Requests for type approval should be made to:
Road Crime Section
Public Order and Police Co-operation Unit
Home Office
5th Floor
Fry Building
2 Marsham Street
London
SW1P 4DF.
9.2
Road Crime Section will normally recommend test laboratories to carry out
type approval testing in accordance with procedures laid down by HOSDB.*
Manufacturers or their approved agents are expected to bear the full costs of the
private test laboratory’s evaluation work. On completion of their work, the private test
laboratory will submit a report on their evaluation of the device to HOSDB. HOSDB
will submit the results to Road Crime Section for consideration to be given to
obtaining the agreement of the Secretary of State for the Home Department to formal
type approval.
9.3
To back up type approval, Road Crime Section prepares a supporting agreement for
signature by the manufacturer and by Home Office officials which is primarily
directed at preventing the manufacturer from altering the device in question in any
way without the prior approval of the Secretary of State. Manufacturers must agree:
i
not to change the device without the agreement of the Secretary of State;
ii to ensure that the type and serial number of each device is clearly identified by
an indelible marking;
iii to ensure that the serial number is unique to each device and that each device
is numbered consecutively;
iv to ensure that any repair or calibration facility relating to the device is open to
inspection;
v to supply free of charge to the Secretary of State a full circuit diagram of the
device with all the circuit components clearly indicated;
and vi if required, to supply a device free of charge to the Secretary of State and that
the Secretary of State shall not be responsible for any damage caused to the
device while it is in his possession.
This agreement must be signed by the manufacturer prior to the Home Secretary
signing the formal type approval document.
* The results of checks and tests carried out by the bodies and laboratories of other member states, including in particular
those in conformity with EN 45000, will be taken into consideration where such results provide a level of accuracy, fitness
and suitability for purpose equivalent to the results of tests carried out in the United Kingdom, and where such bodies and
laboratories offer suitable and satisfactory guarantees of technical and professional competence and independence.
26
Publication No. 15/05
Figures
Figure 1 Camera shutter timing measurement
+
Shutter
Light source
-
Biased
photodiode
Camera
Stop/start
input
Counter/timer
Figure 2 Speed simulator for hand-held radar
Signal generator
approx.
30 cm
Radar under test
Metallised-cone
loudspeaker
Publication No. 15/05
27
Figures
Figure 3 Speed simulator for directional radar using SSB modulator
SSB modulator
Rx horn
CW Doppler radar
Range
Isolators
Tx horn
Power
supply
0o
90
o
Quadrature drive audio oscillator
Figure 4 Possible arrangement of a mechanical Doppler simulator
Waveguide WG.20
Horn
antenna
Motor/gearbox
Dummy
load
Disc approximately 30 cm diameter, pins λ /2 long
28
Publication No. 15/05
Figures
Figure 5 EMC test layout
Remote control
1.5 m
Area of uniform field
Non-conducting bench
0.8 m
Field generation
antenna
1m
Turntable
Pulse
simulator
1 m extension cable
3m
Figure 6 Plan view of a typical EMC test layout
Pulse simulator
alternative positions
Turntable
>1 m
Transmit
antenna
Calibrated
test area
Pulse simulator
Publication No. 15/05
D UT
DUT alternative position
29
Speedmeter Handbook (Fourth Edition)
Figure 7 Simulated TETRA test dual modulation envelope
P RF = 17 Hz
Peak
Peak RM S =
Peak
√2
P R F = 1 8 kH z
30
Publication No. 15/05
Home Office Scientific Development Branch
Woodcock Hill
Sandridge
St Albans
Hertfordshire AL4 9HQ
United Kingdom
Tel: +44 (0)1727 816400
Fax: +44 (0)1727 816233
Email: hosdb@homeoffice.gsi.gov.uk
Website: www.hosdb.homeoffice.gov.uk
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