Radar Equipment for the Measurement of the Speed of Vehicles

OIML R 91 version 2014 Radar equipment for the measurement of the speed of vehicles

t.janssen 1-2-2014 Radar equipment for the measurement of the speed of vehicles

( with or without recording devices ) draft version February 2014

1. SCOPE This Recommendation is applicable to microwave radar equipment for the measurement of at least traffic speed on roads and distance and angle when required to optimize the use of the radar, hereafter, in short, “radar”. The Recommendation states the conditions that the radar must satisfy when the results of measurements are to be used in legal proceedings. The legal interpretation of the results of measurements, the choice of radar types and techniques and the conditions under which these instruments may be applied are left to national regulations.

2. RULES OF CORRECT OPERATION

2.1 Handbook ( see point 4 ) Radar systems shall be installed and used in accordance with the instructions of a handbook issued by the manufacturer and approved with the instrument, at the time of the pattern approval

2.2 Certainty of vehicle identification The construction of the radar system , including the internal logic of the measurement process, shall ensure that, when the instrument is used in accordance with the handbook, an indicated speed and all other relevant information cannot be attributed to the wrong vehicle even where vehicles are passing or overtaking, or when the radar is mounted in a moving vehicle.

The radar system shall have a direction discriminator. However, because of its limited effect, a direction discriminator does not always offer a complete solution and additional means shall be used to ensure correct operation. With current technology, such as irregular signal discrimination, tracking radar, vehicle identification is possible even in dense traffic. Where there is no other solution the radar system shall invalidate its own result when two or more vehicles with different speeds pass simultaneously through the radar beam unless the radar system is capable of measuring multiple vehicles separately at the same time. The radar shall be equipped in such a way that no

Update OIML R91 version February 2014 TMJPage 2 misunderstanding can arise in relation to the indicated or recorded measurement value(s).

2.3 Aiming device If the radar speed meter shall be deployed at a fixed measurement angle, then the radar system shall be fitted with an aiming device. The relative error of measurement attributable to misalignment of the aiming device shall not be greater than 0.5% of the angle of measurement or 0.3 % of the actual speed. The aiming device may be omitted if the radar system is to be used with a beam that is practically parallel to the direction of traffic movement ( angle of incidence not exceeding 10 5 degrees [or 0,5% of actual speed) ) or when the radar system is capable of automatically correcting the measurement angle of the measured vehicle.

2.4 Radiation pattern of antenna The approval of a given angle of incidence is left to the national regulations. For beam axes not parallel to the direction of traffic movement, angles of 15 to 30 degrees are recommended or automatic compensation of the angle of incidence of the measured vehicle can be used to ensure correct speed measurements of up to but not limited to four lanes of traffic. The handbook shall give details for positioning and adjustment of the aiming device, for all foreseeable installations ( roadside, bridges, gantries, patrol cars, etc… )

Using multiple antenna structures and an appropriate modulation of the radar transmission can allow measurements of vehicles over much wider area, both in range and angle. The radiation pattern used may then cover a significant wider area then described above. In this case provision shall be made to prevent indications from locations in the radiation pattern in which the position information is unreliable.

When the radar is installed and used in accordance with the handbook, no measurement shall be possible in those parts of the antenna beam where an incorrect angle of incidence may result in relative speed measurement error greater than +/- 2% . Errors resulting from tilting of the radar in relation to the surface of the road shall also be considered.

Update OIML R91 version February 2014 TMJPage 3 Note: This requirement may be satisfied by signal processing or by special shaping of the radiation pattern using the latest available technologies.

2.5 Time span for speed indication If it is possible to use the radar system without a suitable recording device ( see point 2.6 ), the visual indication of speed shall remain visible and shall inhibit any further measurements until it is freed reset by a positive action. No event or action during this time may influence the result or have any effect on subsequent measurements. These requirements do not apply to results below a giventhe set speed threshold limit.

2.6 Recording devices If an ( image ) recording device records the result of the radar speed measurement, then the record shall indicate at least the vehicle whose speed is measured, date and time of the measurement, the measured speed and vehicles direction of travel, the measurement location, the sensitivity of the radar speed meter(, if this is variable), serial number of radar system, etc.

If a camera is used , the correct relationship between the direction of the radar beam radiation and that of the optical axis of the camera shall be ensured by mechanical set up or by operations described in the handbook by which the correct aiming of the system is verified by other means such as the resulting picture, template. etc…

2.7 Attended radar ( stationary measurement ) For attended use of a radar system the same specifications as for unattended radar systems in point 2.8 shall comply, but without the use of

a recording device.

2.8 Automatic and unattended radar ( stationary measurement ) Radar systems designed for operation under circumstances where it is not possible for an operator to verify continuously their satisfactory performance shall provide a level of confidence “near to certainty” that the error of each measured result shall be within the permissible limits. The measurement set up shall have such properties that it can be established

Update OIML R91 version February 2014 TMJPage 4 with certainty by means of the recording to which vehicle the measured speed relates, irrespective of the number and type of vehicles on the road section where the measurements are carried out. The certainty of the said recording shall be at least equivalent to that obtained if a second measurement is available, obtained by means of a different, independent measurement method whose measurement error is not greater than 10% of the actual speed measurement. If this condition cannot be met, the invalidity of the measurement result shall be unequivocally indicated by the measurement instrument on the image recording device, or the measurement result shall be eliminated.

Note: The automatic checking of the instrument’s essential operation is advised in point ….of this Recommendation. Furthermore, with such unattended operation it is strongly advisednecessary that redundant measurement techniques such as, for example, taking two pictures of the offending vehicle separated by a specified time interval or distance interval to be used. Another option could be to use one or two still images and/or a short ( sequential) video clip (with sufficient time interval) to achieve an independent method of checking the original speed measurement by the radar system.

2.9 Mobile radar speed meters Should we include an extra point for the mobile measurements with radar system installed in a moving vehicle and using the own speed of the vehicle and the measured speed of the overtaking or passing vehicle with a radar system??yes, see Dutch regulation 2.10 Automatic exclusion of inaccurate power supplymove to general clause Speed measurements shall be inhibited when the power voltage and temperature varies beyond the specified limits.

2.11 Overall functional test The radar shall incorporate an internal test generator checking device of simulating a measurement for the purpose of verifying the correct operation of the radar system, that is independent of the measuring circuits, and by

Update OIML R91 version February 2014 TMJPage 5 which, at switch-on and additionally at operator’s willcommand, ( or automatically??) the instrument is checked overall. Its test signal is introduced as early as possible into the signal chain following the microwave circuits and shall check at least every non intermittent failure correct operation of the low frequency and result handling circuits, including circuits necessary for the functioning and accuracy of the speed indication. Records shall confirm that these tests have been performed successfully. The manufacturer shall provide an internal simulation device which enables the operator to perform this test.

( which parameter for a failure of test ?? MPE in 7.1.3.3: 1 km/h and 1 % )

The manufacturer radar shall provide have a simulation/test input which enables metrological tests to be performed in a laboratory for pattern approval and verification. It must be possible to measure the accuracy of the speeds simulated by this device and it must be as accurate as possible to meet the national regulations (this belongs to the test equipment).

3 CONSTRUCTION

3.1 Speed indicator and speed range In radar systems useable without data recording device the (speed) indicators shall be readable by two operators simultaneously in ambient conditions corresponding to the conditions of use for which the instrument is suitable according the handbook.

The speed measuring range shall be equal to the indicating range include at least the range 30 – 150 km/h (20 -250 km/h or 10 – 156 mph ??)

3.2 Mechanical strength The instrument must be well and solidly built. The materials used must guarantee sufficient strength, stability, resistance and consistency for normal operational use and shall meet the national legislation.

3.3 Resistance to extremes of climate

3.3.1 Operational temperature The manufacturer must indicate the ambient temperature limits within the radar system can be operated in compliance with the requirements of the national legislation. When these temperature limits are exceeded, instruments

Update OIML R91 version February 2014 TMJPage 6 designed for automatically/unattended operation shall automatically go out of enforcement/ operationeliminate the measuring results or continue to operate correctly up to 10 degrees Celsius outside these temperature limits. These minimum temperature range s must shall be a minimum of -10 up to and including + 50 degrees Celsius.

3.3.2 Storage temperature When out of service or in storage the radar system shall be capable of withstanding ambient temperatures of -25 to + 85 degrees Celsius

3.3.3 Relative humidity The radar system shall be resistant to relative humidity of 95% - non condensing of the ambient air, both under operational ( see point 3.3.1 ) and storage conditions ( see 3.3.2 )

3.3.4 Weather resistant The parts of the radar system that are exposed to the weather shall be protected against dust and water spray when all the accessories are fitted.

3.5 Reliability of electronic and logical components

3.5.1 Reaction to disturbance Radars shall undergo test showing their reactions to:

To be supplied by Ambler Thompson

3.5.2 Protection against electronic failure

3.5.2.1 Discontinued Discontinuous ( digital ) signals The reliability of the results produced by ( digital ) signals such as transfers, storage, indications, etc. must be guaranteed, either individually ( step by step ) or in blocks( global ), using redundant operations for software monitoring or equivalent procedure to ensure correct operation. Each fault in the consistency of the operations shall inhibit further measurements.

Elements and components used in such operation ( program memories, transfer memories, processors, cabling, indicators, etc.. ) shall be checked at least every time the equipment is switched on, by special checking operations, unless they are checked automatically by the logical measures as mentioned above.

Update OIML R91 version February 2014 TMJPage 7 Errors shall be clearly indicated and the handbook shall explain the measures to be taken.

3.5.2.2 Software programs faults Should we use OIML guidelines and also parts of Welmec 7.2 D31 is to be used

To be supplied by Roman Flegar

3.5.2.3 Continuous signals ( analogue signals )

3.5.2.3.1 Microwave circuitry shall ensure a long term stability of tuning over at least 2 years of approximately +/- 0.2 % in frequency.

If the radar transmission is modulated then the short term stability and accuracy of such modulation may have a profound effect both on the accuracy of speed measurements and on the certainty of vehicle identification. The realization of the microwave circuits must be such that the limits of speed accuracy and certainty of vehicle identification set out in the user handbook are realizable in the intended environments. Typically this is achieved by associating the main frequency microwave generator with a separate fixed frequency oscillator circuit of significant higher stability, such that its stability can be in part, impressed upon the main microwave generator. A Phase Locked Loop ( PLL ) is an example of such an association.

3.5.2.3.2 The gain of analogue channels shall have no influence on results, or its effect shall be periodically checked conform national legislation.

4.0 Handbook The manufacturer shall provide each radar system with a handbook which shall be approved at the same time as the pattern approval. This handbook shall contain at least:

- The theory of operation of the equipment

- Installation/set-up instructions

- An explanation of the general lay out ( operation schematic )

- Detailed specifications of normal operating conditions

Update OIML R91 version February 2014 TMJPage 8 - Operation modes

- Information of the main causes/sources of errors

- An overview of the influence quantities affecting the measurement, and of the partial errors they may introduce.

5.0 Protection against tampering It shall be possible to seal or otherwise protect the radar system in such a way that those parts which, if tampered with, could lead to errors in measurements or metrological unreliable operation.

6.0 Identification of the equipment The radar system and each separately housed sub unit shall carry, in indelible lettering at least the following information:

- the name( or trade mark ) and address of the manufacturer or his representative

- the type indication and serial number of the radar system

- year of construction

- the unit in which the measured variable is expressed

- the measurement speed range

- type approval number, if applicable or all information as required by national legislation.

7.0 Pattern Type approval

7.1.1 Test conditions Reference value range

Ambient temperature +20⁰ C -10⁰ C to + 50⁰ C

Ambient humidity 60% either value, non-condensing Power voltage nominal -150%,+2010% of nominal Frequency nominal nominal +/- 3 2 % ?? Separate between AC and DC power

Update OIML R91 version February 2014 TMJPage 9 Radars shall be tested at +20⁰ C and at the minimum and maximum temperature, or as specified by the manufacturer, with different DC power voltages; humidity and power frequency shall be varied only if they have a noticeable influence.

For each factor mentioned above, its variation throughout the whole defined range shall not induce a change of indication greater than 50% of the moduli of the maximum permissible errors given in point 7.1.2 and 7.1.3.3.

7.1.2 Testing of micro wave section Radiation pattern and power limitations conform point 2.4 shall apply Aiming device conform point 2.3 shall apply Frequency range and oscillator stability conform national legislation

Note: Pattern approval is also dependent of certification by the authority for communication equipment

7.1.3 Testing of the low frequency section

7.1.3.1 Doppler radars For Doppler radar the frequency fd of the simulated Doppler signal the theoretical speed indication shall be computed from:

Vd = 0.5 x fd x ( λ/cos α )

Where: λ = the emitted wave length Α = the average effective angle of incidence 7.1.3.2 Modulated radars For all other type of radars, used this should be discussed and see also point 2.9 Proposed text could be: The general required specifications as under points ….. ….. shall be deemed to be met with regards to the width of the radar beam if the proportion of the maximum error which is dependent on the size of the half value angle does not exceed 2.5% of the actual speed. With regard to the effect of secondary maxima of the antenna characteristics, the secondary maxima and also the main maximum and the maxima at the other frequencies after reception of the transmitted signal have a power ratio of at least 30 dB.

Update OIML R91 version February 2014 TMJPage 10 7.1.3.3 Maximum error (this should be in the requirements, not under type approval The maximum error under laboratory research shall not exceed 1 km/h for simulated speeds not greater than 100 km/h and 1% of the simulated for speeds greater than 100 km/h. Speed simulation shall be carried out by simulating a singular point that moves at a uniform speed along a straight line through (the centre) of the antenna. The simulated speed corresponds to this uniform speed multiplied by the cosine of the measurement angle , if applicable. Should measured value be rounded up / down or truncated???to the nearest integer. Maximum error for frequency having influence on the measuring result: 0,3 % (for example transmit frequency and time base for measuring fd)

7.2 Tests of effects of influence factors and disturbances The tests that shall be performed and the criteria of acceptance are described in xxxxxx and not clear to me at the moment who is responsible for this part. Probably the existing Annex in OIML R91 which refers to D11 can be used for a major part. Update with edition 2013 of OIML D 11.

7.3 Metrological field tests.

To be performed after all laboratory tests have been completed???? Information to be supplied by Walter Fasel

7.4 Conformity to approved pattern

The approved pattern is defined by the instrument’s characteristics determining metrological integrity and conform the specifications of this document. A test/approval certificate shall be issued by the certifying institute on the basis of an examination conducted by that institute. This examination shall investigate those aspects that are crucial to the suitability of the radar speed system with or without a recording device. This document shall describe at least used equipment and calibration dates, test set up, method of testing and applied standards and results , etc …

Update OIML R91 version February 2014 TMJPage 11

Update OIML R91 version February 2014 TMJPage 12