Having dealt with the administrative side of Type Approval to UNECE Regulation 10, Revision 5, Amendment 1 (8 October 2016), hereafter referenced as R10.05, in the first three blogs in this series, this installment begins looking at the tests themselves commencing with the radiated emissions requirements of Annexes 4 and 5 and radiated immunity requirements of Annex 6.
RADIATED EMISSIONS (Annexes 4 and 5)
R10.05 separates emissions testing of vehicles into two parts: Broadband (Annex 4) and Narrowband (Annex 5). The test set-up is the same for both measurements, however the operating state of the vehicle and measurement detector used differ between the annexes.
Broadband emissions is a compulsory test as there are multiple potential sources of this type of interference on vehicles. Typically, broadband radiation is produced from irregular switching systems e.g. air conditioning; motors e.g. windscreen wipers, heating/cooling fans; electromechanical components e.g. relays, switches and solenoids; and from fast edge, high energy switching systems e.g. DC to DC converters, displays, PWM LED lighting controllers, motor controllers. As the name implies, the interference occurs over a broad range of frequencies, often many harmonic orders above the fundamental frequency. Generally, the more energy that is switched, the higher the emissions will be.
Narrowband emissions are primarily due to intentional switching operations on discrete frequencies or, as the name indicates, in narrow bands of frequencies. Typical sources of Narrowband interference include microprocessor clocks, screen refresh circuits and radio frequency transmitters/receivers. Because of its nature, the source of a Narrowband emission is usually easy to identify as the frequency coincides with a known clock, or harmonic, of the vehicle systems.
TEST FACILITIES
Annexes 4 and 5 specify that testing should be performed on an Open Area Test Site (OATS). However, testing may be performed in an Anechoic Lined Shielded Enclosure (ALSE) provided that the measurements correlate with those obtained on an OATS. For details of the test sites and comparison of the benefits and drawbacks in each case please refer to the forthcoming White Paper that accompanies this series of blogs.
ANTENNA LOCATIONS & POLARIZATION
Measurements are taken on each side of the vehicle with a fixed antenna height of 3.0 m or 1.8 m, determined by the measurement distance, 10 m or 3 m respectively. The measurement distance is defined as the separation between the antenna reference point and the nearest metal part of the vehicle under test. Because the antenna height is fixed, there is no requirement to height-scan the antenna in R10.05.
Measurements are taken in both vertical and horizontal polarizations.
If the vehicle under test is physically large, it may be necessary to measure in multiple locations to ensure that the entire vehicle area is captured within the 3 dB beamwidth of the antenna. This is a particular concern when measurements are being performed at a 3 m test distance.
STATE OF VEHICLE DURING TEST
In the case of broadband emissions testing, the engine is turned on and set at 1500 rpm (for vehicles with more than one cylinder), and all systems that could produce broadband interference and can be permanently turned on by the driver or passenger must be in operation at full load. Some typical examples include headlights on full beam, heating on maximum, heated seats operational at maximum, CD/DVD player running and windscreen wipers on full speed. Systems that only operate for short periods e.g. electric windows, indicators, electric mirrors are not operational for broadband emissions testing.
Vehicles with electrical traction systems i.e. electric vehicles and hybrid electric vehicles, are tested for broadband emissions dynamically either on a dynamometer (rolling road) or on insulated axle stands with the vehicle speed set at 40 km/h or at maximum if less than 40 km/h. In the case of hybrid vehicles testing is required in both electric drive and in internal combustion engine drive configurations.
Vehicles that have a rechargeable electric energy storage system (REESS) are also tested in “Charge Mode Coupled to the Power Grid” for broadband emissions. This testing will be covered in a later blog in this series when covering Annex 13 (conducted emissions of vehicle charging systems).
Narrowband emissions testing is performed with the ignition on, but without the engine in operation. All vehicle systems with oscillators operating at frequencies above 9 kHz, or with repetitive signals, that can be permanently turned on by the driver or passenger are turned on with normal loading. Some typical examples include LED headlights on dipped beam, audio system operational from a USB stick or tuned to a radio station and cameras active.
There is no requirement to test vehicles with electric traction systems or REESS for narrowband emissions.
Radio transmitters must be operational and in transmit mode. Please refer to the third blog in this series for further details.
MEASUREMENTS & LIMITS
Measurements are taken with a scanning receiver or spectrum analyser, the measurement parameters of which are specified in Annexes 4 and 5. R10.05 specifies measurements in the range 30 MHz to 1000 MHz, although it should be noted that this range will increase in future revisions of the regulation.
Broadband limits are specified using a quasi-peak detector, however a peak detector measurement can be made with a 20 dB increase in the applicable limits. This is helpful as peak detector measurements are much faster than quasi-peak measurements, however if measurements are on or above the limit, then quasi-peak measurements must be taken on the corresponding frequencies as the final result.
Narrowband limits are specified using an average detector.
MEASUREMENT PROCEDURE
OATS and ALSE test sites will often be equipped with a remotely controlled turntable to speed-up testing. The vehicle under test is positioned with the engine reference point in the middle of the turntable so that both side measurements can be taken with a single antenna.
As the state of the vehicle is different for broadband and narrowband tests, this arrangement can also save considerable set-up time.
Modern receivers and spectrum analyzers are usually controlled via software that applies correction factors for the measurement system and logs the results automatically. The end result is then a series of plots and/or tables identifying the maximum measured emissions overlaid with the applicable limit.
Testing performed on an OATS is complicated by the presence of ambient signals within 6 dB of the applicable limit, or frequently, above it. There are techniques that can be used to obtain meaningful results in these circumstances, however this is an advanced subject beyond the scope of this blog.
RADIATED IMMUNITY (Annex 6)
Malfunction or failure of vehicle electronic systems due to exposure to electromagnetic fields could potentially cause loss of control of the vehicle, false warnings to the driver, or false operational indication to other road users. The presence of these immunity related systems means that the vehicle must be tested for immunity to radiated interference in accordance with Annex 6 of R10.05.
TEST FACILITIES
Testing is performed in the range 20 to 2000 MHz fundamentally using a signal generator, amplifier and antenna. Because RF signals are intentionally generated and fed into free-space, this type of testing should be performed in an enclosed environment i.e. an Anechoic Lined Shielded Enclosure (ALSE) in order to avoid interference with radio broadcasts, television broadcasts, aeronautical beacons and communications, emergency service communications, cellular communications and a host of other services. Annex 6 of R10.05 does allow for the use of an outdoor test site where it can be shown that the test will not contravene any applicable legal requirements i.e. the test will not interfere with anything. Given the frequency range and services operating within it, this is only really an option for test sites in remote locations.
Annex 6 also allows the use of the Bulk Current Injection (BCI) method for large vehicles that are over 12 m in length and/or over 2.6 m wide and/or over 4 m in height. Further information on BCI testing is covered in the next Blog on Annex 9, and in the forthcoming White Paper that accompanies this series of blogs.
ANTENNA LOCATION & POLARIZATION
Testing is performed relative to a reference point on the vehicle, where the field strength is established during calibration prior to testing. In the case of a passenger car or small van, this is 1 m above the plane on which the vehicle sits and 1 m behind the vertical plane on the centerline of the front wheels. The vehicle centerline is aligned with the reference point and the antenna is then positioned at least 2 m away horizontally at a fixed height determined by the physical boundary of the antenna radiating elements, which must be greater than 250 mm above the floor of the test chamber. If the electrical/electronic systems are predominantly located in the rear of the vehicle, then instead of facing the antenna, the vehicle faces away from it rotated 180 degrees about the center of the vehicle.
R10.05 specifies that only vertical polarization is required for Type Approval tests.
Large vehicles e.g. buses, may need multiple reference points in order to expose all electronic systems to the required field strength within the 3 dB beamwidth of the radiating antenna. Where additional test points are necessary, they are agreed with the Technical Service prior to test.
STATE OF VEHICLE DURING TEST
The majority of electrical/electronic systems on the vehicle are tested with the engine or electrical drive turning the wheels at a steady speed of 50 km/h on an appropriately loaded dynamometer (rolling-road) or on insulated axle stands. All electronic systems that can be permanently turned on by the driver or passenger are in normal operation.
A minimum set of test conditions and performance criteria are defined in Annex 6, however any electrical/electronic system with an immunity related function that is to be included in the Type Approval must be evaluated during testing. It may be necessary to perform the test multiple times in order to ensure complete coverage.
One immunity related system that cannot be tested with the vehicle in this configuration is the braking system. In this case Annex 6 specifies a “Brake cycle” condition, where the vehicle is stationary with the brake pedal depressed.
If a particular electrical/electronic system that is involved in direct control of the vehicle cannot be operational during testing due to the configuration e.g. self-leveling suspension that ‘fights’ against the strapping down of the vehicle to the chamber floor (to prevent an expensive car shaped hole in the end of the test chamber!), then it can be evaluated separately and evidence of compliance with the regulation provided along with the test report for the vehicle.
In the case of ‘REESS Mode Coupled to the Power Grid’, testing is performed with the engine off and the state of charge of the energy storage system kept between 20% and 80% of maximum to ensure that charging is taking place during the test. Annex 6 only specifies one performance criterion for this test at present, and that is to ensure that the vehicle is not set in motion by the applied field. Clearly this means that the vehicle must be strapped to the floor of the test chamber for the previously stated reason!
TEST LEVEL & MODULATION
The test level is set in R10.05 at 30 V/m rms in over 90% of the range 20 to 2000 MHz, with a minimum of 25 V/m rms throughout the range.
Approval Authorities may require that testing is performed at higher test levels in order to provide additional confidence in the performance and allow for any minor production variations, however this is for the manufacturer to agree with the Technical Service prior to test.
The applied field is amplitude modulated (AM) in the range 20 to 800 MHz, to a depth of 80% at 1 kHz to simulate the type of narrowband signals that may impinge on the vehicle from external sources.
In the remainder of the frequency range, 800 to 2000 MHz, the applied signal is pulse modulated (PM) with a TON [N.B. Subscript] of 577 s [N.B. Special Character] and period of 4,600 s [N.B. Special Character], to simulate the type of narrowband pulsed signals typical of GSM cellular communications.
TEST PROCEDURE
In order to cover the full range of 20 to 2000 MHz, 2 or more antennas will normally be needed. In each case the field is applied at successive frequencies separated by defined steps in the referenced standard ISO 11451-1 Third Edition 2005, with the appropriate modulation at the calibrated test level. Each frequency is maintained for a minimum of 2 s, however where particular systems take longer to complete one operational cycle it may be necessary to dwell for longer in order to capture any immunity related effects. A longer dwell time increases the time that the test takes to perform.
Laboratories take differing approaches to apparent failures of the vehicle systems during testing. Some will simply state that the vehicle has failed, others will go over the frequency range two or more times to ensure that the failure is consistent and can definitely be correlated with the test and not some other e.g. timing related, effect. Systems that periodically reset themselves in normal operation for instance can lead to false failures being reported if this checking approach is not taken. Others spend time quantifying the apparent failure and provide details of the field level at which the failure occurs.
It should be remembered that R10.05 is only concerned with immunity related systems, so failures of the audio system for instance do not necessarily constitute a failure of the vehicle with respect to Type Approval.
MONITORING & PERFORMANCE CRITERIA
As modern vehicles become ever more complex, the task of monitoring the vehicle during testing becomes more onerous. A laboratory will typically monitor the exterior of the vehicle and dashboard with fibre-optically isolated cameras (to avoid unduly influencing the test environment), and will monitor the passenger compartment for any audio disturbance. However, there may be systems within the vehicle that cannot be monitored, as there is no associated warning on the dashboard. In these cases, often the vehicle diagnostic bus will be monitored before, during and/or after the test for any error reports/logs or indications that something has not performed as expected. Where this is not possible then the manufacturer must work with the test laboratory to establish an acceptable monitoring scenario.
Annex 6 provides a minimum set of performance criteria for common vehicle systems e.g. vehicle speed, direction indicator, lighting, horn. The performance criterion/criteria for any other system with an immunity related function must be agreed with the Technical Service in advance of testing e.g Incorrect operation of lane departure systems affecting the steering.
In the next instalment in this series of blogs on R10.05 we will look at radiated emissions and immunity testing of electrical/electronic sub-assemblies in accordance with Annexes 7, 8 and 9.
REFERENCES
- UNECE Regulation 10, Revision 5 (9 October 2014):
- UNECE Regulation 10, Revision 5, Amendment 1 (8 October 2016):
- CISPR 12: 2001 + Amendment 1: 2005 – Vehicles, boats, and internal combustion engine drive devices – Radio disturbance characteristics – Limits and methods of measurement for the protection of receivers except those installed in the vehicle/boat/device itself or in adjacent vehicles/boats/devices
- Please note that this standard has been withdrawn, but is available for download for a nominal fee:
- https://webstore.iec.ch/publication/12029
- CISPR 25: 2002 + Corrigendum: 2004 – Radio disturbance characteristics for the protection of receivers used on board vehicles, boats, and on devices – Limits and methods of measurement
- Please note that this standard has been withdrawn, but is available for download free of charge:
- https://webstore.iec.ch/publication/12216
- ISO 11452-1 Third Edition 2005 – Road vehicles – Vehicle test methods for electrical disturbances from narrowband radiated electromagnetic energy – Part 1: General principles and terminology
- Please note that this standard has been superseded and that ISO standards are not available free of charge.
- https://www.iso.org/standard/37998.html
- ISO 11452-2 Third Edition 2005 – Road vehicles – Vehicle test methods for electrical disturbances from narrowband radiated electromagnetic energy – Part 2: Off-vehicle radiation sources
- Please note that this standard has been superseded and that ISO standards are not available free of charge.
- https://www.iso.org/standard/37999.html
