Analysis of the Necessity of Electromagnetic Compatibility Testing for Vehicle ECALL Products

I. Analysis of Testing Necessity

Regulatory Mandatory Requirements

The EU has mandated all new vehicle models to be equipped with eCall systems since 2018. China has also initiated the development of the national standard "Vehicle Accident Emergency Call System." EMC testing is a necessary condition for product market access.

Functional Safety Assurance

ECALL systems need to reliably transmit location information and the Minimum Set of Data (MSD) during accidents. Electromagnetic interference may cause communication failure, endangering rescue response timeliness.

Market Access Threshold

International markets (such as the EU, Russia) require certification according to standards like UN R10, CISPR 25. Domestically, compliance with GB 34660, GB/T 18655, etc., is required.

Technical Complexity

ECALL systems integrate GNSS positioning, cellular communication (2G/4G/5G), voice transmission, and other modules. Multi-band signals are prone to electromagnetic interference.

II. Domestic and International Testing Standards

International Standards

Standard Number	Name	Core Content
CISPR 25:2021	Vehicles, boats and internal combustion engines – Radio disturbance characteristics – Limits and methods of measurement for the protection of on-board receivers	Specifies conducted/radiated emission limits for the 150kHz-5.925GHz frequency band, divided into Class 1-5 levels (Class 5 is the most stringent)
ISO 11452-2	Road vehicles – Component test methods for electrical disturbances from narrowband radiated electromagnetic energy – Part 2: Absorber-lined shielded enclosure	80MHz-6GHz frequency band, field strength 100V/m, simulates the anti-interference capability of automotive electronics in strong electromagnetic fields
ISO 11452-4	Road vehicles – Component test methods for electrical disturbances from narrowband radiated electromagnetic energy – Part 4: Harness excitation methods	100 kHz-400MHz frequency band, maximum injection current 200mA, evaluates the impact of harness coupled interference on the ECALL module
UN R144	Uniform provisions concerning the approval of emergency call devices and vehicles with regard to the installation of these devices	Requires EMC tests covering radiated immunity (ISO 11452), power transient immunity (ISO 7637), etc.

Domestic Standards

Standard Number	Name	Core Content
GB/T 18655-2025	Vehicles, boats and internal combustion engines – Radio disturbance characteristics – Limits and methods of measurement for the protection of on-board receivers	Equivalent to CISPR 25:2021, adds high-frequency test requirements for 5.925GHz
GB 34660-2017	Road vehicles – Electromagnetic compatibility requirements and test methods	Specifies radiated immunity from 20MHz-2000MHz, field strength 100V/m (anechoic chamber method)
GB/T 33014.2-2016	Road vehicles – Electrical and electronic equipment for a supply voltage of 42 V – Electrical loads – Part 2: Electrical tests	Specifies the immunity test methods for ECALL systems in the vehicle's electromagnetic environment

III. Core Testing Items

Electromagnetic Interference (EMI) Testing

1. Conducted Emission

Frequency Range: 150kHz-108MHz
Test Method: Voltage method (LISN network) measures power line interference
Limit Requirements: CISPR 25 Class 5 specifies ≤57dBμV (quasi-peak) at 150kHz

2. Radiated Emission

Frequency Range: 30MHz-6GHz
Test Environment: 1-meter method anechoic chamber (ALSE)
Limit Requirements: Specified by CISPR 25

Electromagnetic Susceptibility (EMS) Testing

1. Radiated Immunity

Test Standard: ISO 11452-2 (Anechoic Chamber Method)
Frequency Range: 80MHz-6GHz
Field Strength Level: 100V/m (80% AM, 1kHz)

2. Bulk Current Injection (BCI)

Test Standard: ISO 11452-4
Frequency Range: 100kHz-400MHz
Injection Current: 200mA (continuous wave)

3. Electrostatic Discharge (ESD)

Test Standard: ISO 10605
Contact Discharge: ±15kV
Air Discharge: ±25kV

IV. Key Testing Equipment

Equipment Type	Purpose
Anechoic Chamber	Provides site for radiated emission/immunity testing
EMI Receiver	Electromagnetic interference signal measurement
Line Impedance Stabilization Network (LISN)	Provides standard impedance and tests power isolation
Current Probe	Signal line conducted interference measurement
Signal Generator	Immunity test signal source
Power Amplifier	Radiated immunity power amplification
Electrostatic Discharge Simulator	ESD immunity testing

V. Key Points of Testing Process

1. Pre-test Phase

Conducted emission preliminary test (LISN + spectrum analyzer)
Radiated emission near-field scan (locating interference sources)

2. Formal Testing Phase

Arrange wiring harness according to CISPR 25 specifications (50mm from ground plane, standardized length)
Simulate vehicle power supply (12V/24V battery)
Multi-detector measurement (peak/quasi-peak/average)

3. Rectification and Optimization

Add filters (e.g., common mode chokes) for超标 frequency bands
Apply metal shielding to high-frequency modules (e.g., GNSS antenna module)