GB/T 40025-2021RF technical requirements and test methods for 24GHz vehicle radio equipment (English PDF)

3.1 Terms and definitions

For the purposes of this document, the following terms and definitions apply.

3.1.1 Equivalent isotropic radiated power; EIRP

the product of the power output to the antenna relative to the antenna gain of the omnidirectional antenna in the specified direction

3.1.2 Duty cycle

in a series of pulses, the ratio of the duration of the positive pulse to the total period of the pulse

3.1.3 Spurious emission

unwanted emission of equipment in spurious domain

3.2 Abbreviations

The abbreviations apply to this document.

EIRP: Equivalent Isotropic Radiated Power

RBW: Resolution Band width

RMS: Root Mean Square

VBW: Video Band width

4.1 Environmental requirements

The equipment manufacturer shall declare in advance the environmental conditions for the equipment to work. The equipment shall work in its nominal working environment.

4.2 RF technical requirements

4.2.1 Equivalent isotropic radiated power

When the transmitter is working at the maximum power level, the equivalent omnidirectional radiation power limit of 24GHz~24.25GHz is 13dBm.

4.2.2 Frequency range

In the case of the maximum power level of the transmitter, the frequency range limit is fL>=24GHz, fH<=26.65GHz.

4.2.3 Occupied bandwidth

4.2.3.1 Overview

The occupied bandwidth of vehicle radio equipment operating at 24GHz~24.25GHz is the signal bandwidth of 99% of the energy of the transmitted signal.

4.2.3.2 Limits

The upper and lower limits of the occupied bandwidth of the vehicle radio equipment operating at 24GHz~24.25GHz shall not exceed the specified frequency range.

5.5 Frequency range

5.5.1 Test configuration

The frequency range shall be measured using the test site described in 5.3.2 and the method in 5.3.3.

5.5.2 Test steps

The test steps are as follows:

a) The transmitter shall be adjusted to the maximum transmission mode;

b) Use a spectrum analyzer to read the start frequency and cutoff frequency at the upper and lower limits of the signal envelope. Radiation power is not more than -80dBm/Hz (EIRP). Record it. Its value shall not exceed the limit requirement of 4.2.2.

5.6 Occupied bandwidth

5.6.1 Test configuration

The occupied bandwidth shall be measured using the test site described in 5.3.2 and the method in 5.3.3.

5.6.2 Test steps

The test steps are as follows:

a) The transmitter is adjusted to the maximum transmission mode;

b) Set the center frequency of the spectrum analyzer = the center frequency of the measured channel. Set RBW=1 MHz, VBW=1 MHz. The sweep width is 2 times the nominal channel bandwidth. Detector RMS, tracking method remains the maximum value;

c) The signal bandwidth of the vehicle radio equipment operating at 24GHz~24.25GHz records the signal bandwidth of 99% energy of […]

5.7 Transmitter spurious emission

5.7.3.2 Test steps

The test steps are as follows:

a) In the case of equipment support, test and record the spurious of the highest frequency band. Set the spectrum analyzer RBW=1 MHz, VBW=1MHz, detector RMS, tracking mode remain the maximum value;

b) Any emission found in the scan that is in the 6dB range below the limit shall be recorded. Analyze the results to exclude the influence of the mixer image.

5.8 Receiver spurious emission

5.8.1 Configuration requirements

If the receiver is in the form of an antenna array, where feasible, only one transmit link (antenna) shall be reserved while other transmit links (antennas) are disabled. If it is not feasible, the method used shall be recorded in the test report.

If only one receiving link is tested, the test results shall be modified to be applicable to the entire system (all receiving links).

The spurious emission power (mW) of a receiving link needs to be multiplied by the number of receiving links to obtain the total receiver spurious emission power of the system.

The tested equipment shall be configured to make it work in a state of continuous reception or no transmission.

5.8.2 Test method for spurious emission less than 40GHz

5.8.2.1 Test configuration

When testing spurious emissions less than or equal to 40GHz, use the test site described in Annex A and the relevant measurement procedures in Annex B for measurement.

5.8.2.2 Test steps

The test steps are as follows:

a) Measure the spurious emission in the range of 30MHz~1GHz. Set the spectrum analyzer RBW=100kHz, VBW=100kHz, detector RMS, tracking […]

A.1 Open test field or semi-anechoic dark room

The open test field or semi-anechoic dark room shall meet the requirements of Annex A in GB/T 9254-2008 for the test field.

In the frequency band below 1GHz, the test distance of the measuring transceiver antenna is not less than 3m. In the frequency band above 1GHz, select the appropriate test distance. The size of the tested equipment shall be less than 20% of the test distance. The height of the tested equipment or the antenna height requirement for substitution is 1.5m. The height of the measuring antenna is required to be adjusted within the range of 1m~4m.

In order to ensure that the reflected wave signal generated by obstacles near the test site has no effect on the test results, the test site shall meet the following conditions:

a) There shall be no conductive objects with a diameter larger than the highest frequency of the test lambda/4 (lambda is the wavelength of the radio wave) in the vicinity of the test site;

b) The connecting cables shall be laid along the surface of the floor as much as possible, preferably under the floor. Use shielded cables for low-impedance cables.

The typical test site layout is shown in Figure A.1. […]

B.2 Alternative measurement

The test data obtained by the test method of B.1 is not the final test result. The actual emission level of the spurious signal generated by the tested equipment needs to be determined by an alternative test. The principle of alternative testing is to replace the tested equipment with a known signal generator, so as to quantify the emission level of each signal generated by the tested equipment.

The test connection is shown in Figure B.2. Place the alternative antenna instead of the tested equipment in the original location. And it is vertical polarization. The signal generator frequency is tuned to the test frequency of each signal in the test process of B.1. Adjust the output power of the signal generator. Make the measurement spectrum analyzer obtain the same test level as recorded during the B.1 test. Then the radiated emission power of the corresponding frequency signal is the calculated value after the sum of the output level of the signal generator and the gain of the alternative antenna minus the loss of the connecting cable. In this way, the actual radiated power of each frequency signal is obtained. […]