QCVN 99:2015/BTTTT 1.4.16. Transceiver OBU The equipment is placed fixedly on a vehicle transmitting reply signals to a detection signal. 1.4.17. Transponder As part of the equipment OBU without being spontaneous in the 5.8 GHz band. 1.5. Symbols ATNAT2 Attenuation of AT2 ATNBLN Attenuation of BLN ATNCA1 Attenuation of calibrated coaxial calibration 1 D Distance between the phase center of transmitting antenna and receiving antenna ddisplace Horizontal displacement of the antenna phase center of TTA and RTA dF1 Distance from the transmitting antenna to the first Fresnel ellipse dF2 Distance from the first Fresnel ellipse to the receiving antenna D0,EUT The largest linear direction of the antenna under test EIRPTSM e.i.r.p referenced the transmitting spectrum mask ∆f RSU Frequency error of RSU ∆fs Frequency error of the subcarrier fc Center frequency of the receiver f ObuTx Actual center frequency of the lower and upper side band of the upward channel fMSS1 Frequency of MSS1 foffset Offset frequency fs Nominal subcarrier frequency of OBU fTX Nominal subcarrier frequency of RSU fTX,actual Actual center frequency of the downward carrier fu Nominal center frequency of unwanted signals fu1, fu2 Center frequencies of the unwanted signal Gc The conversion gain Gcoit Correction gain GOBU,Rx OBU gain of the receiving antenna GOBU,Tx OBU gain of the transmitting antenna GRSA Gain of the receiving substitution antenna GTA Gain of the test antenna GTSA Gain of the transmitting substitution antenna GRSU,Tx The transmitting antenna gain of RSU k coefficient of expansion (coefficient of convergence) m Modulation index 7
QCVN 99:2015/BTTTT of the signal between RD and transmitting antenna connector RSU. Record all the value of PTSM corresponding to the carrier frequency fTx and offset frequency foffset Spectrum mask TSM in each case of combination of the carrier frequency fTx and frequency offset foffset performed by EIRP of OBU is calculated by the formula: EIRPTSM PTSM .GRSU ,Tx The parameters in the formula above correspond to the frequencies f fTx foffset. The results obtained will correspond to each case combined between the center frequency fTx and offset frequency foffset. All these values are not exceeded the limit as in 2.1.3.3. Repeat step 6 to step 22 in the transmit RSU mode having modulated carrier with test signal TS1. 3.2.1.4. Unwanted emission of transmitters 3.2.1.4.1. General Independent with the environmental parameters by the manufacturer, the test process is only carried out in normal conditions as defined in 3.1.1. Figure 1 - Model of unwanted radiation measurement of transmitters The basic requirements and measurement guidelines as in Appendix A, Appendix B. The parameters of description and limit (see 2.1.4). The test process is done by measuring the radiation in all the bands corresponding to the active state as shown in Table 2. It should be known in advance the center frequencies fTx of RSU as in 3.1.3. 21
QCVN 99:2015/BTTTT Measurement procedures are as follows: Prepare the measurement location selected from Appendix B. Initial arrangement of OBU as a necessary condition in step 4 must be based on the direction M0 as shown in Figure 2, which means the axial direction of OBU must be directed right to the center part of the test antenna. Figure 2 – The directions Mi of OBU Turn on the monochromatic output signal of MSS1, adjust to the frequency fTx determined for channel 1 (see Table 6). Adjust output power of MSS1 so that PRSA is measured by a power meter PM1 which is equivalent to the value: PRSA = Pinc x GRSA x ( ) Replace RSA by OBU so that the phase center Mc of OBU coincides more and more with the rotation axis of turntable as possible. If not knowing the phase center Mc of OBU and there is no visible antenna, the center of OBU will be selected for replacement. Adjust the axial direction of OBU as required. Set OBU into the test mode so that OBU plays back the test signal TS2 with the subcarrier frequency fs. Measure the greater value of the power level Pmax in two bands from the receiving equipment, use the value of range bandwidth 100 kHz and record the value Pmax along with the direction of OBU Mi (i = 0,1,2,3,4) and the value of fs and fTx (i = 0,1,2 , 3.4) Repeat step 6 for other values of the subcarrier frequency fs. Repeat steps 3 through 7 for the center frequency fTx determined for channel 4 according to Table 6. If OBU is type B, continue to step 10, otherwise skip to step 11. Repeat step 1 to step 8 for all remaining OBU directions indicated by M1, M2, M3, and M4 in Figure 2 to determine the parameter U4a. Replace OBU by the sub-antenna TSA calibrated to left hand circular polarization with the gain GTSA and reflectivity at the antenna connector in conformity with the space of center frequency fTx listed in Table 6 so that the antenna phase center coincides with the phase 24
QCVN 99:2015/BTTTT Figure B.2 – Test model with two test antennas Test the parameters of EUT Adjust the incoming signal power to EUT Measuring process using substitution antenna B.3. Requirements for test B.3.1. Measurement distance In the open measurement space or in the anechoic chamber (non-reflective room) measurement distance in Figure B.1 and Figure B.2 must make sure the antennas on both sides on the radio transmission line must in the electromagnetic field in the remote area of the remaining antenna. This distance d must satisfy 3 following conditions: > 2. ( , + , ) , > 5. , + , à > 2. 38