Document ID: chunk:federal_register_of_legislation:F2024L00089:reg:800:p15
Version: federal_register_of_legislation:F2024L00089
Segment Type: reg
Provision Reference: reg 800 (pt 15/16)
Character Range: 70000–72948

km/h for the speed of 10 km/h or less and of ±1 km/h for any other speeds. The speed of 5 km/h is the lowest target speed. If the vehicle cannot be operated at this speed within the given precision, the lowest possible speed below 10 km/h shall be used instead.

              4.3.4. Method (E)

              The AVAS shall be mounted rigidly in an indoor facility, by means of the equipment indicated by the manufacturer. The microphone of the measuring instrument shall be placed at 1 m distance from the AVAS in the direction where the subjective sound level is greatest and placed at a height of approximately the same level as the sound radiation of the AVAS.

              The sound emission shall be measured at simulated speeds of 5 km/h to 20 km/h in steps of 5 km/h with a tolerance of ±0.5 km/h for each test speed.

              4.4. Measurement Readings

              4.4.1. Test Method (A)

              At least four measurements shall be made at every speed specified in paragraph 4.3.1.. The emitted sound shall be recorded during each passage of the vehicle between AA' and BB' for each microphone position. From each measurement sample a segment taken from AA until -1 meter before PP' shall be cut out for further analysis.

              4.4.2. Test Methods (B), (C), (D) and (E)

              The emitted sound shall be measured at every speed specified in correlated paragraphs above for at least 5 seconds.[18]

              4.5. Signal Processing

              For each recorded sample the average auto power spectrum shall be determined, using a Hanning window and at least 66.6 per cent overlap averages. The frequency resolution shall be chosen to be sufficiently narrow as to allow a separation of the frequency shift per target condition. The reported speed per sample segment is the average vehicle speed over the time of the sample segment rounded to the first decimal place.

              In case of test method (A) the frequency that is intended to be changed with the speed shall be determined per sample segment. The reported frequency per target condition fspeed shall be the mathematical average of the frequencies determined per measurement sample and rounded to the nearest integer. The reported speed per target condition shall be the mathematical average of the four sample segments.

       Table 4
Analysis of the shifted frequency per target condition per side
              Test run
Target speed  per        Reported speed (average per sample segment)  Determined frequency of interest  Reported Speed per target condition  Reported frequency of interest per target condition
              target                                                  (fj, speed)                       (average of the reported speeds)     (fspeed)
              condition
km/h           No        km/h                                         Hz                                km/h                                 Hz