7.2 Overall loss/loudness ratings

26.1323GPPRelease 18Speech and video telephony terminal acoustic test specificationTS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

7.2.1 General

The SLR and RLR values for GSM, 3G, LTE, NR or WLAN networks apply up to the POI. However, the main determining factors are the characteristics of the UE, including the analogue to digital conversion (ADC) and digital to analogue conversion (DAC). In practice, it is convenient to specify loudness ratings to the Air Interface. For the normal case, where the GSM, 3G, LTE, NR or WLAN network introduce no additional loss between the Air Interface and the POI, the loudness ratings to the PSTN boundary (POI) will be the same as the loudness ratings measured at the Air Interface.

7.2.2 Connections with handset UE

7.2.2.1 Sending loudness rating (SLR)

a) The test signal to be used for the measurements shall be the British-English single talk sequence described in ITU-T Recommendation P.501 [22]. The spectrum of the acoustic signal produced by the artificial mouth is calibrated under free-field conditions at the MRP. The test signal level shall be -4,7 dBPa measured at the MRP. The test signal level is calculated over the complete test signal sequence.

b) The handset terminal is setup as described in clause 5. The sending sensitivity shall be calculated from each band of the 14 frequencies given in table 1 of ITU‑T Recommendation P.79 [16], bands 4 to 17. For the calculation, the averaged measured level at the electrical reference point for each frequency band is referred to the averaged test signal level measured in each frequency band at the MRP.

c) The sensitivity is expressed in terms of dBV/Pa and the SLR shall be calculated according to ITU‑T Recommendation P.79 [16], formula (A-23b), over bands 4 to 17, using m = 0,175 and the sending weighting factors from ITU‑T Recommendation P.79 [16], table 1.

7.2.2.2 Receiving loudness rating (RLR)

a) The test signal to be used for the measurements shall be the British-English single talk sequence described in ITU-T Recommendation P.501 [22]. The test signal level shall be -16 dBm0 measured at the digital reference point or the equivalent analogue point. The test signal level is calculated over the complete test signal sequence.

b) The handset terminal is setup as described in clause 5. The receiving sensitivity shall be calculated from each band of the 14 frequencies given in table 1 of ITU‑T Recommendation P.79 [16], bands 4 to 17. For the calculation, the averaged measured level at each frequency band is referred to the averaged test signal level measured in each frequency band.

c) The sensitivity is expressed in terms of dBPa/V and the RLR shall be calculated according to ITU‑T Recommendation P.79 [16], formula (A-23c), over bands 4 to 17, using m = 0,175 and the receiving weighting factors from table 1 of ITU‑T Recommendation P.79 [16].

d) DRP-ERP correction is used. No leakage correction shall be applied.

7.2.2.3 Receiving loudness rating (RLR) in the presence of background noise

This test shall be performed with the volume control at the maximum setting.

a) The downlink test signal to be used for the measurements shall be composed from the British-English material of clause 7.3 in ITU-T Recommendation P.501 [22]. The signal is a concatenation of the following parts (see also Figure 15a6):

1) The complete female short conditioning sequence (which includes a leading 5 s silence which is here used for conditioning the UE under noise-only conditions). The level shall be -16 dBm0 active speech level (ITU-T P.56) measured at the digital reference point or the equivalent analogue point.

2) Pause 1 sec.

3) The first 5 s of the male short conditioning sequence. The level shall be -16 dBm0 active speech level (ITU-T P.56) measured at the digital reference point or the equivalent analogue point.

4) The complete single-talk sequence. The test signal level shall be -16 dBm0 measured at the digital reference point or the equivalent analogue point. The test signal level is calculated over the complete single-talk test sequence.

b) The background noise playback shall be set up and calibrated according to handset related descriptions in ETSI TS 103 224 or ES 202 396-1. The "Pub Noise (Pub)" recording is used. This scenario is available for both playback systems and is described in sub-clause 8.2 of TS 103 224 (8-channel recording) and sub-clause 8.2 of ES 202 396-1 (binaural recording). The type of background noise reproduction used for the test shall be reported.

c) The handset terminal is setup as described in clause 5 and the relevant noise playback specification, TS 103 224 or ES 202 396-1. Set the volume control to maximum.

d) The start of the recording of the artificial ear signal and the start of the background noise playback shall be synchronized to ensure consistent timing of repeated recordings, and allow background noise cancellation by subtraction in the time domain as described below. The noise playback shall be looped with a 20 ms crossfade at the loop point.

e) The background noise and downlink speech stimulus are applied and a recording of the artificial ear DRP signal is performed. The sound file is saved (file1). The playback is stopped.

f) The recording described in e) is repeated, this time with muted downlink signal. The soundfile is saved (file2).

g) A subtraction of the samples is performed (file1-file2). The resulting time signal contains the output of the UE to the artificial ear, where the background noise has been essentially eliminated. For further analysis, the duration of the conditioning sequence and the receive delay from POI to DRP is discarded, resulting in a time signal containing only the single-talk sequence.

h) The RLR is calculated according to sub-clause 7.2.2.2.

Figure 15a6 Downlink test signal

7.2.3 Connections with desktop hands-free UE

7.2.3.1 Sending loudness rating (SLR)

The spectrum at the MRP and the actual level at the MRP (measured in 1/3-octaves) are used as references to determine the sending sensitivity SmJ.

b) The hands-free terminal is setup as described in clause 5. The sending sensitivity shall be calculated from each band of the 14 frequencies given in table 1 of ITU‑T Recommendation P.79 [16], bands 4 to 17. For the calculation, the averaged measured level at the electrical reference point for each frequency band is referred to the averaged test signal level measured in each frequency band at the MRP.

7.2.3.2 Receiving Loudness Rating (RLR)

b) The hands-free terminal is setup as described in clause 5. If a HATS is used, then it is free-field equalized as described in ITU-T Recommendation P.581. The equalized output signal of each artificial ear is power-averaged over the total duration of the analysis; the right and left artificial ear signals are voltage-summed for each 1/3-octave frequency band; these 1/3-octave band data are considered as the input signal to be used for calculations or measurements. The receiving sensitivity shall be calculated from each band of the 14 frequencies given in table 1 of ITU‑T Recommendation P.79 [16], bands 4 to 17.

For the calculation, the averaged measured level at each frequency band is referred to the averaged test signal level measured in each frequency band.

d) No leakage correction shall be applied. The hands-free correction, as described in ITU‑T Recommendation P.340 shall be applied. To compute the receiving loudness rating (RLR) for a hands-free terminal (see also ITU-T Recommendation P.340), when using the combination of left and right artificial ear signals from the HATS, the HFL_E has to be 8 dB instead of 14 dB. For further information see ITU-T Recommendation P.581.

7.2.4 Connections with hand-held hands-free UE

7.2.4.1 Sending loudness rating (SLR)

The spectrum at the MRP and the actual level at the MRP (measured in 1/3-octaves) are used as references to determine the sending sensitivity SmJ.

7.2.4.2 Receiving loudness rating (RLR)

For the calculation, the averaged measured level at each frequency band is referred to the averaged test signal level measured in each frequency band.

d) No leakage correction shall be applied. The hands-free correction as described in ITU‑T Recommendation P.340 shall be applied. To compute the receiving loudness rating (RLR) for hands-free terminals (see also ITU-T Recommendation P.340), when using the combination of left and right artificial ear signals from the HATS, the HFL_E has to be 8 dB instead of 14 dB. For further information see ITU-T Recommendation P.581.

7.2.5 Connections with headset UE

Same as for handset.

7.2.6 Connections with electrical interface UE

7.2.6.1 Sending junction loudness rating (SJLR)

a) The test signal to be used for the measurements shall be the British-English single talk sequence described in ITU-T Recommendation P.501 [22]. For electrical interface UE, the active speech level of the signal shall be calibrated to -60 dBV for analogue and to -16 dBm0 for digital connections. The test signal level is calculated over the complete test signal sequence.

NOTE: The specified electrical levels correpond to an acoustic level of -4.7 dBPa at MRP.

b) The reference signal to be used for the calculation shall be the same as the test signal and is calibrated to ‑16 dBm0 (independent of analogue or digital connection).

c) The terminal is setup as described in clause 5.1.6 and the test signal is transmitted in sending direction. For the calculation, the averaged measured level at each frequency band is referred to the averaged reference signal level measured in each frequency band.

d) The sensitivity is expressed in dB. The sending junction loudness rating (SJLR) is calculated according to equation A-23d of ITU‑T Recommendation P.79 [16], bands 4-17, m = 0.175 and the weighting factors for JLR according to Table A.2 of ITU‑T Recommendation P.79 [16]. For the calculation, the average measured level at the output of system simulator for each frequency band is referred to the reference signal.

7.2.6.2 Receving junction loudness rating (RJLR)

b) The reference signal to be used for the calculation shall be the same as the test signal and is calibrated to ‑39 dBV for analogue and to ‑16 dBm0 for digital connections.

c) The terminal is setup as described in clause 5.1.6 and the test signal is transmitted in receiving direction. For the calculation, the averaged measured level at each frequency band is referred to the averaged reference signal level measured in each frequency band.

d) The sensitivity is expressed in dB. The receiving junction loudness rating (RJLR) is calculated according to equation A-23d of ITU‑T Recommendation P.79 [16], bands 4-17, m = 0.175 and the weighting factors for JLR according to Table A.2 of ITU‑T Recommendation P.79 [16]. For the calculation, the average measured level at the output of the electrical interface UE for each frequency band is referred to the reference signal.