G.3 Presence of echo cancellation

26.1323GPPRelease 18Speech and video telephony terminal acoustic test specificationTS

The intention of this test is to check whether an echo cancellation of the electrical interface UE is active or not when a Bluetooth headset or reference interface connects with settings according to Clause G.1.

Requirement:

Echo Cancellation should not be active for electrical interface UE in this case. The echo loss measured should be 20 dB ± 2 dB when an artificial echo path of 20 dB is introduced between receive and send path.

Test method

1) The compressed real speech signal as described in clause 7.3.3 of ITU-T P.501 [33] shall be used as a test signal, which shall be band-limited according to clause 5.4 and calibrated to a level of -10 dBm0.

2) The electrical interface is setup as described in clause 5.1.6 with enabled echo path, and the test signal is transmitted in receive direction.

3) The first 17.0 s of the test signal (six sentences) are discarded from the analysis to allow for convergence of the acoustic echo canceller (EC). The analysis is performed over the remaining length of the test sequence (last six sentences).

4) The analysis shall be conducted in 1/3-octave band intervals as given by the R.10 series of preferred numbers in ISO 3 [54]. For the calculation, the averaged measured echo level at each frequency band is referred to the averaged test signal level measured in each frequency band.

5) The echo loss is calculated according to ITU-T Recommendation G.122 [8], annex B, clause B.4 (trapezoidal rule). For narrowband mode, the default frequency range from 300 Hz to 3 400 Hz is used. For wideband, super-wideband, and fullband mode, the frequency range from 300 Hz to 6 700 Hz is used instead.

6) The calculated echo loss is corrected by the sum of SJLR and RJLR measured with the same connection parameters and as specified in clause 7.2.6 for narrowband, 8.2.6 for wideband, 9.2.6 for super-wideband or 10.2.6 for fullband mode.

Annex H (informative) :
Determination of ECRP for handset providing non-traditional earpiece