TIA-920 spec_Handdfress

1、8 Handsfree Send Frequency Response The send frequency response is the overall response of the transducer, send amplifier, and the codec send filter. The send sensitivity is expressed in terms of dBV/Pa. 9 9.1.1.1. Measurement Method The send frequency response is measured directly in 1/3rd octave b

2、ands or converted to 1/3rd octave bands according to IEEE Std. 1329, clause 9.3.8. The measurement is made over a minimum range of 100 Hz through 8000 Hz. For desktop handsfree, use the measurement set-up shown in Figure 13. For other handsfree devices, use the RTP. The test signal level shall be -4

3、.7 dBPa at the MRP. 10 9.1.1.2. Requirement The handsfree send response should be within the limits given in Table 10 and shown in Figure 14. The limits break at the crossover frequencies of the ISO R10 series of preferred frequencies. The crossover frequencies may be adjusted up to 3% to accommodat

4、e non-R10 1/3rd octave measurement data. The frequency response mask is a floating or “best fit” mask. 8 9.4.2. Handsfree Receive Distortion and Noise 910 9.4.2.1. Method of Measurement Handsfree receive distortion and noise is measured according to IEEE Std. 1329, 9.4.6. Apply a test signal, at the

5、 levels given in Table 13 and at the following frequencies: 315, 502, 1004, 2008 and 3150 Hz. The ratio of the signal power to the total A-weighted distortion and noise power is measured. The reference volume control setting shall be used. 11 9.4.2.2. Requirement The ratio of the signal power to the total A-weighted distortion and noise power should be above the limits given in Table 13, unless the measured sound pressure is less than -50 dBPa. The measurement microphon