Acoustic规范和测试 Base Band 瞿雪丽 2002/1/30

有关声音的基本知识 声音的定义：声音是很多振动波的组合而成 , 此振动波的频率能被人耳接收到的范围就是声音。 声音的单位：声音的单位是用分贝(dB)来量测计算的。声压指针( SOUND PRESSURE LEVEL) 的定义是指单位面积所受到的压力( N/M2 ) 。N： 牛顿， M2：米平方。 标准音源：标准音源是由一发音源, 其音频为 1KHZ ，能够密合的偶合到标准麦克丰后量测到 1 Vrms 的电压信号，此1KHZ的发音源必须为94dBspl。 1 Pa = 94 dBspl 1 Pa = 0 dBpa SPL = 20 log 10 ( X / 20 exp –6 pa ) If x = 1 pa SPL = 94 dB

GSM ACOUSTIC测试设备 1. 测试固定架 ( Telephone Test Head ) : B&K 4602B 2.           仿真耳 ( Ear Simulator ) : B&K 4185 ( type 1) 3.           人工嘴 ( Artificial Mouth ) : B&K 4227 4.           标准音源校正器 ( Acoustic Calibrator ) B&K 4231 5.           仿真耳之电源供应器 ( Microphone Power Supply ) B&K 2690A0S2 6.           音频功率放大器 ( Audio Power Amplifier ) WQ1105 7.           GSM音频分析仪 ( GSM Audio Analyzer ) R&S UPL- 16 with B8 OR B&K 3108 8.          数字模拟转换接口 ( DAI Interface Box ) GSM solution vendor must supply. 9.           个人计算机 ( Personal Computer ) PC-486 10.          GSM 射频分析仪 ( Air Interface for GSM ) R&S CMD- 55/65 with option CMD-B5. 11.          GSM Acoustic 测试专用软体 ( 配合厂商提供 )。 50 db(A) 的隔音室 ( Acoustic Shield Room )

1 Sending sensitivity/frequency response The sending sensitivity frequency response is, as a function of the input test tone frequency, the ratio expressed in dB between the output level, represented by the PCM bit stream at the Digital Audio Interface (DAI) and the input sound pressure in the artificial mouth required to obtain this. 有关语音输入频率的测试，用PCM比特流来描述的在DAI处的输出与人工嘴处的输入的比值，单位是dB。（DAI/MRP） 测试目的和要求是符合GSM规范，如下表：

Frequency (Hz)) Upper Limit (dB Lower Limit (dB) 100 200 300 1000 2000 3000 3400 4000 -12 4 -6 -9

2 Sending loudness rating(SLR) （发送声音响度等级） The Sending Loudness Rating (SLR) is a means of expressing the sending frequency response based on objective single tone measurements in a way which relates to how a speech signal would be perceived by a listener. 单音信号测量基础上的发射频率响应，测量涉及到语音信号是如何被收听者接收到的。 The Sending Loudness Rating (SLR) shall be 8 +/- 3 dB. Initial conditions：The DAI of the MS is connected to the SS and is set to the operating mode "Test of acoustic devices and A/D & D/A".

3 Receiving sensitivity/frequency response The receiving sensitivity frequency response is, as a function of the input test tone frequency, the ratio expressed in dB between the output sound pressure in the artificial ear and the input level, represented by the PCM bit stream at the Digital Audio Interface (DAI), required to obtain this. 人工耳处的输出声压和DAI处用PCM比特流描述的输入等级的比值，用dB来表示。（ERP/DAI） 测试目的和要求是符合GSM规范，如下表：

Frequency (Hz) Upper Limit(dB) Lower Limit (dB) 100 200 300 500 1000 3000 3400 4000 -12 2 * -7 -5 -10

4 Receiving loudness rating（RLR） （接收声音响度等级） The Receiving Loudness Rating (RLR) is a means of expressing the receiving frequency response based on objective single tone measurements in a way which relates to how a speech signal would be perceived by a listener. 单音信号测量基础上的接收频率响应，测量涉及到语音信号是如何被收听者接收到的。 The nominal Receiving Loudness Rating (RLR) shall be 2 +/- 3 dB. If a user controlled receive volume control is provided the equipment shall meet this nominal value for at least one setting of the control. If a user controlled receive volume control is provided the Receive Loudness Rating (RLR) shall not be less than -13 dB when the control is set to maximum. Initial conditions：The DAI of the MS is connected to the SS and is set to the operating mode "Test of acoustic devices and A/D & D/A".

5 Side tones 5.1 Side Tone Masking Rating(STMR) （侧音屏蔽等级） expressing the path loss from the artificial mouth to the artificial ear based on objective single tone measurements in a way that relates to how a speaker will perceive his own voice when speaking or how a listener will perceive the background noise picked up by the microphone. 表示从人工嘴到人工耳的路径损耗，对单音信号的测量，并涉及到说话者怎样接收到自己的声音或麦克风接收到背景噪音。 The nominal value of the Side Tone Masking Rating (STMR) shall be 13 +/- 5 dB. Where a user controlled receiving volume control is provided the STMR shall meet the requirement at the setting where the RLR is equal to the nominal value.

5.2 Listener Side Tone Rating (LSTR) 背景侧音等级是在仿真量测电话在吵杂环境中使用时由送话端回到受话端的量。 The value of the Listener Sidetone Rating (LSTR) shall not be less than 15 dB.

6 Telephone Acoustic coupling Loss (TAL) 6.1 Echo Loss (EL) The echo loss is the path loss from the input of the reference speech encoder of the SS to the output of the reference speech decoder of the SS. SS:system simulator SS参考语音编码的输入与SS参考语音解码的比值。 shall be at least 46 dB. Initial conditions：The DAI of the MS is connected to the SS and is set to the operating mode "Normal operation". The SS sets up a speech call according to the generic call set up procedure.

6.2 Stability margin 目的: 测试手机的听筒放置在光滑面时是否会产生哨叫不安定的现象。 目的: 测试手机的听筒放置在光滑面时是否会产生哨叫不安定的现象。 测试方法: 将手机之音量调到最大的位置，受话器面朝下，然后放置在光滑面的木卓上。由仪器端来回注入一音源到受话器之使其产生回授振动效应。 规格: The stability margin shall be at least 6 dB.

7 Distortion（失真） 7.1 Sending The transmit signal to total distortion ratio is a measure of the linearity of the transmitter equipment 发送信号对总失真的比值，测量手机发射设备的线性度。 测试方法: 先在人工嘴的MRP 处产生1KHz音频使其在DAI 的输入端呈现0dBm0 的信号。此信号被校正为0dB ARP( Acoustic Reference Point )。然后依照下例表格规定，其送话失真度不得小于其要求。

relative to ARL（ dB ） Level ratio（ dB） -35 17.5 -30 22.5 -20 30.7 -10 33.3 33.7 +7 31.7 +10 25.5

7.2 Receiving The receive signal to total distortion ratio is a measure of the linearity in the receive equipment. 接收信号对总失真的比值，测量手机接收设备的线性度。 测试方法: 先在DAI 处产生1KHz 0dBm0音频信号，此信号传送到待测电话的受话器。然后依照下例表格规定，测量其受话失真度不得小于其要求。

Receiving Level at DAI ( dBm0 ) Receiving Ratio ( dB ) -45 17.5 -40 22.5 -30 30.5 -20 33.0 -10 33.5 -3 31.2 25.5

8. Sidetone distortion（侧音失真） The sidetone distortion expresses the linearity of the sidetone path in the handset. 表示手机中侧音路径的线性度。 测试方法: 在人工嘴的MRP ( Mouth Reference Point ) 上产生 –4.7dBPa的 315Hz , 500Hz和 1KHz 的单频音源送到手机之听筒送话器上。同时测量在听筒受话器上的测音失真度。 The third harmonic distortion generated shall not be greater than 10 %.

9 Out-of-band signals 9.1 Sending（传送之频道外信号） 目的: 主要测量手机在送话中受到频道外之信号干扰时在传送时的御制能力。 测试方法: 在人工嘴的MRP ( Mouth Reference Point ) 上产生 –4.7dBPa的 4.6KHz 到8KHz的单频音源送到电话机之听筒受话器上。在DAI的传送处量测此信号的量和 1KHz信号的量相比。其比值不得小下列规格。 Applied sine-wave frequency Limit (minimum) 4,6 kHz 8 kHz 30 dB 40 dB

9.2 Receiving（接收之频道外信号） 目的: 主要测量手机在受话中受到频道外之信号干扰时 的御制能力。 目的: 主要测量手机在受话中受到频道外之信号干扰时 的御制能力。 测试方法: DAI 设定在 Acoustic Devices 和 A/D & D/A 模示。测试架构参考受话频率响应测试。由DAI产生 500Hz,1KHz,2KHz,3.35KHz 电压为0dBm0的讯号量传送到电话机之听筒受话器上，测量在人工耳接收到由4.6KHz 到8KHz 之间的接收量。此讯号的量和 1KHz讯号的量相比。其比值不得小下列规格。 Image signal frequency Equivalent input signal level 4,6 kHz 8 kHz -35 dBm0 -45 dBm0

10. Idle channel noise 10.1 Sending（静态传送杂音 ） 目的: 主要测量电话机在静态时所传送的杂音量。 测试方法: DAI 设定在 Acoustic Devices 和 A/D & D/A模示。测试架构参考送话频率响应测试且必须在40dBA以上的隔音环境。但在测试过程中关闭人工嘴，同时测量在DAI 上的噪声量相对0dBmp 为参考。 规格: Idle Channel Sending Noise < 64 dBmp。

10.2 Receiving（静态接收杂音 ） 目的: 主要测量电话机在静态时所听到的杂音量。 测试方法: 将待测电话机的受话器控制音量设定在正常的位置DAI 设定在 Acoustic Devices 和 A/D & D/A模示。测试架构参考受话频率响应测试且必须在40dBA以上的隔音环境。但在测试过程中关闭人工嘴及DAI 到受话器讯号，同时测量在受话器上的噪声量相对0dBpa为参考。 规格: Idle Channel Receiving Noise a. Normal Volume < -57 dBPa(A)。 b. Max. Volume < -54 dBPa(A)。