标准测试之-ITU-T P.1110
概述
车内免提系统的集成是一个充满挑战的话题。麦克风和扬声器的布置，各种背景噪声的情况，以及由RF引起的问题，都显著影响语音质量。VoiceX实验室采用全自动测试系统，实现ITU-T P.1110指定的宽带测试，测试主要关注于：
- 标准的电话测量要求，如单向通话下的频率响应和响度
- 单讲及双讲通话下的回声性能和信号幅值变化
- 背景噪声传输质量
Frequency Response Idle Channel Noise Check for Spec. Peaks 50ms
Echo Attenuation during DT Comfort Noise: Spectral Adjustment
测试结果实例
P.1110可供汽车行业的制造商和供应商用于测试和优化完整的免提系统及其子系统（麦克风、扬声器、耳机以及用于与移动网络互连的、具有短距离无线传输链路的电话），例如：
- 内置免提系统
- 售后免提车载套件
- 有线耳机
- 无线耳机
测试布置
ITU-T P.1110是国际电信联盟（ITU）提出的车内宽带语音免提通信质量测试方法和要求。采用测试系统和人工头等设备用于车内免提通讯的自动化测试，实现自动分析及免提系统的优化。
P.1110规定了通话测试的一系列标准值，例如接收及发送方向的响度等级、空闲信道噪声、带外信号抑制、回声衰减及最小激活信号等。另外，P.1110考虑了其他几个重要的方面：
车舱内测试示意图
- 依据适用车型，在车辆对应原始位置安装免提终端。或在车舱内进行测试，还原车辆内部的典型声学特性。
- 分别在安静场及噪声场进行测试。模拟目标车辆的真实驾驶声学环境，综合考虑了车辆行驶速度、发动机和车身等的影响。
- 采用人工头模拟免提终端的使用者进行测试。
- 主要关注对话参数如双讲性能及背景噪声传输质量。
- 附加目标手机的蓝牙传输测试。
这其中的一些测试基于第三代移动电话的当前标准，如3GPP，另外一部分基于听觉测试。
应用
- 免提终端语音质量自动化分析
- 车载免提终端的声质量的测试及优化
- 车内免提麦克风和扬声器的优化定位。
- 手机的蓝牙测量
车载免提终端测试
测试信号
- 符合ITU-T P.501的真人语音信号
- CSS信号（复合源信号）
- 人工语音
- 激活序列
- 指定噪声序列
- 语音序列
- 用于回声测量的AM/FM调制正弦信号
- 背景噪声
测试项
下表给出P.1110测试项
SMD Title for Wideband Test
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10.01.1 Microphone Sensivity 1kHz |
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10.01.2 Microphone Frequency Response |
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10.01.3 Microphone Front to Back Ratio, high/low Sens. |
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10.01.4 Microphone Distortion |
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10.01.5 Maximum Sound Pressure Level |
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10.01.6 Self Noise |
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10.02.1 Microphone Output Level in the Car |
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10.02.2 Overload Point |
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10.02.3 Microphone Frequency Response AV/CSS |
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10.02.4 Idle Channel Noise |
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10.02.5 SNR Improvement |
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11.02.1 Delay SND HFT Unit & with/without Equipment |
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11.02.2 Delay RCV HFT Unit & with/without Equipment |
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11.03.2 Sending Loudness Rating |
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11.03.3 Binaural RLR nominal/maximum volume |
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11.03.4 Variation of Loudness Rating Sending |
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11.03.5 Variation of Loudness Rating Receiving |
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11.04.1 Frequency Response Sending |
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11.04.2 Frequency Response Receiving |
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11.05.1 One Way Speech Quality Sending |
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11.05.2 One Way Speech Quality Receiving |
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11.06.1 Check Listening Quality Stability Sending |
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11.06.1 Check Listening Quality Stability Receiving |
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11.07.1 Idle Channel Noise Sending |
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11.07.2 Idle Channel Noise Receiving |
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11.08.1 Out of Band Signal Sending |
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11.08.2 Out of Band Signal Receiving |
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11.09 Distortion in Sending |
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11.10 Distortion in Receiving |
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11.11.1 Terminal Coupling Loss nominal/maximum Volume |
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11.11.2 Echo Level vs. Time |
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11.11.3 Spectral Echo Attenuation |
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11.11.4 Initial Convergence |
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11.11.5 Initial Convergence BGN |
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11.11.6 Echo Performance Time Variant CSS |
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11.11.7 Echo Performance Time Variant P.50 |
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11.11.8 Activatio ttenuation Range |
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11.12.1 Attenuation Range DT Sending |
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11.12.2 Attenuation Range DT Receiving |
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11.12.3 Echo Attenuation during Double Talk |
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11.12.4 Detect Sent Speech Attenuation DT |
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11.13.2 Background Noise Transmission after Call Setup |
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11.13.3 Speech Quality in the Presence of BGN |
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11.13.4 BGN Transmission with Far End Speech |
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11.13.5 BGN Transmission with Near End Speech |
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11.13.6 Comfort Noise Level/Spectral Adjustment |
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12.01.1 Delay SND with/without Equipment |
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12.01.2 Delay RCV with/without Equipment |
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12.02.2 Junction Loudness Rating Sending |
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12.02.3 Junction Loudness Rating Receiving |
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12.02.4 Linearity in Sending |
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12.02.5 Linearity in Receiving |
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12.03.1 Sending Sensivity Frequency Response |
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12.03.2 Receiving Sensivity Frequency Response |
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12.04 Noise Cancellation Sending |
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12.05.1 One Way Speech Quality in SND POLQA |
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12.05.2 Speech Quality Stability in SND |
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12.05.3 One Way Speech Quality in RCV POLQA |
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12.05.4 Speech Quality Stability in SND |
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12.05.5 Verification of Disabled Echo Control |
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U ‐ Junction Loudness Rating RCV Volume Control |
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U ‐ Junction Loudness Rating RCV/SND P.50 |
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U ‐ One Way Speech Quality RCV/SND PESQ |
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U ‐ AGC Test SND/RCV |
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U ‐ Switched Level SND/RCV |
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U ‐ Variation of Echo Loss [P.50] |
