ITU-T P.1140标准：车载紧急呼叫语音通信规范

音频测试

需积分: 47 145 浏览量更新于2024-07-15 2 收藏 1.93MB PDF 举报

身份认证购VIP最低享 7 折!

领优惠券(最高得80元）

"ITU-T P.1140标准主要关注汽车紧急呼叫系统中的语音通信质量，旨在确保在车辆内部进行的免提紧急呼叫时达到理想的通信效果。该标准由国际电信联盟(ITU)的电信标准化部门发布，适用于2017年3月及之后的相关测试与实施。该文档详细阐述了车载紧急呼叫系统（eCall）的语音通信要求，以满足车舱内通话的特殊需求，确保在紧急情况下能够快速、清晰地进行通信。在P.1140推荐中，涉及到的关键知识点包括： 1. **汽车紧急呼叫系统(eCall)**：eCall是一种自动或手动触发的车载系统，当发生交通事故时，它能自动或由乘客操作向紧急服务中心发送包含位置信息的报警信号，以加快救援响应时间。 2. **音频测试**：为了确保eCall系统的语音通信质量，需要进行一系列的音频性能测试。这些测试可能包括音频带宽、信噪比、回声消除、延迟、失真和互调失真等参数的评估。 3. **ITU-T系列标准**：P.1140是ITU-T一系列关于电话传输质量、电话安装和本地线路网络的标准之一。这些标准构成了通信质量评估的综合框架，如P.10关于语音终端特性，P.30关于参考系统，P.40关于客观测量设备，P.50关于电声学的客观测量，P.60关于与语音响度相关的测量，P.70和P.80关于客观和主观的语音质量评估，P.900关于IP端点的传输性能和QoS方面，以及P.1000关于多媒体服务的音视频质量。 4. **传输参数对客户感知的影响**：P.1140考虑了传输参数如何影响用户对通信质量的感知，比如语音清晰度、稳定性、延迟和丢包率等。 5. **主观与客观评估方法**：标准涵盖了使用客观和主观评估方法来确定语音通信质量的方法，包括P.800系列中对多媒体服务的音视频质量的评估。 6. **紧急呼叫中的通信质量**：在紧急呼叫场景下，通信质量尤为重要，因为清晰、及时的信息传递可能直接影响到事故处理和生命安全。 7. **合规性测试**：制造商和开发者需要遵循P.1140的标准，以确保其车载紧急呼叫系统符合法规要求，能够通过各种实际和实验室环境下的测试。 ITU-T P.1140标准对于汽车电子、通信技术、交通安全以及相关法规制定者和测试机构都具有重要的指导意义，它为车载紧急呼叫系统的语音通信设定了标准，以确保在紧急情况下的有效沟通。

资源详情

资源推荐

Rec. ITU-T P.1140 (03/2017) 5

NR Noise Reduction

PCM Pulse Code Modulation

PN Pseudorandom Noise

POI Point Of Interconnection

PSAP Public Safety Answering Point

QoS Quality of Service

RF Radio Frequency

RLR Receive Loudness Rating

RLR

min

minimum Receive Loudness Rating, achieved with background noise

SLR Send Loudness Rating

S/N Signal-to-Noise ratio

TCL Terminal Coupling Loss

TCLw weighted Terminal Coupling Loss

Access-specific delay (round trip)

asr

Access-specific delay in receive

ass

Access-specific delay in send

imps

Implementation dependent send delay IVS

impr

Implementation dependent receive delay IVS

Receive delay IVS

r,S

Built-up time (send direction)

rtd

Round trip delay IVS

rtdimp

Implementation dependent round trip delay IVS

Send delay IVS

5 Conventions

dBm: Absolute power level relative to 1 milliwatt, expressed in dB.

dBm0: Absolute power level in dBm referred to a point of zero relative level (0 dBr

point).

dBm0p: Weighted dBm0, according to [b-ITU-T O.41].

dBm0(C): C-weighted dBm0, according to [b-ISO 1999].

dBPa: Sound pressure level relative to 1 Pa, expressed in dB.

dBPa(A): A-weighted sound pressure level relative to 1 Pa, expressed in dB.

dBSPL: Sound pressure level relative to 20 µPa, expressed in dB; (94 dBSPL = 0 dBPa).

dBV(P): P-weighted voltage relative to 1 V, expressed in dB, according to [b-ITU-T O.41].

dBr: Relative power level of a signal in a transmission path referred to the level at a

reference point on the path (0 dBr point).

Vrms: Voltage – root mean square.

6 Rec. ITU-T P.1140 (03/2017)

6 Test set-up and preparation

6.1 Test arrangement

The acoustical interface for the in-vehicle system (IVS) is realized by using an artificial head

or head and torso simulator (HATS) according to [ITU-T P.58]. The properties of the artificial head

shall conform to [ITU-T P.58] for send as well as for receive acoustical signals.

All IVS emergency call implementations are connected to a system simulator conforming to the

required transmission standard with an implemented, calibrated audio interface.

For narrowband mode in GSM networks, the full rate (FR) codec or adaptive multi-rate (AMR)

codec can be used. If the AMR codec is used, the bitrate of 12.2 kbit/s is used.

The settings of the system simulator shall be chosen so that the audio signal is not influenced by any

signal processing (e.g., DTX).

The test signals are fed electrically to the system simulator or acoustically to the artificial head.

The test arrangement is shown in Figure 6-1.

P.1140(15)_F6-1

4-wire

Test system

Air interface

POI

(Electrical interface)

System simulator

Speech

transcoder

Speech

transcoder

RF-interfaceRF-interface

Hands-free

signal

processing

IVS

Figure 6-1 – Test arrangement for emergency call IVS (see [ITU-T P.1100])

6.2 Test arrangement in a car

The transmission performance of car hands-free terminals is measured in a car cabin. In order to

simulate a realistic driving situation, background noise is inserted using a four-loudspeaker

arrangement with subwoofer, while measurements with background noise are conducted.

In Figure 6-2 the simulation arrangement is shown. More information on the test arrangement can

be found in [b-ETSI ES 202 396-1]. The source signal used is recorded by a measurement

microphone positioned close to the hands-free microphone. If possible, the output signal of the

hands-free microphone can be used directly. The recordings are conducted in a real car. The

loudspeaker arrangement is equalized and calibrated so that the power density spectrum measured

at the microphone position is equal to the recorded one. For equalization, either the measurement

microphone or the hands-free microphone used for recording is used. The maximum deviation of

the A-weighted sound pressure level shall be 1 dB. The third octave power density spectrum

between 100 Hz and 10 kHz shall not deviate more than 3 dB from the original spectrum. A

detailed description of the equalization procedure can be found in [b-ETSI ES 202 396-1].

For microphone arrays, distributed microphones or directional microphones a more sophisticated

background noise simulation technology is recommended. This method is based on a sound-field

simulation technique described in [b-ETSI TS 103 224]. Using this technology a more accurate

equalization can be performed and the sound-field generated can be reproduced correctly in

magnitude and phase up to a frequency of 2-3 kHz. A detailed description on the application of the

Rec. ITU-T P.1140 (03/2017) 7

method can be found in Annex B. The background noise playback system is time-synchronized to

the recording process in the measurement system in order to guarantee reproducibility of recordings

in the presence of noise.

P.1140(15)_F6-2

Background

noise (BGN)

System

simulator

Measurement

system

Subwoofer

IVS

(HF)

Left

Right

Front

Rear

Loudspeaker

equalization

BGN playback

synchronization

Left

Right

Figure 6-2 – Test arrangement with background noise simulation

6.3 Positioning of the emergency call IVS

The IVS, especially the acoustical interfaces (microphone/loudspeaker), are installed according to

the requirements of the manufacturer. The positioning of the microphone/microphone array and

loudspeaker are given by the manufacturer (e.g., also for aftermarket solutions) or defined by the

installation in the vehicle. If no position requirements are given, the test laboratory will define the

arrangements. The exact positioning has to be documented. IVS terminals installed by car

manufacturers are measured in the original arrangement.

If not stated otherwise the measurements are conducted with the HATS placed at the driver's

position. For manually generated emergency calls it is assumed that the driver is communicating

over the IVS with the public safety answering point (PSAP). Thus, a normal diver position is

assumed and reproduced by the HATS during tests positioned in the driver's seat for the

measurement, if not stated otherwise. For testing automatically generated emergency calls

additional positions, the co-driver's and the two outer passengers' back seat (2nd row), if available,

are used as described in the individual test cases.

The driver's position has to be in line with the average user's position; therefore, all positions and

sizes of users have to be taken into account. Typically, all except the tallest 5% and the shortest 5%

of the driving population have to be considered. Detailed information can be found in [b-SAE

J941]. The size of these persons can be derived, e.g., from the "anthropometric data set" for the

剩余63页未读，继续阅读

DarcySun

粉丝: 1
资源: 12

ITU-T P.1140标准：车载紧急呼叫语音通信规范

ITU-T 标准

06 ITU-T P.862 语音质量测试标准.pdf

ITU-R BT.1120-7 建议书 高清晰度电视演播室信号数字接口

ITU-T H.225.0：包基多媒体通信系统的呼叫信令与媒体流封装

ITU-T T.38：2007版传真通信协议

ITU-T P.862.3 中文解析：语音质量客观测量指南

ITU-T P.910：多媒体应用主观视频质量评估方法

itu-t g.165

make menuconifg中的 -*- CRC ITU-T V.41 functions 介 绍

ITU-T F.735.1

itu-r p.528-4

itu-t g.9807. 1

我没在最新版的ITU-T G.984.3的第8.2.1.3节中找到这段说明，你是参考哪一版的协议，请给出出处

itu-t g.993.2 (vdsl2)

itu-t k.21中文版

itu-t g.7041/y.1303

itu-t g.8260

itu-t g.8262

itu-r s.580-6 中文

最新资源

ITU-R BT.1120-7 建议书高清晰度电视演播室信号数字接口

make menuconifg中的 -*- CRC ITU-T V.41 functions 介绍