Quectel GSM Series Audio Design Manual
  1. Manuals
  2. Brands
  3. Quectel Manuals
  4. Control Unit
  5. GSM Series
  6. Audio design manual

Quectel GSM Series Audio Design Manual

Hide thumbs
Table of Contents

Advertisement

Quick Links

Download this manual
GSM
Module
Audio Design Guide
GSM/GPRS Series
Version: GSM_Module _Audio_Design_Guide_V3.0
Date: 2013-05-24
www.quectel.com

Advertisement

Table of Contents
loading
Need help?

Need help?

Do you have a question about the GSM Series and is the answer not in the manual?

Questions and answers

Related Manuals for Quectel GSM Series

Summary of Contents for Quectel GSM Series

  • Page 1 Module Audio Design Guide GSM/GPRS Series Version: GSM_Module _Audio_Design_Guide_V3.0 Date: 2013-05-24 www.quectel.com...
  • Page 2 QUECTEL OFFERS THIS INFORMATION AS A SERVICE TO ITS CUSTOMERS. THE INFORMATION PROVIDED IS BASED UPON CUSTOMERS’ REQUIREMENTS. QUECTEL MAKES EVERY EFFORT TO ENSURE THE QUALITY OF THE INFORMATION IT MAKES AVAILABLE. QUECTEL DOES NOT MAKE ANY WARRANTY AS TO THE INFORMATION CONTAINED HEREIN, AND DOES NOT ACCEPT ANY LIABILITY FOR ANY INJURY, LOSS OR DAMAGE OF ANY KIND INCURRED BY USE OF OR RELIANCE UPON THE INFORMATION.

  • Page 3: About The Document

    GSM/GPRS Modules GSM Module Audio Design Guide About the document History Revision Date Author Description 2009-11-02 Tracy Zhang Initial version 1. Added some acronym. 2. Added a Audio Power Amplitude manufacturer. 2009-11-20 Tracy Zhang 3. Added a solution to TDD noise. 4.

  • Page 4: Table Of Contents

    GSM/GPRS Modules GSM Module Audio Design Guide Contents About the document ........................... 2 Contents ............................... 3 Table Index ..............................5 Figure Index ..............................6 Introduction ............................7 1.1. Summary ............................7 1.2. Safety Information ........................7 Audio Circuit Design ........................... 9 2.1.
  • Page 5 GSM/GPRS Modules GSM Module Audio Design Guide Appendix A ............................35 GSM Module Audo Design Guide Confidential/Release 4 / 35...
  • Page 6 GSM/GPRS Modules GSM Module Audio Design Guide Table Index TABLE 1： AUDIO HARDWARE CONFIGURATION ..................9 TABLE 2： REFERENCE DOCUMENT ......................35 TABLE 3： DESCRIPTION OF ECHO AND TDD NOISE ................35 GSM Module Audo Design Guide Confidential/Release 5 / 35...
  • Page 7 GSM/GPRS Modules GSM Module Audio Design Guide Figure Index FIGURE 1：MICROPHONE REFERENCE CIRCUIT FOR AIN1&AIN2 ............10 FIGURE 2: RECEIVER REFERENCE CIRCUIT FOR AOUT1 ................11 FIGURE 3: RECEIVER REFERENCE CIRCUIT WITH AUDIO POWER AMPLIFIER FOR AOUT1 ....11 FIGURE 4：SPK REFERENCE CIRCUIT FOR AOUT2 ................... 12 FIGURE 5：RECEIVER REFERENCE CIRCUIT WITH AUDIO POWER AMPLIFIER FOR AOUT2 ....

  • Page 8: Introduction

    If not so, Quectel does not take on any liability for customer failure to comply with these precautions.
  • Page 9 GSM/GPRS Modules GSM Module Audio Design Guide GSM cellular terminals or mobiles operate over radio frequency signal and cellular network and cannot be guaranteed to connect in all conditions, for example no mobile fee or an invalid SIM card. While you are in this condition and need emergent help, please remember using emergency call.

  • Page 10: Audio Circuit Design

    GSM/GPRS Modules GSM Module Audio Design Guide Audio Circuit Design M1x and M95 have two hardware audio channels except M80. Three audio channels are defined in software. AT+QAUDCH is used to read and set the software audio channel. This chapter provides audio interface circuit and some solutions to resolve TDD noise and ECHO issues.

  • Page 11: Audio Circuit Reference

    GSM/GPRS Modules GSM Module Audio Design Guide 2.1. Audio Circuit Reference 2.1.1. M1x 2.1.1.1. Microphone Reference Circuit M1x module provides electrets-microphone bias voltage for AIN1 and AIN2. Microphone reference circuit is shown as below: Close to Microphone Differential layout 10pF 33pF Module Electret...

  • Page 12: Receiver Reference Circuit

    GSM/GPRS Modules GSM Module Audio Design Guide 2.1.1.2. Receiver Reference Circuit Close to speaker Differential layout 33pF Module 10pF SPK1P 10pF 33pF SPK1N 10pF 33pF Figure 2: Receiver Reference Circuit for AOUT1 Close to speaker Differential layout Amplifier 33pF 10pF circuit Module SPK1P...
  • Page 13 GSM/GPRS Modules GSM Module Audio Design Guide Close to speaker Differential layout 33pF 10pF Module 22uF SPK2P AGND Figure 4：SPK Reference Circuit for AOUT2 Close to speaker Differential layout Amplifier 33pF 10pF Module circuit SPK2P AGND 33pF 10pF Figure 5：Receiver Reference Circuit with Audio Power Amplifier for AOUT2 Note For the value of C1 and C2, please refer to input impedance of audio power amplifier.

  • Page 14: Headset Reference Circuit

    GSM/GPRS Modules GSM Module Audio Design Guide 2.1.1.3. Headset Reference Circuit Close to Socket Differential layout 4.7uF 10pF 33pF MIC2N Module MIC2P 22uF SPK2P 10pF 33pF Amphenol 9001-8905- AGND AGND Figure 6：Headset Reference Circuit 2.1.2. M95 2.1.3. Microphone Reference Circuit M95 module provides electrets-microphone bias voltage for AIN1 and AIN2.

  • Page 15: Receiver Reference Circuit

    GSM/GPRS Modules GSM Module Audio Design Guide 2.1.3.1. Receiver Reference circuit Close to Receiver Differential layout 10pF 33pF Module SPK1P 33pF 10pF SPK1N 10pF 33pF Figure 8：Receiver Reference Circuit for AOUT1 2.1.3.2. Headset Reference Circuit Close to Module Close to Socket Differential 33pF 4.7uF...

  • Page 16: Spk Reference Circuit

    GSM/GPRS Modules GSM Module Audio Design Guide 2.1.3.3. SPK Reference Circuit Close to Speaker Differential layout 10pF 33pF Module LOUDSPKP 10pF 33pF LOUDSPKN 8 ohm 33pF 10pF Figure 10：SPK Reference Circuit GSM Module Audo Design Guide Confidential/Release 15 / 35...

  • Page 17: M80

    GSM/GPRS Modules GSM Module Audio Design Guide 2.1.4. M80 2.1.4.1. Microphone Reference Circuit M80 provides electrets-microphone bias voltage for AIN1 and AIN2. Reference circuit for microphone is illustrated as following figure. Close to Microphone Differential layout 10pF 33pF Module MICxP Electret 10pF 33pF...
  • Page 18 GSM/GPRS Modules GSM Module Audio Design Guide Close to speaker Differential layout 33pF 10pF Module 22uF SPK2P AGND Figure 13：SPK Reference Circuit for AOUT2 Close to speaker Differential layout Amplifier 33pF 10pF circuit Module SPK2P AGND 33pF 10pF Figure 14：SPK Reference Circuit with audio power amplifier for AOUT2 Note TPA6205A1 from TEXAS INSTRUMENTS is recommended, which is a audio power amplifier device and can driver a 8Ω...

  • Page 19: Headset Reference Circuit

    GSM/GPRS Modules GSM Module Audio Design Guide 2.1.4.3. Headset Reference Circuit Close to Socket Differential layout 4.7uF 33pF 33pF MIC2N Module MIC2P 22uF SPK2P 33pF 10pF Amphenol 9001-8905-050 AGND AGND Figure 15：Headset Reference Circuit 2.1.4.4. SPK Reference Circuit Close to speaker Differential layout 10pF 33pF...

  • Page 20: Ringtone

    GSM/GPRS Modules GSM Module Audio Design Guide Notes 1. Capacitors have to place close to audio component or audio interface and layout must be short. 2. Antenna interface must be stay away from audio components and layout of audio circuit. Layout of power supply must be stay away from audio and cannot be parallel.

  • Page 21: Hands-Free Application At Channel Ain1/Aout1

    GSM/GPRS Modules GSM Module Audio Design Guide AT+QAUDCH=0, ringtone will output via AOUT1) 2.3. Hands-free Application at Channel AIN1/AOUT1 Channel AIN1/AOUT1 could be used as hands-free function, because input audio signal is differential circuit and it is a good way to suppress common-mode noise. SPK circuit is recommended as following: R313 100K...

  • Page 22: Suggestion For Audio Layout

    GSM/GPRS Modules GSM Module Audio Design Guide 2.4. Suggestion for Audio Layout Power supply ripple, unbalanced ground and RF burst radiation have negative effect to audio layout. Layout of MIC1P/MIC1N, SPK1P/SPK1N must meet the rule of differential signal. Moreover, these two pairs of signals should be separated from each other by flooding ground to avoid echo issue from SPK signal to MIC signal.

  • Page 23: Suggestion For Mechanical Design

    GSM/GPRS Modules GSM Module Audio Design Guide Reduce power voltage ripple, especially the power supply in audio circuits. A wide layout is used from power source (like adapter interface, battery connector, or LDO output pin) to audio power supply. Good antenna matching is also important to reduce power ripple. The filtering capacitors and ESD protection devices should be connected to main digital ground, and other audio components should use AGND from the module interface.
  • Page 24 GSM/GPRS Modules GSM Module Audio Design Guide In these five paths, internal air-path and direct air-path are the first influential factors. Other three factors (vibrations through casework, vibrations through PCB, distant echoes) are secondary. How to deal with echo issue from internal air-path: Separating microphone from internal space of chassis by foam or rubber ring can effectively suppress the inner echo interference.
  • Page 25 GSM/GPRS Modules GSM Module Audio Design Guide Figure 21 shows recommended design for speaker socket. Figure 21：Speaker socket design A good way to suppress the internal echo path is to seal the rear cavity of receiver, which is usually expensive. The rear cavity of receiver and speaker is important for good voice quality. A sealed rear cavity with sufficient space could produce a good voice output.

  • Page 26: Component Of Spk

    GSM/GPRS Modules GSM Module Audio Design Guide 2.7. Component of SPK A SPK and receiver with higher sensitivity, flatter frequency response, less THD and impedance of 32Ω(receiver), 16Ω(receiver) or 8Ω(speaker) is recommended. These technical data are often shown in data sheet of SPK and receiver. For SPK, its frequency response and THD performance can be tested by speaker test system.

  • Page 27: Component Of Microphone

    GSM/GPRS Modules GSM Module Audio Design Guide Figure 23：SPK THD Note Horizontal axis is frequency, longitudinal axis is distortion and unit is % Figure 23, the three colors represent three venders’ products. After comprehensive comparison, the green one performs the best, and the blue one is second, and the red one is the worst. 2.8.

  • Page 28: Description And Suggestion

    GSM/GPRS Modules GSM Module Audio Design Guide Description and Suggestion M1x, M95 has two audio channels in hardware, named AIN1/AOUT1 and AIN2/AOUT2. Three channels are defined in software, named channel 0, channel 1 and channel 2. Software channel 0 is applied in hardware channel AIN1/AOUT1, software channel 1 and channel 2 are applied as hardware channel AIN2/AOUT2.

  • Page 29: How To Modify Volume

    GSM/GPRS Modules GSM Module Audio Design Guide Reference Parameter <n> Normal audio channel (default) Headset audio channel Loudspeaker audio channel 3.1.2. How to Modify Volume 3.1.2.1. AT+QMIC AT+QMIC is used to modify the analog gain of microphone. It can increase or reduce the gain of microphone.

  • Page 30: At+Clvl

    GSM/GPRS Modules GSM Module Audio Design Guide <gain-level> Range is 0 - 15 3.1.2.2. AT+CLVL AT+CLVL is used to modify the analog gain of receiver. It can increase or reduce loudness of downlink speech. AT+CLVL Test Command Response AT+CLVL=? +CLVL: (list of supported <level>s) Read Command Response AT+CLVL?

  • Page 31: At+Qsidet

    GSM/GPRS Modules GSM Module Audio Design Guide 3.1.2.3. AT+QSIDET AT+QSIDET is used to adjust the side tone gain. AT+QSIDET Test Command Response AT+QSIDET=? +QSIDET: (list of supported <gainlevel>s) Read Command Response AT+QSIDET? +QSIDET(NORMAL_AUDIO): <gainlevel> +QSIDET(HEADSET_AUDIO): <gainlevel> Write Command Response AT+QSIDET=<gainlevel> If error is related to ME functionality: +CME ERROR: <err>...

  • Page 32: Echo Algorithm

    GSM/GPRS Modules GSM Module Audio Design Guide 3.1.3. Echo Algorithm AT+QAPS is used to modify echo algorithm parameters of all three software audio channels. AT+QAPS Set Command Response AT+QAPS=<mode>,<type>,<channel> +QAPS: <op>,<para1>[,<para2>[,<para3>]][,<setting>] ,<setting> Set Command Response If <op> is read, AT+QAPS=<op>,<para1>[,<para2>[,< para3>]][,<setting>] +QAPS:<result list>...
  • Page 33 GSM/GPRS Modules GSM Module Audio Design Guide When para1=0/1, para3 is a must and 10 elements consist one batch. <setting> List of integers, with dot (“.”) separated. Note <setting> Par0： （AEC）Acoustic echo control NLP control word Par1： （AEC）AEC control word Par2：...

  • Page 34: Description Of Par0, Par2 And Par12

    AT+QAPS=1,4,2, "254.224.3208.31.57351.24607.400.132.80.4325.99.0.16392.0.0.0" Note Quectel module has configured default parameters in software. For some special applications, such as AIN1/AOUT1 being applied in hands-free, or echo issue caused by bad circuits or mechanical structure. Some of parameters can be modified to fix echo issue. Advices of audio parameters in different application are provided in the next section.

  • Page 35: Recommended Application Field

    GSM/GPRS Modules GSM Module Audio Design Guide 3.1.3.2. Recommended Application Field There are some recommended parameters when module works in voice or DTMF application, shown as below: Voice AT+QAPS=1,4,0,"96.253.10756.31.57351.31.400.0.80.4325.99.0.20488.0.0.8192" AT+QAPS=1,4,0,"128.253.10756.31.57351.31.400.0.80.4325.99.0.16392.0.0.8192" AT+QAPS=1,4,0,"192.253.10756.31.57351.31.400.0.80.4325.99.0.16392.0.0.8192" AT+QAPS=1,4,0,"192.253.10756.31.57351.31.400.0.80.4325.99.0.8223.0.0.8192" AT+QAPS=1,4,0,"192.253.5256.31.57351.31.400.0.80.4325.99.0.8223.0.0.8192" AT+QAPS=1,4,0,"192.253.2218.31.57351.31.400.0.80.4325.99.0.8223.0.0.8192" AT+QAPS=1,4,0,"248.253.2218.31.57351.31.400.0.80.4325.99.0.8223.0.0.8192" DTMF AT+QAPS=1,4,2,"128.224.2218.31.57351.24607.400.132.80.4325.99.0.8223.0.0.0" AT+QAPS=1,4,2,"192.224.750.31.57351.24607.400.132.80.4325.99.0.2079.0.0.0" AT+QAPS=1,4,2,"224.224.511.31.57351.24607.400.132.80.4325.99.0.513.0.0.0" AT+QAPS=1,4,2,"128.253.2218.31.57351.24607.400.132.80.4325.99.0.8223.0.0.0" AT+QAPS=1,4,2,"192.253.750.31.57351.24607.400.132.80.4325.99.0.2079.0.0.0"...
  • Page 36 GSM/GPRS Modules GSM Module Audio Design Guide Appendix A Table 2： Reference Document Name Remark M1x_AT_Commands_Manual AT Commands Manual Mxx_Hardware_Design Hardware Design Table 3： Description of ECHO and TDD noise Noun Explanation Talking quality can be obviously affected when echo problem is present. Description of ECHO issue: The far end could hear its own voice from the module side (the near end) in talking.

This manual is also suitable for:

Gprs seriesM1xM95M80

Table of Contents