1 Introduction
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According to the "2005 Guangzhou Traffic Development Annual Report" published by Guangzhou City, the number of motor vehicles in Guangzhou was 1.774 million in 2005; according to the "Legal Evening News", the number of motor vehicles in Beijing could exceed 3 million in May 2006. . The Olympic Games will exceed 3.3 million units; according to a group of data released by the GSM Association in 2006, the number of GSM mobile phone users exceeds 2 billion, the largest in the Chinese market. The above three different sets of data show that more and more people are driving a motor vehicle and communicating with the outside world via a GSM terminal.
At this stage, many motor vehicles are equipped with vehicle terminals. It is mainly used for car navigation, vehicle scheduling, vehicle monitoring and so on. Many terminal devices rely on manual operation of the display terminal, such as the driver to view important short messages sent by the vehicle dispatch center or friends. View maps of navigation terminals, etc. This will result in the driver not being able to concentrate while driving, and its direct consequences may lead to serious traffic accidents.
Voice communication is the most natural way of communication for human beings. If many operations of the vehicle terminal can be replaced by real-time voice, it will help reduce the incidence of traffic accidents. For example, the GSM Modem receives a short message and the driver does not have to manually view it. The speech synthesis system can be automatically broadcasted; the direction and road name of the driver can be prompted in real time; the traffic condition can be broadcasted in real time. Let the driver know the current traffic situation, and understand the real-time information of road traffic congestion, so as to avoid congested road sections and reach destinations faster. The in-vehicle terminal with voice function can improve the intelligence of the vehicle terminal, the safety and comfort of the vehicle driving, and make the user more convenient and more user-friendly.
2 speech synthesis and GSM M0dem
2.1 Speech synthesis technology
Speech synthesis technology is a technique that artificially generates phonemes, syllables, words, and sentences according to predetermined programs and instructions using a computer, an intelligent system, and the like.
At present, speech synthesis technology has been developed to convert any text into a continuously understandable natural statement output in real time. The corresponding technology is usually called text synthesis, or text to speech (TTS), which involves acoustics and language. Learning, voice digital signal processing technology, multimedia technology and many other disciplines. The principle of syntactic synthesis: According to the results of prosodic modeling, the corresponding speech primitives are extracted from the original speech library, and the prosody characteristics of the speech primitives are adjusted and modified by using specific speech synthesis techniques, and finally the actual speech is synthesized. .
2.2 Speech Synthesis Module
This design uses a high-end Chinese speech synthesis module XF-S4240 developed by Anhui Zhongke Daxun Information Technology Co., Ltd. The module can receive the text to be synthesized through the UART, SPI and 12C interfaces, and directly synthesize it into a voice out (Line out).
This module is used. InterSound4.0 KT system as a module core, a lightweight Chinese continuous speech synthesis system.
The features of the XF-S4240 module are as follows: Support for the synthesis of any Chinese text. Supports the synthesis of English letters. It is pronounced alphabetically when encountering English words; supports four internal code formats: GB2312 (Simplified Chinese encoding), GBK (National Standard Extended Encoding), Unicode (character encoding), Big5 (Traditional Chinese encoding) With dual speakers: male voice, female voice; intelligent text analysis processing algorithm, can correctly identify and process numerical values, numbers, time and date and some commonly used weights and measures symbols, with strong multi-tone processing and Chinese surname processing ability; support software Adjust speech rate, intonation, volume, etc. 2.3 GSM Modem
GSM Modem is a very important terminal device for GSM mobile communication systems after GSM mobile phones. As a main GSM network access device, GSM Modem is a kind of data terminal equipment combined with traditional modem and GSM wireless mobile communication system, so it is also called wireless modem. Its emergence opened the door to GSM network data communication and its applications. This design uses the third generation GSM dual-band ModemTC35i produced by Siemens. This module can be widely used in POS terminals, handheld devices, mobile computers, wireless phones, traffic control and navigation systems, rapid management security systems, remote monitoring, remote copying. Tables, vending machines and other systems.
3 hardware design of the vehicle terminal
The system hardware is based on the ARM7 series Smart ARM2200 embedded platform of Guangzhou Zhou Ligong MCU Development Co., Ltd. The main controller of the platform adopts the 16/32-bit ARM7TDMI-S microcontroller IPC2210 produced by Philips. It has rich external interfaces such as industry standard UART, high speed I2C interface (400 kb/s), SPI interface, A/. D conversion interface, etc., can be easily interconnected with other peripherals.
The underlying software of the system uses the μCliunx kernel, which is a Linux system designed for the micro-control field and is suitable for microcontrollers without a memory management unit (MMU).
The XF-S4240 module communicates with other end devices via the UART, SPI and I2C interfaces. The system design uses the I2C interface of the SmartARM2200 embedded platform to communicate with the 12C interface of the XF-S4240. The XF-S4240 is set as the slave device, the default address is 0x80, and the Smart ARM2200 is set as the master device. The GSM Modem is connected to the universal serial port 2 of the SmartARM2200 embedded system via a standard UART port.
4 software design
4.1 Communication protocol for voice module synthesis
Regardless of whether the XF-S4240 is connected to other intelligent systems using UART, SPI or I2C, the upper layer communication protocol of the speech synthesis module is the same. The control commands for speech synthesis will be introduced below.
All commands and data sent to the XF-S4240 are encapsulated and transmitted in a "frame" manner.
The length of the frame header is one byte, which is defined as hexadecimal "0xFD"; the length of the data area occupies two bytes, the high byte is first and the low byte is after. The length of the data area is variable, but must be less than 1,024 bytes. The data area contains command words, command parameters, and synthesized voice information.
The meaning of this frame: 0xFD indicates the frame header, and 0x00 0x0A indicates that the data area length is 10 bytes. 0x01 indicates the speech synthesis command, 0x00 indicates that the text format is GB2312, and the remaining hexadecimal code is the GB2312 code of Zhongshan University [3].
4.2 TC35i GSM Modem Communication Protocol
The TC35i GSM Modem communicates with other terminals using a universal serial interface, and the communication protocol uses the AT command set. This design mainly reads the short message of GSM Modem. The specifications related to short message transmission mainly include GSM 03.38, GSM 03.40 and GSM07.05. The first two focus on the implementation of the SMS technology (encoding method), which specifies the DTE-DCE interface standard (AT command set) of the SMS. The AT command starts with AT. For example, AT+CMGL=0 (GSM 07.05 version) indicates that the latest received short message is read, and AT+CMGC indicates that a short message is sent.
There are 3 receiving and sending modes for short messages: Block Mode, Text Mode and PDU Mode. The PDU mode is the most commonly used and supports all phones, and any character set can be used. The following is an ASCII string in PDU mode. The short message center number (SMSC) is +8613800200500 and the sender number is 13826468897. The message content is "Sun Yat-sen University", and the "PDU string" by reading it is: " 08 9l 68 3l 0820 00 05 F0 04 0D 91 68 31 28 46 86 98 F7 00 0860 30 02 11 82 21 80 08 D0 D6 BD C9 F3 B4 A7D1". It is known from the above PDU string that the "PDU string" must be decoded in order to obtain the required user information. The data structure of the "PDU string" decoding is given below.
4.3 Application design and process
The application of the embedded platform SmartARM220 is running on the μCliunx kernel, and the application cannot directly operate on the hardware. In order to communicate between the hardware and the external device, the corresponding device driver must be called. This article mainly deals with UART driver and I2C driver. The design method of embedded driver is omitted here.
5 Conclusion
The vehicle-mounted terminal based on the speech synthesis technology and the voice module XF-S4240 can be widely applied to navigation systems, vehicle scheduling, vehicle monitoring, and the like. Due to the versatility of the technology, it can also be applied to other occasions that require speech synthesis technology, such as queuing system, bus station, and the like. At present, the speech recognition technology has achieved great results, but the effect is not as good as the speech synthesis technology. I believe that people can use the more advanced voice technology to communicate with the machine naturally!
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