Telematics application mode and system design essentials
In the car's infotainment system, the basic equipment in the past was the analog AM / FM audio broadcast and music CD player, which provided entertainment and traffic conditions for drivers and passengers. With the evolution of technology, in addition to audio broadcasting towards digitalization, vehicle GPS navigation and digital TV / DVD / VCD playback functions, as well as voice calls and information connection functions of mobile phones (GSM / GPRS), have been developed. Emerging TelemaTIcs applications and services.
This integrated system can provide real-time traffic guidance, guide the best driving route (avoid congested roads), provide car status diagnosis, car recovery, parking reservation, electronic toll collection (Electronics Toll CollecTIon; ETC) and conduct emergency situations Diversified value-added services such as calling. The following will introduce the application mode and system design essentials of TelemaTIcs.
TelemaTIcs emerging application model
For driving, the emergence of the concept of Telematics can be said to be a major breakthrough in the history of automobile development. It breaks the limitation of the individual cars that was originally an island, so that cars with Telematics can always know their location through GPS, and Send location information to relevant service providers, which can provide road rescue, lost car retrieval and other services. At present, Yulong's TOBE Automobile Action Secretary, North American GM's OnStar, and Toyota, Honda, Nissan and other Japanese car departments have similar services.
In addition to the telematics services of individual car manufacturers, many countries including Europe, the United States, Japan and other countries have actively promoted telematics-related emergency rescues related to telematics to national or even transnational contingency systems. In the eCall project promoted by the eSafety Forum under the European Union, all new cars are scheduled to have eCall equipment after September 2009. This equipment will combine three functions of collision detection, GPS and mobile communication. The Pan-European unified emergency telephone number 112 is automatically notified at a time. In addition to the geographic location of the vehicle, eCall is also set to transmit data and data. The dual channel of voice and information allows 112 operators to determine the appropriate rescue method.
Vehicle condition sensing and diagnosis
In addition to road rescue, lost car recovery and emergency rescue, the Telematics system can also integrate various sensing systems on the vehicle to provide vehicle owners with automatic detection of vehicle performance and vehicle conditions, such as tire pressure detection (TPMS), and It can provide driving assistance and warning functions, such as pre-collision warning or front road condition monitoring; through the Telematics system, the operation status of the mechanical and electronic components in the car can be remotely transmitted back to the car factory, and then remote diagnosis (Remote Diagnosis) service ; Insurance companies can also determine what level of insurance premiums should be paid in the event of an accident based on real-time or offline monitoring records of driving behavior (such as the black box of an aircraft). Of course, the vehicle owner can also obtain auxiliary driving information from the remote, such as traffic condition information or the vehicle condition report after the remote diagnosis by the depot.
Electronic toll collection and workshop communication
Another important application of Telematics is the electronic toll collection system (Electronic Toll Collection; ETC). Because ETC helps to alleviate traffic jams at toll stations, it can also save personnel management costs and reduce toll station construction costs. The country has actively begun active deployment. The realization of ETC system must use Automatic Vehicle Identification (AVI) technology, AVI can also be divided into specific short range communication technology (Dedicated Short Range Communication; DSRC) and autonomous vehicle positioning system (Vehicle Position System; VPS) Two identification techniques. The so-called DSRC technology is to use the fixed-point communication sensing equipment installed on the roadside to interact with the on-board unit for communication identification to perform the charge deduction action; the VPS system uses the on-board unit with integrated vehicle positioning function. When the vehicle travels on a toll road, the deduction is reported to the back-end accounting center.
In addition to the application of electronic toll collection, DSRC can also be used for another novel concept, namely workshop communication. When the vehicle and the vehicle are close to a certain distance, the two vehicles will automatically connect and exchange information on nearby traffic conditions, such as traffic jams, accidents, and dangerous road sections. This application has an excellent concept, and does not need to be led by a specific service provider. The development focus is that there must be a considerable number of cars with this communication function, and different models and brands must be able to communicate with each other to play. utility.
RDS-TMC
In the Telematics system, in addition to the use of mobile communication networks (GSM, GPRS or 3G) to obtain information such as transportation, hotels, entertainment, weather, and booking from service providers, such information can also be obtained through general radio broadcasting methods. service. At present, the most famous is the Digital Navigation System (Radio Navigation System) promoted by the European TMC (Traffic Message Channel) alliance. In this system architecture, car drivers can set the frequency of receiving RDS (Radio Data System) subcarriers themselves, and then provide driving dynamic route guidance through the TMC-enabled navigation system. In addition, TMC can also be combined with digital broadcasting (DAB) or mobile networks, so it is extremely developmental. At present, Europe, Germany, France, the United Kingdom, Hungary, Spain, Austria and the Netherlands have provided this service. In the future, it will increase to more than 20 countries.
System architecture analysis
Telematics is a system that combines GPS, communications, information, in-vehicle bus protocol (CAN / LIN / MOST), and in-vehicle audio-visual entertainment devices, and must also rely on mobile communication networks, customer service centers, and telematics service providers. ; TSP), application software and other related components can work together to receive and transmit the two major information (automotive information and off-vehicle information) one-way or two-way. Its system architecture must include the following units:
Central controller
The main controller / processor of the Telematics vehicle-mounted machine is the core of calculation and control. The entire controller has a reinforced shell and conforms to vehicle specifications (-40 ° C to + 85 ° C or 105 ° C, shockproof, drop resistant, and high stability). As workloads continue to increase, the requirements for such main controllers / processors continue to increase, gradually increasing from 16-bit MCUs to 32-bit MCUs, and even using highly integrated SoC application processors; at the processor core In terms of aspect, it can be roughly divided into two levels: ARM7 and ARM9. The next generation of high-end products will be equipped with a more powerful ARM11 core and adopt an advanced 65nm process.
Communication module
The main controller / processor of the Telematics vehicle-mounted machine must connect various wireless technology modules through interfaces such as UART. In addition to wireless two-way communication technologies such as Bluetooth, 2G / 2.5G / 3G, and DSRC, it also includes GPS and Radio RDS. , Satellite Radio, DVB-T / DVB-H / T-DMB and other unidirectional receiving wireless technologies. These technologies have three basic building blocks of antenna, radio frequency and fundamental frequency.
Flat display and man-machine interface
The flat display can be divided into flat liquid crystal displays of the front seat and rear seat systems. The former can display the information inside and outside the car provided by the center console, and the latter can provide various entertainment movie and television screens for the passengers. Operation needs to provide simple and friendly human-machine interface software and hardware technology, such as panel control, infrared remote control, voice activation, touch screen.
Communication in the car
Use the Telematics System to communicate with the entire vehicle system (Vehicle Systems), and use the multimedia system to convey various warning and reminder messages inside the vehicle. For example, the emergency call device (SOS Button) is an emergency call button and a service call button built in the central controller or indoor dome light. 
"Figure 1 Telematics system architecture diagram"
Essentials of GPS system design
In the Telematics system, the GPS receiver is already an indispensable core. There are four main indicators for evaluating GPS performance, namely: Time to first fix (TTFF), Position accuracy, Sensitivity, and channel number. Among them, the most valued indicator is TTFF. Under the cold start condition without satellite data, the first positioning time of most GPS receivers on the market currently needs at least 35 to 38 seconds. If you encounter a poor reception environment, you will need it more often More than a minute.
The GPS receiver includes two parts: radio frequency (RF) and digital base frequency. Looking more closely, it consists of the RF front end, GPS engine, processor (usually ARM7), memory (ROM / RAM) and real-time clock (RTC) composed of IC and other units; externally there are passive or active antennas, and with temperature-compensated oscillator (TCXO); if there are special application requirements, you must use external Flash EPROM or Serial EEPROM and other memory .
These units can adopt discrete methods to improve design flexibility, and can also adopt an integrated strategy, that is, integrate multiple units into a system on chip (SoC), single package (SiP) or module, To reduce the difficulty and cost of design. Taking ST's Cartesio system single chip as an example, it integrates the fundamental frequency and RF functions into a small QFN-68 package. It uses ARM7TDMI as the core in the base frequency part, and the clock can be up to 66MHz; in the radio frequency part, it is an active antenna system, which contains an interface that is easy to connect with the passive antenna; in addition, it also has built-in ROM and SRAM memory. Because only a few external components are needed, it can reduce the overall bill of materials (BOM) cost; its small size can make the product design more thin, light and short, and has the advantage of low power consumption; not only that, such integrated products also allow Engineers save the research effort to adjust the integration of radio frequency and base frequency, which can accelerate the time to market. 
"Figure 2 Architecture diagram of automotive application processor integrating GPS function"
In addition, there are some points that need attention in system design, including reduction of power consumption and suppression of noise and interference. For GPS receivers, the operation of correlators is the main source of power consumption, so it is best to control each correlator channel separately, that is, when it is not necessary to start all channels, the system can automatically adjust to only start Correlator channels needed to reduce power consumption. In addition, through the use of backup batteries, the power supply voltage can be reduced, which also helps to save power consumption.
The process of changing from high frequency to low frequency is the main link of noise generation. In this process, the generation of noise must be properly suppressed, for example, the signal harmonics of SAMP CLK are minimized to avoid mixing in the intermediate frequency (IF) link This can be achieved by configuring appropriate resistors between the RF front end and the correlator. In addition, the layout and wiring of each unit on the circuit will also affect the interference situation, so proper planning is required.
Other design issues
Multimedia system
In the design of in-vehicle multimedia systems, more advanced processing architectures are needed to meet complex audio-visual application functions. In addition to the main processor core, special hardware design is necessary, such as decentralized processing through dedicated hardware such as video accelerators, audio accelerators, 2D / 3D graphics accelerators, Java accelerators, and acceleration hardware Resources and speed up the work.
The multimedia system of the car is still based on audio, and today's car audio sub-system must support multiple audio standards, such as MP3, AAC, AAC +, WMA, Midi synthesis, and high-end multi-channel audio, such as MP3Pro, MWA, DTS- ES, AAC, Dolby Digital-EX, etc., also have to provide noise suppression, echo cancellation, stereo enhancement and surround sound effects. In addition, the enhanced 3D drawing accelerator can be used for mapping and display functions of the man-machine interface.
In terms of automotive audio broadcasting, there are currently a variety of analog and digital specifications in the world, including the existing AM and FM channels, and the weather channel in the United States. Analog audio broadcasting is still the mainstream application of today's car broadcasting. The core architecture includes an AM / FM receiver and playback mechanism, an audio power amplifier that drives multiple speakers, and the receiver includes an RF demodulator (tuner) and signal processing. Audio processor.
Digital audio broadcasting can be divided into terrestrial broadcasting, including DAB / DMB, Digital Radio Mondiale (DRM), HD Radio, and satellite broadcasting, including XM Radio, Sirius and WorldSpace. Among them, digital audio broadcasting allows the base station to use spectrum more efficiently, improve reception performance, and make it easier to use. In addition to the transmission of sound, it can also transmit video and data services at the same time, so it has become an important application for automotive entertainment trend.
Technically, digital audio broadcasting converts high-frequency analog signals to intermediate frequencies, and then to digital signals. Through digital signal processing (DSP) technology, including tone, volume, gradual increase and decrease and balance, and sound The parametric equalization and other audio effects can be digitized, which can effectively improve the reception stability and audio quality.
"Figure 3 Digital Audio Broadcasting System Hardware Architecture Diagram"
CAN bus protocol
One of the biggest differences between the telematics system of the vehicle and the independent equipment such as PND is that the telematics system must often support in-vehicle communication protocols. The current common or developing in-vehicle communication protocols include CAN, LIN, MOST, FlexRay, byteflight, In vehicle, etc. For Telematics, the CAN protocol is the most important. CAN has excellent fault tolerance, can support decentralized and critical real-time control with high safety level under harsh temperature, pressure and dust environment for a long time, and has the characteristics of low cost and easy to build, so it is widely used Used in the vehicle manufacturing industry.
"Figure 4 Speed ​​and Application Position of Different Communication Protocol Technologies"
CAN is widely used in automotive electronic systems. Its high-speed CAN protocol is often used in automotive power or transmission control units, such as automotive engine control units, automatic transmission control units, ABS control units, airbag control units, etc .; low-speed CAN It is used in car body systems, such as centralized control locks on car doors, car windows, trunk locks, rearview mirrors and interior ceiling lights. With the remote control function, the CAN controller can also receive and process remote control signals or control other anti-theft systems.
When the Telematics system obtains performance information about the body, automobile power / transmission, etc. through the CAN bus, many value-added emerging applications can be developed, such as driver assistance / warning information, remote diagnosis, and emergency rescue. However, because each car manufacturer has its own set of agreed norms and practices, this type of application development must be closely coordinated with the car manufacturer to be able to do it.
Automotive grade standard
A car is composed of many components. Although these components are large and small, the driving of the car is closely related to life safety. Each component is required to achieve the highest quality and reliability. Therefore, another important feature of the development of automotive electronic equipment is that it needs to meet the strict automotive grade (Automotive Grade) certification, and even needs to achieve the ideal state of zero defect (Zero Defect). For automotive components, the biggest driving force for products is often not "advanced technology" but "quality level." Although the Telematics system is not directly related to driving safety, it is still subject to strict requirements for automotive grade certification, which is a bottleneck that consumer electronics manufacturers can hardly cross.
At present, several important quality management systems and related specifications have been developed in the automotive industry, including various specifications proposed by the Automotive Electronics Council (AEC), as well as QS-9000 and TS 16949. In addition, component suppliers will also propose their own set of control practices based on these specifications, such as ST ’s Automotive Grade Qualification. In addition to meeting AEC and quality management system specifications, ST has also developed some strict control practices. For example, special screening and testing methods are used in the manufacturing process, as well as the exclusive High Reliability Certified Flow (HRCF) test program.
"Figure 5 History of the evolution of the automotive industry standards"
Conclusion
For the automotive market, although Telematics has been discussed for a long time, it will take some time for true rapid growth. This aspect is related to the longer design time of automotive electronics. On the other hand, Telematics needs a complete set of infrastructure to work together. However, the time for Telematics to take off is approaching. With the maturity of related product technologies and the cost reduction, the installation threshold of telematics has been greatly reduced. In addition, car owners have very obvious needs for LBS, anti-theft, and emergency rescue. In addition, governments of various countries have clearly set a timetable related to emergency rescue. It is estimated that from 2009 to 2010, a large number of Telematics will be adopted.
In terms of business opportunities, the Telematics system must integrate GPS positioning and audiovisual multimedia technologies. At present, Taiwan can be said to be an important design and manufacturing town for GPS-related equipment (especially PND), but to enter the automotive interior market, it still lacks the requirements for automotive grade certification, CAN agreement construction, and in-vehicle radio broadcasting. In addition, Taiwanese equipment manufacturers are accustomed to thinking in terms of a consumer market, which is very different from the automotive market with a very long life cycle. Therefore, by cooperating with component manufacturers that have long invested in automotive component design, they can enter the market faster.
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