CMMB Car Digital TV System Application Solution

1 Introduction

China Mobile Multimedia Broadcasting (CMMB) is a mobile multimedia broadcasting and television technology with independent innovation and independent intellectual property rights in my country. Since the official broadcast before the 2008 Beijing Olympic Games, it has completed the network coverage of 320 cities above the prefecture level in the country, and built The world’s largest mobile multimedia broadcast and television network. As an open technology and industrial platform, the CMMB technology standard has formed a complete industrial ecological industry chain from chip manufacturing to transmitting equipment and receiving terminals. In terms of CMMB receiving terminals, many mature and stable personal terminal products supporting CMMB have been launched in the current market. Meanwhile, CMMB is expanding and promoting applications in some professional fields. In the field of automobiles, CMMB vehicle-mounted receiving terminals that provide different models and solutions are emerging and applied, and the combination of automobiles and CMMB has become a new business growth point for the entire CMMB industry. Some terminal manufacturers have launched various forms of CMMB terminal products and modules suitable for automobile installation.

In this paper, through the analysis of CMMB on-board digital TV solution, it focuses on in-depth research and summary of CMMB on-board after-installation system solutions, and analyzes the characteristics, advantages and disadvantages of each scheme in detail. The installation scheme is illustrated by an example, and finally the development direction of the CMMB vehicle digital TV scheme is discussed and prospected.

2 CMMB car digital TV solution

CMMB car digital TV is mainly divided into pre-installation, quasi-pre-installation and post-installation solutions.

The CMMB on-board pre-installation solution refers to the pre-installation and adjustment of the CMMB on-board receiving equipment and its services before the whole vehicle is rolled off the production line. For the entire car audio and video system, product development and production need to be carried out in accordance with the requirements of the car regulations, and there are very high requirements for the function, performance, and reliability of the product. Therefore, product development, testing, road testing, and production require considerable investment in all aspects. more time for validation and optimization. At present, major domestic brand car manufacturers have carried out product project approval, and integrated the design and implantation of the CMMB function as an important function of the entire vehicle audio and video system.

The CMMB vehicle-mounted pre-installation solution is mainly aimed at the models of various brands that are already in production. According to the market sales needs, the CMMB vehicle-mounted receiving equipment is implanted into the vehicle after the vehicle is offline and distributed to various sales channels, and then enters the channel for sales.

The CMMB on-board after-installation solution is mainly aimed at the cars that have already been sold. Since the CMMB function is not standard, car owners can choose to purchase and install the CMMB on-board after-installation system in 4S stores and other regular auto parts sales channels according to their own needs to realize the complete vehicle. CMMB system service.

3 CMMB vehicle after-installation system solution

The CMMB products currently installed on the market are generally post-installed products. The vehicle central control screen or headrest LCD screen is used as the Display carrier, and the CMMB function is integrated. In this way, services such as navigation can be provided during normal driving. You can watch TV programs when you are resting, improve the practicability and serviceability of the multimedia audio and video navigation system, and realize various applications of navigation, watching TV, and listening to radio.

For CMMB vehicle after-installation system solutions, its product types and types are diverse, this article will introduce in detail. For different car brands, different model configurations, and different installation schemes, the required accessories and procedures are different, so the installation cost and time are also different, but all require the equipment and lines to be hidden. Design, do not damage the original car interior decoration.

The following will focus on introducing several typical solutions of the current CMMB vehicle after-installation system.

3.1 Option 1.Multimedia all-in-one solution for special cars

The special-purpose multimedia all-in-one machine developed for a specific model usually replaces the original car audio and video system, and installs a multimedia all-in-one machine with CMMB function in the central control of the car. At present, the design of all-in-one machine products in many domestic aftermarket markets is to mold the structure of the center console according to the different styles of the car to make an integrated car machine, and it is a special machine for special vehicles, which requires professional installation. The specific terminal form is shown in the following figure:

Figure 1. Example of an all-in-one multimedia machine for special cars

3.2 Option two. CMMB Car TV Box Solution

This solution is mainly aimed at the fact that the original car central control system already has an LCD screen and audio and video input interfaces. By adding a CMMB car TV box terminal, the video signal is introduced into the central control screen. The operation mode is generally divided into remote control or touch screen. Professional installation is required, and there are restrictions on car configuration. For example, some low-profile models without a central control display cannot be installed. At present, many domestic brands offer this product. The specific terminal form is shown in the following figure:

Figure 2. CMMB car TV box product example.

3.3 Option three. CMMB car TV box + headrest LCD display solution

This solution embeds the LCD screen into the front headrest of the car, and displays the CMMB signal on the headrest screen by installing the CMMB on-board TV box for rear passengers to watch. This solution has good versatility and is convenient for rear passengers to watch, but the headrests of the front seats need to be modified, the process and installation are more complicated, and there are restrictions on car headrests, and some vehicle headrests cannot be embedded in the LCD screen. The shape of the CMMB car TV box and headrest LCD screen is shown in the following figure:

Figure 3. CMMB car TV box and headrest LCD display product example.

3.4 Option Four.Portable Vehicle PND/GPS Terminal

At present, the portable vehicle-mounted PND/GPS terminal is mainly installed on the front windshield of the vehicle through a suction cup. It has strong functions and is easy to install, but the receiving sensitivity is slightly worse than that of the vehicle-mounted TV box. Rear passengers are inconvenient to see. The specific vehicle PND/GPS terminal form is shown in the following figure:

Figure 4. Portable Vehicle PND/GPS Product Example

3.5 Comparison of CMMB vehicle after-installation solutions

Table 1 Comparison of CMMB vehicle after-installation system solutions

4 Examples of CMMB in-vehicle after-installation system installation solutions

Due to the different configurations and after-installation facilities of various models, and involving circuit modification and operation training, a professional installation team is required; the following will combine the actual installation process and the installation scheme and installation process of scheme two and scheme three. Give an example.

This installation example requires three video outputs for the CMMB digital TV box, which not only introduces the video signal into the car audio and video system of the original car central control, but also installs two sets of headrest screens to provide CMMB video programs for rear passengers to enjoy. The program is mainly divided into two parts: “CMMB car TV box”, “headrest display”. The overall structure of the system is shown in the figure below.

Figure 5. Example of CMMB in-vehicle after-installation system installation scheme

“CMMB Car TV Box” is mainly responsible for receiving CMMB signals, processing CMMB TV data, receiving user’s remote control commands, and connecting to the original car’s 12V car power supply. It has three video outputs and can support simultaneous display on multiple monitors. The video signal is sent to the headrest display and the original car central control display through the CVBS video interface, and the audio stereo signal is output to the original car audio through wired or wireless, and output through the original car audio.

The “headrest display” is to display the image part to the user, and it is necessary to embed the LCD screen into the headrest of the car through a modification process.

An example of the specific installation configuration list of the entire system is as follows:

Table 2 Configuration list of vehicle digital TV receiving terminal

In the actual installation, the installation process of the CMMB car TV box is roughly as follows:

Figure 6. Example of CMMB car TV box installation process flow

5 Summary and Outlook

The development route and direction of CMMB terminal technology are mainly reflected in the support and terminal realization of various data value-added services and interactive services. The technical standards, specifications and test verification work are the preparatory stage of the business, and the final realization of the technology should be completed through the application of the actual business, including the realization in different application scenarios and application fields.

In the field of automobiles, traditional car audio and video systems can only provide VCD, DVD audio-visual functions, and map navigation functions. CMMB is the first system independently developed in China to provide high-quality radio and television programs and information services for mobile receiving terminals. , not only can provide car owners with clear and smooth radio and TV program services, but also with the development of CMMB terminal technology and data services, data services based on CMMB broadcast network can be provided during normal driving, including real-time road condition query, financial information, car owners Care, information push and other value-added information services. The CMMB in-vehicle receiving equipment can improve the practicability and serviceability of the multimedia audio-visual navigation system, which can effectively fill the gap of radio and television coverage and services for the passengers, and meet the urgent needs of car owners to watch TV and listen to the radio anytime, anywhere.

For the CMMB vehicle after-installation system, it will inevitably develop from a non-standard to a standardized direction that meets the requirements of the vehicle level, and more solutions and products suitable for vehicle applications and easy to install will be introduced. At the same time, for the CMMB car digital TV system, it will not only be popularized and popularized in the after-installation market in the automotive field, but also will develop from the after-installation market that has been widely used to the pre-installation market that is standard in the original car.