Design of ARM-based digital video surveillance system

Design of ARM-based digital video surveillance system

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Source: Electronic Engineering album by: Wang Qin Yang Zhen

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Introduction

Image and video surveillance systems are systems that use computer and communication technology to monitor information in target regions. They are often used in transportation, energy, public security, telecommunications, military, and other departments. As the application fields of image and video monitoring systems continue to expand, remote image and video monitoring systems have emerged, meeting the requirements of remote monitoring. Digital video surveillance systems are based on computer or embedded systems and video processing technologies. they comply with international standards for image data compression. A new monitoring system that comprehensively utilizes technologies such as image sensors, computer networks, automatic control, and artificial intelligence. As the digital video surveillance system digitizes video images, digital surveillance has many advantages over traditional analog monitoring systems. Digital video systems can make full use of the computer's rapid processing capabilities to compress, analyze, store, and display them. Digital video processing technology improves image quality and monitoring efficiency, making the system easy to manage and maintain. The entire system is modular, small in size, easy to install, use, and maintain. It is precisely because the digital video monitoring technology has the advantages unmatched by the traditional analog monitoring technology, and conforms to the current development trend of digitalization, network and intelligence in the information society, therefore, the digital video monitoring technology is gradually replacing the analog monitoring technology, which is widely used in various industries. Embedded systems are widely used in various fields of society due to their small size, strong real-time performance, high cost performance, and good stability. ARM-based embedded digital remote monitoring is a new application based on modern communication technology. This design is an embedded system that monitors the scene in real time with the ARM hardware platform as the core, and transmits video images to the host through wireless networks, in order to achieve analysis, storage, display, and other functions, compared with the traditional analog monitoring system: its networking costs are greatly reduced, the system volume and weight are greatly reduced, and operation and maintenance are easier.

1 monitoring system solution introduction

The network structure design of the remote monitoring system directly affects the system performance. Currently, there are roughly three solutions to achieve the network architecture of the monitoring system. They are described as follows:

(1) Using proxy servers

The proxy server is generally used by a PC. On the one hand, the TCP/IP protocol is run to implement the Internet access function, and on the other hand, the proxy server is connected to the embedded system through a simple bus structure (RS232, RS485, etc. 1. In the system, you only need some code to communicate with the proxy server. The advantage is that it can easily solve the problem of device Internet access, and the development is difficult. The disadvantage is that the access cost is relatively high, which is not conducive to large-scale promotion. This solution is suitable for large or expensive industrial devices, and is not suitable for low-price devices.

(2) Implementing the Internet access function by directly implementing TCP/IP protocol on the embedded processor. This solution does not use the operating system, which greatly saves resources, but has high requirements on the performance of the processor, at the same time, it increases the difficulty of development and technical implementation. 2.

(3) A network monitoring system based on ARM Linux

This scheme is similar to the second scheme, but it only uses the Embedded ARM Linux operating system and runs the TCP/IP protocol on the operating system. At present, most embedded operating systems have TCP/IP protocol stacks, which reduces the difficulty of development and makes implementation more flexible. Because the operation of the embedded operating system requires a considerable amount of processor resources and storage space, there are also high requirements for hardware configuration. The third solution can save the development time and shorten the development cycle. Generally, the monitoring system must configure an industrial computer or high-performance microcomputer as a server in the control site to store intermediate data, handle events with high real-time requirements, and respond to monitoring requests from the monitoring terminal.

2 Monitoring System Hardware Design

The network monitoring system is based on ARM Embedded. It adopts the TCP/IP network protocol standard. The system has simple networking, large amount of data transmitted, fast speed, and simple system structure. Small sizes and low prices. Remote computers can detect devices through WEB Browsers without additional programs, and applications are easy to develop and complete information sharing. In this system, ARM is responsible for program control and network communication, and the image and video acquisition modules are responsible for data acquisition and processing. After the data or command data is transmitted, the ARM system transmits or displays the command data on the LCD after the command processing, and the system uploads the processing result through the network interface. After receiving the data command, the system sends the result to ARM after algorithm processing, the drive D/A outputs, or data processing based on A/D input. The system has the following basic functions: data collection, data analysis and processing, program control, and network transmission.

2.1 ARM Video Monitoring Platform

3 shows the development platform of the video monitoring application system. ARM system expansion slots and device expansion slots are used to add interfaces such as Ethernet interfaces, Haikou data storage interfaces, and PCMCIA to ARM systems, or for other functional development boards, added the CMOS image acquisition and VGA display functions for the ARM system.

Among them, the VGA interface is to achieve 4096-color display through the resistance network. Registers related to SRAM access include: SDRAM control register, 16-bit low read address, 16-bit high read address, read data register, 16-bit low write address, 16-bit high write address, write data register; with CMOSImage AcquisitionThe relevant registers include the CMOS collection control registers and the CMOS collection status registers. The registers related to the VGA display are the VGA display control registers. It has the following features:

(1) good real-time performance, meeting the real-time requirements for data collection and data processing.

(2) high cost effectiveness. The system cost should be as low as possible when the requirements are met.

(3) good controllability, able to achieve remote control and data transmission.

2.2 Data Collection Module

The video source signal comes from a highly integrated CMOS digital image sensor module mb86s20, which is a product of Fujitsu. Mb86s02 not only integrates a CMOS image sensing array, an automatic gain signal amplifier, an analog-to-digital converter, but also color signal processing and micro-lens, including all front-end processing of image collection, you can directly output digital signals. Module System diagram 4.

Mb86s02 is based on the CMOS process and uses an active pixel sensor, which is different from the traditional CCD sensor.

(1) imaging process

CCD and CMOS use the same photosensitive material. Therefore, the basic principle of electron generation after light is received is the same, but the reading process is different: CCD is transferred by frame or line in combination with synchronous and clock signals. The entire circuit is very complex and reading speed is slow. CMOS reads signals in a dram-like manner, the circuit is simple and the reading speed is high.

(2) Integration

The CCD reading circuit using special technologies is complicated. It is difficult to integrate A/D conversion, signal processing, automatic gain control, precision amplification and storage functions into a single chip ~ A multi-channel non-standard supply voltage is also required for the combination of eight chips. With the help of a large-scale integrated manufacturing process, CMOS image sensors can easily integrate the above functions into a single chip. Most CMOS image sensors have both analog and digital output signals.

(3) power supply, power consumption, and volume

CCD requires a variety of power supplies, with a large power consumption and a large volume. CMOS only needs one single power supply (3 V ~ 5 V) power supply, the power consumption is equivalent to 1/10 of CCD, and the high integration of CMOS chip can be quite small.

(4) performance indicators

The ccd technology is quite mature, while the cmos technology is booming. Although the quality of high-end cmos images is not as good as ccd at present, some indicators (such as transmission rate) have exceeded ccd. Due to the advantages of cmos, many domestic and foreign organizations have applied cmos image sensors to develop many outstanding products. This article mainly introduces the development status and latest developments of commercialized cmos image sensors, hoping to help the development of downstream products.

The biggest advantage of CMOS technology is that each pixel unit can be integrated with one or more transistors, which has the advantages of low power consumption and miniaturization. It is very suitable for handheld devices and can reduce system power consumption and volume, improves battery efficiency. Its High Integration greatly simplifies the design of image application systems.

The main features of MB86S02 are as follows:

L/7 inch image sensor, valid pixels: 352x288, 0.11 million pixels in total;

Ultra-Low Power Consumption: 30 MW @ 15fps;

Outputs 8-bit Parallel CMOS digital signals in YCbCr422 or YUV422 format;

Color signal processing includes automatic gain, automatic exposure, automatic white balance, and Gamma Correction;

Registers are set through the standard I2C serial interface;

Supports the CIF (352 × 288) QCIF (176 × 144) format;

CCIR656 Standard Header output;

Anti-blinking function;

Low Power Consumption mode;

Power Consumption in power-down mode: 3 μs;

The embedded processor is connected to the MB86S02 CMOS Image module. After reading the image data, it is stored in the external high-speed SRAM through the synchronous SRAM interface, then, the UART module or RTL8019 module can send the stored image data to the PC, and the receiving program on the PC will display the received image. You can select the image collection, address reset, serial port sending, and network port sending functions through the buttons on the debugging board.

3 Monitoring System Software Design

5 shows the flowchart of the Main ARM program. The ARM processor obtains the image information and executes the compression program. The compressed files are transmitted to the monitoring host through the public telephone line. Because the system uses the same image resolution and constant table, the file header is the same. To reduce the amount of data transmitted, the file header is automatically added by the software on the monitoring host.

The system also uses a modem to remotely connect resume data through a public telephone network. The Modem at the remote image monitoring terminal is on standby, it uses the "ATS0 = 3 & D0W & W1" command to set it as an automatic response mode. After three rings, the system automatically disconnects from the host. After the "Data Storm", it establishes a connection with the caller. The modem of the monitoring center is set up or hung up by the monitoring software.

After the data connection is established, ARM receives the "CONNECT" string, indicating that the communication line is successfully connected. In this case, you can use the remote data connection established by the modem just like using a common serial port. After receiving the collection commands sent from the monitoring center, ARM completes image acquisition and compression, and then directly sends the image data to the monitoring center in the form of ASCII code through the serial port, wait for the next collection command after completing one operation.

In applications, image data needs to be received from the MODEM, and the file header must be stored in the local hard disk as a standard JPEG image or MPEG video format. The received image is displayed at the corresponding position in the dialog box, which requires a decoding program. You do not need to write it yourself. The Windows operating system supports JPEG or MPEG format. The MsCOMM control is Microsoft Communication Controller 6.0, which is contained in VC 6.0. The MsCOMM control allows you to easily access the serial communication port of the PC. Access to the MODEM is implemented through the serial port. The external MODEM is connected through the real PC serial port, and the built-in MODEM is controlled through a virtual serial port.

4 Conclusion

Video surveillance technology plays an important role in the security prevention of political, economic, military, and cultural facilities. With the development of multimedia and computer network technologies, the video monitoring system has gone through the development stages of analog monitoring and digital monitoring, and has now reached the network digital video monitoring stage. The low-cost digital remote Image Monitoring System Based on ARM processor is a software and hardware working platform with high reliability and efficiency for embedded system development. It uses the integrated digital video acquisition module, directly obtain digital image signals. Image Compression does not use a dedicated compression chip, but is implemented by the compression software inside the high-speed processor. Finally, the package is sent through the public telephone network.

This article focuses on the application development and process of ARM embedded image and video monitoring, and provides a solution to build an embedded image and video system with low development costs and ease of use. Developed a remote video monitoring system for practical applications using ARM embedded processor and Linux operating system, suitable for monitoring applications with low resolution, low cost, and long distance. Its features and advantages include:

This paper constructs an ARM Embedded Processor development platform and proposes a low-cost development process for embedded systems.

The front-end uses a cheap integrated and highly integrated digital video acquisition module, which simplifies the design of the system front-end and greatly reduces the front-end cost.

Write a simple embedded operating system program, dynamically load the application program, and speed up its execution.

Signal Processing uses an embedded system built on a high-speed, high-performance ARM processor to compress images through software.