Application of USB digital camera in GPS real-time

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Application of USB digital camera in GPS real-time monitoring system


this paper introduces a solution to realize vehicle wireless real-time image monitoring based on the existing GPS vehicle management system and USB digital camera

key words

usb GPS CMOS GPRS CDMA digital camera real-time monitoring

I. Introduction

in recent years, with the continuous development and improvement of GPS technology, GPS vehicle terminal has been widely used in taxi, logistics vehicle, long-distance bus and other vehicle management systems. It has realized the functions of vehicle positioning, tracking and scheduling, and achieved good economic benefits. However, the existing GPS vehicle management system can not fully meet the special requirements of some vehicles, such as the real-time image monitoring of long-distance buses and the anti robbery of taxis. In view of the above situation, a solution is proposed: Based on the existing GPS vehicle management system, expand the USB host interface on the GPS vehicle terminal, connect the USB digital camera, and realize the real-time image monitoring of the vehicle

II. System implementation

1.usb digital camera

Figure 1 USB digital camera block diagram

as shown in Figure 1, USB digital camera is mainly composed of three parts. The DSP part adopts the image processing chip zc0301p of Zhongxing micro company, and the image sensor selects 300000 pixel CMOS sensor pb0330. In order to obtain better image effect in the case of low illumination at night, the night vision compensation infrared LED matrix controlled by photosensitive resistance is added, and the infrared LED is automatically turned on for compensation at night or in the case of low illumination

zc0301p chip adopts image light source automatic gain reinforcement technology, automatic brightness and white balance control technology, color saturation, contrast, edge enhancement, gamma correction and other advanced image control technologies. With CMOS sensor, all technical indicators can be comparable to CCD. Support USB 1.1 interface; Compatible with Twain standard; Up to VGA resolution (640 × 480)。 Up to 15 frames per second in VGA mode, at CIF (52 × 288) and SIF (320 × 240) the rate of 30 frames per second can be reached in the mode; It also provides 640x480 format high-definition still image capture mode and supports standard JPEG compression mode

2. system scheme

gps vehicle terminal can expand multiple USB host interfaces by using USB HUB chip, and each USB host interface can be connected to a USB camera, which can basically meet the requirements of vehicle image monitoring. Generally, a hemispherical USB camera can be installed on the ceiling in front of the co driver in taxis to monitor the situation in the whole car. For buses, a USB camera can be installed in front and in the middle of the car respectively

the working principle of the system is shown in Figure 2. The USB camera installed on the vehicle captures the status in the compartment in real time, and transmits the compressed image data or video to the GPS vehicle terminal through the USB interface. The GPS vehicle terminal uses the wireless public communication network platform GPRS or CDMA network to transmit the data to the monitoring center. As required, relevant staff can obtain the on-site dynamic image in the vehicle through the Internet, Understand the real-time running status of the vehicle

Figure 2 system schematic diagram

at present, the data communication between the on-board GPS terminal and the monitoring center is transmitted through the 2.5G GPRS or CDMA wireless network platform, and the 2.5G gprs/cdma bandwidth can not meet the requirements of transmitting complete and smooth video streams. So China is still in the deep development stage of industrialization, information, urbanization, marketization and internationalization. In practical application, image data transmission is still the main mode. There are three working modes, namely,

1) timing transmission, such as taking an image every 10 seconds and uploading

2) command mode. The monitoring image is obtained through the command issued by the monitoring center

3) event triggering, For example, by opening and closing the door and other events to trigger the uploading of monitoring images

in some cases, the video data of the USB camera can also be stored in the U disk through the GPS vehicle terminal and played back on the computer afterwards. It is expected that when 3G is launched in the future, the GPS vehicle will eventually make the whole experiment process more smooth. The end communication module can also be upgraded to 3G, and the vehicle wireless real-time video monitoring can be fully realized

III. summary

this paper makes full use of the existing GPS vehicle management system resources, combined with the USB digital camera, proposes a vehicle wireless image monitoring solution with high cost performance, which realizes the vehicle positioning, tracking, scheduling and wireless image monitoring functions, and has achieved good results in practical application. It has been highly praised that users can mass produce a full range of 210v~1000v electrode foil products


1.vimicro Inc Ltd., Co zc0301plus_ 1001.1_ EN Datasheet 2005.3

2. GPS vehicle terminal description of Shanghai Feitian Communication Technology Co., Ltd. November 2005

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