Application of the hottest USB camera in GPS real-

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Application of USB camera in GPS real-time monitoring system

I. monitoring system

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

II. System implementation

b 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 control technology company, and the image sensor adopts 300000 pixel CMOS. Therefore, there are often problems with sensorpb0330. In order to obtain better image effect under low illumination such as night, add the night vision compensation infrared LED matrix controlled by photosensitive resistance, and automatically turn on the infrared LED for compensation at night or under low illumination

zc0301p chip adopts image light source automatic gain reinforcement technology, automatic brightness and white balance control technology. The jaw distance of tensile testing machine is 125mm, and the experimental speed is 125mm/min ± 12.5mm/min. The sample is stretched to a certain elongation, 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 USB1.1 interface; Compatible with Twain standard; Up to VGA resolution (640 × 480)。 In VGA mode, it can reach the rate of 15 frames/second, and in CIF (52 × 288) and SIF (320 × 240) the rate of 30 frames per second can be achieved 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 usbhost interfaces by using USBhub chip, and each usbhost interface can be connected with 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 a taxi to monitor the situation in the whole car. For a bus, 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 below. The USB camera installed on the vehicle captures the situation in the car in real time, and transmits the compressed image data or video to the GPS on-board terminal through the USB interface. The GPS on-board terminal uses the wireless public communication network platform GPRS or CDMA network to transmit the data to the monitoring center. According to needs, 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 Schematic diagram of the monitoring system

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 cannot meet the requirements of transmitting complete and smooth video streams. The supporting blow molding machines such as the Chunlei talent project of Ningbo Institute of materials are one of the categories with the largest commercial deficit in the national plastic machine market. Therefore, in practical application, it is still mainly to transmit image data. 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 trigger, For example, by opening and closing the door and other events to trigger the upload 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 then played back on the computer afterwards. It is expected that in the future, when 3G is launched, the communication module of GPS on-board terminal can also be upgraded to 3G, which will fully realize wireless real-time video monitoring of vehicles

III. summary

this paper makes full use of the existing GPS vehicle management system resources, combined with USB digital camera, puts forward a cost-effective vehicle wireless image monitoring solution, which realizes the functions of vehicle positioning, tracking, scheduling and wireless image monitoring, and has achieved good results in practical applications, and has been praised by users. (end)

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