Wireless vehicle monitoring technology is emerging with the development of video surveillance technology. Prior to networking, vehicle monitoring products mainly focused on analog standard definition. In recent years, with the rapid development of security IP, network HD has become the mainstream of the market, the richness of camera functions and license plate recognition technology have also been further developed, and the development of the entire vehicle monitoring technology has shown a trend of diversification and iterative acceleration.
Due to the characteristics of non-stop moving of vehicles, wireless communication network technology has become the only choice for data transmission and management operations of in-vehicle video surveillance. At present, with the breakthrough and innovation of communication technology in the field of 3G/4G, 3G/4G wireless mobile technology has become the mainstream wireless communication technology in the current domestic market. As a part of mobile monitoring, vehicle monitoring implements remote video browsing, remote control, geographic location, voice intercom and other functions through 3G/4G network to meet the needs of customers' remote video viewing and remote emergency command, and provide application customers with anytime Wireless video surveillance services anywhere are widely used in police patrol, mobile command vehicles, financial escort vehicles, etc. At the same time, due to the limitations of some special industries, wireless portable monitoring systems can also be used to meet user needs.
As far as mainstream manufacturers in employment are concerned, the general vehicle monitoring system is composed of three parts: a vehicle terminal, a 3G/4G network and a monitoring center. The vehicle-mounted terminal is the front-end device of the wireless vehicle-mounted monitoring system and is generally installed in various vehicles in secret. The vehicle-mounted terminal device is mainly composed of various devices such as a wireless vehicle-mounted terminal, a tablet computer, a high-definition vehicle-mounted pan/tilt camera, a vehicle-mounted mounting bracket, and an equipment box. . When the system is turned on, you can browse the images in real time through the tablet computer, control the rotation of the vehicle-mounted pan/tilt camera, and conduct two-way voice intercom with the back-end monitoring center.
In the specific case application, refer to the application case of the vehicle monitoring system deployed by Hubei Forest Police. The entire plan is to build a wireless audio and video transmission system covering the entire area under the jurisdiction of the forest public security, based on the application requirements of the Forest Public Security Law Enforcement Department of the Forestry Department and relying on 3G/4G wireless communication networks of telecom operators. Installed on the roof of 100 forest public security patrol vehicles with dedicated on-board pan/tilt cameras, which can monitor the dynamic information of the law enforcement site in real time, and at the same time understand the traffic conditions on the pavement, which is convenient for commanding the forest public security patrol vehicles to choose the best route to achieve forest public security. Remote supervision and management of law enforcement. During major emergencies, live broadcast or video file playback can be performed through the 3G/4G network, and voice intercom can be conducted between the command center and on-site personnel through wireless transmission equipment, which is convenient for emergency command and realizes remote visual command.
Reference technology for wireless vehicle monitoring
In the face of customers, although the merchants have different focuses on the main product technical features, many security and non-security technical requirements are similar, and after many unique functions and technologies appear, the market will soon be in a period of time. There are products of the same technical function type. When distinguishing the advantages and disadvantages of wireless vehicle monitoring products and their functions, the following key reference technical indicators need to be judged.
H.265 codec technology
The newly upgraded H.265 encoding technology, compared with H.264 under the same image quality, the video size encoded by H.265 will be greatly reduced, further improving the wireless image transmission experience.
1080P real-time video surveillance
The front end can be connected to 1080P high-definition vehicle-mounted pan/tilt camera for real-time video monitoring, and the wireless vehicle-mounted terminal supports real-time video remote browsing, and can remotely monitor high-definition vehicle video in the monitoring center in real time.
Video storage playback
The wireless car terminal has a car hard disk, supports up to 1080P high-definition storage, which is convenient for front-end storage and saves network resources. It can choose whether to bring audio recording when recording. The car video can be queried and downloaded remotely, and the download speed of video files can be configured to support abnormal disks. It can be repaired automatically when the disk is abnormal.
When the monitoring point is abnormal, the on-board alarm linkage is mainly an external alarm device, that is, the driver can report to the monitoring center during an emergency during driving, and can conduct two-way voice communication.
The built-in GPS module can report the GPS location information of the vehicle, realize the tracking of the vehicle's movement track, and fully understand the vehicle's movement. Historical video playback can simultaneously display the trajectory of the vehicle running, and can also expand Beidou positioning.
It can capture the live image in front, and then save it on the hard disk of the car to facilitate retrospective. The snapshot can be captured through three ways: alarm linkage snapshot, motion detection, and switch alarm.
It can provide one-way two-way audio codec input and output, and two-way voice intercom with the back-end monitoring center.
Automatic sleep, remote wakeup
The device can be set to auto sleep function. When there is no video stream transmission, the device defaults to no stream transmission within five minutes, then disconnect the 3G/4G network to save money. If the wake-up device goes online, you can wake up the front-end dormant device with phone or SMS. It supports triggering the device to go online by dialing a phone call and sending a text message to the device's SIM card. Only phone numbers that have been added to the phone and text message whitelist in advance have the right to activate the 3G/4G network connection. Phone and SMS whitelists support up to 5 phone numbers.
Binary activation online and offline
Support the switch to activate online and offline, when the parallel port generates an alarm, 3G/4G goes online, and after the parallel port alarm is restored, 3G/4G goes offline, which can save the tariff.
As the vehicle will have bumps and vibrations on the road during operation and have a certain impact on the equipment, in order to ensure the normal and stable operation of the equipment, the audio and video input and output interfaces and power interfaces of the equipment are designed with aviation plugs to ensure that the interface is firm and not Will be loose, built-in wire rope shock absorber, the hard disk is placed on the shock absorber, can effectively resist horizontal and vertical bumps, to ensure the reliable operation of the hard disk, complete video data.
Stream bandwidth adaptive technology
Due to the characteristics of the signal transmission of the 3G/4G network itself, narrow bandwidth, easy interference, instability and other factors will cause the wireless bandwidth to fluctuate. For this reason, Kodak has launched the independently developed KWTP wireless transmission protocol to do the transmission of the code stream The reliability guarantee can be automatically adjusted according to the current network conditions, which improves the stability and efficiency of video and audio transmission.
HD Portable PTZ Camera
As a mobile video collection source for wireless portable image transmission equipment, the HD portable infrared PTZ network camera supports a maximum resolution of 1080P. It contains a replaceable battery module to achieve independent power supply, and its own WiFi module can transmit the encoded image to the portable host. With 5 powerful magnets at the bottom, it can be adsorbed on the surface of any magnetizer, and the installation method is more diverse.
The wireless portable image transmission equipment has a built-in 16AH large-capacity rechargeable battery, which can be used by the portable host to work alone for more than 12 hours. At the same time, it can also provide a 'UPS' function to power the portable pan-tilt camera and tablet computer in the emergency situation of external equipment feeding. .
The modular design of the vehicle-mounted host is to realize the pluggable replacement of each key module, for example, the wireless module is pluggable, and the hard disk is also pluggable. If it is not modular, for example, under the 3G wireless communication protocol, I bought a DVR, but suddenly 4G appears, then when I want to replace the original device, it is necessary to replace the whole, not just a module. .
Anti-shake and fog-passing technology needs to be improved
Since the application environment faced by the car camera is not fixed, the environment encountered is also more complicated and changeable. Urban roads, rural roads, mountain roads and mud are all possible, resulting in the inevitable in the process of moving the car camera It is necessary to consider the impact of vehicle bumps and shakes, as well as image clarity in severe weather conditions such as smog.
At present, the camera's anti-shake technology does not have a very good solution in the industry. It mainly depends on the algorithm to achieve the stability of anti-shake. Other manufacturers have tried on the lens, but the effect needs to be further tested. The fog-passing technology of vehicle monitoring is not different from that of ground monitoring. The current advanced fog-passing technology is 'optical + algorithm fog-passing' as the mainstream technology. For this third-generation fog-passing technology, each manufacturer has different Understanding. On the whole, in addition to the camera's own hardware configuration, it mainly depends on the advantages and disadvantages of the fog penetration algorithm between various brand manufacturers and the fog penetration effect in practical application cases. Digital fog can retain the original color of the image, and the image restoration ability is slightly worse than that of optical fog. Optical fog penetration is due to the use of infrared imaging, and the image restoration ability is good. After adding the third generation fog penetration technology of algorithm fog penetration, a better fog penetration effect can be obtained, and the image is still clear under dense fog.