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Vehicle-mounted hard disk video recorder belongs to the traditional embedded hard disk video recorder subdivision mall. It is a new special product developed with the use of digital video and audio coding technology in vehicles. The on-board hard disk video recorder is connected with the leading technologies such as digital video and audio codec, hard disk storage of capacity data of large pharmaceutical pure water equipment in harsh environment, car electronics, wireless video network transmission, GPS satellite positioning, etc., so as to complete the video and audio monitoring of passenger transport work, special vehicle work and other related fields. As a subdivision mall of traditional embedded hard disk video recorders, vehicle-mounted hard disk video recorders are also welcomed by many security companies.

Vehicle-mounted hard disk video recorder is not a new product of the times in terms of security work. But as far as the technical content is concerned, I'm afraid as long as the talent who has actually done the work of vehicle-mounted hard disk video recorder can get it.

I. The Difference between Vehicle-mounted Hard Disk Video Recorder and General Hard Disk Video Recorder

The general hard disk video recorders use 220V alternating current. The stability of voltage and current is relatively stable for food and water equipment. Moreover, because the general hard disk video recorders have a fixed azimuth environment and relatively few vibration opportunities, the anti-seismic function of the general hard disk video recorders can be neglected. But car-mounted hard disk recorders are different. First of all, the voltage and current on the car can not be understood according to the conventional way of thinking. The voltage on the car is 12/24V, but in fact, the 12V car can not achieve 12V voltage stabilization, and the 24V is the same. So the plan of the power board is very important. The plan of the power board should take many aspects into account.

II. Power Planning of Vehicle-mounted Hard Disk Video Recorder

In order to ensure the normal operation of the vehicle-mounted hard disk recorder, the first thing is to ensure the stable output power of the power board.

In the fixed narrow voltage environment, because the input voltage and current base is stable, and from the electrical point of view, the output power decides the input power, so in general, only one adapter is needed for the power supply of hard disk recorder. An adapter is nothing more than a transformer plus a filter circuit, a little conscience plus one. Protection circuit, no conscientious protection circuit is installed, so the cost of general hard disk video recorders and protection costs are relatively cheap.

But for VHDR, the first thing to do is to narrow and refine the dynamic voltage and current. How to ensure the normal operation of the VHDR is very important. But on the other hand, the input power of the equipment is fixed. According to W=U*I, the current changes when the voltage changes. The direction of the change of voltage and current is always opposite. So suppose the lower the starting voltage is, The relative starting current will increase.

Microscopically, it is so simple, but it will take a lot of effort to achieve this function and ensure the normal operation of the equipment. The first battle is to plan the protection circuit. It is necessary to know that the power board of the VHDR will experience hundreds of shocks in less than an hour, the protection circuit is not well done, and the power board will be damaged slightly. If it is damaged, it will directly break through the power board and burn the motherboard.

3. Seismic Plan of Vehicle-mounted Hard Disk Video Recorder

The anti-seismic plan of the VHDR is very important. The original is how to protect the hard disk. Because the hard disks at that time were all mechanical rotary-shaft hard disks, the distance between the read-write head and the disk surface was only a few microns, assuming that the read-write head was attached to the disk surface with the naked eye, but even if you don't understand the hard disk, you should understand that the 5400-turn hard disk should be rolled at least 90 times per second, assuming that the read-write head is attached to it, not much. For a long time, the head of reading and writing was worn out. At such a close distance, assuming that the anti-seismic work is not good, only a little bit of tremor in the read-write head, a little bad in the hard disk and a little crash in the read-write head are needed. So the hardware anti-seismic is very important.

IV. Fault Tolerance and Error Correction Ability of Hard Disk Video Recorder on Vehicle

Fault-tolerant and error-correcting ability of hard disk is a difficult problem that hard disk has always been striving to deal with, whether in IT hardware or software work. For an embedded system, it is very difficult to achieve a perfect fault-tolerant and error-correcting plan. But for the original plan of embedded system, the original plan of embedded system is to seek very good stability and implementation speed, but there is a problem that can not be neglected is poor portability, so once the plan can not be changed too much. So its initial planning ideas are very important. Embedded systems for hard disk error-tolerant correction, then a useful method is the ability to read and write control.

V. Selection Standards for Vehicle-mounted Hard Disk Video Recorders

Car-mounted hard disk video recorders should pay attention to the following aspects when choosing according to different work needs:

1. Anti-tremor

Although the embedded system is chosen as the general DVR, the vehicle-mounted DVR technology is more messy than the general DVR, and the key points of demand processing are different. Therefore, they are two completely different concepts. Vehicle-mounted DVR is used in mobile vehicles. Because of the different vehicle and road conditions, the tremor ratio is large, which has a great impact on hard disk reading and writing data, and has a great harm to the equipment. Therefore, anti-seismic technology has become the most basic demand for vehicle DVR. At that time, the first thing to do was to reduce the vibration of the whole machine, the hard disk shelf and the hard disk.

In the security work, the car-mounted DVR shopping mall was still relatively chaotic, and the users did not know much about it. Therefore, it was often found that the general DVR was used to fake the appearance of the car-mounted DVR. Therefore, the detailed practical function needs to be inquired personally before you know it.

2. Voltage stabilized power supply

Voltage stability is another important technology of vehicle DVR. Because the vehicle will burn, brake and step on the accelerator during the journey, these actions will cause the output voltage of the vehicle to fluctuate differently, which simply constitutes the burning of the vehicle DVR. Therefore, it is necessary for vehicle DVR to have wide voltage input to get used to this voltage change. At that time, the general choice of 6 to 36V wide voltage to meet the needs of mobile vehicles.

At the same time, we also need to pay attention to the fact that if the car bumps and suddenly goes out and the power supply is cut off, the on-board DVR will have the function of automatic power protection to ensure that the data in the hard disk will not be thrown away.

3. Heat dissipation

Because of the influence of environment and climate, the change of temperature difference is relatively large in the working process of vehicles.

This puts forward high demand for heat dissipation function of vehicle DVR. Therefore, if the heat dissipation function is not good, the life of the product will decline, and it will also affect the monitoring function. At that time, some products were heat dissipation through fans, and some were heat dissipation through fuselage. Therefore, when choosing to buy, it is better to work for a period of time, then measure the fuselage temperature, and watch the actual effect of the picture.

4. Picture clarity

The clarity of the picture directly affects the monitoring function, so when purchasing the product, it depends on which processing chip the product chooses, which compact format, and what resolution it supports. At that time, the product support was generally from CIF to D1, using D1 video, CIF transmission. To inquire about the actual effect, we need to record a video at different resolutions, inquire about the playback effect of the video, whether the picture is clear, whether there is delay.

5. Interface firmness

In the car, due to braking, acceleration, distance shaking, tremor is relatively large. If the interface is not strong, the wiring may drop at any time, causing the picture to tremble, the video to be thrown away, and the power to be thrown away. Therefore, when purchasing products, we should carefully inquire whether the interface is solid. Some manufacturers combine most of the interfaces on the back panel and replace them with a multi-needle interface, which bundles all the data lines together and plays an excellent role in the firmness of the interface.

6. Wireless transmission

In addition to providing local video and forensic information, vehicle-mounted DVR also needs to send the video information back to the control center in time, so that the control center can know the situation of the vehicle in time and deal with it jointly. Therefore, wireless transmission is particularly important.

At that time, mobile GPRS and Unicom's CDMA network were the first choice. However, due to the bandwidth and cost, real-time transmission could not be achieved, and only 5-7 frames in CIF format could be transmitted in one second. Therefore, users can check whether the transmitted pictures are clearly circulated in the control center.

7, waterproof

Vehicles are usually cleaned every day, especially on buses. After the bus arrives at the station, the staff will use water to wash the carriage. If the waterproofing function is not good enough, the water droplets may enter the cabinet. When the vehicle burns, the equipment may be burned down. Therefore, the waterproofing function of DVR can not be neglected.

8. Dustproof

Dust is indispensable for passengers to get up and down during the bus trek. Therefore, there is also a high demand for dust-proof products. When choosing products, users should try to choose products with completely closed shell and good interface sealing. Prevent dust from entering into the cabinet and affect the stability of the product.

9. Delicacy

Vehicle DVR products are looking for miniaturization plans, which are not only exquisite appearance, but also to meet the narrow equipment environment in the car. Because the models of large buses, small buses and private cars are different, and the space inside the car is also very different, so when choosing products, we need to choose different scales of on-board DVR according to the model.

10. High Integration

Vehicle DVR is not only a single product, not just a camera for surveillance and video, but also should have a rich interface, which can be integrated in some large projects, so that the space will be larger.

So you can check whether the interface is rich, whether it provides some protocols, whether it is convenient to upgrade, whether it is compatible with access channels.

11, hard disk

Generally speaking, hard disk space should be large enough, otherwise there will be no space in less than a month.

There is also an interface to copy the data directly without disassembling the machine. Together, in order to meet the needs of customers, the quality of hard disk must be reliable, can not be used less than a month to break down.

12. Alarm Settings

Vehicles have always been the blind spot in the monitoring area, and the vehicle-mounted DVR just makes up for this gap. Therefore, in addition to video recording, vehicle DVR should also have alarm function. When something happens on the vehicle, the alarm signal can be uploaded to the control center through the alarm equipment in the vehicle. The control center knows the situation in time, and jointly dispatches. Therefore, we can inquire whether the vehicle DVR has the functions of open door video recording and alarm video recording.

13. GPS Positioning System

GPS positioning system is very important for buses, police vehicles and banknotes. It can implement uniform distribution and timely grasp the detailed orientation of vehicles. At that time, most vehicle-mounted DVRs were only used as single computers, but the products reserved the interface of GPS and other functional modules. Through the interface, the GPS positioning module can be equipped to complete the satellite positioning and remote control.

14. Black Box

Black box, also known as "vehicle trek recorder", is one of the important functions of vehicle DVR. It can record all the data of the whole working process of the motor vehicle, and complete the handling and supervision of the driver through the supporting computer software. When the vehicle speeds or other violations occur, the black box will transmit the information to the control center and play an early warning role.

15. Media Playing

In the past, vehicle-mounted DVR mainly used video recordings, but now it has diversified functions. Playing entertainment programs can not only meet the entertainment needs of passengers, but also bring new business opportunities for operators. This function can accept radio and TV signals, can pre-store DVD, VCD and other entertainment programs, and can insert advertisements.

Author: Hangzhou Water Shield Technology Co., Ltd.

Website: http://www.zjhzjd.com/

Key words: pharmaceutical pure water equipment, chemical industry water equipment, food water equipment