In the past two years, a variety of car DVRs (car DVRs) have appeared on the market. As a market segment of traditional embedded DVRs, car DVRs (definition of car DVRs) have also ushered in many security. The pros and cons of the enterprise.
The car DVR in the security industry is said to be a new product of the era, but the technical content, I am afraid that only those who have actually done a car DVR can understand. 
First, what is the difference between a car DVR and an ordinary DVR?
Ordinary hard disk recorders use 220V alternating current, the stability of voltage and current is relatively stable, and then because the location of ordinary hard disk recorders is fixed, there is almost no relative vibration opportunity, so the seismic function of ordinary hard disk recorders can be neglected. But the car DVR is different. First of all, the voltage and current on the car can not be understood according to the conventional idea, the voltage on the car is 12/24V, but in fact, the 12V car can not be regulated by 12V, the same is the 24V, so the design of the power board It is important that the power board is designed with many aspects in mind.
Second, how to design the power supply of the car DVR?
In order to ensure the normal operation of the car DVR, first ensure that the output power of the power board is stable.
In a fixed narrow voltage environment, since the input voltage and current are basically stable, and the electrical output determines the input power, the power of the ordinary hard disk recorder only needs one adapter. One adapter is nothing more than a transformer plus A filter circuit, a little conscience plus a protection circuit, no conscience protection circuit is not installed, cheap, so the average DVR cost and maintenance costs are relatively low.
But for the car DVR, the first thing to do is to narrow the dynamic voltage and current. How to ensure that the car DVR works normally, stable voltage and current are very important, but on the other hand, the input power of the device is fixed. It can be known from W=U*I that the current is also changing when the voltage changes. The direction of current change is always the opposite. So if the starting voltage is made lower, the relative starting current will increase. On the macro level, it is so simple, but it can do this function stably and ensure the normal operation of the equipment. It takes a lot of work. The first thing to do is to protect the circuit design. You must know that the power supply board of the car DVR is within 1 hour. After experiencing hundreds of impacts, the protection circuit is not doing well, but the power board is damaged, and the board is burned directly by the power board.
Third, how is the anti-shock of the car DVR designed?
The seismic design of the car DVR is very important. To put it bluntly, it is actually how to protect the hard disk. Because the current hard disk is a mechanical hinge hard disk, the distance between the head and the disk is only a few micrometers. If you look at the head with the naked eye, the head is attached to the disk, but even if you don't understand the hard disk, you should understand that 5400 The rotating hard disk needs to be rotated at least 90 times per second. If the head is attached to the top, it will not be used for a long time, and the head will be worn away. Such a close distance, if the earthquake is not good, as long as the head has a little bit of vibration, light hard disk bad, heavy head and head crash (hard disk terminology). So hardware shock resistance is very important.
Fourth, the car DVR hard drive fault correction is how to design?
A: The fault tolerance and error correction capability of the hard disk is a problem that has been solved in the IT hardware industry or the software industry since the hard disk was available. For an embedded system, it is very difficult to achieve a perfect fault-tolerant error correction design! But the design of the embedded system is intended: the embedded system is originally designed to pursue better stability and speed of execution, but there is a problem that cannot be ignored is the poor portability, which makes it impossible to design once it is too Big change. So its first design idea is very important. Embedded systems for fault tolerance correction of hard disks, the current effective way is read and write control capabilities.
Car DVR purchase standard
First, anti-vibration
Although the embedded system is the same as the ordinary DVR, the car DVR technology is more complicated than the ordinary DVR, and the key to be solved is different. Therefore, the two are two completely different concepts. Vehicle DVR is applied to mobile vehicles. Due to different vehicle conditions and road conditions, the vibration is relatively large, which has a great impact on the hard disk read and write data, and the damage to the equipment is very large. Therefore, seismic technology has become the most basic requirement for vehicle DVRs. At present, there are mainly measures such as shock absorption of the whole machine, shock absorption of the hard disk frame, and shock absorption of the hard disk.
In the security industry, the current vehicle DVR market is still chaotic, and users' awareness is not deep. Therefore, it is often found that ordinary DVRs pretend to be vehicle DVRs. Therefore, the specific actual effect needs to be personally examined to know.
Second, the regulated power supply
Voltage stability is another important technology for in-vehicle DVRs. Since the vehicle may have ignition, braking, stepping on the throttle, etc. during driving, these behaviors may cause fluctuations in the output voltage of the vehicle, which may easily cause the vehicle DVR to burn out. Therefore, the onboard DVR must have a wide voltage input capability to accommodate this voltage change. At present, a wide voltage of 6 to 36 V is usually used to meet the needs of mobile vehicles.
At the same time, it should be noted that if the vehicle suddenly collides and the vehicle is powered off, the vehicle DVR should have the function of automatic power protection to ensure that the data in the hard disk will not be lost.
Third, heat dissipation
Due to the influence of the environment and the weather during the operation of the vehicle, the temperature difference changes greatly.
This puts high demands on the heat dissipation performance of the vehicle DVR. Therefore, if the heat dissipation performance is not good, the life of the product will be reduced, and the monitoring effect will also be affected. At present, some products are cooled by fans, and some are cooled by the fuselage. Therefore, when purchasing, it is best to run for a while, then measure the body temperature and watch the actual effect of the image.
Fourth, image clarity
The clarity of the image directly affects the monitoring effect. Therefore, when purchasing the product, it depends on which processing chip is used, which compression format, and what resolution is supported? At present, the product support is generally CIF to D1, using D1 video, CIF transmission. To observe the actual effect, you need to record a video at different resolutions, observe the video playback effect, whether the picture is clear, and whether there is a delay.
Fine Chemicals,Dyclonine Hydrochloride,Pinane Hydroperoxide,Ferrous Oxalate
Henan Tianfu Chemical Co.,Ltd , https://www.tianfuchem.com