BySigismondo Eisenhower 2019-07-24 293
In the selection and purchase of smart security cameras, we should focus on the following aspects.
Angle of view is the field of view of the camera, which is mainly determined by the focal length of the lens. Common 2.8mm, 4mm, 6mm and other different focal lengths, the larger the focal length, the smaller the angle of view.
Because the concept of focal length is not intuitive enough for ordinary users, intelligent security cameras usually mark the range of gaze angle and the distance suitable for monitoring (mainly refers to the distance that can see the 1.8m height of human objects).
The bigger the viewing angle is, the more objects can be seen at the same distance, and the larger the scope of the picture is. However, the general picture distortion is more serious, and the ability to distinguish small and medium objects in the picture is worse. The smaller the viewing angle is, the fewer objects are seen and the smaller the scope of the picture is, the stronger the ability to distinguish the small and medium objects in the picture is. Therefore, for the perspective, we should choose according to the scope of our own monitoring, rather than simply the bigger the better or the smaller the better.
Resolution refers to the pixel density of the camera, which largely determines the clarity of the camera (the size of the sensor also determines the clarity of the camera), so it can be said that it is the most important performance parameter. At present, the common resolutions of smart security cameras on the market are 480p, 720p, 960p and 1080p. Their clarity increases in turn. At present, 480p smart security cameras are mostly used in low-end entry products. The picture resolution is about 640*480 pixels. They have low clarity, blurred picture and low price. Unless the budget is very tight, it is generally not recommended to choose them. The mainstream products on the market are 720p and 1080p, both of which have good clarity. Of course, 1080p is better than 1080p. The resolution is generally around 1920*1080, which is what we usually call "full HD". The price is the highest and the effect is the best.
It should be noted that different resolutions have different requirements for network and storage. The higher the resolution, the more storage space occupied by the same time video, the higher the network transmission rate required for stable transmission. For the same length video, 720p data is about three times as much as 480p data and 1080p data is about 2.3 times as much as 720p data.
The function of the platform is to allow the camera to rotate from top to bottom, so that it can use the camera to view larger areas. Some of the platform cameras can rotate 360 degrees, that is to say, the front and rear of the camera can rotate through the platform to achieve video surveillance. The camera with a platform is more flexible, but it can only monitor one position at the same time. Although patrol inspection (automatic rotation monitoring) can be achieved, it is impossible to monitor around the same time, and there will be omissions. Therefore, the panoramic camera is not suitable for all-weather monitoring areas.
There are three main storage modes for smart security camera data. One is local storage, the other is local NAS or hard disk video recorder storage, and the other is cloud storage.
The local storage is the simplest. It can be realized by inserting a memory card into the camera body. It does not need to occupy network bandwidth. The disadvantage is that when the camera is lost, the video will also be lost and may leak, so the security is not strong enough.
Local NAS or hard disk recorders (NVR) store video data from cameras in NAS or hard disk recorders in the same LAN. When the bandwidth of the LAN is occupied, the loss of cameras will not lead to video loss. However, NAS or hard disk recorders need to be added, which is suitable for users with NAS or hard disk recorders.
Cloud storage is the real-time upload of video data from cameras to cloud servers. It takes up broadband network bandwidth in the home. At the same time, because it takes up storage space of vendor servers, cloud storage generally needs to pay. Its advantage lies in the security of data storage, even if the home camera is lost and the hard disk recorder is damaged, it will not affect the camera data.
The three storage modes have their advantages and disadvantages. Most intelligent security cameras also support two or three storage modes. Users can choose one or more storage methods according to their own needs.
The storage time of the video can be calculated according to the code rate of the camera and the capacity of the storage medium. In the case of normal video recording, the code rate of 1.5Mb/s after compression of a camera is taken as an example. The data amount of a day is 1.5Mb*24 hours*3600 seconds=16200MB, that is 16.2GB. If using 1T hard disk, the recording time can be 1000G_16.2=61.7 days. Of course, when the mobile surveillance video is turned on, the still picture will not be recorded, and the recording time can be greatly prolonged.
Intelligent security cameras can be divided into wired intelligent security cameras and wireless intelligent security cameras. Wired smart security cameras need special wiring to connect cameras and switches. Generally, the camera can use POE mode to supply power, that is, a network cable, while transmitting data to the camera, which requires the camera, switch support POE function, and the POE power supply capacity of the switch can meet the needs of (multiple) cameras.
If POE power supply is not available, the cable camera needs to be equipped with power cord and network cable. The advantage of wired camera is that it does not occupy WiFi bandwidth and the wired transmission is more stable. Wireless cameras need only access to power supply, WiFi connection network, as long as reserved power supply, installation and use are more convenient, but WiFi bandwidth is occupied, and transmission stability is slightly lower than wired mode.
Mobile detection means that the camera can automatically identify the moving objects in the snapshot screen, so as to achieve security alarm and reduce the amount of data stored. At present, the mainstream intelligent security cameras have mobile detection function, and the sensitivity of mobile detection function can be set. Mobile detection has strong practicability in the application of home, shop, baby and so on. With some software, it can also realize the functions of capturing mobile photos and sending them to APP or Wechat.
The main problem of mobile detection is that it is easy to be triggered by mistake, such as the change of light and shadow, the movement of trees caused by wind, and the movement of pets. Therefore, some intelligent security cameras have introduced the human detection function, that is, they can detect human-shaped mobile objects, which greatly reduces the false trigger rate.
Some intelligent security cameras with panels also have mobile tracking function, which is to find moving objects in the picture area. When moving out of the picture, they can control the rotation of the panels to lock moving objects in the picture. To some extent, this function enlarges the monitoring ability of the camera on the platform. Although there are not many cameras equipped with this function at present, friends in need can consider it.
The night vision ability of the camera can be achieved in two ways, one is a high-sensitivity sensor, which is often called a star-level camera, and the other is the use of infrared supplementary light. Intelligent security cameras commonly used in families are usually realized by infrared light supplement. In the night or when the brightness is dark, the camera can not receive enough light, so it can turn on the infrared supplementary lamp. Because human can not see infrared light, this light will not affect people. The camera can automatically remove the infrared filter in front of the lens to receive infrared light for night vision.
Under night vision, because the image monitored by the camera is reflected infrared, the color information of the object is lost and the black-and-white image is recorded, but the functions of mobile detection can be used normally.
Maximum infrared distance is an important parameter in night vision, which mainly shows how far objects can be seen by the camera at night.
Star-level camera can still get good picture quality and color information when its brightness is very low, even close to 0. It is mostly used in professional monitoring system.
Intelligent security cameras generally have voice intercom function, remote through the mobile phone APP can see the camera pictures and voice, while voice transmission to the camera to play. Early voice intercom function is relatively weak, the ability of video cameras to play voice is relatively poor, the effect is not good, but now the mainstream products on the market in voice intercom has been very practical, and it is very convenient for friends who need it.
For smart security cameras, although most of them are used indoors, there are many requirements for outdoor use. One thing to note here is that the protection requirements for cameras in outdoor and indoor environments are different. Cameras used indoors generally do not have the ability of waterproof and dust-proof, so they can not be used outdoors. Outdoor cameras generally have the ability of waterproof and dust-proof. The protection level is IP65 or higher, which is enough to cope with the outdoor rain, snow, dust and so on. Of course, the manufacturing cost is higher, and the price is more expensive than the indoor cameras with the same performance. They can be used both outdoors and indoors.
Today, when privacy is not well protected, the risk of privacy leak is aggravated by the camera. It is common for the camera to be cracked. For home security, the security of the camera must be guaranteed. To improve the security of camera, the most powerful means is encryption transmission. Camera products of mainstream manufacturers all have the ability of encryption transmission. Security can be guaranteed without losing passwords. But some cheaper early products do not have the ability of encryption transmission. Therefore, when choosing and purchasing, we must pay attention to the purchase of encrypted transmission power. Capable cameras, while setting complex passwords to prevent password leakage.
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