📹 How to choose a video camera for surveillance: features, overview of models

What is a video surveillance system

The simplest video surveillance system can only consist of one camera. For example, car cam - the simplest example of an autonomous video surveillance system with recording.

To organize monitoring of large areas - shopping centers, industrial facilities and construction sites, the system can be a chain of video cameras with a central hub. Most often, the central hub is just a computer with cameras connected to it. In any case, even in the most complex configuration, a video camera is the main component on which the quality of the resulting image and the reliability of the surveillance system as a whole depend.

How to choose a camera for video surveillance

Cameras differ in several basic parameters, on which the performance of the system, its reliability and the final cost depend. These parameters become most relevant when you need to scale an existing surveillance system. And to know what exactly is worth connecting and what is not is extremely important.

By type of signal transmission

This criterion is very complex and confusing. Many different standards, algorithms and approaches have already been invented, with the help of which a signal is transmitted. Well, let's figure it out.

There are two main ways to transmit a video signal: digital and analog. In analog transmission, the image is converted into an analog signal, that is, it continuously changes over time in a certain range. For clarity, it is most often displayed as a sinusoid. The simplest example is analog television, which we could receive earlier with any antenna.

The digital signal is transmitted using a sequence of time-separated codes. This is a more modern type of data transfer that is capable of delivering high quality and scalable for any need. IP cameras work just like that. Actually, when they talk about digital video surveillance, they most often mean them.

Until recently, the analog method of data transmission was slowly fading away, as it ceased to meet modern video quality standards. For example, he could not transmit a signal in HD, Full HD, and even more so 4K. Nevertheless, there are still many video surveillance systems in the world, the entire infrastructure of which is based on analog transmission. Therefore, new high definition formats were created. Now the market is dominated by 3 main standards: HDCVI, HDTVI and AHD.

The first is a Dahua development, a completely closed technology based on luma-chroma separation quadrature amplitude modulation. Due to the fact that the format is patented, in order to start producing compatible equipment, you need to go through licensing from the developer. And this affects the final cost of the product and, in some way, limits the possibilities for expanding surveillance systems.

HDTVI is an open standard with limitations. Like HDCVI, it uses separation into luminance and chromaticity, but the algorithm for eliminating interference and increasing clarity has already been developed by Hikvision. Actually, she is mainly engaged in promoting the format. HDTVI is interesting for its hybridity - you can use both IP and analog cameras in a common system. True, you need a hardware video encoder, which will add additional costs.

AHD is the most open format of them all. Moreover, it can simultaneously work with all types of equipment - simple analog, digital or high definition analog. That is, this free technology is the best solution for a system that is planned to be constantly expanded and modified.

With the advent of analog high definition technology, image quality has become almost the same between analog and digital.

At the place of installation

Cameras intended for external use are equipped with special protective covers that protect against the harmful effects of rain, temperature and sun. For very low temperatures, a built-in heating mechanism can be used. Well, for indoor use, you can buy a simple model of the device.

By body type

There are a lot of body types, each of which is designed to solve a narrow problem.

Here is a short list of the main types:

• modular. It is simply a camera module that is available inside any model with a housing. This type opens up great opportunities for integration into almost every existing or just emerging system. In fact, this is a part of the constructor that can be connected to anything - home surveillance, video peepholes, surveillance of the outer perimeter;
• cylindrical chambers. They have a ready-made body and a mounting system, mainly to the ceiling. Can be equipped with a rain cover. The fastening mechanism allows you to set the desired fixed angle;
• domed. Outwardly, it looks like a hemisphere made of plastic, with a modular camera placed inside. They are very often found in entrances and other internal premises;
• peephole. It has the shape of an eyelet. Designed for installation in the entrance loops of the premises. Usually has a large viewing angle, but at the same time greatly distorts the picture, like a regular door peephole;
• anti-vandal cameras. Usually they have the shape of a sphere, a reinforced hull, protected from physical and natural influences. Installed in crowded places. Capable of withstanding significant physical stress;
• dummy. An interesting solution when you need to prevent illegal actions, but, at the same time, you want to save money. A dummy at a distance is practically indistinguishable from the original camera. It will make the criminal wonder whether it is worth doing something illegal.

By functionality

Probably the most interesting criterion. There is plenty to choose from here, since the functionality can be very different. These include Wi-Fi support, built-in modems for wireless transmission over mobile networks, offline recording to a flash drive, or the presence of a motion detector. In general, functionality usually varies in degree of convenience. Naturally, the more functionality, the more expensive the camera is.

By monochrome or color mode

Black-and-white cameras are cheaper than their color counterparts and are used in those systems where the very fact of the presence of movement or penetration is important, and the color does not play a special role. They can also be used for shooting at night, since there is still no color in infrared mode.

Colored should be installed where color matters. For example, in a parking lot, to determine the color of a car, in order to identify it, if necessary. Therefore, the field of application should also be taken into account when choosing. This will allow you to save money and choose the most optimal camera option.

By image quality

The quality of the surveillance camera transmits the picture depends on how accurately the object or the identity of the intruder can be identified. Despite the fact that the quality is considered to be the resolution of the camera, this is not entirely true. Quality is a combination of several parameters. We will list them:

• permission. Today even children know what resolution or the notorious “megapixels” is. This is the number of points to which the camera can transform the image. It is logical that the larger the number, the clearer and better the picture. The resolution limit for high definition analog cameras is 1920 × 1080 megapixels. Digital ones can transmit full-fledged 4K;
• photosensitivity. An important parameter for round-the-clock surveillance. If it is even simpler, then the light sensitivity is understood as the minimum amount of illumination in order for the camera to display the picture. Usually in model specifications it is measured in Lux. The dependence here is inversely proportional - the smaller the number, the greater the day-night range the camera will be able to shoot. For example, 20,000 lux corresponds approximately to a cloudy day, and a clear, moonless night corresponds to 0.001. That is, if we need to monitor only during the day, we can choose a model from 100 lux. In general, there are solutions with installed IR emitters and a special filter on the camera, which provide a good picture even in pitch darkness;
• dynamic range. Most often abbreviated as WDR. A device that supports this technology can automatically adjust the white and black levels in the picture when there is a high difference. That is, if there are areas with bright white and dark black in the picture, then WDR will align them in such a way that details on both black and white will be clearly distinguishable.

Popular outdoor camcorder models

Among similar models on the market, you can find products from both well-known brands and little-known Chinese companies.

The former are usually high-quality and tested devices, the reliability of which the manufacturer can guarantee. Naturally, they are more expensive. Chinese counterparts are, almost always, a pig in a poke. How long and how such a camera will last is unknown. But their cost is always pleasantly surprising.

Hikvision DS-2CD055FWD-I

An interesting model for organizing full-fledged round-the-clock video surveillance. Since the device is digital, its maximum resolution is 2560 × 1920 pixels. And in this mode, the camera is capable of recording video at 20 frames per second in one stream. By the way, about streams - there can be a maximum of 3. Additional technologies WDR, BLC and 3D DNR are responsible for image enhancement. The transition from night mode to day mode is automatic. An RJ-45 interface is provided for connection. You can also write data to a microSD flash drive with a capacity of up to 128 GB. The camera has smart analytics that can detect the intersection of permitted areas, as well as recognize faces in the frame. The camera can operate at temperatures ranging from -40 ° C to + 60 ° C. The approximate cost of the camera is about 12,000 rubles.

Hikvision DS-2CD055FWD-I

Dahua DH-SD22204T-GN

Digital video camera in a protective hemispherical casing with a rotary mechanism. The maximum resolution is 1920 × 1080 megapixels at 25 frames per second. Faster video at 50 frames per second can only be obtained at 720p resolution. The camera is equipped with an IR cut filter and has a high light sensitivity, which allows you to get an excellent picture even in the darkest time of the day. From the functionality, you can highlight the possibility of panoramic shooting and tilt. For remote monitoring, there are applications for Android and iOS platforms. The cost of the camera is 14,400 rubles.

Dahua DH-SD22204T-GN

HiWatch DS-I103

It can be said to be a budget camcorder for home use. Its cost is relatively low - 4300 rubles. For this money, the user will receive a good PTZ camera with a maximum resolution of 1280 × 720 pixels. The broadcast can go in two streams - the main one with a maximum resolution of 25 frames per second and an additional one - in a resolution of 640x480 megapixels. Day and night modes can be switched both automatically and according to a schedule. The camera is capable of responding to movement. Connection is possible via Ethernet interface. The permissible temperature range is from -40 ° C to + 60 ° C.

HiWatch DS-I103