Comparison Dahua DHI-VTO6521H vs Dahua DHI-VTO6221E-P

Call panel installation method.

— Mounted. Installation by hanging from fixtures placed on a wall, door frame, or other suitable location. This method is quite simple, besides, it allows you to relatively easily change the location of the device. On the other hand, it is less reliable than embedding, and it is easier for hooligans or thieves to rip such a panel from its attachment point.

— Embedded. Installation in a niche in a wall or other surface — in such a way that only the front side of the device is outside. and any movement of the device is also fraught with serious difficulties. Nevertheless, it also has advantages: it is almost impossible to remove the call panel from a niche without a special tool, and even with tools, this task takes time and effort.

— Mounted / built-in. This category includes outdoor panels that allow both of the installation options described above. Thus, the user can independently choose a method, depending on what is more important in this case: ease of installation or its reliability.

This protection describes how much the calling panel body. Protects sensitive internal components from dust and moisture. Standardly, it is designated by the letters IP with two numbers after them IP44, IP65, etc. The first digit means protection against penetration of solid objects and dust; its individual values correspond to the following levels of protection:

4 - protection against objects with a diameter of more than 1 mm
5 - dust protection (complete protection from contact; dust can penetrate inside, but does not affect the operation of the device)
6 — dust-tight (the housing is fully protected from dust and contact). br>Smaller values do not occur and there is no point in indicating them.

The second number characterizes protection against moisture, here the values can be as follows:


4 - protection against splashes from any direction;
5 - from jets from any direction;
6 - from sea waves or strong water jets;
7 - possibility of short-term immersion to a depth of up to 1 m (without the possibility of constant operation in submerged mode);

Of course, calling panels are not designed to be submerged under water - the latter option only characterizes a high degree of moisture resistance.

In some models, one of the numbers may be replaced by the letter X - for example, IPX7. This does not mean that there is no protection, but that the corresponding parameter is not IP certified. At the same tim...e, the degree of uncertified protection can be quite high - for example, the example above corresponds to the possibility of complete immersion under water, which requires a high degree of closure (at least dust resistance level 5).

The range of air temperatures in which the call panel maintains normal performance.

Outdoor panels installed outdoors and in unheated rooms are subject to the greatest temperature fluctuations, therefore, it is with this installation that this parameter should be paid special attention. At the same time, we note that even the most “heat-resistant” models must be protected from sunlight. If the conditions in the room are comfortable for people all year round, then they will be quite normal for the call panel, in such cases you can not look at the operating temperature at all.

Camera sensor resolution in megapixels (millions of pixels).

The higher the resolution of the matrix, the higher the video resolution can be, the more detailed the image is capable of providing the camera. At the same time, note that as the number of megapixels increases (without changing the size of the matrix), the size of each individual pixel decreases, which increases the likelihood of noise and deterioration in the overall image quality. Therefore, in itself, high resolution is not necessarily a sign of high quality — a lot depends on other points, in particular, on the size of the matrix.

The maximum video resolution that the camera can record.

The higher the video resolution, the more details you can see on it, the fewer little details will be blurred. On the other hand, high resolution means large volumes of video materials, which, accordingly, requires capacious media for storing them and fast communication channels for broadcasting video in real time. One of the popular resolutions in calling panel cameras is Full HD (1920x1080 pixels).

The horizontal viewing angle provided by the camera on the entry panel of the intercom.

This parameter has a double meaning: other things being equal, a wider field of view allows you to cover more space, but reduces the size of individual objects in the frame. So it’s worth choosing according to this indicator, taking into account what is more important for you — good visibility on the sides or an additional degree of increase. As for specific values, in modern outdoor panels they can vary from 50° (directional cameras) to 166° (ultra wide-angle lenses with a minimum of dead zones on the sides).

The vertical size of the space covered by the video panel camera, in other words, the angle between the two lines connecting the lens with the top and bottom edges of the viewed scene. The meaning of viewing angles is described in detail above in paragraph “Viewing angles horizontally”; we only note that they are usually smaller vertically than horizontally, and in many models this parameter is not indicated at all due to its secondary importance.

Possibility of operation of the camera, which is equipped with a video panel (see "Type"), in the night shooting mode, using infrared illumination. Such illumination is invisible to the human eye, but it is perfectly perceived by the camera sensor. It allows you to get a clear picture without using visible light sources and arranging unnecessary "illumination" — except that the colours in such an image are lost, it turns out to be black and white.

LED backlight. The camera has a video panel (see "Type") with LED backlight. Like the infrared one described above, this backlight is designed to work in the dark; however, it provides light visible to the human eye. The latter, on the one hand, allows the camera to produce a relatively natural colour image, on the other hand, it can create inconvenience for the guest due to bright light in the eyes.