In box
The main components and the number of their copies supplied as standard equipment.
— Intercom. This section specifies delivery options
with several internal units that can be connected to one call panel. Such a complete set will come in handy if it is necessary to establish a connection for several subscribers or install internal intercoms to service one subscriber, but at several points (for example, to organize an intercom or deploy equipment in a large house).
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With a call panel. The presence of a call panel directly in the intercom package. This option for supplying equipment eliminates the need to buy a call panel separately — the standard call device is most often optimally suited to a given intercom model, while difficulties may arise with the selection of a third-party panel.
— Number of subscribers. In this context, it is implied that several subscribers can be called from the complete call panel, and their specific number is indicated.
Number of ports
The total number of ports for wired connection of various equipment provided in the intercom; in fact — the maximum number of wired devices that can be simultaneously connected to the intercom.
Keep in mind that this number may be less than the total amount of supported devices. This is especially true in models with the possibility of using additional monitors (see "Connected monitors"): such devices are often connected in series, "chained" and occupy only 1 port. Thus, for example, an intercom for 2 calling panels and 3 monitors can have only 3 connectors — one for calling panels and one for monitors. Note also that the LAN port in IP intercoms (see "Device type") is also taken into account in this calculation.
Alarm inputs
The number of
alarm inputs provided in the design of the intercom.
Such inputs allow the intercom to receive service signals from other elements of the security system — various sensors (motion, opening, temperature), cameras and video surveillance recorders, etc. This provides additional features for setting up the security system for certain events: for example, you can provide automatic activation of the video intercom camera when an opening sensor on an external wicket or gate is triggered. The specific functionality of alarm inputs for each model should be specified separately; however, anyway, such connectors allow you to increase automation and reduce dependence on the human factor. And the number of such inputs corresponds to the number of control components of the security system, which can be simultaneously connected to the intercom directly, without the use of additional equipment. Most often, it ranges from 3 to 8, and in some models it reaches one and a half dozen.
Half duplex
In this case,
half-duplex communication means such a communication format in which the interlocutors cannot simultaneously speak and listen to each other. Only one of them can speak at a time, like talking on a walkie-talkie, where you have to constantly switch from transmitting to receiving and vice versa. In intercoms, such switching can be carried out both with a button and with the help of voice activation: the system turns on the transmission when it hears the voice of the speaker, and switches to reception when it does not hear it.
Half-duplex models are not as convenient as full-duplex models (with the possibility of simultaneous talking), but they are somewhat cheaper.
Operating temperature
The temperature range at which the intercom is able to work normally.
If the device is installed in a residential area or office, you can not pay much attention to this parameter: the temperature in such an environment rarely goes beyond +18 ... +25 °C, such values are normally tolerated by any intercom. But if the device needs to be placed in a "non-standard" microclimate — for example, an unheated warehouse, where conditions do not differ much from outdoor ones, or a production workshop with a high temperature — you should make sure that the chosen model can normally endure such conditions.
Separately, we note that even the most “heat-resistant” intercom cannot be exposed to prolonged exposure to sunlight.
Night shooting (IR)
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.
Video resolution (TVL)
Resolution of the image produced by the camera of the video panel (see "Type").
In such cameras, an analogue signal format is often used, and for it the resolution is usually denoted not in pixels, but in TVL — TV lines. The number of TVL displays how many horizontal lines (lines) will fall on each frame. This number, in turn, determines the size of the final image in pixels; the technical features of this parameter are such that there is no rigid dependence here, and it is easiest to convert TVL to pixels using special tables. Here is a variant of such a table for the most popular resolutions:
— 380 TVL — 640x480 pixels;
— 420 TVL — 720x576 pixels;
— 480 TVL — 800x600 pixels;
— 560 TVL — 933x700 pixels;
— 600 TVL — 1024x756 pixels;
— 800 TVL — 1080x960 px;
— 1000 TVL — 1600x1200 pixels;
The higher the resolution of the camera, the clearer and more detailed the image from it will be, and the higher the cost of the video panel, all other things being equal.
Horizontal viewing angle
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).
Operating temperature
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.
