Intercom connection type
Type of connection with additional monitors (see "Number of monitors") supported by the intercom
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Consistent. With this type of connection, all external security devices — calling panels, cameras, locks, etc. — are connected only to the main intercom. Additional monitors used in the system are connected in a "chain", one after another, and work only through the main unit; you cannot connect security equipment directly to an additional monitor. With this format of operation, the number of security devices is limited by the capabilities of the main intercom, but they can be accessed from any system monitor.
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Parallel. Like serial, this option assumes the presence of a main intercom and additional monitors. The key difference lies in the fact that you can connect your own video cameras to each controlled monitor, which will be controlled only from this monitor. This option is convenient when organizing security systems with several separate video surveillance zones: for example, the main monitor can be installed at the main entrance, and the additional monitor at the service entrance, and each of them will only work with the camera above the corresponding door.
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.
Display support
The number of additional monitors that can be connected to the intercom at the same time.
This function is relevant only for video-enabled models — video intercoms and IP intercoms (see “Device type”). In such models, the intercom itself is called a monitor — an indoor unit with a screen. This paragraph indicates how many additional indoor units can be connected to this model. The need for such a connection arises in cases where access to the security system must be provided from several points at once — for example, in a private house on several floors, where it would be inconvenient to run from floor to floor to the intercom. In this case,
intercoms with access to 3 monitors,
4 monitors or more are appropriate.
Note that the format of multiple monitors working together may be different, see "Connection Type" for more details.
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.
More features
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Android OS. The advantages of the Android OS include flexibility, which allows you to install third-party applications, thereby increasing the functionality of the device. Such applications may include SIP phones, programs that allow video surveillance, and others. But it is worth noting that such devices are not very suitable for the role of using a full-fledged tablet; firstly, most have a stationary location, and secondly, as a rule, the power of intercoms is not so high. Also, various restrictions may be set separately by the manufacturer; this must be clarified separately.
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Wi-Fi module. The Wi-Fi wireless communication module is found only in
IP intercoms(see “Device type”). This function allows the device to connect to the network wirelessly - this is much more convenient than pulling cables, and the quality of communication is usually indistinguishable from a wired one. Another option for using Wi-Fi is a direct communication to a smartphone or tablet and using such a gadget as a remote control with an external screen; however, such an opportunity is provided relatively rarely.
- Mobile app. This feature means that the device can be operated via a smartphone or tablet with a special application installed on it. Such applications are usually released immediately for both of the most popular mobile operating systems today - Android an
...d iOS; however, it would not hurt to clarify this point separately. In any case, control from a mobile device can have very extensive functionality (including even the ability to work via the Internet, in some models); and interacting with a device through a gadget that you can always keep with you is definitely more convenient than going to an intercom or other stationary equipment every time.
— SIP protocol. The intercom's support for the SIP protocol allows the intercom to redirect the signal from the calling panel through the telephone network to a mobile device, a stationary PBX or a computer with the appropriate software. Such a function may be useful, for example, in an office where there are a lot of visitors, and going up to the intercom every time to answer is inconvenient. Additional SIP capabilities in different models may vary significantly; they should be clarified separately.
- DVR support. The ability to operate the intercom in video recording mode from calling panels or from separate surveillance cameras. In most of these models, recording is not carried out constantly, but only when the call button is pressed or another event occurs - for example, a motion detector is triggered (see below). Video is most often saved to a memory card (see “Card Reader” below). In any case, this function allows you to find out who called the intercom at “inopportune hours”; it can also be useful in other situations - even to restore the picture of an emergency that came into view of the cameras.
— Internal communication (Intercom). This function allows you to make calls between intercoms on the same network. Depending on the implementation and settings, there is an addressable intercom, when you enter the number (identifier) of the device on the network to which you want to make a call, as well as options for setting up a general call, when the call goes to all devices on the network. In any case, this function will be useful if there are several intercoms in the network, so you can call, for example, a neighbor.
- Speakerphone. A hands-free function similar to that found in telephones. In this mode, a loud speaker and a sensitive microphone are used for conversation, located in the intercom body and allowing you to communicate comfortably at some distance from the device (up to a meter, or even more). This function is especially important for models with a handset (see “Execution”) - it allows you to talk without holding the handset. But devices without a handset, by definition, operate in a hands-free format.
- A voice message. An analogue of the answering machine function in phones, when the subscriber can leave a message if the owner of the intercom does not respond to the call. The function can be implemented in different ways, but in any case it is similar to the one with the usual expression: “Leave your message after the sound signal...”.
— Picture in picture. The ability to display a second image on the intercom screen, in addition to the main image. In this way, you can, for example, check the situation in the visibility range of a surveillance camera without interrupting communication with the visitor via the main video panel. The additional picture is small in size and is usually displayed in one of the corners of the screen.
- Motion Detector. A function that allows the intercom to detect movement in the visibility range of connected cameras and respond to it. The specific method of such a reaction may be different in different models: turning on recording, sending a notification to a user-specified device, sending a signal to an alarm output, etc.; These details should be clarified separately. In any case, the motion detector reduces the likelihood of missing significant events in the field of view of the cameras.
— Built-in memory. Built-in memory is found in video and IP intercoms (see “Device type”) and is usually intended for storing data from surveillance cameras. However, the volume of such memory is usually small, and it is usually used only for photographs (for example, to capture the faces of visitors); Video recording, if provided, is carried out on a memory card (see below). In any case, it would not hurt to clarify the operating features of the built-in memory separately.
- Frame. The ability to operate the intercom in digital photo frame mode - when photographs stored in the device’s memory (or stored on a memory card) are displayed on the screen (usually in slideshow mode). A mandatory feature of models with this function is a fairly large color screen - only on it photos will be normally visible; The intercoms themselves are usually video or IP models. The main purpose of the photo frame mode is aesthetic: showing beautiful pictures, the intercom plays the role of additional decor for the number.Screen resolution
Resolution of the display installed in the intercom.
All other things being equal, a higher resolution provides a smoother and more detailed image, but it does affect the cost of the screen. In addition, all the benefits of high resolution are lost if the camera you are using does not support it. In general, this parameter is secondary: it is selected by the manufacturer based on the screen diagonal and the general functionality of the device, and for many screens it is not indicated at all - it is believed (and quite reasonably) that the resolution is in any case sufficient for its intended use. Therefore, there is no point in chasing
a Full HD screen ;
an HD display, or even
an SD one, will be enough.
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).