Display size
Diagonal size of the intercom's own display.
In modern intercoms, there are displays ranging in size from 2 "to 10" —
smaller screens are non-functional, larger ones are unreasonably bulky and expensive. At the same time, you can normally view the image on almost any display from this range — if you lean close enough to it.
With all this in mind, it makes sense to specifically look for
a large screen (10 ") if you need to see it normally from a long distance (a metre or more), or if you do not want to strain your eyes once again, peering into a small image. Golden the middle is
the 7" display.
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.
Connectable surveillance cameras
The number of video cameras that can be simultaneously connected to the intercom. The mode of operation with these cameras can be different — a mosaic of several signals at once, switching between signals with each one displayed on the full screen, etc. However, anyway, to work with several video cameras, it is desirable that their corresponding number be directly claimed in the intercom — otherwise you will have to resort to installing additional equipment.
The simplest modern intercoms allow the connection
of 1 or
2 cameras, in more advanced ones this number can reach
4 or
more.
Consumption (standby)
The amount of energy consumed by the intercom in standby mode. In this mode, the device is energized and is in a state of readiness to receive a call; no functions are used, and the readiness itself does not require a lot of energy. Therefore, the value of this parameter, usually, is rather low, and you should pay attention to it only if you fundamentally strive for maximum efficiency of the installed equipment.
Consumption (during operation)
Power consumption of the intercom in the operating mode. Usually, this item indicates the value for situations where the device's functions are used to the fullest — in particular, when the display is on and the speakerphone is on (if any, see above). Note that the consumption in the operating mode rarely exceeds 20 W, so in most cases it is more of a reference, and not a practically significant parameter.
