Comparison Dahua DH-VTH5221D vs Dahua DH-VTH1550CH

Ways to connect devices.

— Wired. Connecting intercom system components through cables ensures stable and reliable signal transmission. In such a connection, a regular wire is used to connect the outdoor call panel with the indoor panel located inside the building. Wired connections provide high-quality sound and image, minimizing interference, and are ideal for stable system operation over long distances. This also enhances security, as wired connections are less susceptible to external influences compared to wireless solutions.

— LAN (RJ-45). Connection via RJ-45 port using an Ethernet-type network cable ("twisted pair"). This option is convenient as devices can be connected to a local computer network, providing several advantages. First, access can be configured on any computer or gadget within the network. Second, many such models can operate without intercoms and other specialized equipment — through an application on a computer/gadget. Third, laying the network cable from the panel to the router/switch is often easier than organizing an analog connection. Fourth, the number of panels and other specialized equipment within the "local network" can be almost unlimited — for example, all the call panels of an apartment building or a large office center can be connected into one network. Additionally, access to the call panel can even be set up via the Internet if desired, providing...

— Wi-Fi. Connection via the wireless Wi-Fi standard. Thi...s option provides nearly all the capabilities of the aforementioned LAN (RJ-45), but has certain differences. The most noticeable is the lack of cables, significantly simplifying installation and connection. Even relatively modest Wi-Fi devices are powerful enough to operate confidently over distances of a couple dozen meters or through 1-2 medium-thickness walls. The most functional and thus the most popular type of analog wired connection. Suitable even for high-end video panels, though it actually appears in all categories of devices — from budget to top-tier.

— RJ-45. Connection via RJ-45 port using an Ethernet-type network cable ("twisted pair"). This option is convenient as the call panel can be connected to a local computer network, providing several advantages. First, access to the panel can be configured on any computer or gadget within the network. Second, many similar models can operate without intercoms and other special equipment — through an application on a computer/gadget. Third, laying the network cable from the panel to the router/switch is often easier than organizing an analog connection (e.g., using 4 wires — see above). Fourth, the number of panels and other special equipment within the "local network" can be almost unlimited — for example, all call panels of an apartment building or large office center can be connected into one network. Furthermore, access to the call panel can even be configured via the Internet, allowing you to communicate with visitors and manage access to the premises even when you're not present.

— Wi-Fi. Connection via the wireless Wi-Fi standard. This option provides nearly all the capabilities of the above-mentioned RJ-45 but with certain differences. The most noticeable is the absence of wires, which significantly simplifies installation and connection. Moreover, even relatively modest Wi-Fi devices are powerful enough to operate confidently over distances of a couple dozen meters or through 1-2 medium-thickness walls. The second nuance is the possibility of direct connection with smartphones, tablets, etc., without using computer networks; this possibility should be confirmed separately, but it is in this format, for example, that video calls operate (see "Type").

— RJ-45 / Wi-Fi. Supports both of the above-described connection methods. Such panels are maximally versatile; however, in practice, the ability to freely choose between LAN and Wi-Fi is rarely required, yet it significantly affects the cost. Therefore, this option has not gained much popularity.

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.

The number of outdoor panels that can be connected to the intercom at the same time.

The call panel is an external panel through which the guest sends a call to the owner of the intercom and communicates with him. Such a panel should be at each door "covered" by the intercom. This means that the number of supported outdoor panels corresponds to the maximum number of doors with which this model can be used. The simplest option is 1 calling panel, but in fact this is often not enough. Therefore, models that can block 2 doors at once are more popular — for example, the main and service entrances to the office. And in the most advanced intercoms, it may be possible to connect 4 calling panels at once, or even more.

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.

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.