Comparison Dahua VTO2311R-WP vs Dahua DHI-VTO2211G-WP

— Motion detection. A sensor that allows the calling panel with a camera to respond to movement in the camera’s field of view. The specific reaction method may be different, depending on the model and settings of the entire system: turning on recording or broadcasting to an external device, sending a notification to the customer, sending a signal to the alarm output (see below), etc.

- Mobile app. This feature means that you can work with the calling panel 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 and 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 the panel through a gadget that you can always keep with you is definitely more convenient than every time going to the intercom or other stationary equipment.

— Face recognition. The facial recognition function is one of the types of biometric access systems. It is based on a digital camera, often complemented by a built-in backlight for identifying faces in the dark. Initially, such devices were not very accurate: they could be confused by changes in facial hair or makeup,...the appearance or disappearance of glasses, and some models could be deceived using photography. With rare exceptions, facial recognition today uses advanced algorithms and high-end cameras with 3D scanners that read a three-dimensional model of the face. The device stores the customer library in its memory. The function is found in flagship calling panels.

— SIP protocol. The device supports the SIP protocol. This is a standard originally created for Internet telephony - the transmission of information (audio, video, special data) over telephone networks in digital format using the IP protocol (the same one on which the Internet is built). Internet telephony is quite popular nowadays, especially in business: it allows you to establish effective interaction between individual departments of a company, even tech located in different countries. Accordingly, if the building already uses equipment for Internet telephony, then SIP support can significantly facilitate the integration of the calling panel into the overall security system.

— Reading contactless keys. The presence in the design of the intercom calling panel of a module for reading data from contactless keys. They can be in the form of smart cards, key fobs or other devices that contain a microchip with a unique identifier. When the customer brings the key to the reader, the system identifies it, checks it against the database and allows access if there is a match. Note that the intercom calling panel can record not only the response time, but also the identifiers themselves - this provides advanced capabilities for access control and visitor registration.

— Alarm input/output. As a rule, calling panels with this function are equipped with both inputs and outputs; the number of both may be more than one. In general, these connectors are used to transmit control signals between different ones within a security system; they allow you to build a very advanced system and provide additional capabilities for managing its functions. At the same time, we note that the alarm input or output is not necessarily responsible for triggering the alarm - it all depends on the specific settings. For example, a signal from such an input can serve as a command to turn on the “night” IR illumination or start recording video from surveillance cameras.

— Display. Its own screen, installed directly on the calling panel, allows you to display various additional information useful for the visitor. The specific functionality of such a screen can be different - from a simple indicator that can show only numbers (for example, the number of a called apartment or office) to a full-color display suitable for two-way video communication. However, in any case, this feature increases the convenience and clarity of using the calling panel.

— Night shooting (IR illumination). The presence of an infrared illumination function in the camera video panel (see “Type”), which allows you to obtain a visible image in the dark and even in complete darkness. IR illumination is not visible to the human eye, but is well perceived by the sensors of modern digital cameras. True, the image in this mode can only be black and white, but in most cases this is not any significant drawback.

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

— Illuminated buttons. The design of the calling panel includes backlit buttons. The function allows you to see the keyboard normally even in low light conditions - in the evening, at night, in cloudy weather, when placing the panel in a dark place, etc. Note that the backlight usually covers other significant elements of the panel - for example, the location of the sensor for a smart card or key.

A card reader is a device for working with removable memory cards. Such media are used to record data, which allows you to save events occurring in front of the calling panel at the right time.

Diagonal size of the surveillance camera matrix. This parameter is traditionally indicated in inches and fractions of an inch.

With the same type (see above) and the number of megapixels (see below), larger sensors are considered more advanced. This is due to the fact that a large sensor size means a larger area of each individual pixel — and this, in turn, increases the amount of light falling on each pixel, has a positive effect on light sensitivity and reduces noise. Large sensors are especially important for working in low light conditions, including with IR illumination (see "Design and capabilities"). However, for calling panels, matrices are mainly limited to 1/4" and 1/3" sizes. Other options are much less common.

Video compression format (codec) used by the door panel camera.

In practice, this information is important mainly for assessing compatibility with other special equipment, as well as when viewing captured video on household media players. This point is not important for interaction with a computer: most modern operating systems have extensive sets of built-in codecs, and if necessary, additional codecs can be installed separately. However, different video compression formats also have some specific features, here they are:

- H.263. The oldest of the codecs widely used in digital cameras of calling panels. It was created back in the mid-1990s for efficient video transmission over low-bandwidth channels; nowadays it is considered obsolete and is found extremely rarely in calling panels, and exclusively as an addition to the more advanced H.264 (see below).

- H.264. A codec widely used in modern video equipment, including for transmitting high-definition video. It provides a good compression ratio while maintaining quality, and is not particularly demanding on computing power, which is why it is extremely popular in our time.

- H.265. The newest and most advanced of the formats found in calling panels. It provides even higher efficiency than H.264, supports resolutions up to 8K, but has quite serious hardware requirements. As a result, support for this standard is...rarely found in calling panels.

Horizontal size of the video panel covered by the camera (see "Type"); this size is most conveniently indicated by the angle between the lines connecting the camera lens with the left and right edges of the scene being viewed.

Theoretically, the wider the viewing angle, the more space the camera is able to cover and the less likely it is that some details will remain out of the frame. At the same time, taking into account the specifics of the use of outdoor panels, it is usually not necessary to equip them with wide-angle cameras; moreover, such optics would be inconvenient due to distortion and reduction effect. Therefore, most models have horizontal viewing angles in the range of 60 – 80 ° — this is quite enough for the intended use.

The vertical size of the video panel covered by the camera (see "Type"), in other words, the angle between two lines connecting the lens with the top and bottom edges of the scene being viewed. The value of the 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 because of its secondary importance.

This value characterizes the angle of coverage of the image diagonally, this figure is usually slightly larger than the horizontal angle, this is due to the fact that the frame that we see is already in a rectangular form, usually with an aspect ratio of 3 to 4 or 16 to 9, and part of the frame can be circumcised. This indicator, along with the horizontal and vertical viewing angles, allows you to estimate from what distance the visibility of the interlocutor will be acceptable.

The amount of energy consumed by the call panel.

The operating temperature range of the call panel is the air temperature at which the device is guaranteed to remain operational.

If the panel will be used in a residential apartment, house, office or other premises with similar conditions, you can ignore this indicator: all modern models have a temperature range that is more than sufficient for such conditions. But if the device is planned to be installed on the street, it is necessary to make sure that its operating temperatures correspond to climatic features. It is worth noting here that nowadays panels are produced both for very cold weather (-30 °C and below), and for extreme heat(+50 °C and more). A high temperature threshold is also important if the device will be exposed to direct sunlight — under sunlight, the case can heat up to very high temperatures, noticeably higher than that of the surrounding air. And some models combine frost and heat resistance.