In world, according to the census, now about 65% of citizens live in high-rise buildings permanently. In large cities, this figure will be even higher. And what is the first way to control access to an apartment building? Of course, this is an intercom doorbell panel on the access door. The vast majority of these devices are analog audio call panels, models with the possibility of video shooting are much less common. The classic coordinate – matrix intercom at the entrance to the staircase and the tube in the apartment provides access control for several generations. In this way, the simple problem of two-way audio communication and opening the door is perfectly solved.
However, taking into account the development of high technologies, it would be strange not to take advantage of existing experience. Many firms have done so. Now the market has a large number of models of IP call panels. In addition to the basic tasks, this intercom is immediately equipped with a video module, the ability to call on several devices, recording video to the archive. A variety of hybrid, modular solutions, models in specialized, protected enclosures are offered. Manufacturers give the buyer a choice of complete set of the call panel, which allows to significantly expand its functionality.
The most versatile and scalable here is the use of SIP – intercoms that have all the advantages of IP devices. Additionally, the concept of the Internet of things is satisfied – all SIP devices will work easily on the same network. Independent laboratory CCTVlab tested multi- subscriber SIP intercoms.
WHAT WAS TESTED
What do you expect to get from a high-quality outdoor video wall? In the first place – high-quality video signal, regardless of the time of day or background environment. Well and, of course, high-quality two-way audio communication – the basic functionality of any intercom. Thus, in the laboratory investigated the following functionality:
+ Video quality in various conditions
+ Sound delay
HOW TO MEASURE
1. The viewing angle was determined by the actual field of view of each panel.
2. Image resolution was measured by special tables:
+ With normal lighting 500 lux.
+ When illuminated from the built-in backlight when the light is off in the room.
3. Shooting a person was carried out at a distance of 0.5 m from the panel:
+ with normal lighting was carried out at 500 lux
+ when illuminated from the built-in lighting was carried out on the street at night.
+ at a counter flare in a frame from a powerful light source.
4. The resulting time delays in the device were measured:
+ between audio and video
+ between the audio signal from the visitor to the operator
+ between the audio signal from the operator to the visitor.
+ A brief assessment was made of the interface capabilities of each panel.
TEST RESULTS BEWARD DKS15120
It has the highest resolution in the test 1064 lines when illuminated with 500 lux and 1045 lines when illuminated from the built-in backlight. Possesses the viewing angle maximum in a test of 135 degrees. Also, the model is one of the leaders in delay time 0.08 with video relative to sound, 0.2 with operator panel, operator panel with 0.13 s.
When shooting a visitor in the room, his face remains visible in normal conditions and in backlight. When shooting at night with built-in backlight, the image retains good detail.
The interface has a wide range of camera configuration and image. Present setting SIP, duration of the conversation, alarm events on the opening of doors, control opening doors, watching videos from the panel and control the speaker volume and others. It is possible to disable echo cancellation.
TYPES OF LENSES
Currently there are several options for lenses in video intercoms: pinhole, Fisheye and wide-angle. Pinhole performance is characterized by stealth and compactness. The viewing angle is small, but the face of the visitor, thanks to this, looks bigger and closer to the intercom. The wide-angle lens allows you to see the visitor well at a sufficiently close distance, at the same time you can see a small area near the visitor. Fisheye has a large field of view, but visually removes the visitor’s face and reduces its image. Accordingly, the image of the person making the video call on the monitor will be different. The laboratory took a picture of a visitor standing in the center of the image at a distance of 45 cm from the intercom.
Another situation is real and rather ordinary, when the intercom is located on the wall next to the controlled door. The visitor made a call and went to the door to wait until it is unlocked. Or, the person at the entrance is not opposite the intercom lens. Lautortor shot the visitor at a distance of 45 cm from the intercom when he shifted 20 degrees from the center of the image. All panels allowed in these conditions to accurately recognize the visitor.
Multi-subscriber calling panels have confirmed that they are easily able to cope with our tests. They provide two-way high-quality audio communication and video surveillance sufficient for recognition. Prospects for implementation in an existing access control system or developing a new system with a heart in a video intercom are very broad. They allow the installer to design a reliable security system at the facility. The possibilities of using the SIP protocol are impressive, it allows theoretically to embed any compatible device anywhere in the system. Given this, the installer should pay close attention to such panels.
Intercom systems that are compatible with the SIP protocol have unlimited scalability and extensibility. Due to this, the implementation of any integrated security system solution is allowed in the building. The use of IP devices in residential areas or large office centers will allow you to create a developed secure infrastructure for monitoring and surveillance. At the same time, its operation will be available for both installation companies and residents. The access control capabilities of each panel will further expand the facets of the application of the classical principles of intercom in the modern developing world.
The full version of the article is posted on the website of the independent laboratory CCTVlab.