German security provider ABUS Security-Center explains video surveillance needs in project planning, installation and component selection.
Video surveillance is primarily used for monitoring buildings and company premises. Surveillance cameras are also used for personal identification and access control. Aside from secured areas, surveillance can be found in medicine to monitor patients, science for microscopy, measurement engineering and industry to monitor assembly lines. Video software defines the entire system's capabilities.
From surveillance cameras to danger detection systems, video surveillance technology is multifaceted. This overview of options, with expert advice on technical issues, offers planning tips for video surveillance systems.
1. Are lighting conditions suitable?
The light intensity from available light sources must correspond to camera sensitivity, which should be measured. This can also be calculated by wattage, area reflection characteristics and geometric distance from cameras. Short camera distances have a positive effect.
2. How should lighting be positioned?
The quality of the lighting should increase depending on the desired amount of detail in the recording. The light spectrum for the light source at night and in the day should be similar.
Cameras should be mounted outside the light source. To avoid flickering camera images, the camera should not be mounted directly on the light source. It should not be directed into the beam of vehicle headlights.
The light source should be directed on the monitored area, not the camera. If the surrounding area is too dark for the camera, then an infrared illuminator may help.
3. What should the camera watch for?
Before cameras are installed, the operator must know what to watch for onscreen. Users must determine whether an overview of a large parking lot suffices or if identification of individuals and license plates is required. It is impossible to achieve both with a single camera. The operator must specify the video system for perception, detection, recognition or identification (see Table 1).
4. Which lens to use?
Clearly displaying objects requires measuring the optimum distance between the camera and object, along with the object's width. The focal length can be calculated after both measurements are taken. In millimeters, focal length is equal to the camera-object distance in meters, multiplied by the sensor size in millimetres and divided by the object width in meters. A 1/3-inch sensor would be entered as 4.8 millimeters, while a 1/4-inch sensor would be 3.6 millimeters.
5. Installation location and power supply?
A lower IP protection class is suitable for indoor cameras, but outdoor cameras must be waterproof, dustproof or have additional protective housing. Power is usually supplied over a DC 12 V or AC 230 V connection. As a mains power supply is rarely available at the installation location, a video-combi cable for analog cameras is recommended. Apart from the BNC connector for video files, two wires for the power supply are integrated into the system. Network cameras are usually powered by PoE.
6. How is data transmitted?
There are several ways to transfer camera video signals to the monitor, including cable (coaxial and dual-wire transmission), wireless transmission and network transmission.
Cable transmission: The most inexpensive method is by coaxial cable (RG59). One advantage is BNC connections are available on virtually all video surveillance devices. Ranges of up to 150 meters are possible, with dual-wire transmission extending range up to 2 kilometers.
Wireless transmission: Although wireless video offers wider transmission ranges, it is more expensive and more prone to malfunction. It limits the number of cameras which can be connected.
Network transmission: Network cameras (LAN or WLAN) are increasingly used in video surveillance. Provided a local network is available, installation is simple and global access is possible.
7. How are recordings saved?
Recording technology has changed, with different media types are available for recording, saving and managing data. Computers combined with special PCI monitoring cards and digital recorders are used. As network cameras are a growing trend, hybrid digital recorders with intelligent functions and user-friendly video management are in demand.
Files can be stored to hard disks, CDs, DVDs, USB devices or SD cards. Image rate is crucial for recorder storage. The human eye sees 24 images per second as a fluid action, with 25 fps classified as “real-time.” The video is less fluid when recording at 12.5 or 6.25 fps, but may be sufficient, depending on the requirements. In general, the more images recorded per second, the more data is written, taking up more storage.
Compression also matters. Without it, a real-time recording from a single day would take up several DVDs. Common compression types are MPEG-4, M-JPEG and H.264.
8. How can digital recorders and video cameras be expanded for a complete security solution?
Modern cameras and recording units feature alarm inputs and outputs, which be programmed through video management software. For example, sensors or intrusion detectors can be integrated into the video surveillance system via the alarm inputs. The recorders can be programmed to begin recording when a detector is triggered, such as for video verification. A high-performance digital recorder is then transformed into a professional danger detection system.
9. Which software issues should I watch for?
Video software influences the range of applications for a video system. The software is the central point where video signals come together for processing, display and management. High demands are made on these programs. They should handle many channels with high image rates and resolutions, offer a wide range of functions and be operated intuitively and swiftly. The software must display and manage several analog and digital cameras, as well as record. As a result, the maximum number of channels is a decisive aspect for video management software.
Aside from performance, simple operation ensures proper use in critical situations. The ideal solution can adjust the user interface according to user requirements or abilities. Uncomplicated access to important functions should be the priority. Live image display, recording, alarm management and video analysis should quickly identified. The archive and search functions should also be clearly structured. Following an incident, the corresponding images must be found quickly according to date, time, camera, video analysis information, PoS data or triggered alarms.
Another central aspect of professional video management software is the presence of intelligent security functions (see table above).
10. Analog or IP ?
Despite the paradigm shift in network camera revenues overtaking analog sales, older analog cameras are still preferred to network cameras sometimes. Network cameras have integrated video servers, and transmit the recorded video images to the local network or Internet. The live images from the camera can be displayed, saved and managed on computers worldwide. Each camera is assigned an individual IP address for this purpose. This technology makes network cameras larger and more expensive compared to analog models. Hidden video surveillance on an extra-small scale cannot take place. The range of available analog cameras remains larger — particularly when carrying out video surveillance under extreme conditions such as underwater recording or intense backlighting.
However, digital technology has key advantages such as higher resolution, global access and remote installation. The cameras are integrated into existing networks and the recorder does not need to be located on-site. Analog cameras can be integrated into a network by video servers.