Video surveillance

Reading time 5 minutes

Updated – January 21, 2023

Video surveillance is becoming more and more important as the number of burglaries, thefts and other crimes increases. It makes sense to equip your house and yard with video cameras. On the one hand, this is to act as a deterrent and, on the other hand, to be able to identify the intruder if necessary.

The number of offers is almost unmanageable. Prices range from two to four-digit euro amounts. The differences in quality are corresponding.

At first, like everyone who is interested, you tend to prefer the cheaper offers. But as soon as it comes to obtaining usable images at night, the wheat is separated from the chaff.

Below three-digit euro amounts, the yield is meager in terms of an acceptable price-performance ratio. However, there are extremely good products between 130 and 280 euros, especially those from probably the largest camera manufacturer Hikvision. They are produced in very large quantities and are preferred for use in industrial, public and private environments.

Camera models

A distinction must first be made between so-called bullet and dome cameras.

With the bullet camera, the direction of view is clearly visible from a distance. The orientation of a dome camera can only be seen up close. In the latter design, the camera sits under a glass dome, within which the camera - in the PTZ version - can be rotated by 355 degrees and the inclination can be changed by around 75 degrees.
Due to the black color of the camera, it is difficult to see it under the glass dome, let alone see which area it covers.

What both designs have in common is that they can be equipped with a fixed focus, motorized zoom function and IR diodes (night vision), WLAN, LAN connection and POE (Power Over Ethernet). In the POE version, no separate power supply is required for power supply as long as the switch provides POE. This variant is the best choice.

You should distance yourself from WiFi. Simple WiFi transmitters are enough to disable the cameras. Without proper CAT.6 cabling and powerful, administrable switches, serious video surveillance makes no sense!

Whether a zoom function is required depends on the application. If the camera location is further away from the area to be monitored, it is advisable to choose a camera with a zoom function and good (!) IR illumination, possibly also via additional spotlights.
With regard to the zoom function, a distinction must be made between digital and optical zoom. The optical zoom is to be preferred. With digital zoom, pixelation can be noticed very quickly.

Motorized rotate/tilt or zoom functions are preferable if the recordings are constantly monitored and object tracking is desired manually.

Cameras that automatically track recognized objects cost four-digit euros. They are used in public and industrial application scenarios.

The PTZ (Pan Tilt Zoom) marking indicates that the camera can be panned horizontally, vertically and the lens can be zoomed.

If a camera provides an audio function, a distinction must be made as to whether it is unidirectional (sound recording) or bidirectional (sound recording and playback) audio.

The right lens

Depending on the application and budget, different lens equipment is available. What needs to be taken into account will be explained here.

As in photography, light intensity is particularly important, especially when it comes to night vision. The smaller this value (e.g. f = 1.2), the larger the lenses, the more light is available for processing by the image sensor.
The light sensitivity of the sensor is given in lux and is usually 0.001 .. 0 lux.

The focal length determines the area captured. The best way to determine which focal length is suitable is to use a drawing. Common fixed focal lengths are 2.8 mm with a field of view of 80 to 100 degrees.

The longer the focal length (for zoom lenses), the smaller the field of view becomes (12 mm -> 31.6 degrees), the shorter the focal length, the wider the field of view (2.8 mm -> 96.7 degrees).

The distance between two cameras should be such that the object to be observed is no more than 5 meters away. The reason is simple: a face or license plate should be able to be enlarged to such an extent - even at night - that it remains clearly visible without becoming pixelated. Distances of 10 meters are still possible during the day, but not at night. This is definitely the limit – without additional headlights.

Recommended (dome) cameras

HIKVISION 2CD2155FWD-I

Fixed focus
– 2.8mm 80.0°
– 4.0mm 63.5°
– 8.0mm 33.0°
– 12.0mm 16.0°

Resolution 20 / 25 fps 2560 × 1920 px

HIKVISION DS-2DE2A404IW-DE3 (PTZ)

Focal length variable 2.8 .. 12 mm, opt. Zoom, 100° .. 30°
Resolution 2560 x 1440 px

HIKVISION DS-2DE3A404IW-DE/W (PTZ, bidirectional audio)

Focal length variable 2.8 .. 12 mm, opt. Zoom, 96.7° .. 31.6°
Resolution 20 / 25 fps 2560 × 1440 px

IR additional headlights

The installation of additional IR headlights requires a power supply, usually 230 V, less often direct voltage 12/24 V.

The headlights must not cover the lens of the camera, otherwise it will be blinded and therefore overexposed.
It is also important to check whether the camera is sensitive to IR in the visible or invisible range. Additional headlights should be selected accordingly.

In the price segment up to around 500 euros, IR diodes are usually installed that emit visible IR light (dark red 850 nm). Cameras that have IR diodes in the invisible IR range (940 nm) are above this price limit. This also applies to the corresponding IR spotlights.

Raytec offers a large selection of very good 850 / 940 nm IR spotlights in the price segment of around 250 - 2,000 euros each (e.g. with visible IR 850 nm RM100 PLT-AI-120).
The comparatively high price results from the exclusive use of selected IR diodes, excellent heat dissipation and a sophisticated energy concept, resulting in a very long service life.

Supposedly cheap headlights in the visible IR range are in the two or three-digit euro range. However, they sometimes have IR diodes that fail within a short period of time and very inhomogeneous illumination because there is neither a constant power supply nor solid heat dissipation.

You should stay away from seemingly cheap offers. If you buy cheap, you buy twice and therefore more expensive.

Camera mounting/cabling

In private environments, cameras are predominantly mounted below the roof overhang, protected from the weather. Cameras for outdoor mounting are usually designed according to the IP65 standard, which means they can be exposed to rain or snow.

If you want to monitor a square, rectangular or L-shaped building, you will need eight cameras: two on each corner of the building. In this way, two cameras record each visitor. So someone will always record the face.

If possible, LAN cables should not be laid as installation cables, but rather in the form of ready-made cables. On the one hand, this is more cost-effective because no connection boxes are required, and on the other hand, it avoids sources of error regarding the terminal contacts to be made using the lay-on tool and also saves the corresponding working time.

If you have eight cameras, you need one 10 port switch, eight connections for the cameras and one for the outgoing line to the router or NVR (Network Video Recorder).
You should avoid simple switches because the data stream from 16 high-resolution cameras is considerable and quickly exceeds the performance limits of “cheap” switches.

Of course, a 230V power supply line with a socket for the switch is required, which can be mounted centrally in the roof shelter if necessary.

NVR

An NVR offers the option of storing the video streams from the cameras over longer periods of time. The recording duration depends on the capacity of the installed hard drives. With approximately 8 TB (tera bytes) of storage space, up to eight weeks of video material from 16 cameras can be recorded in high-resolution mode (e.g. the NVR Hikvision DS-7716NI-E4-16P).

The NVR is usually delivered without hard drives. Installing the hard drive is relatively easy, even for laypeople. The only thing that needs to be taken into account when making your selection is the physical dimensions of the HDDs and the maximum supported storage size of the controller in TB.

Hard drives suitable for continuous operation should be certified for use in NAS (Network Attached Storage) systems, e.g. the series Red from Western Digital with 8 TB Capacity. They have an MTBF (Mean Time Between Failure) of around twice that of normal hard drives, namely 1.2 million hours. In addition, you should ensure that the manufacturer has a guarantee period of at least 5 years.