Video surveillance: an overview for installers, architects and owners

The basics for a better selection of video technology


It's like buying a car: if you want a blue car that can take you from Bremen to Munich, there are many vehicles in the running and good advice is difficult to give. However, when we are talking about moving house, for example, most cars will not work - or at least are not efficient. In this case, the move is the decisive information, because it causes specific requirements the vehicle must meet. However, the user must know that the move is a crucial piece of information - and also that there are cars that are built especially for moving house. Let's transfer this to video surveillance: Each video system is unique and in the beginning you must answer question: which problem should video surveillance solve?



The foundation of a good selection: the requirement profile in video surveillance

Every project and every building is individual. You should therefore clarify the following basic points in advance:

  • Do you need live images from video surveillance?
  • Should the video surveillance be saved as a recording?
  • Do you need an event-based recording?
  • Do you want to receive a notification on the mobile device in case of certain conditions and events?
  • Do you need remote access to the camera via mobile phone or tablet?
  • How are the lighting conditions - and do they always stay the same?


KfW is subsidising burglary protection with 20% for the first 1,000 euros of investment and 10% for each additional 1,000 euros. A conversion measure of 2,000 euros would therefore be subsidised with 300 euros. KfW's maximum funding is 1,600 euros. This 1,600 euro total funding is therefore based on 15,000 euro costs. In detail, the following measures are involved:

In the field of security we call this a requirement profile, sometimes also a 'task profile.' This is the first step towards the right choice of system, camera and recorder.

System selection: the advantages and disadvantages of analogue systems

Nowadays, analogue cameras also deliver high-resolution HD images - the statement that analogue technology is outdated is therefore no longer correct and therefore not a sensible selection criterion. To make it easier for you to choose between digital and analogue technology, we have compiled the advantages and disadvantages:

1st advantage: the installation of analogue systems is easier

You plug the right cable into the camera. The cable goes to the recorder - running. You don't need a complex configuration to get a picture on your computer. Usually you do not need to install any drivers either. The recorder is directly connected to the computer. Video surveillance could not be easier.

2nd advantage: with analogue systems there are (almost) no latencies

With analogue technology, there are no time delays in transmission which are noticeable to humans. There are simply no other devices that could cause these so-called latencies. When the camera transmits an image, you see it in real time. When it comes to surveillance where every second counts, the smallest possible latency is important. If you want to monitor a production line where there is an emergency stop switch, there must not be a three to five second latency.

 

Caution with 12-volt cables: interference signals from other devices

12-volt cables are not as well shielded as normal video cables. If you have to lay 12-volt cables, make sure that no other signal is 'scattered'. For example, if buildings have a mobile phone transmitter on the roof, the 12-volt cable must not be too close to it. We recommend a distance of 50 centimetres.

3rd advantage: with analogue video surveillance you are safe from hacker attacks

An analogue system is safe from hacker attacks, because there is nothing to hack: the analogue system is self-contained and therefore completely secure.

4th advantage: analogue HD recorders can cope with many older existing systems

The modern, analogue HD recorders support several video formats and are backwards compatible. You can therefore continue to use existing cameras with composite video output signal and integrate them into a new HD system.

The only disadvantage of analogue video surveillance:
You're 'on a leash.'


 

Attention with 12-Volt cables: voltage drop

With central power supply via video combination cable, there is a voltage drop depending on the cable length and cable cross-section. For great cable lengths, the 12-Volt supply should be provided by a decentralised power supply unit near the camera position.


The advantages and disadvantages of digital network IP systems

Network IP technology has a good reputation because it provides many new functions. But by no means all users need these features. And digital video surveillance technology also has advantages and disadvantages of which users and installers should be aware.

­­1st advantage: video surveillance in higher resolutions

Network IP technology offers resolutions of five megapixels and more. Analogue technology usually stops at 2 megapixels.

2nd advantage: power over Ethernet (PoE) - power supply via network cable

With PoE, the network IP technology offers the possibility to realise data transmission and power supply via a network cable. This means that you do not have to lay separate power lines. This makes installation simpler and often more cost-effective.

3rd advantage: more functions are available

As a rule, digital systems provide many more features in the camera itself: The camera can send status mails and upload images, serve as its own server and has built-in analytic functions.

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1st disadvantage: basic IT knowledge is required for installation

What is a port, a gateway, firmware? At least you should have heard these words before. You may need to make settings on the firewall. So the user should know their way around a computer at least a little.

2nd disadvantage: system maintenance is required

The image retrieval of network IP cameras is done by PC, smartphone, tablet or network recorder. The operating systems of these devices are subject to frequent changes through firmware updates. Therefore, an update of the camera firmware is often necessary. Make sure to carry out regular system maintenance.

3rd disadvantage: the data streams of several network IP cameras should not be underestimated

Especially with high resolution a stable, strong periphery is needed. If you want to transmit a 4-5 megapixels image continuously with several cameras, you cannot just do this with any PC. You need a strong graphics card (GPU) - on-board solutions are usually not enough. Cameras with very high resolution can sometimes generate up to 16 Mbps data traffic per camera. If we assume five cameras, this is already 80 Mbps of pure continuous data traffic. If a web shop, a CRM, an internal network or a lot of e-mail traffic is also connected to this network, problems may occur. If the data streams from the camera to the recorder are separated from the rest of the network, the operational reliability is higher.

Our tip: always set up a separate computer network for the cameras.

Popular functions of surveillance cameras

In good lighting conditions, almost every camera takes good pictures nowadays. If the conditions are ideal and there are no special requirements, users can rely on a solid all-round surveillance camera without worries.

Flexible data saving: mainstream substream separation

There are some functions that are not found in all cameras, but are still important. The most important, because most useful in use, is the mainstream substream separation: the camera provides a high-resolution mainstream for recording and a lower-resolution substream for remote access via mobile phone or tablet. Often recorders can also record both streams independently.

Analytics or motion function: detect and report intruders

Many users want to monitor whether a person crosses a certain optical line within the camera's visual range. Often these requirements are made by users in outdoor areas. The user then asks: "Can the camera always record and notify me if something moves?" Many can do that. What the user really wants to ask is: "Can the camera record if someone enters my garden, i.e. gets over my garden fence?” The important background knowledge is: The 'motion detection function' of most cameras works on the basis of gray values. This means that 'motion' for the camera is a change in contrast within the image. This is where the analytics function comes into its own, which can be found in many digital cameras: it can, for example, distinguish with great certainty between a dancing snowflake and a person moving from left to right. To do this, you can use this feature to define an area within the camera's visual range that is relevant to your security. However, this function can only be a support for the user's requirements. Often, a weatherproof and jet-proof photoelectric sensor for outdoor applications is more reliable and easier to use.

Privacy Masking: avoiding trouble with neighbours

Other people's cameras near your own private property often arouse suspicion, even among neighbours. If the visual range of your camera covers a small part of the neighbouring property, you or the user should talk to the neighbours. Due to the privacy masking of most cameras, you can easily exclude this area from surveillance and recording. You or the user can show this to the neighbours and thus create more understanding and trust.


Field of view: combine wide angle and close-up

For a private garden it is not reasonable to monitor a large area with only one camera and at the same time to expect portrait shots. It is better to proceed tactically: use a camera that has a very wide field of view to overlook the garden area. Then use a separate second camera to get close-ups of possible intruders close to the house. This is a much more efficient solution than trying to accomplish both tasks with just one camera. The basic rule is to clearly define the tasks and then divide them up.

  1. One camera with a small focal length to film the action, with a wide viewing angle and a large visual range.

  2. One camera to identify people, with a long focal length, small visual range and higher resolution per displayed meter in the visual range.


That is how you can also solve it in a business environment: covering shelves with high quality goods at a wide angle, filming the area around the entrance door in high resolution.

Regardless of the overall resolution of the camera, the following applies: in order to recognise persons or license plates, you need at least 250 pixels per displayed meter.

Light sensitivity: video surveillance in sunny and inconsistent light

There are cameras that work especially well in so-called 'backlight situations'. Ask the user or think about it yourself: Does backlighting occur at the place where the camera is used? Are there everyday situations in which backlighting interferes with the camera? This can be backlighting of a car on a road, spotlights of stages or hall lighting, headlights of forklifts. There is also the phenomenon of a wet road in low sun, which can easily dazzle a camera with poor backlight compensation. Then there are many areas where the lighting conditions on a surveillance image are very different. For example, one half of the image could be in shadow and the other half in sunlight. To compensate for these light conditions, you need a WDR camera, a camera featuring a Wide Dynamic Range.

Recorder: consider data rate, infrastructure and storage capacity

The basic factor for selecting the recorder is the number of channels. This is a point that is easy to understand and check: one channel per camera. However, there is more to consider.

The data rate: often underestimated

Not every recorder can process large amounts of data at once. Again, values such as resolution, video codec, bandwidth and frames per second should be adapted to the user's needs. Cameras usually output compressed video streams in MJEPG, H264 or H265 formats. The user can set the video codec and maximum bandwidth individually for each camera.

 

Calculation example: data volume from cameras and recorders including mainstream and sub-stream

As an example for the amount of data we take a recorder with a bandwidth of 60 Mbps. The recorder can therefore process 60 megabits per second. Often a camera transmits a data stream with 8 Mbps in the mainstream. The sub-stream can also transmit up to 4 Mbps data if the appropriate settings are made. For example, a single camera transmits 12 Mbps of data, so the recorder is already busy with five cameras - regardless whether it has 8 or 16 channels.

The infrastructure: how many additional data sources are in the network?

Don't forget that even a network is limited in its bandwidth. At the beginning it is useful to ask: How much data load does the network transfer and which data sources are to be considered in the entire company or household?

The transmission of your camera images will jerk when the network is busy.

Especially streaming services in the private sector or company networks with numerous applications and users often cause a high data base load. If network IP cameras with their large data volumes are added, the network is quickly overloaded. The image transmission rate of the individual cameras then drops massively and the latency times become very high. Good video surveillance is then no longer guaranteed.

Be careful when accessing the camera images remotely via Internet: The decisive factor is the upload bandwidth, not just the download bandwidth. An example: Many DSL tariffs today allow high download speeds, but only an upload speed of one megabyte per second, i.e. 8 megabits. This would mean that the maximum DSL data volume would already be reached with the mainstream or mainstream of only one high-resolution camera. If a streaming platform is running simultaneously, the bandwidth is already overloaded.

The storage capacity: how long do you want to store recordings?

Here too, many users misjudge when it comes to the pure data volume. In applications where the cameras record for long periods of time, a great deal of data accumulates. This could be the surveillance of a production line, a shop or a parking lot. The requirements of the user are then easy to calculate.

A basic rule for a HD camera in continuous surveillance is: 4 gigabytes per hour per camera.

Here it becomes clear why a sub-stream is indispensable: remote access via mobile phone would otherwise not be possible, as these large amounts of data overtax every mobile phone connection.

If very long recording periods are required, it can make sense to use a 16-channel recorder for just one or two cameras, as it has more storage capacity.

Conclusion: proceed methodically with video surveillance and plan with leeway

Ultimately, the most important aid in choosing the right video surveillance:

Determine the task profile as precisely as possible. Plan one camera more for long distance or close monitoring than one too few. Be sceptical of all-rounders - sometimes they are a good solution, however, mostly well combined specialized solutions are a better match. Always plan with a little leeway. If a recorder can just about handle the data rate when there is just enough memory, you are not equipped for unforeseen changes: maybe you want to record a few hours longer, maybe you need a higher resolution than you thought? If you are unsure, consult a specialist - usually a specialist dealer for security technology can already help you or refer you to a specialist installer.

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