Digital CCTV – in the last few days alone we have received a number of requests from customers who have been advised by somebody to upgrade their cctv system to digital.
Of course it is time to upgrade to High definition Video – In an era of 4K and 8K video what is the point of sticking with VGA resolution!
The question is “do you upgrade to digital HD or Analog HD”?
My first question is what the perceived benefit or motivation is for specifically requesting a digital upgrade.
So far the response has been – so that I can view the system remotely, and my it guy suggested it.
I have configured multiple systems of both IP and HD Analog – IP is always more expensive.
Cable Infrastructure and Savings
You Save cable with digital?
Decentralized hubs – PoE switches and Baluns
Just as you can decentralize the cable points with PoE switches for IP, the same can be achieved with distributed video baluns and even dvr’s, with HD analog. In the case of analog– you can use a single cable for 4 cameras if it’s standard category 5 or 6 cable. (Yes you do need to provide an additional power cable) but you will ultimately save cable in the HD Analog configuration, more so than with the digital solution.
Figure 1: Power Over Ethernet Switch
One issue with decentralized PoE switches or even distributed analog baluns, is that you need power at the location of the switches or baluns. If you are going to use the existing power outlets in the factory – they can just be switched off – deliberately or accidentally. When that happens, that segment of cameras will shut down.
In the distributed switch architecture, you need to secure the switches, and provision tamper proof electrical supply.
Re-Using existing cable
In many cases, you can upgrade your system and re-use the existing coaxial cable that is already in place. This is very dependent on the age and condition of that cable.
A single cable for Video and Power
You can use the same cable for video and power (PoE) in a centralized digital System?
I see this over and again – a youtube video demonstrating how analog cameras need two cables – one for power and one for video. What about poweraxial cable – hasn’t anybody heard of this. Powerax is basically a single cable, you only pull it once and connect it to the DVR and PSU in the central location.
Powerax Cable – Video and Power
A further development in this regard is the emerging power over coaxial (POC) standard. Analog systems are currently available that use a single cable for both power and video.
Network Connected and Remote Access
A digital system is on my network, so I can remotely access it?
An analog DVR can be just as easily connected to your network, you can access the cameras freely across the network, or remotely – just as you can with a digital system.
Figure 3: DVR connected to Network
High Resolution Video (HD)
IP cameras can record higher resolutions?
Yes they can – if you are aiming at really high resolution that is. HD Analog systems currently stream and record 8 Megapixels. If you need more than 8 Megapixels then certainly IP cameras can achieve that.
You will likely need a a high end, high capacity recorder or server, plenty of storage and high bandwidth availability on your network.
With high resolution cameras, you have enhanced zoom capabilities.
If the video is high usage, and high risk. If it relies on a high degree of evidential video that involves zooming in to minute detail, then more than 5 megapixel may be of benefit.
AI and Intelligence
A digital system provides intelligent analytic?
HD analog systems also provide intelligent analytic right on the DVR.
This is simply an issue of intelligence and recording on the edge or centralized.
HD Analog provides AI algorithms that can handle intruder detection, smart search functions – searching by object.
Edge Processing
One issue with having everything on the edge – (all the recording and processing is done on the camera) is that it’s all dependent on the network – if the network goes down, there is no link between the cameras and your central station.
When the network is back up – there may be a lot of catch up work to be done, transferring data that is held on the edge, along with the real time data. That data can place the network under strain. An HD analog system, contains everything on the local DVR – although some functions are also unavailable during a network outage.
Processing on the edge needs more expensive cameras. Each camera must be equipped with it’s own processing ability. Processing on a central device utilises economy of scale. Singular resources and hardware can be used for multiple cameras without duplication of resource. Duplication of resource is one reason why Digital systems are more expensive.
Another area where edge based solutions present duplication is with the effort required to secure each camera against hackers and intrusion. There are multiple devices and multiple paths of attack when digital devices are processing on the edge, as opposed to the single device that needs to be protected in the HD analog system.
Cloud Solutions
In my opinion, one scenario where IP is going to be a clear choice is when cloud based solutions are employed.
Where a central server is employing economy of scale locally – a cloud based solution is employing economy of scale across multiple servers. There is a breakage point. The cost of duplicated resource on the camera is balanced out by the savings achieved by sharing resources in a cloud.
Hardware Limitations
Digital Systems don’t limit you to the number of cameras a recorder can handle?
Apparently since IP cameras can be connected to a switch and don’t have to be connected directly to the recorder or server – the amount of cameras are not limited by the server.
I have already covered the cable saving issue earlier, so we won’t go over it again.
All systems though are limited. The core issue is bandwidth capacity of the digital server or analog recorder.
Analog systems are simply built in convenient capacities. A system that can only handle 50 Mbps usually is built to accommodate 4 cameras. If you want 32 cameras, you get a system that is designed to handle 240 Mbps. You don’t pay for resources that you don’t need with an analog system.
In digital systems – the server or nvr may not have a physical connection limit, but it has the same bandwidth constraint. The server or nvr has a limit on the bandwidth that it can process. The number of cameras that can be linked digitally to that server is limited by the same bandwidth factor. You cannot exceed that number of cameras, even in the digital system without significant trade offs in other performance criteria.
Digital Wi-Fi
Digital systems can connect without wires?
On a small scale, inside a standard home – Wi-fi can be a very convenient method of saving on cable infrastructure and installation costs.
Figure 6: wi-fi cctv camera
While there are methods to eliminate cabling in Analog systems – wi-fi is generally the easiest wire free system. There are ethernet over power devices and analog wireless devices, but they are no match for wi-fi.
Generally though – professional installers will always recommend a wired solution first. Wi-fi has some limitations.
Running high bandwidth cameras over your home wi-fi system, is also going to have a negative impact on your consumer experience when you use other devices connected to the same network.
Some environments just do not lend themselves to heavy infrastructure deployment in the form of civils to bury fiber optic, or other cable.
Decentralized and network connected recorders also may be impractical in some environments.
In these situations wi-fi is an alternative solution and digital surveillance would be the right choice.
Wi-Fi can be expensive though and can have reliability issues. It only becomes cost effective when it eliminates extensive civil work and labor costs.
Latency – Delay
Something that is not stressed enough is known as latency. Latency is basically a delay from the time data or video is sent from the camera to the time it is viewed on the display.
Latency is far more significant in digital systems than analog systems.
The nature of the IP protocol, and the heavier reliance on available network bandwidth along with other factors, ensure that IP surveillance has a factor of magnitude higher latency effect than HD analog systems.
Latency can be between 300-400ms. That might not sound significant – but in real terms it’s enough to result in you only seeing some-one breaking through your gate, when he already appears in your office with a weapon. You will rarely find casino’s, for instance, accepting this degree of latency.
Summary
In concluding, I think it’s important that consumers are aware of the two different formats – HD Digital vs HD Analog.
HD Analog always costs less – not because it’s a lower quality, but simply because of build logistics.
There is a tendency for some to hype up digital surveillance, by misrepresenting the facts.
Consumers should particularly note the issue of latency in digital surveillance systems. Near real time surveillance – imo, is nearly always significant.
In circumstance where you really need the minute detail available from deep zooming into images at higher than 5 megapixel, a digital system will be your solution.
Where you are using a cloud based infrastructure, digital surveillance without physical hardware recorders on site – may be your preferred solution.
Where large scale civil work will be too labor intensive or impractical, wi-fi would be a suitable medium for digital surveillance.
Personally – in 80% of scenario’s I am sticking with HD analog systems.
I can save costs on infrastructure deployment by decentralizing the distribution infrastructure – either with video baluns or decentralized placement of the recorders themselves.
The hardware is less costly.
I will have the entire system accessible on the network and remotely.
I can achieve up to 5 megapixel recording and display.
I can run video, power and data over a single co-axial cable.
I can have intelligent detection and searching.
I can see what’s happening – live, in near real time.
I can interface the system with my alarm system.
Article by Brandon Joubert – Director Gensix Technology Pty Ltd
