- Consumer Electronics & Personal Gadgets
Analog or IP Systems-Which one is preferred
The traditional analog security cameras capture an analog video signal and transfer that signal over coax cable to the Digital Video Recorder (DVR). Each camera may be powered by plugging in the power supply. The DVR converts the analog signal to digital, compresses it, and then stores it on a hard drive for later retrieval. Monitors for viewing the video are connected to the DVR, or it can be set up to publish over an internal network for viewing on PCs. The DVR can be set up to broadcast over the Internet and can add password protection and other features. When broadcasting over the Internet, the video for all of the cameras is transmitted as one stream (one IP address). Therefore, it is very efficient. (See Figure 1)
Figure 1- Analog system structure
In IP systems each network camera captures an analog image but immediately converts it to digital inside the camera. Some digital processing can happen right at the camera, such as compression and motion detection. The digital video stream is then broadcast over the IP network using Ethernet (CAT5) cable. The power supply may be plugged in at the camera or can be run over the Ethernet cable by using Power-Over-Ethernet (POE) adapters. The CAT5 cable for each camera is plugged into a switch which feeds into the network hub. As with all network devices, some set-up needs to be done for each network camera to set up its IP address and other identifying attributes.
Software is required on each PC that you want to view the cameras or playback video. However, each camera has a separate stream and has its own IP address or port. This can greatly affect bandwidth as we'll see below. When viewing remotely each camera can be pulled up individually by its IP address. (See Figure 2)
Figure 2- IP system structure
Main differences between Analog and IP systems
As said before, the typical analog system combines one or more analog cameras, each connected to a central digital video recorder (DVR) system via separate point-to-point coax cables. Video content is viewed in real-time on a SPOT monitor and an integrated Pan-Tilt-Zoom (PTZ) controller enables fast remote manipulation of individual cameras to change views in real time. In comparison, IP-based systems offer a high degree of flexibility for connecting various intelligent mega-pixel IP cameras over multi-point Ethernet infrastructures via relatively low-cost CAT5 cabling. Extended IP networks support remote access over the Internet via secure browser connections or mobile devices. Digital video systems including standalone network video recorders (NVRs) enable a variety of advantages for image manipulation, high definition, embedding metadata, search capabilities, etc. (See Figure 3)
Figure 3- Differences between Analog and IP systems
Major differences between analog and IP systems are latency, cable type, maximum cable run distances, infrastructure requirements.
Sometimes even a small amount of delay between the live action and when the video is displayed can make it impossible for a camera operator to track a subject as it moves. In PTZ applications, low delay is critical, and analog video is the lowest-delay option available. In contrast, digital cameras connected over IP networks incur latency at every step of their journey due to the packet-based nature of IP-based communications.
However, IP over CAT5 Ethernet cabling will always incur some latency. The need to compress (and later decompress for viewing) the video from the camera using standards like H.264 adds additional latency to the signal. This can add seconds of delay, making it difficult or impossible to use PTZ to track movement in real-time.
●MAXIMUM DISTANCE PER CABLE RUN
Another important difference is the maximum achievable distance for coax-based analog signals vs. CAT5-based Ethernet IP communications. Coax links can deliver CVBS video streams and PTZ control functions in real-time over point-to-point cable runs of up to 300 meters for standard-grade cable and up to 500 meters for higher-grade RG59 cable. In contrast, structured CAT5 cabling in IP networks is limited to a maximum of 100 meters per cable run. Because of this, a 500m run would require the use of at least 4 switches, routers, or hubs, etc. Depending on the network configuration, security requirements and latency tolerance, an IP-based surveillance application can provide remote monitoring over long distances.
●INSTALLING THE COAX-BASED SURVEILLANCE SYSTEMS
Removing the coax and replacing it with CAT5 Ethernet cabling, routers, etc. would take a similar if not larger investment. Being able to re-use some or all existing installed base of coax cable saves an enormous amount of money, which can be redirected toward anything from more cameras to higher company profits.
Migration from Analog to IP cameras
As said before, in today’s world of video surveillance and security the market is moving towards IP based systems. The video surveillance industry has been adopting digital, networked IP technology that delivers benefits in terms of camera intelligence, multi-point communications, video compression, and recorded videos with HD quality. Moving from CCTV system that can be transmitted over hundreds of meters of coax cable to an IP system that is limited to 100m (See Figure 4) causes many to rethink the change, regardless of the benefits of IP. They want the advantages of IP video, but cannot afford a major disruption to their existing CCTV services or the cost of building out an entirely new infrastructure.
Figure 4- Simple Migration from Analog to IP Systems
The most common reasons for migration from analog to IP systems are:
● Better image quality through megapixel resolution and progressive scan image sensors.
● Lower cost and more flexible infrastructure through Ethernet cabling, Power over Ethernet functionality and ability to transmit multiple channels of video, data, audio & PTZ control through a single cable.
● Digital encoding guarantees image quality over long distance transmission and wireless transmission.
● Convenience and advanced playback functionality of digital recording
● Acceptability to an IT department that is now responsible for installing, configuring and maintaining the infrastructure
● Ability to rapidly respond to emergencies by dynamically relocating cameras, monitoring stations and storage systems anywhere on the network, including the use of temporary wireless, laser-based and microwave-based connections to extend the reach.
Different methods for migration from Analog to IP systems
There are different methods for migration from analog to IP systems, here you can see some of them|:
- Scrap the existing analog system and install completely new IP cameras running across either a new or existing network. For anyone with a system of twenty or more analog cameras this is not likely to be attractive.
- Encode all of the outputs from the existing analog cameras into IP format. This would normally be done in the control room so that existing cabling is unaffected. Once the camera signals have been converted to IP the rest of the system responsible for recording and playback would be IP based. There after cameras will be replaced with IP units at the end of their life.
- Replace existing digital recorders with hybrid units, which will accept both traditional analog camera connections and IP cameras. New hybrid technologies integrating both IP and analog video offer options for migrating from CCTV to IP without the disruption or expense of replacing coax infrastructures – and without the IP distance limitations. These new hybrid technologies enable cost-effective deployment of new mixed-technology installations that optimize performance, features, responsiveness and price.
- With any large analog CCTV system there has been a major investment in installing the coax cable infrastructure (hence "Closed Circuit" TV). In many cases there will not be a network cable close to an existing analog camera location. The options then are to either encode the video signal at the control room or to install line converters which enable the coax cable to be used as network cable.
As said before, analog CCTV was perfect for its time, but advances in technology have changed the game significantly. Digital (recording) and ultimately IP CCTV offer many advantages over the older analog technology. After years the companies consider options to use IP and analog cameras together in what is called a hybrid camera. It has a new video surveillance technology that can simultaneously transmit both IP and analog signals on a single coaxial cable. It allows customers to easily migrate to HD IP video surveillance systems with minimal investment, utilizing their existing analog infrastructure. (See Figure 5)
Figure 5- Hybrid system structure
The hybrid systems deliver the following advantages:
● Cost-effective and environmentally-friendly surveillance systems that can be easily migrated from an analog CCTV system to an IP network-based system, making the most of any existing surveillance infrastructure (e.g, coaxial cables, local power supplies, matrix switchers, controllers, and video wall monitors)
● Simultaneous use of IP HD video and analog SD video
● Utilization of the advanced features and functionalities offered by IP network cameras
● Extended cable length of up to 1,000 feet (300 m)
● Minimized latency of analog video for live monitoring
Hybrid cameras can be used in a wide variety of surveillance applications, and in locations such as commercial facilities, financial institutions, office buildings, casinos, airports, government-related facilities, and schools.
What are the right tools for migration from Analog to IP systems?
Here are a few products that can help you migrate from analog to IP systems:
1. Hybrid Digital Video Recorders (HDVR)
A “Hybrid” Digital Video Recorder or HDVR are becoming even more popular as companies begin the process of migrating to IP camera systems. These are recorders that have a video compression card built directly into the unit. The compression card is so that standard coaxial cable cameras can be directly connected to the recorder. The advantage of a “Hybrid” recorder is that it can also accept IP video streams through its network connection. These “Hybrid” recorders can provide exceptional scalability and an easy migration path from existing analog cameras to network IP cameras.
2. IP Video Encoders
An IP video encoder converts standard analog cameras into digital IP video streams. Using video encoders allows for a company to save the existing cameras and converts to a Network Video Recorder or NVR. IP video encoders can convert a single camera or up to 16 cameras with a single unit. These are very helpful devices for companies that have large systems but don’t have the budget to convert all the cameras over to network IP cameras in a single phase.
3. Ethernet over Coaxial Cable Media Converter
A media converter allows for Ethernet over coax. This means TCP/IP based communication can take place over coax as the cable medium instead of Fiber or CAT5/5e/6 cabling. The media converter allows the system designer to replace an analog camera with IP cameras without replacing the existing cabling infrastructure for the analog cameras. Some of media converters can even provide Power over Ethernet to the cameras, although this is not always needed because power should already be at the location previously used for the analog camera. These devices can be a lifesaver or budget saver for companies with large analog systems. These media converters utilize the existing coaxial cable infrastructure and IP cameras to be transmitted over the existing cable (See Figure 6). This solves two costly problems. First, the cost of cabling numerous cameras again can be very expensive. Second, Ethernet cable has a distance limitation of approximately 300 feet. Using a coaxial media converter at either end of a coax cable can extend the distance up to 5000 feet.
Figure 6- Ethernet over coaxial cable media converter
These three devices make migrating from an analog camera system to a network IP camera system much more cost effective.