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Thread: CCTV - IP vs ANALOG

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    Default CCTV - IP vs ANALOG

    In Brief

    Choosing between IP and analog security cameras is one of the first and hardest choices facing any prospective buyer of a CCTV system, whether it is for home surveillance or for monitoring a business. Both types of systems have advantages and disadvantages, and manufacturers don't try to make it easy to decide between them. There is a lot of hype and marketing buzz right now because of the growth of the industry.

    Both types of cameras work through the use of CCD and CMOS chips. These chips turn visible light (and in some cases infrared light) into a signal.

    Analog cameras turn this signal into something that a television can see, very much like a camcorder.

    IP based cameras do something a little more complicated. They take the information from the chip and feed the analog signal into an encoder. This encoder is combined with an onboard web server. This allows for the camera to become a network device. This allows it to be viewed by users over an existing or new network like a web page.

    Analog cameras have been around since the 1970's, starting out as vacuum tube based devices. Since then the cameras have gotten better and better. Improvements to resolutions have occurred every year. But the improvements go beyond increasing resolution. Auto-iris lens have made dealing with florescent lighting situations easier. Backlight controls have been introduced to help with bright lights coming into an area, like light streaming in through a window next to a door. Privacy masks built into PTZs can handle some of the concerns over misuse of CCTV cameras.

    Analog cameras have a variety of ways of transmitting the signal, from wireless to coax, to Cat5 using different connector types. This makes long distance runs in the same building much easier since you can use the right and most cost effective cable for each run. The variety of cable types can be both confusing and useful at the same time.

    Cat5 works for very short runs that are less than 250 ft. Professional grade baluns can be run up to 2500 ft.

    IP cameras grew from the humble web cameras. The idea behind them was to move some of intelligence from the DVR to the camera itself. Many of the current IP cameras have their own built in motion detection. This allows some cameras to record to SD cards inside the camera itself, offering a layer of redundancy. Other features include adding an analog output to the camera so that it can become a bridge between an analog system and an IP based system.

    IP cameras can be connected to a network by either wireless transmissions or by Cat5. Through the use of switches/hubs/and routers the Cat5 can be extended almost indefinitely. The use of IP cameras can require the installation of new RJ-45 jacks. Existing jacks generally are not well placed to secure the camera's connections. Some IP cameras are hybrid in nature, allowing for both network and analog connections. Toshiba's line of IP cameras generally has this feature.

    Analog Pros:

    1. Cost: Analog cameras generally have a better price to performance ratio then IP.

    2. Flexibility of design: There are many varies of camera types, from small covert cameras to large PTZs to indoor domes with IR. This can make fulfilling certain goals easier by using a camera designed for your needs.

    3. Compatibility: Analog cameras put out either NTSC or PAL signals. In North America, almost any camera you buy will be NTSC. This makes it easy to use existing cameras, or mix and match vendors for equipment.

    4. Maturity: Many of the teething problems have been worked out. Things like privacy masks (blacking out an area for privacy on a PTZ) and back light compensation exist from lesions learned in the past.

    Analog Cons:

    1. Analog cameras don't have some of the features like built in digital zoom that IP have, except at the highest price points.

    2. Wireless Analog cameras have problems with interference and are unencrypted. Anyone can view the signal.

    3. Analog cameras can be harder to deal with over long distances.

    IP Pros:

    1. Better wireless support: Analog wireless has more problems with interference then network based cameras. The 802.11x standards have encryption built into them.

    2. IP cameras can take advantage of already existing wiring.

    3. Adding one or two cameras at a remote site can be easier.

    IP Cons:

    1. High bandwidth use: It varies by camera but 500kbps to 1.5 Mbps is a common range.

    2. Cost: Because of the cost of the hardware that is moved onto the camera, IP cameras cost more then comparable analog cameras.

    3. Vendor lock-in: Many third part applications support more then one type of camera but most vendors only support their cameras. Given that not all brands support all features, it can make selecting the right brand hard unless you turn to a third party.

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    We use both analogue and IP cameras. The only advantage is see to analogue is reliability.

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    Another great post intelliGEORGE.

    The only thing I don't agree with is "Vendor Lock-in" as an IP Con. Here is an extract from an article I wrote that explains why....



    What are our options for integrating IP cameras so that they become an integral part of a security alarm system?

    Most cameras come with some form of built-in motion detection, however, the unpredictability of this technology prevents it from being used to trigger an alarm panel into calling a Monitoring Center. Using motion detection would also require that there be some way to arm and disarm the cameras so that they do not send images when people are legitimately moving around the protected premises. Due to the familiarity and simplicity of arming and disarming an alarm panel, one option is to have the panel trigger cameras only when it is armed. This way, images are only sent to the server in the event of an alarm activation.

    This can be done by connecting a cable from the panel to the trigger input of the camera if it has one. The preferred method however, is to trigger and control the camera via software commands from the Monitoring Center server. The more expensive IP cameras provide a full range of software commands that allow control of pan, tilt, zoom, pre and post alarm triggering and other common features. Whilst lower cost cameras do not generally offer these features, the majority of them do support jpeg snapshots at various resolutions which provides the industry with a starting point for mainstream video verification.

    Overview of Vendor Neutral Video Verification

    The snapshot feature allows an installer to fit a camera from manufacturer X alongside one from manufacturer Y and Z. This provides great flexibility for the installer as they are not tied to a specific camera manufacturer. It is also ideal for the Monitoring Center as they are not reliant on a specific server application.

    In preparation for viewing and recording images from the protected premises, the Monitoring Center database stores various camera related parameters alongside well known alarm parameters such as event definitions and zone lists.

    Basic camera parameters determine what type of alarm events and which zone numbers should trigger the recording of individual cameras. They also specify the total number of images to be recorded and the time interval between them.

    Each IP camera requires a slightly different software command to trigger it, so the Monitoring Center maintains a database of custom commands which they can build up over time to support any brand of camera used by their installers.

    Every second counts in the triggering and recording of images from IP cameras. Remembering how long it takes to send an alarm signal using traditional protocols, starting a recording 10-15 seconds after an alarm event would almost certainly mean losing some of the most important footage.

    There are different ways to overcome this depending on the available features of the alarm panel, the IP alarm device and the camera. A high spec camera would use a “pre-alarm” feature where it might send the server ten seconds of footage prior to the alarm and twenty seconds after it. Lower spec cameras would provide a snapshot command facility which can be triggered by the use of panel outputs and IP device inputs as already described.

    The Snapshot Command in Action

    As an example, we will say that Mr. Smith has an alarm system, an IP alarm transmitter and an IP camera installed at his home. The transmitter and camera are plugged into his router and connected via the internet to an IP enabled Monitoring Center.

    His account number at the Monitoring Center is 1234 and he has requested that 10 snapshot images be recorded at 2 second intervals in the event of an alarm. This information should be entered into the database at the Monitoring Center and checked every time an alarm signal is received. Here are the database fields and data that might be used for Mr. Smith:

    Account Number: 1234
    Number of Snapshots: 10
    Snapshot Interval: 2
    Zones That Trigger: 2,3,4
    Camera IP and Port:
    Snapshot Command: /CamImage.jpg?UserName=abc&PassWord=xyz

    When an alarm signal from account code 1234 is received, the server software checks the database to find that Mr. Smith has a camera and that images should be recorded on the server if the alarm was from zones 2,3 or 4 (zones 5,6,7 and 8 might be used to trigger a second camera). The software concatenates the IP address of the camera and the snapshot command together so that the following command is sent in a loop, ten times, to Mr. Smith’s camera at two second intervals…



    The end result is that ten jpeg images are written onto the hard drive of the monitoring server and optionally displayed to an operator for further analysis.

    Now let’s break down the snapshot command and consider the prerequisites of Mr. Smith’s network and camera setup in order for it to work correctly.

    Firstly, you will notice that is used instead of an IP address. This tells us that Mr. Smith does not have a fixed IP address allocated to him by his internet service provider and that he has registered something called a dynamic domain name. Put simply, this is a method of keeping a domain name linked to a changing IP address. Typically, when a user connects to the Internet, the user's ISP assigns an unused IP address from a pool of IP addresses, and this address is used only for the duration of that specific connection. A dynamic DNS service provider uses a special program that runs on the user's computer (some IP cameras also support this), contacting the DNS service each time the IP address provided by the ISP changes and subsequently updating the DNS database to reflect the change. In this way, even though a domain name's IP address will change often, we do not have to know the changed IP address in order to connect with Mr. Smith’s camera.

    The :800 in the command lets us know that Mr. Smith’s router has been setup with port forwarding and that port 800 points to his camera. There is an IP alarm device that can overcome the requirement for port forwarding in order to trigger cameras, but generally speaking there is no way to get to Mr. Smith’s camera without port forwarding.

    Each camera manufacturer has their own set of software commands for controlling cameras and the /CamImage.jpg? part of our example snapshot command is just one such variation.

    Most snapshot commands contain a question mark and this tells the camera that a number of parameters will follow. These are normally used to set the resolution and compression of the image and to provide security credentials.

    In summary, with the help of specialist software on the server at the Monitoring Center and an IP alarm adapter at the protected premises, low cost IP cameras can be easily integrated with alarm systems to provide basic video verification.
    Developer of VoIP2Go at ozvoip.net - Alarm compatible VoIP Network

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