Following is an examination of the core components of these systems to provide a better understanding of how a Wireless IP-Surveillance system functions and the many end user benefits it delivers.
Network Camera
Network camera technology makes it possible to have a camera at one location and view live video at another location over the network/Internet. If a building is equipped with an IP network, then the necessary infrastructure already exists to add network cameras. A network camera performs many of the same functions as a standard analog CCTV camera, but it does so with greater functionality at a substantial cost saving. Because network cameras plug directly into the existing net via an Ethernet port, companies can save thousands of dollars by avoiding wiring their facilities with coaxial cabling as required for analog cameras.
When computers are already in place, no additional equipment is needed to view network camera output. The output can be viewed in its simplest from in a Web browser at the computer monitor and in more complex security solutions with the aid of dedicated software, IN cases where analog cameras are already installed, video servers can be employed to digitize the analog signal, thus incorporating such a camera into the high-functioning Wireless IP-Surveillance system and making those images available in any location required.
A modern network camera will typically include a lens, optical filter, image sensor, image digitizer, image compressor and a web server with network and phone modem interfaces. More advanced network cameras can also include many other attractive functions such as, motion detection, alarm inputs/outputs and email support.
Surveillance Wireless Networking Technology
Wireless networks offer higher capacities at significantly lower costs than wired data networks. Reliable and easy to deploy, they primarily come in two varieties: point-to-multipoint and point-to-point systems. For security and surveillance applications, point-to-multipoint systems are the most relevant, but point-to-point can also be used for longer distances and higher bandwidth requirements.
Point-to-multipoint Wireless Systems
Using IP packet radio transmitters, standard Ethernet interfaces, and an easy-to-deploy design, these systems enable high-speed network connections to multiple Ethernet switches, routers, or PCs from a single location. The system consists of multiple wireless bridges, called Subscriber Units (SU), that communicate with a wireless Base Station Unit (BSU). Network cameras can be connected to a SU, which can be conveniently located wherever necessary. The Subscriber Units transmit the digital data back to a centrally located BSU. Transmission capacities vary from 11 Mbps to 60 Mbps and transmission distances can be from three to as far away as 12 miles.
Point-to-point Wireless Ethernet Bridges
While point-to-multipoint systems provide connectivity from one location to multiple locations, point-to-point bridges connect two locations. These systems offer higher capacities and greater distances than the point-to-multipoint systems. When used for security and surveillance, they are ideal for backhauling video data from the local central site where a Base Station is located to a central command and control center that's located farther away. They are also ideal for connecting to a remote site under surveillance up to 40 miles away from the center. Point-to-point systems are available in capacities ranging from 11 to 430 Mbps data rate.
PC Server and Software
Although the Motion JPEG images generated by an IP-Surveillance system are native to most standard Web browsers, the true value of IP-Surveillance products is best realized when utilizing professional monitoring and recording software, which turns a PC server into a network video recorder (NVR). While IP-Surveillance video can be viewed directly from a normal web browser without the need for dedicated software, it is strongly recommended to use a software application in combination with the cameras. This software provides the user with more flexible viewing options and, more importantly, the ability to store and manage the video, with an NVR. Dedicated software is installed onto a PC for monitoring, storing, replaying and conveniently managing video images, to create a synergy that offers a level of system functionality vastly superior to any contemporary analog system on the market today. The software can be a stand-alone solution for a single PC or a more advanced client/server-based application providing support for multiple simultaneous users. Any system from one to thousands of cameras can be deployed, and scaled in steps of one. In some cases, the end user can select software to implement support for multiple systems such as video and access control. Selecting a suitable software package to match the application and system goals is one of the keys to designing an effective and successful system.
Common Misconceptions Related to Wireless IP-Surveillance
We've seen that Wireless IP-Surveillance technology offers an impressive array of end user benefits in addition to a very attractive total cost of ownership (TCO). However, as with any relatively new technology, there may be a number of misconceptions regarding technology performance that may give potential users pause in implementing Wireless IP-Surveillance. Below are important clarifications addressed to several common misperceptions regarding this technology.
Security
IP-Surveillance: Although primarily used as a domain for public information, the Internet can also be used to transfer all types of sensitive information-provided the correct security measures, such as firewalls and password protection are implemented. With an increasing number of banks and financial institutions regularly using the Internet as a medium for global money transactions, it has emerged as a proven medium for other secure applications like surveillance and security monitoring. In combination with an organization's firewall, Axis' IP-Surveillance technology allows product security to be tightly maintained using available internal password-protected security settings. In stark contrast to this new digital technology, analog surveillance systems have no encryption of information whatsoever, making it extremely easy for anyone to tap into the cables and illicitly view "secure" video transmissions.
Wireless: Security can be an area of concern for those considering the use of fixed wireless devices to transmit data. Because fixed wireless bridges transmit signals into the "air," there is a perception that anyone could possibly "steal" the user's data. Top of the line wireless providers will incorporate a variety of counter-measures to ensure rigorous security of data. These include: Password protection-protection at two levels, one for the monitor and one to provide monitor/modify privileges. Transmission protection/ encryption-unique transmission signals that require the same maker's equipment at both ends for decoding. In addition, "line of site" transmission, as opposed to omni-directional transmission ensures that only antennas firmly in the radio frequency target area can receive the data. Data coding-potential intruders would have to obtain a unique transmission code set by the administrator to decode the data. Most potential data thieves don't have the several million years needed to run through all the codes so as to get to the data. Should someone try to capture the data, but not provide the proper codes at regular intervals, transmission is immediately terminated. If further proof of the secure nature of wireless transmission is required, look to the many high-level military installations that use it-they cannot afford to use a risky technology.
Bandwidth
IP-Surveillance: Today, most computer networks are 100 Mbps Ethernet networks. In practice this means that the maximum usable bandwidth is around 50 Mbps. Consequently, one network camera, transmitting the highest resolution image at the maximum frame rate (30 frames per second) can potentially consume 5 Mbps. This means running an IP-Surveillance system on an office network simultaneously with other data applications could prove problematic. However, these potential difficulties can be easily overcome by employing the following techniques:
- Switched networks: By using network switching-a common networking technique today-the same physical computer and IP-Surveillance network can be separated into two autonomous networks. Even though these networks remain physically connected, the network switch logically divides them into two virtual and independent networks.
- Faster networks: As the price of hubs, switches, and routers continues to fall, the affordability of Gigabyte networks increases. Reducing the effect of limited bandwidth, the trend towards faster networks increases the potential value of remote monitoring over networks.
- Event driven frame rate: 30 frames per seconds (fps) on all cameras at all times is more than what is required for most applications. With the configuration capabilities and built-in intelligence of the network camera/video server, frame rates under normal conditions can be set lower, e.g. 1-3 fps, to dramatically decrease bandwidth consumption. In the event of an alarm, if motion detection is triggered, the recording frame rate speed can be automatically increased to a higher frame level.
Wireless: Bandwidth is a natural concern when it comes to wireless transmission. Proxim's outdoor wireless networking solutions offer capacities ranging from 11 Mbps to 860 Mbps, by using different radio technologies. Basically, there are two major radio technologies employed for transmission-Frequency Division Duplex (FDD) and Time Division Duplex (TDD). TDD is typically used in multipoint environments, while FDD technology is used for high-speed point-to-point connectivity. By employing the right technology, end users can ensure sufficient bandwidth over required distances to support the number of cameras needed in any given deployment.
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