Video systems are becoming a part of our everyday lives. When video surveillance systems first hit the market in the mid 80's, they immediately made a major impact on crime prevention and the way crimes are investigated. Early video systems required a hardwired connection between the camera and the recording system. Recent innovations in wireless video transmission are changing that requirement.
Wireless video systems are popping up all over the place to satisfy a range of consumer requirements. From wireless baby monitors to high-end high-definition wireless broadcast systems, wireless video systems are available in a wide range of prices, features and functions.
Most modern, consumer grade wireless video systems will fall into one of the following frequencies; 900 MHz, 2.4 GHZ or 5.8 GHz. Almost all of the affordable consumer grade wireless cameras on the market fall into the 2.4 GHz range.
Every wireless video system consists of a camera, a transmitter, a receiver, an antenna and a power supply. Transmission ranges can vary greatly depending on the frequency, the antenna and the rated power output.
With the exception of higher end, high power broadcast quality systems; most wireless video systems do not require a license from the Federal Communication Commission (FCC) to operate. No matter what frequency you plan on using, if you are installing a high powered installation, especially near a highway or an airport, you should secure the appropriate FCC license.
For the best results and the longest range, most wireless video transmission systems require a clear line of site between the transmitter and the receiver to operate consistently. Wireless video signals do not penetrate very well through glass, walls, concrete, trees, steel or other obstructions.
In addition, other RF signals around the same frequency can cause interference or be interfered with by wireless video systems. In the 2.4 GHz range popular with most security applications, interference can be experienced between cordless phones, microwave ovens, local television broadcasts, computer monitors, power supplies or wireless LAN/WANs. Sometimes interference problems can be solved by re-locating the transmitters or receivers.
Since 90% of consumer grade wireless video systems fall into the 2.4 GHz category, we will discuss the features of both the 2.4 GHz analog and digital systems and the limitations and benefits of each.
The entire 2.4 GHZ bandwidth allocated for consumer use is from 2,412 MHz to 2,462 MHz. As per the FCC standards, there are 11 possible channels which are 22 MHz wide with a 5 MHz spacing interval between each.
In order to allow multiple cameras on the same system, residential, consumer grade 2.4 GHz analog video transmitters such as a wireless baby monitor or a front door camera require fixed frequency, non-overlapping channels to reduce interference.
These 2.4 GHz analog wireless cameras are some of the most popular video surveillance systems for consumers and end users, yet very few professional security providers will offer these wireless cameras.
At best, professional security installers consider the 2.4 GHz analog video systems as low-end residential solutions which are notoriously unreliable. The analog 2.4 GHz cameras are easily identified by their price tag which is usually in the $ 69.00 to $ 140.00 range per camera.
If you take away the benefit of their low cost, there are several inherent limitations to Analog 2.4 GHz video transmission including:
In the 2.4 GHz range, there are only 4 available non-overlapping channels. This limits these systems to a total of 4-cameras, each of which is tuned to a different pre-defined frequency. Each of these fixed frequencies is capable of transmitting about 11 mega-bits per second of data (Mbps).
Because the analog 2.4 GHz wireless video transmitters are on fixed frequencies, they are especially susceptible to interference from outside sources. A typical transmission range for an analog 2.4 GHz wireless video link is about 200 to 300 feet when installed outdoors with a clear line of site. The relative transmission distance is greatly reduced when installed indoors with some lower end analog systems typically providing about 10-30 feet.
Since these cameras are transmitted on a fixed, un-secured open frequency, the signal is easily intercepted and can be seen by anyone with a 2.4 GHz 4-channel receiver. A voyeur or a burglar could simply drive around a neighborhood with a receiver and see inside your home. If you have one of these systems installed, perhaps a burglar is watching you right now.
In 1997, the Institute of Electrical and Electronics Engineers (IEEE) created the first Wireless Local Area Network (WLAN) standard which was named 802.11. The original 802.11 utilized the 2.4 GHz frequency to allow reliable transmission of 2-Mbps of bandwidth. In 1999, the standard was upgraded to 802.11b which supports up to 11 Mega-Bits per Second (Mbps) which was comparable to traditional Ethernet connectivity speeds.
The 802.11 protocol works by sub-dividing the entire 2.4 GHz frequency into channels and switching between them during transmissions. As the signal is sent, it sends a packet of data at one frequency and then hops to the next channel and sends another packet and so on, until the entire data package is sent.
In 2003, WLAN products began supporting a new 2.4 GHz wireless standard called 802.11g which supports a bandwidth of 108 Mbps of data. The days of cost effective, reliable and secure wireless video transmission have finally arrived.
The added features and benefits of using internet protocol cameras and 802.11g for wireless video transmission in a security application are many.
The 802.11g protocol utilizes digital bi-directional signals which support the use of pan/tilt/zoom functions and presets found in many newer cameras. The digital signal used is duplex (bi-directional) as opposed to the simplex (one-way) binary signal used in analog type systems.
Because 802.11g utilizes the entire 2.4 GHz frequency spectrum, interference is greatly reduced and longer transmission ranges can be expected. If an area of the frequency is noisy then the transmitter/receivers will adapt the signal by sending smaller packets in the noisy affected area and larger packets in the non-effected areas of the frequency. A wireless IP video system will offer almost the same performance as a professional grade wired system with a reliable transmission range of 150-200 feet.
If the camera is to be located further than 200 feet, directional antennas are available which can increase the distance to 600 or more feet. If a greater distance than 600 feet is required, point to point, long range directional type systems can increase the distance to several miles.
In addition to standard 64/128-bit WEP Security, 802.11g protocol allows data packets to be encrypted using a 40-bit RCA key. When considered in conjunction with the inherent security built into DSSS spread spectrum technology, the data signals are at least as secure as data traveling over a wired network.
The 802.11g protocol can support a much larger number of wireless cameras by using a medium access control or MAC layer called CSMA/CA or Carrier Sense Multiple Access/Collision Avoidance. The collision avoidance in 802.11g supports the use of CTS/RTS signals (clear to send/ready to send) which tell each camera on the system when it is O.K. to begin transmitting or receiving data thereby avoiding interference.
Any hardwired IP Camera that is installed on your intranet or internet that is using the same CODEC (Coding & Decoding) algorithm can be integrated into the same software viewing and recording system.
An IP addressable camera system can be viewed or recorded from a properly equipped computer from any location in the world. This can allow you the freedom to move anywhere on the planet while still keeping track of your assets. In addition, if you ever decide to move your head end recording equipment to a different location, you simply pick it up and move it. No wires to re-route.
One thing to remember when deploying a multi-camera wireless IP based video system is that processing multiple streaming video signals places a substantial work load on a computers CPU.
Hard Wired systems have video capture cards which are installed in the PC/DVR. These cards take up to half of the work load off the computers CPU. Because wireless IP video systems do not have the help of these capture boards, the computers CPU must handle 100% of the processing workload.
What this means is that as you add cameras to a wireless system the total frame rate or the total images per second which can be viewed and recorded will decline due to the increased workload.
Some people shy away from IP and network security solutions because they appear to be complicated and difficult to set up. The fact is the initial set up does require some expertise and knowledge but the operation and day to day use of the systems are no different than using any other PC based security camera system. The required computer skills are minimal. If a person can check email, use a word processing program or load and play any type of game on a PC they most likely possess the skills needed to use and manage a PC based system.
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