Wireless surveillance failures and problems are well known. These deployments are especially hard because they demand expertise in surveillance, IT and RF. Have problems in any one of these areas and the likelihood that your system fails increase greatly.
In our experience, out of these 3 areas, security integrators typically have the least amount of expertise in RF. For 'normal' wired surveillance projects, you can be an excellent integrator only knowing surveillance and IT. However, for wireless, understanding how video is transmitted by radio is critical to avoiding big mistakes.
Making this more challenging, using RF in surveillance forces lots of unclear tradeoffs:
- The more power your radio transmits, the more likely your video will 'make it' to the other side. However, you need to be cognizant of legal limitations in the commonly used unlicensed frequences.
- The narrower the beam width of your antenna, the further your camera can be from your site. However, this can make it more difficult to line up your radios and can cause problems in designing systems that 'talk' to multiple cameras.
- Unlike wired transmission which is generally very stable, wireless surveillance throughput can vary significant, can drop out of the blue or due to the weather or vegetation growth. Integrators need to factor in potential issues and plan for likely risks.
- You can choose from many radio frequencies but you need to be careful because important tradeoffs exist in bandwidth capacity, interference likelihood and ability to transmit through obstacles.
To this end, unlike wired, you generally need to carefully plan wireless systems and run the numbers to make sure you can accomplish what you propose. This is even more complicated because you have to be explicit and factor in your resolution, your transmission control (e.g., CBR vs VBR), the scene complexity captured, your frame rate, etc. Even if you establish a link, the link may be insufficient to deliver the bandwidth you need (or implicitly promised to the user).
In this report, we provide videos and explanations of the basic concepts and key issues in using radios to transmit surveillance. Our goal is to help you understand the fundamentals so you can avoid mistakes and know where to focus your efforts in designing and deploying projects.
For those of you planning to do wireless surveillance projects regularly, we recommend studying for the CWNA certification. When we were integrators, we did so as a team and it greatly helped our techs understand the underlying technology and challenges in our wireless surveillance deployments.