If you are an electrical contractor who offers voice/data/video, fire or other low-voltage systems and services, you’ve probably been getting more inquiries from end-users who want to retrofit their aging security systems. Place your bets on the fact that they want to know about closed-circuit television surveillance (CCTV).
CCTV is more than just installing cameras. The electrical contractor also should be well-versed in video transmission and storage, because for facility managers, the overriding concern today is whether they have adequate space to record transmissions and can manage video smoothly and efficiently throughout their operations.
For the integrator/electrical contractor, digital video recording and storage are crucial components of every state-of-the art CCTV solution. DVRs can be piggybacked off access control, intrusion detection and other hardware and software, making them a complete solution for the end-user—including retail theft prevention, point-of-sale monitoring or a host of other scenarios that add substantiated accountability. And, when you can add features and functions to a system, the end-user has a multivalue tool that may be a more cost-effective and all-around solution for the business environment.
Manufacturers, distributors and other low-voltage contractors can offer a wealth of practical information. Many manufacturers offer charts for their DVRs to estimate how much recording you can expect to achieve using various combinations of frames per second (FPS), image quality, hard disk drive (HDD) sizes, etc. More sophisticated units offer built-in calculators on screen that show how much time you will have based on the settings.
Storage capacity and whether to store to a PC-based or standalone system are areas that should be fully investigated by the electrical contractor and integrator. It all comes back to the needs of the end-user and the facility.
The following factors are prime considerations in video storage capacity:
• Hard disk drive (HDD) size: Bigger is better, but prices are still restrictive for the largest disk drive storage units.
• Frames per second (FPS) or picture per second: The more pictures recorded each second, the faster hard drive space is used. Generally, anything over two FPS will suffice in most security applications.
• Resolution or picture quality: Many DVRs offer multiple resolution settings. Higher resolutions yield larger file sizes and quickly fill the hard drive. A mid-range resolution may maximize HDD use yet still provide good picture quality.
• Compression method: Many forms and methods exist; this also effects how much you can record on a hard drive (see sidebar).
• File size: Generally a direct result of the compression method, the file size, expressed in kilobytes, provides an indication of how much space each file should take up.
• Activity detection and scheduled recording: Saves hard drive space by only recording some of the time.
• Alarm inputs: Like activity detection, these inputs are triggered by external devices such as door contacts, space detectors, glass sensors, etc. They, too, can save recording time.
End-users are learning to use their systems to maximize their CCTV recording and boost the overall efficiency of the hard drive while eliminating the recording of unnecessary information. Give them a helping hand by knowing the nuances of this growing security niche. EC
O’MARA is the president of DLO Communications in Park Ridge, Ill., specializing in low-voltage. She can be reached at 847.384.1916 or firstname.lastname@example.org.