PoE technology is regulated by the IEEE 802.3af standard and is designed to not degrade the network data communication performance. When evaluating PoE-enabled network cameras, it is important to look for those that are based on the IEEE standard, to ensure that any brand network switch can be chosen, providing a truly open system.
Progressive scan: Progressive scan capability is found only in network cameras, but not all network cameras have this functionality. Progressive scan involves exposing and capturing the entire image simultaneously, as opposed to analog interlaced scanning which is the exposing and capturing of only half of the lines in the image and then the other half 17msec later. With interlaced scanning, if an object is moving the image will become blurry. In a progressive scan image all lines are scanned in perfect order so there is virtually no "flickering" effect.
While interlaced scanning may be sufficient under certain conditions, progressive scan technology allows for far better image quality on moving objects. In a surveillance application, this can be critical in enabling the user to view detail within a moving image such as a person running away or the license plate on a moving vehicle. When cameras capture moving objects, the sharpness of the frozen images depend on the technology used, and progressive scanning consistently produces the best results in clarity and recognizing important details.
JPEG/MPEG4 standards: It is important for any network camera to follow JPEG and MPEG-4 standards in their entirety. Many vendors claim compliance with a standard, but do not adhere to that standard 100 percent. Full adherence ensures the flexibility to use video for many different applications. It also guarantees that you can view the video many years from now. If a camera uses one company's proprietary compression technology and that company goes out of business, the video will be unreadable in the future. Also, if a company is following the MPEG-4 standards, ask if the licensing fees are paid, and how many licenses are included with each product. Proprietary compression technologies are also not always admissible in court, an important consideration for security and surveillance applications.
Extensive support of Video Management Applications: The security industry migration to network video includes the use of open systems and platforms. Make sure to select a network camera that has open interfaces (an API or Application Programming Interface), which enables a large variety of software vendors to write programs for the cameras. This will increase your choices in software applications and will ensure that you are not tied to a single vendor. Your choice of network camera should never limit vendor options and functionalities.
Vendor history and focus: It is important to make network camera decisions based on estimations of future growth and the need for added features and functionality. This means your network camera manufacturer is going to be a long-term partner. It's important to choose a solid partner, so be sure to look for a company that has a large installed base of cameras, is profitable, focuses on network camera technology, and offers you local representation and support. You want to choose a camera from a vendor where the innovation, support, upgrades, and product path will be there for the long term.
Just like with analog cameras, not all network cameras are created equal. Far from it, and the differences among network cameras are greater and more significant than buyers have experienced with analog technology. The end user has to be smart. Vendors will tell a lot of great sounding stories, but the user has to have a solid list of evaluation criteria, test the different choices, and understand the differences between the available products.
Network Camera Check List Suggestions
- Lens: F2.0 and auto iris for outdoor applications
- Image sensor: Progressive scan CCD image sensor or high quality CMOS
- Resolution: 640x480
- Frame rate: 30 frames per second
- Video formats: MJPEG & MPEG4 at Advanced Simple Profile level 5
- Power over Ethernet: 802.3af compliant
- Audio: G.711 or AAC-LC format
- Software compatibility: Open API supported by many Network Video Recorder software developers
- Security: Multi-level user name/password protection minimum and IP filtering and HTTPS for high security requirements
- Management: Built in web interface and multi-camera management application