What's the difference between Analog, HD-SDI and IP Cameras?
Analog CCTV Cameras
Analog, or standard definition cameras, are still the lowest-cost systems on the market. The image resolution is typically limited to 704 x 480 pixels (about 1/3 of a Megapixel). With the newer 960H technology, the resolution gets bumped up to 960 x 480 pixels, which is considered "entry-level high definition." Even with 960H, the image resolution is still under half a megapixel.
Analog systems are still good for a lot of applications. Homes and smaller businesses may not have the money to spend on more expensive HD quality systems, and in most cases it's better to have some surveillance than nothing at all. Most older systems are analog, so we can use newer analog cameras and DVRs to update or expand existing systems.
It's diificult or nearly impossible to discern details when objects are far away from the camera, especially if the camera has a wide-angle lens. Enlarging the image only causes pixelation which actually makes things worse. Without specialized cameras, reading license plate numbers is almost impossible as well.
HD-SDI Surveillance Cameras
HD-SDI surveillance cameras use the same technology (SDI) as the video cameras used for high definition movies. These cameras are capable of True HD 1080p resolution, which is equivilant to 2 Megapixels. It also uses the same RG59 coaxial cable as analog systems, making upgrades a breeze!
HD-SDI provides impressive images and tends to be less expensive and easier to implement than IP based systems. It's easy to upgrade analog to HD-SDI because it uses the same type of cable. Users can digitally zoom images with much less pixelation, making facees and license plates easier to identify. HD-SDI also has zero latency, or delay, because the images are not compressed until they are recorded.
HD-SDI is more expensive than analog, but not by much. It is more prone problems longer cables because there is no gradual signal loss. It either works or it doesn't. It also relies on true 75ohm connectors but barrel connectors are typically rated at 50ohms, so those are out of the question. It is much more important to buy high quality cable and connectors for these installations.
IP Surveillance Cameras
The surveillance industry is trending mostly towards IP cameras because they are the most advanced technology. Some IP cameras can provide resolutions up to 20 Megapixels, but most are in the range of 1.3 to 3 Megapixels. Hybrid systems exist that support analog and IP cameras on the same recorder.
Because they don't need to be directly connected to the recorder, wiring IP camera systems can be done more efficiently. We can use POE (power over ethernet) switches to act as splitters in areas with dense camera populations, then run a single ethernet cable back to the main network. IP cameras can also connect to third-party analytics devices to provide license plate detection, facial detection, missing object detection and a myriad of other valuable information. These analytics can also trigger alerts to be sent to the user via SMS or e-mail.
Ethernet cable has a maximum distance of 330 feet. Any longer runs will require expensive equipment to extend the range such as ethernet extenders or repeaters. A network switch can also be placed inline to act as an extender. IP cameras also use up a lot of network bandwidth. It's recommended to build a separate network for IP cameras to avoid any problems with added network traffic. Video recorded from IP cameras also eats up a lot of storage space, but careful use of analytics and motion detection can reduce this quite a bit.