CCTV BASICS | A CLOSED CIRCUIT TELEVISION SYSTEMS BASICS

* What is an analog video security system?

Cameras on an modern analog CCTV system send their video in the traditional base band format over COAX or UTP cabling back to Digital Video Recorder (DVR). Here, a video is digitized and stored on hard drives. Most modern DVRs are a network device, and as such can be accessed remotely from the LAN, or with the proper configuration, from across a WAN or the Internet. There are no tapes to change. 

Video is kept on hard drives, typically on a FIFO basis so there is always a rolling video archive of the past X days. So, despite the fact that video is being transmitted from the cameras in an analog format, live and recorded video is still available over the network.

Note: This is technically a hybrid system since video is recorded and retrieved digitally, But, in the industry the term hybrid system typically refers to a system that has some IP cameras, and some analog cameras. So, we refer to a system that uses all analog cameras as an analog system.

* What is an IP video security system?

IP video cameras broadcast their video as a digital stream over an IP network. Like an analog system, video is recorded on hard drives, but since the video is an IP stream straight from the camera, there is more flexibility as to how and where that video is recorded. The DVR is replaced with an Network Video Recorder (NVR), which in some cases is just software since it doesn't need to convert analog to digital. Video footage can then be stored on new or existing network RAID drives as directed by the NVR.

* What is a Hybrid video security system?

Hybrid CCTV systems combine IP and analog video, and can be a great way to transition an analog system to IP without needing to replace all of the existing cameras. Many NVR boxes on the market today are actually Hybrids in that they accept analog cameras, and IP cameras and combine them onto a single platform for the user.

* Why Choose an Analog system?

Cost. IP video security systems are generally more expensive, and sometimes a LOT more expensive. But, because the systems are designed differently from the ground up, there are situations where the cost difference between analog and IP is minimal, and even scenarios

where IP video is cheaper. More detail on the cost differences later.

* Why Choose an IP system?

Resolution. One of the biggest factors driving interest in IP video systems is the high resolution that they can offer. Analog cameras max out on resolution at about 580 TVL which equates to roughly 0.4 mega pixels. High end IP cameras on the other hand, are currently available at resolutions above 5 mega pixels. This high resolution in turn gives the ability to zoom in on video after the fact, and still have usable video.

Another benefit to IP video is that it is much more compatible with wireless. Wireless analog systems are available, but they either have to convert to IP anyway and broadcast over the 802.11 IP network (which adds cost for encoders), or they get crammed onto the over saturated regulated frequencies and often encounter interference.

The Cost differences, in more details:

The cost differences between IP and analog can be significant, but that depends on the particulars of the design. Lets break this down into same prime factors that will affect cost.

The Cameras:

IP cameras are more expensive than analog. There are two reasons for this. First, an IP camera needs an internal encoder which adds to the manufacturing costs. To put things in perspecitive, an external encoder runs from $400 to $1000. Second, IP cameras don't tend to come packaged with things like outdoor housings or infrared emitters. When things like this are required, them must be purchased and installed separately which drives up cost.

The Network:

IP cameras are constantly putting high bandwidth video data onto the network, especially if mega pixel cameras are in use. Without the proper network speeds and traffic control mechanisms, an IP video system can bring your network to its knees. Also, don't forget that each camera needs its own switch port, so more switches may need to be included in the budget.

NVR vs DVR:

DVR costs are fairly simple to understand. A DVR is an single unit, and has a single cost. NVRs on the other hand are more complicated. NVR software is typically licensed on a per camera basis and must be installed on a PC. The storage requirements for mega pixel cameras are significant, and may require additional network storage. When comparing costs be sure to include the software, computer and network storage in the total cost for the IP system's NVR.

Cabling:

IP cameras use UTP cabling (at least 5), and analog cameras can use either coax or UTP (at lease (Cat3). In order to transmit analog video over UTP some inexpensive baluns are required, and coax cabling is slightly more expensive than UTP, so cabling cost for an analog system will be slightly higher.

Power:

Analog systems often involve a centralized power source for the cameras, and IP systems usually use Power over Ethernet (PoE). If the PoE switches are not already in place, they will be more expensive than the power supplies for the analog cameras.

Summary:

IP video will almost always be more expensive, but the availability of much higher resolution recorded images makes it a much more powerful system. The ability to digitally zoom in on recorded video make s identification much more likely.

When Megapixel/IP cameras are discussed, not always does recording and storage come up. Often times, the topic is about the  aforementioned level of clarity. 

With analog cameras, their counterparts, at least most people have heard of the term DVR-Digital Video Recorder. This is the device that records the footage taken in by the analog security camera. We'll discuss some of the operations of the DVR when we compare it to the NVR-the Network Video Recorder, below. And of course in years past, the VCR-Video Cassette Recorder, was in vogue. Thankfully, however, gone are the days that we need to rewind and fast-forward until our fingers have blisters to find an event from weeks prior. But going forward, you're certainly going to be hearing more about the NVR than the VCR.

NVR's, are what Megapixel/IP security cameras store or record to. To learn a little bit about NVR's, lets talk about how they compare to DVR's. In this brief blog post, we just barely scrape the surface of the overall topic below with our four items.

1. With a Network Video Recorder, of course the video input comes from the network-the video has already one format to another. The video is then streamed to the NVR for storage and it can be viewed remotely due to it being on a network.

2. With a DVR, it does the encoding at the DVR itself, not at the individual cameras. Since it digitally compresses the analog feed, it must be located near the feed.

3. Also, an NVR can be located anywhere on the network. What benefit is this? Protection against network failure for one thing. With "mirroring", NVR's can be located throughout the network to provide duplication.

4. Another difference between a DVR and an NVR is access. To view the video that was recorded, you need to be at the DVR (or burn a disk if you want to view it elsewher). But with an NVR, due to its very nature of being on a network, you can view it remotely.

5. Finally, paring security cameras with NVR's is actually more restrictive than doing so with DVR's. So take caution when you buy your cameras and make sure they're compatible before doing so.
So we hope you picked up a few things that helped whether you're looking into DVR's or NVR's. Thanks for spending some time with us today.