Getting the Image from Here to There

A stable transmission infrastructure will help you get the most out of your video system design.


Cons:
• Fiber-optic cable is more expensive than copper, and the connectors are more expensive.
• It also requires the extra cost of transmitters and receivers.

There are other transmission techniques; however, they are usually exceptions. In cases where cable cannot be trenched, for example, microwave or RF techniques can be used. Microwave transmission requires line of sight, which may not always be available. RF is used with directional antennas to limit interference and meet FCC standards. Both methods tend to be expensive and thus are only practical when the standard methods above or below won’t work.

Digital Video Transmission
The newer transmission methods are based on a compressed digital video signal. Analog video can’t be compressed cost effectively. But new ASICs (dedicated LSI chips) and DSP technology have brought down the cost of digitizing and compressing video. Compression is necessary for transporting digital video, since digitization results in a much larger signal than the original analog signal. However, with modern compression algorithms, streaming video is now cost effective. (Streaming video in this article refers to a digitized and compressed video stream.)
Digitization and compression open the door for other transmission methods. Two of the most common of these are telco and IP video.

Telco
In the early stages of remote video applications, streaming video was sent via POTS (plain old telephone service), ISDN and T1. POTS, of course, has a very limited bandwidth. When video is sent via POTS, it is usually not real time, and if it is, the image is reduced in size and resolution in order to fit into the POTS bandwidth. ISDN 2B has a 128Kbs bandwidth, so it can accommodate a real-time picture at limited resolution. T1 is 1.5Mbs, which will accommodate full-resolution, real-time video.

Pros:
• Telco methods offer another option for long-distance transmissions that is cost effective.
• Based on the bandwidth available, telco is a good trade-off in remote applications.
Cons:
• Low-cost methods such as POTS offer limited quality.
• ISDN and T1 are very expensive.

IP Video
The new paradigm in video transmission is IP video. IP video is a streaming video that supports TCP/IP protocol. In short, it is network video. IP video connects directly to Ethernet and can be handled as normal network data.
Today we see IP cameras and IP domes; these are cameras that connect directly to the local Ethernet infrastructure. IP video can go anywhere in the world via a LAN/WAN. There are also encoders and decoders available, allowing users of existing analog systems to convert them to IP video.

Pros:
• IP video offers unlimited distance and can be controlled and viewed from a PDA phone, laptop or other mobile device.
• It can be managed by internal IT departments, saving costly outside maintenance.
• With IP video, adding a camera is simple and cost effective.
• IP video is also available in wireless form using 801.11 standards.
• It is encrypted for security.
• It is cost effective and offers low-cost recording using standard network recorders.
• It eliminates the need for an analog matrix switch, and it offers analytics.
• Open IP video has multiple business applications within the corporation. When the CSO is looking at ROI, it is easy to get other departments to help cost-justify the installation of or conversion to IP video.

Cons:
• IP video has fewer cons than pros, but many perceived negatives. For example, networks are perceived to be unstable. This is not a valid assumption. The IT industry has developed products that ensure a stable system.
• There is a perception video will overload existing networks. This again is not a valid assumption. There are products and algorithms that reduce the network load.
• There is a perception that streaming video is of lower quality than analog. This argument is partially true. However, the latest algorithms offer high-quality video in a relatively narrow bandwidth.
• The major downside of IP video is the lack of awareness in our industry of its value and how to implement it.