The meaning of Optical Budget; Web-Based Video Issues

Oct. 27, 2008

Fiber Connections
What does it mean when a fiber modem is advertised as having "13 db optical budgets"?

A: The optical budget, also known as maximum attenuation, includes the fiber connector loss of signal amplitude at the transmitter, receiver and/or transceiver. Adding fiber connections and bends in the fiber contributes to the fiber path, which adds dB losses and reduces distances.

"Optical budget" is a generic term referring to the quantitative amount that is available. If connections, splices, and distance exceed the optical budget, problems occur at the receive site in the way of amplitude and electronic integrity of the signal.

Consider, from an application standpoint, the relevance, for example, if a product says an optical budget of 13 dB can transmit up to 3.2 miles. A lesser spec would not travel that far. A greater spec would travel further, provided there were not a number of splices along the way!

Web-Based Applications
My client is considering a "web-based video" application. What are some of the issues I should discuss with my client?

A: The security industry is seeing many computer software developers enter the security world. Initially, many manufacturers or software developers will offer products with different approaches to solving technical challenges. As time goes by, the industry will migrate to the best solution. This is why web-based systems are being developed.

The video information to be transmitted and received needs to be converted from analog to digital signal or start as a digital signal. In either case, the "digital packet" that is to be transmitted needs to be zipped (contracted) to be sent over any transmission source and unzipped at the other end.

When traveling as a digital packet, it needs to conform to TCP/IP Ethernet interfaces. The signal needs to be significantly smaller to travel over the Internet.

What does this mean to the client? It means the picture being viewed can be viewed on many different sources such as a standard web browser, new technology cell phones, blackberry type units, and PDA's. It offers flexibility and is helpful to your customer to be able to check in on a site from anywhere.

The Quality of Remote Recordings
How practical is using the web-based type system to record and view remotely? Is there enough detail for court-tested replay of the incident? How can I improve the storage and answer my client's request for remote transmission and viewing for a court-tested archive?

A: The confines of broadcast technology are limited so the picture quality when archived remotely is limited. The answer is to provide a quality digital video recorder (DVR) locally and loop the signals to a web-based video application.

Some web-based manufacturers are developing this real world applications for the security industry. You now need to explore these options for your client.

John W. Colley is president of Integrated Security Systems, Ltd. Colley has been in the security industry for 25 years, beginning his experience in the CCTV segment of security and gaining knowledge through field experience, manufacturer training and designing systems to meet customer needs. Colley started his security integration firm 16 years ago, providing design, engineering, installation and service to commercial accounts using integrated systems. Send your CCTV/Surveillance questions to [email protected].