Question The CCTV/Surveillance Expert

Oct. 27, 2008
Using cable modems, specifying cable size and light reflection problems

Q: Cable modems are now available in our area. What do I need to know about them and the video applications that use them?

A: Television Cable companies marketing cable modems typically offer a data line to work in conjunction with the Internet. Many are offering IP Telephone service also. Cable modems are faster than dial up telephone lines and, in most cases, faster than DSL lines. The downside is they are prone to Internet hackers and spammers. As broadband fiber networks become available, the transmission of video signals will be very cost effective and will offer additional flexibility to the customer. If you are interested in DSL for video transmission, the most popular and useful for video transmission are the ADSL and HDSL.

Using the Wrong Cable
Q: Recently, our integration company submitted a R59U CCTV 95% copper braid 20ga center copper wire specification as part of its bid package. The engineer on the project objected and refused the acceptance of the RG 59U cable. He recommended RG6U in its place. Unfortunately, our company did not receive a call from the electrician that won the wire portion of the project. The electrician supplied and installed a RG6U cable, which is only specified for MATV or CATV systems.

To further complicate the matter, the manufacturer of the CCTV products had information on its website and in the manuals that indicated RG6U was an acceptable cable for their product.

After researching the type of cable the electrician used and other RG6U cable that may be used, it was clear the cable would need to be replaced. RG6U is primarily used in cable systems. Is there anything we could have differently?

A: No, I think you did everything right. Producing a position paper to the General Contractor and the electrician would be your next step. Issues are always better understood and, in most cases, handled without problems when they are written not just verbalized. I would recommend that you provide cut sheets with the cable specification to accompany the document you are going to send to the other companies.

In some cases, RG6U with 95% copper shields may be used at greater lengths than standard coaxial cable. The use of a different connector and crimp tool will be required, which is another reason to try and stay with a single RG59U type cable.

Factoring in Light Reflection
Q: My customer has a huge problem with light reflecting off walls, floors, and windows. How do I factor in light reflectance when I quote and recommend equipment?

A: To gauge light reflectance and how it affects the cameras that are used, you should do a day and night camera survey of the area with the actual cameras being proposed. Once you have found the right combination of camera and lens for that application, it should be a baseline for future quotes for that type of light and reflectance.

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].