Posts Tagged ‘ cctv cables ’

CCTV Camera Multiplexers

Friday, July 23rd, 2010

A CCTV camera multiplexer is an electronic unit that is able to combine the video transmission signals from more than one camera into one single channel or transmission. These units are often used where processors, VCRs, Digital Video Recorders or DVRs, and monitors can only handle one input. The multiplexer, also known as a Mux, in essence reduces the multiple camera feeds by creating one output that combines all of the inputs to the multiplexer.

The multiplexer was originally designed to facilitate multiple analog video signals into one output signal for analog recorders. In other words, multiple analog CCTV camera signals were difficult to record simultaneously on an analog signal recorder such as a Video Cassette Recorder or VCR. The CCTV camera multiplexers provided an essential function of combining multiple analog video signals into one output. So instead of using four VCRs to record four different cameras, one VCR could be used.

Although CCTV Camera multiplexers were originally designed to accommodate the difficulty of recording or viewing multiple analog cameras on one source, they are not limited to analog camera use alone. Depending on the design of your system, multiplexers may be needed for use with digital video cameras and/or analog cameras.

CCTV camera multiplexers are available with a variety of multiple inputs and many different features as well. Each camera input to the multiplexer is usually called a “channel.” The most common CCTV camera multiplexers have four, eight, nine, or sixteen channel inputs. Most multiplexers connect to CCTV camera transmission cable using BNC connectors and are designed to use one output which is normally connected to a VCR.

Multiplexers may be either simplex or duplex in function. A simplex multiplexer can only handle the camera inputs, combine them in to one viewable output, and send that output to a device such as a monitor or VCR. A full duplex CCTV camera multiplexer has the same capability of the simplex multiplexer, however it not only allows recording from all the available camera inputs but can display the VCR tape simultaneously.

The majority of CCTV camera multiplexers provide the output display signal in full color. There are a few that are available in black and white only and most color multiplexers provide the option of displaying black and white.

If you are considering the purchase of a CCTV camera multiplexer, be sure to check the display resolution to ensure it meets your requirements. Video display resolutions vary widely between multiplexer units. Video displays of 2CIF (704 x
240) or NTSC 865 x 525 are fairly common.
Additional features may be found on individual CCTV camera multiplexers depending on the manufacturer, type, and other factors. Some of those features may include motion detection, timer and programmable switching, user defined and password protected camera masks.

CCTV camera multiplexers that include motion detection can be a big plus. Since the recording is often being done by a VCR, either additional tapes must be added when the current tape is filled, or a loop-able tape is used and when it reaches the end of the tape, it re-records over the beginning. If the multiplexer has motion detection, it often can be used to turn on and off the recording function of the VCR. If full time recording is not necessary (such as an empty parking lot) and recording is only necessary following a motion event (such as a car parking in the parking lot), this can save tremendous amount of VCR tape space.

Many multiplexers also come with timer and programmable switching. This function allows you to set recording times and cameras on and off. If your system only needs to record in the evening for example, you can program this on the multiplexer. In addition, programmable switching allows you to select what cameras you want recorded.

Password protected camera masks are another useful feature. Since your system contains more than one camera, there may be camera views that you prefer to be restricted to only certain individuals. You can create a camera mask to cover the other camera views so that only the cameras you choose are displayed.

CCTV camera multiplexers can be a useful accessory for any video monitoring and security system, especially older analog type camera systems. Multiplexers come in four, eight, nine, and sixteen input types with a variety of features to suit almost any need. Check with your digital security expert today to see what a multiplexer can do for your system.


CCTV Cable Types

Sunday, September 20th, 2009

So, you have decided that you are going to install your own security camera system. Among the many choices you will have to make is the type of cable you will use to connect your cameras to the DVR. There are many options and your choice will depend on your level of proficiency running the cable, the distance you need to run the cable and the environment the cable will run in. Here is a brief run down of your cable choices:

–          Pre-Fabricated cables:

Pre-fabricated cable are the simplest form of cable because they are basically plug and play and will usually run both your power and video on one cable with the BNC connectors already installed on each end. They are available in various lengths. The most common lengths are 25’ft, 50’ft, 100’ft and 150’ft. They can also be found with power, video and audio in one cable. These cables are usually lower quality than true coax options, but are suitable for most basic installations. They are also among the least expensive options.

–          Siamese Cable:

Most professionals in the security industry will use Siamese cable. Siamese cable is actually the combination of two cables in one. It includes RG59 for video transmission and 18/2 for power. Siamese cable uses a true copper core which is more efficient for transmitting video that pre-fabricated cable. This cable is usually purchased in spools of either 500’ft or 1000’ft and is cut to the length you need. This cable also requires the installer to terminate the cable themselves using their own preferred form of BNC connectors. This option is usually acceptable for runs up to 1000’ft.

–          Combination of Coax and 18/2:

Sometimes you cannot run power and video back to a single point. In this case you can use separate runs of Coax such as RG59 or RG6 and power such as 18/2 or 18/4. This option is usually more expensive but is sometimes the only option. This option is usually acceptable for runs up to 1000’ft.

–          Cat5 or Cat6:

There are several benefits to using Cat5. Eventually the CCTV industry will migrate to an all IP solution. Network cameras do not transmit over Coax. A Cat5 or Cat6 cable would allow you to migrate to IP cameras in the future without the need for new cabling. In order to use Cat5 or Cat6 you will need to use video baluns. Baluns are available with video only, video and power, and video, power and audio. The more pairs used for transmission, the longer the distance you will get. In general, video will transmit up to 1200 feet with passive video baluns and can transmit 2000 or more feet with active baluns. Power will not run those distances, so when running further than a few hundred feet you will need to run power separately.

–          Fiber:

Fiber is typically the best option, but is the most difficult to install and by far the most expensive. The benefit of fiber is the long distances you can run which is typically miles. Fiber would require the use of expensive transmitters and receivers that convert the video signal from analog to digital and back to analog again. You cannot run power over fiber so you would need to run fiber separately.