Color or Black white Security Camera?

Our eyes can see and recall things better if they appear in color – it’s

easier to track down a blond-haired person wearing a green sweater

and black jeans than a dark, grey-black figure that would be produced

in a black and White camera

Color security cameras carry an additional premium in price compared

with black and white cameras. But they are also less sensitive to light

and makes it an impractical option unless good lighting is available.

Black and white B/W security cameras have better resolution and clear

pictures in low light conditions. All infrared security cameras turn to

black and white during low light conditions and résumé to color in good

light conditions. This can be particularly useful where planning

permission makes extra lighting impractical or the security requirement

is such that intruders should not be alerted to the existence of CCTV

surveillance.

Day and night cameras are a fairly new technology. These types of

cameras can operate in full color and have a sensor that switches to

black and white camera when the light condition is lower than 1.5 lux

Troubleshooting signal attenuation in a CCTV Security system.

When you have complain by a customer about a very poor picture generated by a security camera on a closed circuit television (CCTV). There number of factor to cause attenuation and picture distortion.

Upon inspection of the security camera, we found that the CCTV system consisted of National Television System Committee (NTSC) standard video generated and displayed in black-and-white. The main monitoring point of the CCTV system was a warehouse and a weather-proofed housed box security camera located on a 15-ft high mounted atop the building’s roof.

The security camera was connected to a security DVR in a security office some 200 ft away via a 75 ohm Siamese coaxial and power in one cable, which was routed down into the office by means of a pipe type of entry. Power to the security camera was provided via a 12V low-voltage DC link on the same Siamese cable; both the monitor and camera low-voltage DC supplies were simply plugged into a wall outlet convenient to the operator at the guard’s office.

Symptom

The picture quality on the video monitor looked as though contrast control was turn all the way one direction so that there was no contrast at all; the picture looked washed-out and was barely visible, which was a nearly light gray.

Testing procedures carried out

Fisrt step in solving this kind of problems is to start the diagnostics from step one, which is the security camera. Our first task was to go up to the security camera at the roof and see the picture quality and video signal looked like as it exited the security camera. Tyou can perform this test with a mobile monitor or any mobile display that you can connect directly to the camera. his test was much aided by the fact that our handheld, 50 MHz bandwidth, solid state, digitizing oscilloscope with LCD display had an internal battery pack and did not require any AC power for operation.

First Step. 1, the coaxial cable was disconnected at the camera and a BNC style fitting was installed. This fitting was equipped with a 75 ohm terminator resistor on one leg. Then, we connected our handheld oscilloscope into the remaining open end of the BNC connector. The result was a healthy NTSC composite video signal high quality picture. Conclusion: the camera was clearly putting out a good signal, which was about 1.8V across the 75 ohm termination.

The BNC connector was removed and the 75 ohm coaxial cable was reconnected.
Second test

The 2nd test was made at the DVR System end of the cable and right at the point where the cable was connected to the security dvr. Again, the BNC was used, but this time no 75 ohm termination resistor was used with it since the BNC was attached to both the DVR and the cable. The result of this test was that almost no video signal could be seen on our handheld monitor screen.

We then changed the monitor’s vertical scale the Conclusion: the signal loss was occurring along the 75 ohm cable path, or was it?

Security DVRs have been seen to “load down” a signal due to an internal failure on its input circuit; as such, we didn’t want to rule this possibility out. A quick test with the BNC and the 75 ohm termination resistor in place of the video monitor quickly ruled out this possibility; the signal was essentially. We really could conclude that the signal’s loss was occurring along the 75 ohm cable.

3rd test. We placed our handheld monitor into the BNC at the junction of the cable and security DVR. This allowed us to take a relative dB measurement reading, using the original zero-level as the reference. Here we see that the DC loss exists. This loss represents a voltage loss ratio of 4.84:1, or a signal loss of nearly 5V for every volt put into the cable!

How much signal attenuation should you expect on a 200-ft long, 75 ohm coaxial cable? A quick look at the coaxial cable manufacturer’s Master Catalog gave us the approximate answer: around 2 dB of loss at 10 MHz for 200 ft of RG-59/U type cable as used in CATV applications. The whole attenuation chart is shown in the accompanying table below.

Oh yes, since the manufacturer’s information was provided only in dB form, what would we have done if we didn’t understand dB and weren’t working in terms of dB on our handheld monitor? You guessed it. We would have had no idea what was “normal” and what was not on a coaxial siamese cable run of the type being investigated. All we would have had was some guesswork, which is not a very good way to go in most cases.

PC Based vs Stand alone DVR

Security DVR system, i.e. surveillance system has become an integral part of your home or business security solution. When searching to purchase a Security camera or security DVR, you will find that there are certain decisions you need to make before purchasing your first security DVR. There are two basic types of DVR’s available: a stand alone DVR and a PC-based DVR. A stand-alone DVR is a unit that looks like a VCR but is actually a computer running on a Linux base or proprietary operating system designed to function by itself as a digital video recorder. A PC-based DVR is a Regular computer, with a DVR capture card installed and configured, which basically transforms the basic computer into a full functioning DVR system. The system usually runs on windows XP or Linux, which perform on the same basic functions. We will explore each in a little more depth below.

Stand-alone Security DVR System
A stand-alone DVR is a computer board built on one complete circuit board. It looks very similar to a VCR, but it has the entire components that a regular computer has. The system runs on an operating system that is built into a chip / flush memory. For that reason Stand-alone DVR’s are extremely reliable and very easy to install and use. They are usually managed and configured by a remote control like a VCR. The software is built in to the flush memory as firmware and is separate from the data stored on the hard drive.

PC-based Security DVR System
PC-based DVR is a DVR Capture Card built inside a computer. The system is either a tower or a rack mount. Installed within the system is a DVR capture card. This board captures the video from the cameras and works with the DVR software, providing all the necessary, video and recording functions: like, Video compression, converting the video to a file, camera controls and display, record and playback functions.

Stand-alone versus PC-based DVR’s
In general, PC-based DVR’s have more advanced features than stand-alone models. Most of their strength relies on their processing power compared to standalone security DVR systems. PC Based DVR systems are also better suited for upgrades and systems expansions to support multiple hard drives and multi capture cards to support large amounts of cameras
In general when PC base and stand alone DVR came out to the market PC-based DVR’s had much more advanced features than stand-alone models and their processing power was stronger giving them the ability to process images faster and better. They also are better suited for upgrades and system expansions. But as time passed, Stand-alone DVR systems became more and more powerful and became very comparable to PC based DVR system in their performance and functionality. PC based systems still have more upgrade and expansion options, and for this reason most large institutions such as banks, malls, and airports utilize PC-based models rather than stand-alone DVR’s.
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Dvrmaster.com is a website that provides DVR information and clarification on the different types of security Camera and Security DVR’s. It provides affordable and top-of-the-line DVR products as well as providing custom built systems for individuals as well as businesses.