REG No : 53147763X                                    Last Updated on 10th March 2010

INFORMATION CORNER... 

Having some technical doubts in CCTV systems and specifications?

Having some problems troubleshooting your CCTV systems?

No more worries.. you can find most of the commonly asked questions here! If not, please send us an email regarding your doubts! Your questions could be others' questions too!

1. What is DVR? What is the difference between DVD recorder and DVR machine?
2. What is CCD and CMOS means? What is the difference between these 2 types of technology?
3. What is the difference between standalone DVR and network (Internet ready) DVR? What is the security levels between these two types of DVR machine?
4. What is DDNS? How does it work for my DVR system?
5. If I have an Internet-Ready DVR machine, does it mean that my privacy is gone? How to keep my DVR secured?
6. If I registered a domain name with DynDNS or NoIP.com, will my video data be stored at their server?
7. What is Resolution? How does it affect CCTV camera?
8. What is FPS? How does it play a part in a CCTV system?
9. What is LUX? 

What is DVR? What is the difference between DVD recorder and DVR machine?

DVR stands for Digital Video Recorder. Older CCTV systems use video tapes as a recording medium for video images. These video tapes need to change frequently and video quality will reduce after a few overwrite. With the recent high reliability and stability of the computer hard disk, recording video images using these medium becomes popular overnight! Not only that! Since recording of video images are digital, it means that video quality will still be the same even after many times of copying and overwrites! Most of these DVR machines are maintenance free! Just need to make sure to check the blinking light to ensure that they are running!

The difference between a DVD recorder and a DVR machine is DVR machine are meant to run and write on the hard disk 24/7!! It means that they are more highly reliable than Home Use DVD recorder. The secret is DVR machine usually have an internal fan to keep the hard disk cool which made them so lasting. Because DVR machines are purely use for CCTV, they may have additional functions like motion detect recording, support up to multiple cameras recording, frame rate adjustment, individual screen adjustment etc.

What is CCD and CMOS means? What is the difference between these 2 types of technology?

CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor) image sensors are two different technologies for capturing images digitally. Each has unique strengths and weaknesses giving advantages in different applications.

Both CCDs and CMOS imagers can offer excellent imaging performance when designed properly. CCDs have traditionally provided the performance benchmarks in the photographic, scientific, and industrial applications that demand the highest image quality (as measured in quantum efficiency and noise) at the expense of system size. CMOS imagers offer more integration (more functions on the chip), lower power dissipation (at the chip level), and the possibility of smaller system size, but they have often required tradeoffs between image quality and device cost. Today there is no clear line dividing the types of applications each can serve. CMOS designers have devoted intense effort to achieving high image quality, while CCD designers have lowered their power requirements and pixel sizes. As a result, you can find CCDs in low-cost low-power cellphone cameras and CMOS sensors in high-performance professional and industrial cameras, directly contradicting the early stereotypes. It is worth noting that the producers succeeding with "crossovers" have almost always been established players with years of deep experience in both technologies.

Read more about CCD and CMOS technology.

If I have an Internet-Ready DVR machine, does it mean that my privacy is gone? How to keep my DVR secured?

Firstly, you may have an Internet Ready DVR machine, but is it connected to Internet? If it is not connected to Internet, it is just like a standalone DVR machine when the only way to retrieve and view recorded video is come back to the machine itself. This I would say your video clips and privacy are in the most secure form.

However in case your DVR machine is connected to Internet so that you can view online, you will still have two levels of security. The first level is your domain name. Before you need to login to your DVR machine, you need to key in your domain name. Keep your domain name unique so that others will not know easily. The second level is your password. When you key in your domain name, you still need to key in your password in order to view live or playback. This I would say it will be your last line of defence to your video data.

In order to keep your DVR video data secured, choose a creditable CCTV installer as he is the one going to configure your CCTV system. Next is to keep your domain name unique (unless you intend to do a demo site) like ddvrsystem3458.hopto.org instead of 123.hopto.org. Lastly change your login password. This is the general gudeline to keep your DVR data secured.

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If I registered a domain name with DynDNS or NoIP.com, will my video data be stored at their server?

The answer is obviously NO. Firstly, when you register a domain name with these provider, it is just like registering for a new PO box at post office. The only data which is transmitted to these FREE server is only your lastest DHCP IP address. Why need to do so? Because most Internet Service Provider (ISP) gives you a Dynamic IP address for your home or office. This mean that your IP address will change every few days. Therefore if you need to register a domain at DynDNS or NoIP.com to solve this problem. As the router will constantly update the IP address to these servers whenever  your DHCP IP address changes, you will always be able to locate your own IP address just by remembering a domain name. It is that simple! 

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What is Resolution? How does it affect CCTV camera?

Resolution means picture sharpness and is measured in lines of horizontal resolution. The TV picture is always made up of 525 horizontal scanning lines, as if it were painted on a Venetian blind with 525 slats. For this reason, the vertical resolution, the sharpness going from top to the bottom of the picture, always remains the same. If you looked through a window with a giant Venetian blind and could observe a distant ladder and count 525 rungs on that ladder, than you could say you had a vertical resolution of 525 lines. If you couldn't count the rungs, because they were fuzzy or blocked by the slats of the Venetian blind, you would have less than 525 lines of vertical resolution. You could have someone bring the ladder closer and eventually you could count all the rungs.

Horizontal lines of resolution, measure how sharp a picture is from left to right (in the horizontal direction). Imagine aiming your camera at a picket fence. A sharp camera with 400 lines of resolution will allow you to see 400 pickets. A fuzzier camera would see only mush until you zoomed in and perhaps counted 300 pickets across the screen. Note that although the pickets are vertical lines on the screen, you are counting those lines across the screen, horizontally, thus the term horizontal lines of resolution. Although vertical lines of resolution always stay the same because of the way the pictures are made, horizontal lines of resolution vary with the quality of the equipment. The more lines of resolution, the sharper the picture.

A camera image sensing chip (monochrome) with 400 pixels across could register one white picket on one pixel and the black space between the pickets on the second pixel, show the next picket on the next pixel, and the next space on the following pixel and so on. Thus, a CCD chip with 400 pixels across could see 200 pickets and 200 spaces for 400 lines of resolution.

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What is FPS? How does it play a part in a CCTV system?

FPS stands for frames per second in which the measurement of a video clip contains number of image frames within one second. In general, if you want to store all video at 30 frames per second (30 FPS) as opposed to 1 FPS, then that requires 30 times the amount of storage. A unit of measurement used when dealing with video. Each frame is a picture. The frames per second indicate how many times the picture will be changed per second. When using a web-camera, the transmission rate is usually 15 frames per second. TVs use 25-30 frames per second, providing a very good quality picture.

In a CCTV system, FPS is often used to describe the 'smoothness' of the video. Usually human eyes can only tell a difference in FPS up to about 25-30 FPS. Any higher than 30 FPS would not be noticeable to human eyes.

FPS also play a role in determine the amount of memory you need in a CCTV system. The higher the FPS, the better the video quality. However more memory will be used. Very often, more memory can be obtained by adding in bigger capacity harddisk. Since memory are relatively cheap nowadays, DVR capability become a factor of what is the maximum harddisk size you can squeeze in. High-end DVR can usually insert two or more harddisk to accommodate more memory space for higher quality video. 

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What is LUX?

Lux is a measurement based on light produced by a single candle. Candles, as well as regular household light bulbs, produce light that radiates uniformly in all directions. As distance from the light source increases, the amount of light that falls on the object exponentially decreases. (Lux = 1/d2, with "d" being the distance from the source.) The fixed amount of light is simply spread over a larger area, so there's less of it to go around. If you double the distance from your subject to the candle, you do not receive half as much light. You receive 1/4th as much light. Quadruple the distance and you receive 1/16th as much. You can see how 10 lux of light at one meter can very quickly become 1 lux.

Your subject will also affect your camera's light gathering ability. Lux is a measurement of incident light, or the light that is falling on the object. On the other hand, your camera sees and records reflected light, which is light that bounces off the object and makes its way to the lens. Lighter colored, reflective surfaces will reproduce better in low-light situations than dark objects will. Just because 100 lux illuminates an object, do not assume that the camera is seeing a 100-lux subject.