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National Data Contractor Security design and install
Security Surveillance Cameras and DVR systems

With so many different types of security surveillance cameras, DVRs, and security systems on the market, selecting the right system or camera these days is a challenging task.  Even comparing the same security camera and /or DVR by features can be quite a daunting task, as the same features do not  always mean the same quality.   The chipset in a DVR can appear the same as another on paper but act completely different in performance and stability,  as well as the software that controls your DVR functions.  When looking at security and surveillance cameras the most overlooked aspect is the actual image sensor  quality and size.  You could have a quality DVR but cameras with poor lens features and never see a good image, or great cameras and a low qulaity DVR and get the same!   Never let price be your deciding factor of quality.  Just because you purchased the more expensive DVR or security camera doesn't mean it is better.  Choosing the right security and surveillance system means getting a balance of qulaity in all your components that wil  compliment each other.

Before you go out and invest your hard earned money, there are a few points of interest that you should consider when picking out your security DVR, security cameras, and other necessary components to build a security surveillance system.

1) What will you be watching and recording on your security cameras? How many days to record? What size hard drive for security recording?

2) How many security cameras do you need to cover what you want to watch? How far is the range you want to cover?

3) What lens type, fixed, varifocal, wide angle, zoom? What mm lens? How many TVL? Analog or digital? B/W, color or both? Focal length?

4) Are you looking for facial recognition?  License plate recognition?

5) What sensor size -1/3, 1/2, 1/3, or 1/4 inch? Auto iris or manual? What F-number? Cmos image sensor or CCD image sensor?

6) Do you need night vision? Built in infrared LEDs, or night vision projectors? How many IR LEDs? What LUX?

7) Will you have varying focal targets or wide area coverage with no zoom?

8) Do you want to control your security cameras movement and features (ptz) pan, tile, zoom? Remote viewing or on-premise only?

9) Wired or wireless security cameras?

10) What style, bullet camera , torrent camera , dome camera , box camera, covert camera?  Vandal resistant? Weatherproof?

11) DVR security surveillance system or PC based security surveillance system? 

12) How much Recording time do you need on your security DVR? Expandable hard drives?

13) Do you want to record in Full D1 on all channels? CIF / CH?  What video compression?  What pixel resolution? PAL, NTSC, or SECAM? How many fps/ch?

14) Do you want Video format of H.264, MPEG-4, MPEG-2, VOB, ISO, or a combination? MP3 or AC3 audio?

15)Audio in/out? Backups?VGA, HDMI, BNC outputs? USB, e-SATA, network or DVD drive backups?

16) Do you want alarm triggers? Zone mapping? Loop out? Spot out? Call monitor?

In the realm of security and surveillance camera systems the points of interest above are the basic necessitates you should know when buying a surveillance system.  To go yet a step further, you should know the quality of the materials used.  Not all hard drive are created equally, nor are chipsets, lenses, image sensors, software, and every other component in your security surveillance system.  The issue here is that there are so many factors that dictate a quality system that the average buyer just becomes frustrated and often buys a security syteme that does not meet their expectations.  It is for this reason that you should let someone with experience choose your system based on your needs.  

Even those in the industry such as National Data Contractor have gone through trial and error with security surveillance systems.  We've tried new products after thoroughly inspecting all aspects only to come away disappointed.  We install systems that we have used time and time again, and those that we have tested to meet our requirements.  We sell entry level, professional, and enterprise level systems, but even our entry level systems are of good quality and keep our clients happy.


1) Should I go with a Stand Alone DVR Security Surveillance System or a PC based Security Surveillance system?

That depends on your goals and budget.  Generally stand alone systems are less expensive until you get into the high-end stand alone units, at which point the PC-based DVR's begin to look better by price virtue.  Now, you can go all out and build a super computer with multiple hard drives, raid, and multiple 32 channel DVR cards and get up into the thousands as well.   Computer based DVRs have all the usually things like mother boards, cpu, ram, network cards, etc., but also have special DVR cards for capturing video from analog or digital cameras.   PC based DVRs are more flexible than stand alone DVRs but also more complex to use and setup. Gaining access via remote location over the internet requires knowledge of routing and networking.  In addition, PC based systems are susceptible to viruses just as your home computer is, and they rely on an operating system such as windows to be stable.  DVR cards often crash computers if not properly setup and maintained. 

The benefits of stand alone DVR systems are that they are much easier to use, generally just a button push away from controlling any feature, or a few mouse clicks to get into the heart of the controls, which are usually very self explanatory.  Viewing remotely is alo easier, as they come with their own IP address for easy access, those no routing and networking is involved.  Some systems are a little bit of a pain to set up for on line viewing, but one time is usally all it takes to get the grasp.  These units run Linux or Unix operating systems and therefore are less susceptible to virus attacks, crashes, etc, and come with various TV outputs, whereas computer based will require another tuner card .  They are designed to do but one thing, record and playback security video.   So what features should I look for in a DVR?

A) To be continued

2) What is H.264?  H.264 is the latest and greatest in video compressions, and now used widely in most recording devices.  It is basically a big improvement over MPEG-4 in reducing file size without compromising image quality.  MPEG-4 is still widely used in DVRs.  A major issue with  MPEG-4 is the bit rate of images are lowered to meet the level of image quality required by the application calling.  The benefits of H.264 are reduced file sizes and bandwidth usage, higher resolutions and frame rates, and improved megapixel performance. 

3) What is Megapixel Resolution?  Megapixel cameras take video to the next level in any camera that uses it. It provides a much higher resolution than traditional security cameras, produces a clearer video image, increases in the field of view enabling one megapixel camera to cover an area that normally would take multiple non megapixel cameras to cover, all without any loss in image quality.  Megapixel IP cameras are useful for surveillance applications where details are of great importance in identifying details.  

4) What are IP Cameras or Network Cameras?  Ip cameras and Network cameras are one of the same, and are CCTV cameras with a built-in web server that uses Internet Protocol to transmit image data and control signals via a fast Ethernet link.  In short, it's a computer and camera in one package that can stream video on its own via the Internet.  IP cameras have become very popular in the mainstream market for their flexibility and ease of use.  They can be used for wireless operations which saves installation time,  you can remotely monitor and record to a local or remote PC via the Internet, and one of the best features; use the many web enabled features such as passing information over email, SMS, and FTP to warn you of alerts, as well as the option to  control your cameras via pan, tilt, and zoom simply through a web browser.   

5) What type of lens do I need for my security surveillance cameras?  That all depends on your application requirements.  There are various lens types available, and each has a purpose and a proper fit in certain applications.  Placing the wrong lens in the wrong application will certainly disappoint you and/or your client, but make the thief happy, as you'll probably never make out an image.  

A) VARIFOCAL LENS: This type of lens offers several adjustable elements to enable changing the effective focal length (EFL).  The overall focus changes as the focal length changes, thus enabling the image to maintain a clear focused image at any distance allowable by the lens. Varifocal lenses are best suited when you may need to change focal lengths, or move the camera to a new location and change the target zone.  Without a varifocal lens, you would have to purchase a new lens each time you decide to change the focal length for precise imaging.  Varifocal lenses are generally more expensive and come in various apertures, most typically in  2.8-12mm lens, 3.5-8mm lens, 6-60mm lens, and 5-100mm lens.  The higher the mm number, or aperture number, the more zoom you get and the more the image will show greater detail.  On the other side, the smaller the mm or aperture number, the wider the view and less detail you will get.  Also take note that the higher you go in aperture, the less field of view you get, as the image will tighten up and become narrower.  

B) FIXED LENS: This lens type is as the name implies; fixed.  A fixed lens has a set aperture or mm  that cannot be changed.  These lenses are most often used for wide area coverage or for close up detail, but cannot be adjusted either or as with varifocal.   When purchasing a fixed lens you will want to use a lens calculator to make sure you are getting the lens that fits your intended application. 

C) ZOOM LENS: A zoom lens is often mistaken for a varifocal lens, and though they are similar, zoom lenses have a wider range of focal lengths.  Zoom lenses come with a manual iris, a DC iris, or auto iris and  have motors for zoom and focus.  This means you can change the field of view when  zooming in on an object.  Zoom lenses require a remote controller for operation. 

C) FOCAL LENGTH: The focal length of the lens is measured in mm and directly correlates to the angle of view that will be displayed. Short focal lengths provide wide angle viewing while long focal length become narrower and offer telephoto viewing.

D) DEPTH OF FIELD: The depth of field is simply the area within the field of view that is in focus. As mentioned earlier, the depth of field can be influenced by the auto iris, but really comes in to play with a manual iris.

E) F NUMBER: The F Number, also called F Stop, focal ratio, or relative aperture is the aperture ratio that tells you the ratio between maximum and minimum iris openings.  Auto Iris and  DC lenses respond to changing light conditions and the ratio between the iris position when  completely open and completely closed is called the aperture ratio. The F-number needs to be adjusted as per the condition requirements. The lower the F-number the greater the amount of light that is passed to the sensor.  Low F numbers allows for better picture quality even when subjected to low light conditions, so the lower the F number the better.

6) SECURITY CAMERA TVL & RESOLUTION: This is one of the most important aspects to consider when purchasing a surveillance security camera.  Having the right camera resolution makes all the difference when identifying a person of interest.  The resolution is displayed by the number of horizontal TV lines that make up a picture.  In the United States, regular non HD TV displays 480 lines of resolution, so a 480 camera will give you the 480 lines  High Def TV  (HDTV) displays either 1080 or 720 lines of resolution.  Now, just because you get a 700 TVL camera, are you going to get an image like you see from a TV movie in 720?  Perhaps close if the image is shot at the same close distance, but move that image back 80 feet and you will not.  In order to get that good clairty and maximize your 700TVL, you need to put that 700TVL where your target is up close.  Overall, just shoot for a higher TVL and adjust your cameras and you'll get a quality image that you can see plenty of detail with. 

7) SURVEILLANCE CAMERA BODY STYLES:  One of the many questions that come into play is what body style or camera case should I go with.  There are a many types of surveillance cameras styles and each are suited for a specific purpose and environment.

A) BOX CAMERAS:  Also known as professional security cameras, they are more used for professionals that have a specific target. They are very versatile because of the lens changing ability, and are usually not sold with a lens or mount.  Furthermore, you'll need an outdoor enclosure if you are to mount these outdoor.  Most installer use this camera for specific jobs such as targeting license plates and facial recognition.  They generally have more video quality controls over  other styles of security cameras. 

B) DOME CAMERAS:  These are one of the most versatile camera styles offered today, and come in many sub designs. Their mounting options, 3-axis mounting, allows for vertical, horizontal and diagonally mounts, and also very simple to mount to a drop ceiling with a few screws.  The small footprint and dome structure itself is very pleasing in appearance, and with many colors to choose from, it blends well within the area of installation.  The dome structure offers a greater degree of vandal resistance. Having a full dome also conceals the direction of the camera, thus leaving any wrong-doer wondering if they are on camera.  They also come with night vision IR.   The biggest disadvantage is that you have to remove the dome to get to the controls to make changes, and are generally limited to a 12 mm lens.  If longer distances or tighter shots are needed, this may not be the best style for your application, but overall, they are versatile enough to suit many needs.

C) BULLET CAMERAS:  The main aspect of these cameras are simply the small slender footprint that makes the bullet camera inconspicuous, but not covert. It still lets people know it's there, but doesn't stand out like a box camera would.  Bullet Cameras are weatherproof and tend to be smaller than other types of security cameras, ranging from the size of a chap stick container to soda can. The bullet camera style carries the largest selection if you are looking for night vision  infrared cameras.  The most used size is that of a soda can.  The average bullet cameras come in varifocal  2.8 to 12 mm lenses, or fixed lens 3.6 to 6mm with 30-40 IR LEDs and have a range of 100 feet, and a TVL range from 480 to 600.  There are also long range cameras in this style that can image to over 300 feet with an average varifocal lens of 5-50 mm, but extending to 300 or more.

D) HIGH SPEED DOME CAMERAS:  These are some amazing cameras that come with amazing features.  They move via motorized and computerized internals just as the PTZ's do, but they go the extra mile.  They are controlled by a DVR remotely,  through a PTZ controller on premises, or automated. These cameras use RS485 to communicate back to the controller.    They can be programmed to run scan patterns, pan and tilt 360 degrees continuously, auto flip 90 and 180 degrees, scan from .1 to 300 degrees per second, digital and optical zoom, built in lightening protection and more.  They also come with IR night vision and have a range extending beyond 300 feet.   These are for the serious surveillance guru that wants a lot of coverage, speed, and on-demand controls.  They are in the upper tier as far as pricing goes, ranging from one thousand  upwards.

E) TORRENT CAMERAS:  Torrent cameras get their name after the gun torrent that you see on army tanks, though they don't extend out that far.  Some are rather flush to the housing, while some have a short lens extending outward.  Torrent style is just the housing, and these cameras offer all the same features as you'll find on the bullets, such as IR LEDs, varifocal, high resolution, vandal resistant, weather-resistant, 100 plus ft range, etc.  The main difference is just the housing. The adjustablity of the camera is a breeze, as it swivels and points up or down, thus allowing easy pointing.  They mount like the dome cameras, and are very similar. 

G) COVERT CAMERAS:  These are just as the name implies, small cameras hidden in object to remain unseen.  As such, they usually have a small 2-4mm lens and are stuffed in items such as fire alarms, behind mirrors, door chimes, stuffed animals, clocks, toys, etc.  They are good for picking up movement and actions, but not meant for a lot of detail, as most are 380 color TVL and under, though some do have amazing clairty and get up in the 600 TVL B/W.    

H) WIRELESS CAMERAS: Again, they are simply what the name implies; wireless.  Don't be fooled however, as they still need a power source, just no wires leading back to the reciever.  A wireless surveillance camera system transmits the video signal back to a reciever via wireless frequency, usually on a frequency such as 2400-2483.5 Mhz., most in the 2.4 and 5.8 GHz areas.   The reciever decodes, compresses and records the video similar to stand alone DVRs.  The biggest issue is that they often pick up interference noise that degrades the video quality.  The other issue is with outdoor use.  I have yet to try one that held up suitabbly.  They are also affected by storms and often return a very bad image.  However, inside is a bit better, but if you want good quality images and reliable service, stick with wired.  

J) PTZ (PAN, TILT, ZOOM)   Pan /Tilt/Zoom cameras are the most complicated style of security cameras given what they do.  They come in many body styles but are most commonly found in dome cameras.  They move via motorized and computerized internals that allow  the camera to be controlled by a DVR remotely, or through a PTZ controller on premises. These cameras use RS485 to communicate with controls, so your DVR needs to have the appropriate connections, or use an adaptor.   

7) What are CMOS and CCD image sensors? CCD (charge coupled device) and CMOS (complementary metal oxide semiconductor)  image sensors are two different technologies to transform light patterns into an image.  Both types process light and convert it into an electric charge, then process that charge into electronic signals.  For CCD sensors, each pixel's charge is transferred through a limited number of output nodes, usually just one, which is then converted to voltage, buffered, and sent off-chip as an analog signal, thus enabling all pixels to light capture.  This keeps the output in uniform and creates a high quality image. 

For CMOS sensor, each pixel has its own charge/voltage conversions, which are coupled with amplifiers, noise correction, and digitizing circuits for digital bit output.  By incorporating the extra processes in CMOS,  design complexity increases and reduces the available area for light capture, thus lowering its uniformity in image processing.  When a light pattern is analyzed and processed,  a CCD sensor creates a high quality low-noise image, while the CMOS sensors are more susceptible to increased noise, thus degrading the image. CCD is clearly the better choice in that aspect.  CCD sensors consume more energy and operate on a higher voltage value during the reading and conversion processing, while CMOS operates at a lower voltage and consumes much less power, possibly up to 100 times less energy.   

Clearly, CMOS wins the energy battle.   Now,  CCD sensors have been in mass production the longest, and are more refined.  CCD sensors tend to produce higher quality and more pixels over CMOS, and as result, images produced by CCD sensors are much better than those from CMOS sensors. Lastly, the major difference between these two sensors is that the manufacturing costs of CMOS is much less expensive than CCD, so CMOS wins here as well.

So what does all this mean?  Based on the differences above, which are the main points of each, you can see that each has its pro and cons, but overall CCDs tend to be used in cameras that focus on high-quality images, while CMOS sensors tend to be used in lower quality image capturing and have lower resolution and sensitivity.  Each has its own place in the surveillance world, and both can offer excellent performance  if designed properly.  Personally, I tend to favor CCD senors overall, as image quality is the most important aspect when it comes to seeing the persons face clearly, or reading the licenses plate, and being able to identify the person/s that just broke into your office and cleaned you out. 

8) What is auto iris and do I need it?  Auto iris is a movable appeture inside the lens that controls the amount of light allowed to pass through the lens.  In bright light conditions is closes down to allow less light, and in low light conditions it opens widely to allow more light to pass through.  This helps avoid lens glare in direct sunlight or over exposure, as well as brightens the image in low light conditions.  The auto iris can be a tricky gizmo for installers, as it works based on a zone of focus, or its depth of view.  The depth of view will change as the auot iris compensates, thus closing or opening the iris can cause objects outside the depth of view to become unfocused.  This commonly happens from day to night vision and can keep an installer guessing.  The solution is to install the camera in the brightest conditions and use a filter placed over the lens to simulate night conditions, and then adjusting the depth of view to a good balance. This will give you the best performace from your cameras.   Not all cameras have issues like this, as some are very good at balancing the depth of view and focus.