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Surveillance systems: All about the numbers

October 11, 2010
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Reader Question: I’m renovating a building into a carwash and want to install security cameras. What should I look for?

Finding a good system is all about the numbers. The numbers I am talking about can be found in the specifications for any digital video recorder (DVR) or even cameras. The real worth of any surveillance system is measured by how good those numbers are.

Here is the number one lesson I have learned: Shopping for price alone can end in disaster.

On the internet, or even at box-store retailers, you can find complete digital closed-circuit television (CCTV) packages of 4 to 16 cameras, including a monitor and digital recorder. Often they look like great deals — but the wrong system can deal you untold grief.

Many dealers will put together low-end packages to try to lure price-conscious shoppers — these systems suffer from lower-quality, shaky reliability, and will not last the way higher-quality systems will. Low-quality components and a lack of support combine to create an offer that can do more harm than good to your business.

To avoid getting cheap consumer-grade junk, take a closer look at the actual specs of the individual components. If the specs aren’t offered, ask for them. If they are vague and the answer is not satisfactory, or they won’t give them to you at all, move on to another supplier.

How to choose quality cameras
The best cameras consist of two basic, but very crucial elements — the quality of the image sensor and the quality of the parts and engineering of the camera components themselves. Listed in the specifications of each camera, you will find out who makes the guts of the camera. In other words, what name brand chipset is at the heart of this camera?

Two main industry leaders offer several levels of chipsets, so always look for these minimum performance parameters, no matter what type or style of camera used, or whose name is on the outside:
  • Type: Grade A CCD (charge coupled device) imaging chipset;
  • Format: 1/3” or 1/4” focal length (1/3” gathers more light and has a wider view, but 1/4” is fine for high resolution models in well-lit areas);
  • Color or day/night operation (day/night versions turn from color to black and white under low light conditions);
  • TV lines of resolution: 380 to 400 lines for medium resolution cameras, and 480 to 500 lines for high-resolution;
  • Signal to noise ratio (S/N): at least 48db or higher (50db is visibly better); and
  • Voltage: 12V DC is fine for smaller cameras, while 24V AC is usually better, and is required for any camera with heaters.
Mounting location tips
Where each camera will be located at your carwash will determine what type or style of camera to use.

Equipment rooms — For general views of the equipment room almost any type of camera will work here. However, if you turn the lights out when you leave, then a day/night infrared camera that displays a color image under good lighting, then switches to black and white with infrared illumination to see in the dark, is a good choice.

If the equipment room is always well lit and you don’t want anyone to see the camera, then a disguised PIR (passive infrared) motion detector style camera with a pinhole lens is a common choice. Pinhole lenses still give good clear views, but because of the small surface area of the lens and decreased ability to gather light, the room’s lighting needs to be bright.

Changer/vending areas — Since mounting locations around this area tend to be lower, a vandal-proof dome is a wise choice. Cameras mounted lower that are supported on a stalk type of mount can be hit with a stick to turn the camera away from the area, or covered with a cap or rag so that the thieves can work unmonitored.

These types of domes are extremely rugged and have no exposed wires that can be cut, and also have security screws that make it difficult to steal or disable the camera.

Self-serve bays — Good, tight seals and waterproof construction are required in the harsh bay environments.

Large outdoor housings don’t work well in bays because of the tendency for the large glass plate on the front to get dirty and scaly pretty quickly. Small format cameras work well here because they tend to be even more moisture resistant than the larger cameras in housings, and their small lens glass sheds water better with longer intervals between cleanings.

Avoid the tiny bullet cameras that some companies sell, as they are a poor choice for any wet location due to condensation and fogging of the lenses.

Automatic bays or tunnels — This is the most extreme environment for any camera. Be sure to get one that is specially built for this environment. The wrong camera for this location can be rendered useless in a few weeks by the constant moisture, fast changing temperatures and corrosive effects of the chemicals scaling the front glass.

A camera made for this environment should be small in size, high resolution, have a varifocal (manually-adjustable lens), and have a built-in heater that comes on at temperatures of 60 degrees or lower to combat condensation and fogging.

Also ask if the glass lens has a special coating that is designed to resist chemical etching. This type of lens coating means you won’t have to clean it as often, and the scaling deposits will be easier to remove.

Perimeter areas or outlying views — Cameras that are mounted on the wash structure and looking out at outlying areas need to be the large type in the traditional outdoor housings.

This is for several reasons. First, since the lighting tends to be dimmer the farther you get away from the bays, the lens surface area needs to be larger so that the camera can gather more light. Secondly, the large camera housings are more visible and tend to be a deterrent to criminals.

Color cameras are fine for looking toward well-lit areas such as vacuum islands, but when pointing the camera toward darker areas, or when using the camera to pick up license tags, a day/night version that will switch to a black and white picture is really valuable since it can see better under dim lighting conditions.

Lenses: the most important part

The human eye is an incredibly adaptable device that can focus on distant objects and immediately re-focus on something close by. It can look into the distance or at a wide angle nearby. It also has a long depth of field, meaning scenes over a long distance can be in focus at the same time.

By contrast, the basic lens of a CCTV camera is an exceptionally crude device. It can only be focused on a single plane, everything before and after this becomes progressively out of focus. This single focus point must be predetermined and that does not guarantee that an occurrence you want to see will happen in that area.

Therefore, the selection of the most appropriate lens for each camera must frequently be a compromise between what you expect to see and the practical use of the system. It’s not feasible to see the whole wash bay and be able to read all the license tags with one lens. The solution may be to add more cameras or to compromise with a lens strength that is somewhere in between.

One of the best lens types to work with when you install your system is the “varifocal,” or manually adjustable zoom lens. This type of lens gives you a small amount of adjustability to “fine tune” each scene, whereas a “fixed lens” camera is pre-set to a particular view.

As adaptable as the varifocal lenses are, depending on which area of the wash you want to cover, they’re not always the best choice when considering both price and effectiveness.

The following is a list of the most common types of lenses used and where I have found they work best:

• Fixed Lenses: View is fixed and cannot be altered, least costly and usually comes standard with a 3.6mm lens or can be ordered with other options.

A simple camera to use. Arrives pre-set and pre-focused so all you have to do is hang it, plug it in and aim at desired viewing area. Used for short distance shots and general wide-angle views. Ex: Equipment rooms, changers, vending, doors, bays, etc.

• Varifocal lenses: Small amount of adjustability is provided to get the correct width and distance. Available for about $50 on most cameras.

The amount of adjustability varies with each lens, but try to get a camera with a 3.5mm-8mm range for bays, a 2.8mm-12mm range for wide-angle views of outlying areas, and a telephoto range of 5mm-50mm or more when using the camera to capture license tags.

• Zoom Lenses: Usually electrically operated and most commonly part of a pan/tilt/zoom type camera.

Pan/Tilt/Zoom cameras, or PTZ’s, are nifty gadgets that can be used to do the job of several cameras, and have many tricks up their sleeve that can be really helpful. These types of cameras can be remotely controlled over the internet from your PC, and can also be programmed to perform tours and go to preset positions automatically or upon an event.

For example: You can have the camera panning to each bay, then zoom in to capture the license tag, then on to the next bay or area you want to record. You can interrupt the camera to move it around, and then make it go back to its primary job.

Some of the nicer models even have several inputs so that you can attach some type of external sensor to trigger the camera to swing around and capture a license tag on a passing car, or to zoom in on a certain area when there is activity.

The PTZ cameras are certainly a nice tool to have and also make a nifty toy to play with on slow evenings at home, but they do have a few drawbacks that you need to be aware of.

Price is the first consideration. Good quality outdoor rated PTZ’s and accompanying accessories can run close to $2,000 each. In some cases you may be better off with stationary cameras that constantly monitor a scene rather than a moving camera that may miss something that happens when it is looking elsewhere.

Also factor in the fact that PTZ cameras are a mechanical apparatus that will eventually wear out and will need more maintenance than simpler cameras, especially if you have them moving constantly.

Choosing a digital video recorder (DVR)
Deciding to go digital is easy. By now you probably already know all the reasons for switching to digital video recorders, such as the ease of locating events without having to slog through hours of recordings, excellent storage quality that does not degrade after repeated viewings, their ability to multi-task and do several things at once, and smart monitoring that allows multiple recording speeds based on motion or other events.

The hard part is figuring out which type of DVR to use, and how to end up with a good quality recorder that will give you what you expect and is reliable over the long haul. Many times, it’s what you’re not told that causes you grief, so to help you debunk the myths and learn to ask the right questions, here are some helpful tips to look at before jumping into digital video.

PC-based systems
Digital recording can push any system to its limits, and this is especially true with pc-based DVR’s. Most desktop PC’s are not designed to operate long term in the harsh electrical and moisture intensive environments inside most carwashes, yet I have had PC’s at several washes for years with little trouble out of them. When I started putting PC-based DVR’s in my washes, I started having all sorts of problems.

At first my problems were mostly due to buying cheap DVR cards and software. Poor performance, frequent crashes, fuzzy pictures and hardware failures were a constant pain.

Finally, I was able to get high quality cards and software. My performance improved greatly and the pictures were excellent. But the system was still too maintenance intensive and had several inherent problems that I had to deal with regularly. The most frequent problem was lock-ups and reboots. The problem was that the operating system and the main processor did not tolerate being worked at near full capacity non-stop day in and day out.

A good system is capturing and digitizing as many as 480 pictures every second, while serving you and perhaps others remote video via the internet, and allowing an operator at the DVR to be doing something simultaneously. That kind of intensive computing power can work a system to death, and software lock-ups and rebooting are the outcome.

You will also need to de-frag the hard drives every month or so to keep the system operating at peak performance, or it will start to slow down noticeably and performance will suffer. Then throw in the fact that most equipment rooms are not air-conditioned very well, if at all, and this can lead to heat related problems that can severely shorten the life span of the hardware components.

Purpose-built dedicated DVRs
All of my carwashes now have DVR’s that are not PC-based and have been designed and built to perform their tasks non-stop without lock-ups or rebooting.

These stable systems are usually Linux-based, but you would never know that because you only see the graphic interface and menus, and never have to deal with the operating system or even see it. These types of systems are sometimes called stand-alone systems because they do not need a computer or any other devices to operate.

Another common name is an embedded system because the entire operating system and software has been embedded on the processor chip. No software resides on the hard drives; those are reserved for archived footage. This arrangement allows the system to work much faster, and also makes it virtually immune to hacking or viruses. Thus, you can put it on the internet without any worries about picking up a virus or allowing someone to hack into it.

Lately, however, there have been a lot of cheap stand-alone imported DVR’s. Unfortunately it is just as easy to get taken with a cheap knock-off as it is to buy PC cards that are junk.

The following is a list of minimum performance parameters to look for when evaluating a stand-alone DVR. Again, if they try to hide some of the numbers or won’t give them to you at all, move on to another supplier.

Evaluating a stand-alone DVR
Resolution: There is displayed resolution and recorded resolution, and you will need to ask questions about both. Many companies try to tell you that their resolution is 720 x 480. However, when pressed they will admit that number is only for live picture viewing and that the recorded picture size is much smaller, such as 320 x 240 or even less.

The smaller picture size is hard to see, and lacks the resolution or clarity of the larger sizes. Increasing the image size to make out details causes the picture to “pixelate” or appear grainy and fuzzy. Therefore, look for a minimum recording or capture size of 640 x 480, and 720 x 480 is even better.

Frame rate: Once again there are two numbers to look for: display rate and recording rate. These numbers are usually stated as global, meaning that the frame rate number is divided by the number of cameras on the system.

For example: A 60 frame per second system running 16 cameras will be recording the video from each camera at just over three pictures/second. At that rate the video will be jerky and many movements or actions will be missed entirely.

The display rate should be real-time. No exceptions. If the system can’t display pictures in real time, it likely won’t be able to record very fast either. Recording rate is very important as well.

Real time is defined as 30 frames per second per camera. However, if you insist on recording that fast, you will fill up your hard drives in just a couple of days. So a compromise is in order.

The human eye cannot really distinguish the difference between 20 frames per second and 30. In fact, I have found that on a quality DVR, I can record at 15 frames per second and it still looks near enough to real time that I can’t see much difference.

So that should be your minimum recording rate: 15 frames per second times the total number of cameras the system can handle. (i.e.: 60fps on a 4-camera system, 120fps on an 8-camera system, and 240fps on a 16-camera system).

Compression ratio and method: Some systems tout very high compression ratios, such as 1000:1 or 2000:1, as if it were a benefit or feature. While that might sound impressive, higher compression means that the system is stripping more and more resolution out of each picture in order to make smaller file sizes.

The best compression technology available right now uses either H.264 as a compression method, or MPEG4. Both of these methods produce sharp, clear pictures all the time, with just the right amount of compression, and you shouldn’t settle for less. Because anything less means poor quality pictures that let you down when you try to play back an incident to see what happened.

Most of the other handy features such as internet monitoring, motion-based recording and event or sensor-based recording is standard in most DVR’s these days, but make sure that the system will let you do more than just monitor cameras remotely.

Ask if the system allows you to look at pre-recorded archive footage remotely, lets you transfer files over to your own PC, and even record simultaneously on your PC at home or the office. Also ask if the system lets you change all the settings remotely and generally lets you operate the DVR as if you were standing in front of it. All are hallmarks of a quality DVR.

Last but not least, look at the warranty the company provides. A reputable company should give you a fix it or replace it warranty for at least two years. Beware of the system that comes with a 90 day parts and labor or one year parts only warranty. If they won’t stand behind your system, why should you buy it?

If you let the performance numbers listed above be your guide to choosing a good quality system, you will be happy with your system for years to come.

Allen Spears has been in the carwash business for more than 16 years. He currently owns four washes in Texas, is chief engineer at (a division of Rugged CCTV) for the past 14 years, and has designed systems for over 1,800 carwashes during his career. Contact Allen at, or 1-866-301-CCTV.

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