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The Eye in the Sky: Digital Closed Circuit TV Security Systems, Seen or Obscene
by Edward J. Primeau
Remember the 1970s song by The Alan Parsons Project, The Eye in the Sky? The lyrics were, I am the Eye in the sky looking at you; I can read your mind. Perhaps with todays digital technology, reviewing citizens actions, body language and local circumstances, we may not be far behind his lyrics.
Have you ever walked down a city street and noticed video cameras on the top of light posts and telephone poles? Why on earth would anybody want to see that city street let alone you walking down that street? Are public cameras an invasion of privacy or are they "The Eye in the Sky" making adjustments to extraneous elements while making your life easier or are they an invasion of privacy?
Either way, video cameras in public places have become a way of life and you better get use to them because, well just because. They are part of a closed circuit (instead of broadcast) digital video system that has the capability to control your life by regulating extraneous conditions of a given environment around the clock while controlling crime.
That digital video you see literally everywhere is a part of a system known as a closed circuit television system (CCTV) and helps keep our busy world safe and hassle free -- well at least in theory. A city CCTV system is a huge network of cameras, computers and cable that can regulate traffic signals, alert police to automobile accidents, deter crime, solve crime and even save lives. Indoors, those same camera systems do similar activity as well as many others like keep baby safe in hospital nurseryies and monitor critical care units.
The city of Denver, Colorado has the most intricate, complicated and largest CCTV system in place in its downtown district. Hundreds of closed circuit cameras in dozens of municipal locations both indoor and outdoor all connected to a very large computer system that can be monitored in many different locations. Eventually, it is this authors belief that within five years, every major city across America will have a surveillance system similar to Denvers in place. This is the major digital video application.
There are two formats for Closed Circuit TV security systems (CCTV) for smaller business applications. They operate similar to the big city wide systems and all have cameras, computers and cabling. One type is a digital system which incorporates a computer (DVR or digital video recorder) as its recording device and the other is analog which incorporates an analog video recorder or VCR. Both serve the business owner by recording events in their businesses while they are closed after hours or while their backs are turned during business hours.
Both formats are capable to record multiple camera views onto their system and store them for later viewing, reviewing or in the case of a crime committed, identifying criminals. Multiple cameras can be installed at a large or small location and viewed as well as recorded simultaneously on both formats. Analog incorporating multiplexers that switch camera perspectives, digital incorporates software programs that function similarly. The more sophisticated systems like the ones Indianapolis manufacturer Pelco carries, and has in place in Denver, have many adjustments, settings, frame options and video export options as well as signal routing features. The lower end VHS systems are pretty straight forward and easy to operate but have less features and options but can still guard a business like the more sophisticated ones.
Both systems can incorporate point, tilt and zoom cameras or steady non moving static view cameras. The point-tilt-zoom cameras (PTZ) can move to follow action both automatically and manually. Non-moving cameras capture the area under security in a stationary fashion.
The advantage of digital systems is that the quality is far superior to analog (especially when images must be retrieved for identification purposes). Digital formats and compressions make the recorded files smaller so more of the video will fit for longer periods of time in the computer or DVR. Tape or analog systems have limited storage capacity and need to have new tapes inserted which can be costly especially when a tape becomes worn and a crime scene is not recoverable.
Digital video systems use a process called compression which reduces the file size of high quality digital video and can be burned and backed up onto a CD Rom right in the DVR of the CCTV system. Once these files have been identified and isolated, they can be kept forever until deleted.
I have worked as a video forensic expert on cases where analog video was entered as evidence on time lapse VHS tape that has been recycled many times. The examination and authentication process is much different and more difficult for analog that it is for digital. I am expected to produce a high quality image of the crime for the court from a worn out pixilated low resolution analog tape.
When you factor how much it could cost to recover from the crime, pay a forensic expert to try and recover an image, purchasing a digital CCTV system is a much better investment and will produce far better forensic results.
Once a crime has been committed and caught on a digital recording device (DVR), a back up digital video can immediately be made of the crime using digital video technology. This back up, often called "bookmarking" or "Alarm File", is immediately taken out of the normal refresh cue and stored in a safe area for further forensic examination. What could a court do with an analog video surveillance tape? Make copies for all parties with generation loss? Factor in the video tape has been used for 18 months on a one-month recycle process? Try to lift a frame of video off the tape and compare it to a frame of digital video?
There is no comparison. The digital video proves time and time again a much clearer image.
Here are some suggested maintenance tips for both Analog and Digital CCTV security systems:
Clean your camera lenses and weather proof housings monthly. Outdoor cameras and weatherproof housings can become especially dirty and be moved by birds, weather and other unexpected elements. Housings have seals that can become worn out and break to let in vapor that can blur video images.
Test your digital or analog recorder monthly to assure all cameras look good and are pointed at the appropriate areas and replace any poorly functioning cameras or recording equipment. Clean the tape heads of your analog video record deck with a head cleaner that can be purchased from Radio Shack or online from many vendors that still carry analog head cleaning tapes. In addition, demagnetize your analog video recorder tape heads. This will remove magnetic build up that can cause poor record quality.
Defragment your digital video recorder regularly like you do with your computer so your digital system has the available space to function properly and provide a clear, clean image.
Next time you walk down the street and see a camera on top of a light pole, or visit a business and see the cameras on the wall, feel good about them because they have the potential of saving you some time when traffic becomes congested. They can also save a life when a babys vital signs become out of range or deter crime when a crime might have been committed. Now I hope you have a better understanding of the perplexity and complexity of CCTV systems. The Eye in the Sky has become a way of life. Look for them when you cruise the streets of any major city.