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CCTV SYSTEMS

CCTV SYSTEMS. Analog CCTV systems. CCTV SYSTEMS. Analog CCTV systems are still prevalent and in use today, “if it isn't broke don’t fix it” is the prevailing attitude with older systems . We will look at the many different components that make up these legacy CCTV systems.

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CCTV SYSTEMS

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  1. CCTV SYSTEMS Analog CCTV systems

  2. CCTV SYSTEMS • Analog CCTV systems are still prevalent and in use today, “if it isn't broke don’t fix it” is the prevailing attitude with older systems. • We will look at the many different components that make up these legacy CCTV systems. • As a technician working in the CCTV field it is inevitable that you will come across these types of systems.

  3. CCTV SYSTEMS • Here is a mid 60s CCTV console, notice the rotary phones.

  4. CCTV SYSTEMS • CCTV recording started with the reel to reel system which eventually became smaller and then in the late 70s VCRs (video cassette recorder) were introduced.

  5. CCTV SYSTEMS • Here is a basic analog CCTV system with a 4 channel multiplexer, a time lapse VCR and a monochrome CRT (cathode ray tube) monitor.

  6. CCTV SYSTEMS HERE IS AN OLDER CCTV SYSTEM WITH THE SIGNAL FLOW SHOWN: CAMERAS, MULTIPLEXER, DATE/TIME GENERATOR, VCR, SEQUENCER AND MONITOR.

  7. CCTV SYSTEMS • Current analog CCTV systems have few advantages beyond familiarity and cost. • Analog CCTV relies on time-lapse technology. Storage is limited to low-tech tapes, which make maintenance high and search capabilities low. • Analog has low integration potential and provides no opportunity for remote access.

  8. CCTV SYSTEMS • One of the more commonly known and recognized components of traditional CCTV systems are the cameras. • The first type of camera that was commercially used was a vacuum tube camera, similar to CRT monitors and TVs.

  9. CCTV SYSTEMS • The vacuum tube camera has generally been replaced by smaller solid state devices, but can still be found in some surveillance applications.

  10. CCTV SYSTEMS • Before the mid to late 1980s, a video camera tube or pickup tube was used for converting an optical image into an electrical signal. • Several types were in use from the 1930s to the 1980s. The most commercially successful of these tubes were various types of cathode ray tubes or "CRTs".

  11. CCTV SYSTEMS • Another key component in CCTV systems, especially older ones is the switcher. • A switcher allows the user to select which video source to observe.

  12. CCTV SYSTEMS • switchers are manual or sequencing. • A manual switcher allows the user to select a specific video source by pressing a button on the switch faceplate.

  13. CCTV SYSTEMS • A sequencing switcher changes from one video source to the next at timed intervals. • the time between switching intervals is usually every 5 to 10 seconds.

  14. CCTV SYSTEMS • The camera splitter is a device the allows the transmission of a single signal based on the synchronization of multiple signals.

  15. CCTV SYSTEMS • The splitter allows the user to view multiple camera views on a single screen. • The multiplexer is a replacement for the splitter, it combines the output of multiple cameras into a single composite video signal.

  16. CCTV SYSTEMS • multiplexers are available in increments of four, such as 4, 8, 12 or 16. • the four channel or sixteen channel are the most common. • Having more than 16 images on one screen renders the images unviewable.

  17. CCTV SYSTEMS • A date and time generator is a special type of device that superimposes the date and time onto a video signal. • Date and time generators are through-looped, meaning they do not alter the signal except to overlay date and time data.

  18. CCTV SYSTEMS • The signal is passed on to be displayed on the CCTV monitor.

  19. CCTV SYSTEMS • The date and time generator is less likely to be used in newer installations because date and time functions are often provided by newer DVR systems.

  20. CCTV SYSTEMS • In traditional CCTV systems, video is directed to a VCR (video cassette recorder), it is common to find banks of VCR’s managed by a VCR controller in large CCTV infrastructures.

  21. CCTV SYSTEMS • When using a cassette tape to record, you will generally use a T160 cassette tape for extended recording periods longer than 48 hours or a T120 cassette for shorter recording periods.

  22. CCTV SYSTEMS • Analog systems that utilize VCRs require an operator to change VCR tapes on a daily basis. • These tapes have to be archived for a certain length of time.

  23. CCTV SYSTEMS • VCRs used in CCTV systems utilize time lapse recording to extend the amount of video data that can be stored on a single VHS tape. • Time lapse recording means that each camera has a specific amount of time that is recorded. • The inputs are split across a timing interval and stored on a single recording.

  24. CCTV SYSTEMS • Using the extended recording option eliminates the need to change out cassette tapes often and is useful for an unattended recording session over a weekend or holiday period.

  25. CCTV SYSTEMS • Time lapse recording improves the amount of video data available for offline review.

  26. CCTV SYSTEMS • Film is often projected at 30 frames, meaning 30 images appear on the screen every second. • Since the playback speed and the recording speed are the same, the images onscreen appear to move at normal speed.

  27. CCTV SYSTEMS • Even if the camera is set to record at a slower speed, it will still be projected at 30 frames, thus the image on screen will appear to move faster.

  28. CCTV SYSTEMS • A video cassette recorder (VCR) controller allows the selective control of multiple video recorders. • A typical VCR controller provides several operations to control the actions of a VCR. • Traditional VCR’s provide 7 types of control that are supported by a VCR controller.

  29. CCTV SYSTEMS • The 7 types of controls supported by a VCR controller: • PLAY • STOP • FAST FORWARD • REVERSE • PAUSE • RECORD • EJECT

  30. CCTV SYSTEMS • A VCR controller will often support up to 64 VCR’s, multiple VCR controllers can be connected together in a daisy chain. • This allows control of several hundred recorders. • Alarm function support is also a typical feature of VCR controllers.

  31. CCTV SYSTEMS • A sequencer simply sequences through multiple images and presents them on a monitor at a specified time set by the operator (similar to a switcher). • An operator can sequence through a single image at a time or choose to sequence through four or more images at a time.

  32. CCTV SYSTEMS • The final component of a CCTV system is the monitor, in older systems the monitor has been a black and white CRT monitor.

  33. CCTV SYSTEMS • The typical black and white (mono chrome) monitor in legacy systems is a 19” CRT (cathode ray tube). • 9” monitors are also used but the smaller size is better suited for view of only 1 camera image though with the use of a quad switcher 4 images can be displayed on a 9”. • They’re called monitors because they do not contain any tuners like a normal TV.

  34. CCTV SYSTEMS • Will a regular TV work on a CCTV system? • Will a home VCR work with a CCTV system? Both devices would work however you would need an F to BNC adapter and of course just like the old video games you would have to set your TV and VCR to channel 3 or 4.

  35. CCTV SYSTEMS • Though color TV was prevalent in late 70s and through the 80s, CCTV systems still used black and white monitors. • Black and white monitors have traditionally provided much better resolution than color CRT monitors.

  36. CCTV SYSTEMS • A lot has change with the advent of technology and now the amount of equipment required in legacy CCTV systems has been incorporated into one unit, the DVR (digital video recorder). • In the next lecture we will look at the components that comprise a newer CCTV system, you’ll notice the list of components will be much shorter.

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