Chapter 1: Introduction To The Different Technologies
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Introduction to the Different Technologies
Video Surveillance Technologies
This guide is designed to educate you on basic system design and application. It is intended to help you make the right choices when designing a video surveillance system that will meet your expectations.
The first step is to understand the different technologies, their operations and benefits. The technologies range from 20 year old "Analog" to cutting edge "Digital". Your goals and what you want to accomplish will dictate which technology is right for you.
There are 3 types of surveillance technologies to consider. They are:
| Analog/Time Lapse Systems | PC Based Systems | Hardware Based Systems |
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There are a few acronyms which you may or may not know. Just for the record here are the ones that matter.
- BNC: Fitting used to connect coax cable to cameras and equipment.
- CCTV: Closed Circuit Television
- DVR: Digital Video Recorder
- Mux: A four, nine or sixteen camera analog video multiplexer.
Analog & Time Lapse Systems
Monitors & Multiplexers:
Monitors are analog TV monitors which can display one video signal. In other words they have one video input. They are nothing more than high resolution TV's. They range in size from 9" to 25" screens. They are the only way to view cameras with a time lapse recording system. With the addition of a multiplexer you can display 4, 9 or 16 video signals on one monitor. The multiplexer only provides the ability to view multiple cameras on one screen. It does not provide the ability to record.
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Time Lapse Recorders:
With the addition of a Time Lapse Recorder you can record the video signal from a single camera, or a multi-camera view from a multiplexer using a standard VCR tape. Time Lapse Recorders are available in several different versions. Some even record up to 960 hours on 1 VCR tape. But be aware, when you are recording 960 hours on one VCR tape you are only recording 1 frame or picture every 9 seconds. When programming a time lapse recorder we recommend you do not set the recording duration for more than 3 days or 72 hours. This will allow the minimum amount of tape changing and still record enough frames to make the recording useful. This also allows you to record over a weekend without changing the tape. Three days of recording on one tape records 1.5 frames or pictures per second. Not great, but not bad considering this is a 20 year old technology.
| Time Lapse Recorder | Standard VCR Tape |
|---|---|
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Playback:
If a video is recorded in time lapse mode you must use a time lapse recorder for playback. The standard VCR's we all have in our homes can not process the time lapse format and will not provide a useful playback.
Tapes:
Time Lapse Recorders use standard 2 hour VCR tapes. Always make sure you buy only the highest quality tapes. You should also have 10-12 tapes which are rotated in order. For example, if the recorder is set to 72 hour recording or 3 days, the tapes would store 30+ days of video. Changing the tapes also increase the life of the recorder and the tapes.
Analog/Time Lapse System Wiring:
The video signal from each camera (usually transmitted with RG59 coax cable and BNC twist on fittings) are plugged into the multiplexer. One coax cable is connected from the multiplexer to the video input on the TV monitor. A cable from the VCR (out) on the multiplexer is connected to the video (in) on the time lapse recorder. The system is programmed through the VCR's control panel. The monitor displays the programming options. On playback the recorder feeds the multiplexer the video in a special format that allows the multiplexer to provide the monitor a multi camera playback of the video which was recorded.
Analog / Time Lapse System Overview
Benefits:
- The systems are very reliable and no computer skills are required to operate them
Limitations:
- The video quality is considered fairly low compared to the digital systems
- The tape must be changed every three days or more
- The system requires regular cleaning and maintenance on the VCR
- The video quality degrades over time
- The systems do not have the ability for networking or remote viewing, i.e.: Internet & Dial-up
PC Based Digital Video Systems
A PC based DVR is comprised of a computer, video capture cards and custom written software. These systems are considered to be the best bang for the buck. They provide far better video recording clarity over Time Lapse and are easier to use and more flexible than Hardware DVR's. These units are available as kits which you install on your PC or as complete factory built recorders. Some factory models can be expanded as your needs grow, this is not the case with Time Lapse or Hardware DVR's.
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| 4 Camera Kit You provide the PC | 4 Camera PC/DVR | 16 Camera PC/DVR |
PC based DVR's are available in 4, 8, 12, 16 & 32 camera configurations:
PC based DVR's are programmed and operated with a keyboard and mouse. The video is recorded to the computers hard drive in a compressed format. This compression allows a huge amount of video to be stored. On average, a four camera system recording continuously should record at least 30 days of video for all 4 cameras on one single 80 gig hard drive. To double the recording days simply add another 80 gig hard drive.
These systems are designed so they do not require any scheduled action to maintain the video recordings. They record video to the hard drive until a certain amount of disk space is left. Then the system will delete the oldest clips and record the new video. This provides a continuous 30+ days of recordings at anytime.
The video is played back on the computer monitor or is saved to a floppy or burned to a CD. Some systems such as the EZWatch Pro system save the video so it can be played back on any PC with Windows Media Player (a real nice feature). You can also print or save a jpeg image of any specific video frame. These systems allow you to view and playback any combination of cameras without interrupting the systems recording process. Systems such as the EZWatch Pro Series offers the following features:
EZWatch Pro 4.0 HiDef Features
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Cable & Maximum Distance:
CCTV video coax cable is used to transmit the video from the camera to the front end. The maximum distance the cameras can be from the front end is a function of the cable rather than the camera itself. Using RG59 coax, you can extend the camera out to 600'. Using RG6 coax cable, you can extend it to 1000'.
Cameras:
Any professional grade camera that uses RCA or BNC connectors will work with these systems. Please see the "Cameras" section for detail on the various cameras available.
PC Based Digital Video Recorder Overview:
Benefits:
- High Resolution Recordings (640x480)
- Easy to use and flexible
- Saves time playing back video
- Stores large amounts of video or recording days
- Little or no maintenance
- Easy network integration
Limitations:
- The system runs on a PC with the Windows Operating System, users must have average computer skills
Hardware Based Digital Video Systems
A hardware based DVR is built specifically for video recording. These units are built from the ground up to perform one specific function, record video. While they do operate some software internally, the video processing is hardware based. It is this hardware which provides the live viewing and high resolution recording.
Hardware DVR's are available in two different versions. The older style looks much like a VCR but has a hard drive built into it to record the video. A TV or CCTV analog monitor is used to view the video. Their programming is much like a VCR and can be quite confusing. The basic rule with this type of unit is, the more features they have the harder they are to operate. Most are programmed with a hand held remote much like a regular VCR. They do provide high resolution digital recordings which match the quality of a PC based DVR.
Old Hardware Based DVR System
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A newer version of a hardware based DVR is quite innovative. A high quality PC monitor is equipped with the DVR hardware and a hard drive built right into the back of the monitor. The cameras, internet and other connections are located on the side of the monitor. This design saves space, reduces cost and completely eliminated the need for a PC or old style DVR case. These units are programmed and operated with the buttons on the front of the monitor or with a hand held remote. While they are considered easier to operate than the old style hardware DVR they do have some pros and cons. The technology right now only supports a maximum of 4 camera inputs and 1 audio input for recording, and if the monitor goes out the entire system may have to be replaced.
Hardware Based DVR Trend - Monitor/DVR Combined
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Hardware Based Digital Video Recorder Overview:
Benefits:
- High resolution digital video recordings (640x480)
- Live Camera Viewing, No delay.
- Programs with handheld remote, much like a VCR.
- Little or no maintenance
- Saves Space
Limitations:
- Harder to program and operate than PC based DVR's.
- Non-expandable
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